Apologies......

OK.... Shouldn't have used the word supernova for our sun, but would I be right in saying that our sun would emit gases prior to it's final death/ red dwarf status?

Would this gas cloud be sufficint to destroy Earth?

No apology needed.



I'm with you now. As a sun like star ends it's red giant phase it often puffs off it's outer layers as a planetary nebula. I don't know if this event is violent enough to destroy a planet but in the case of the Earth that would be a little academic anyway. The Earth would either have been totally destroyed are reduced to a lifeless cinder many of millions of years earlier when the sun goes red giant and expands to many times its present size.

The European Southern Observatory (ESO) press release 08-07 is reproduced below:

ESO 08/07 - Science Release

24 February 2007
For Immediate Release

SN1987A's Twentieth Anniversary

Looking back at 20 Years of Observations of this Supernova with ESO telescopes

The unique supernova SN 1987A has been a bonanza for astrophysicists. It provided several observational 'firsts,' like the detection of neutrinos from an exploding star, the observation of the progenitor star on archival photographic plates, the signatures of a non-spherical explosion, the direct observation of the radioactive elements produced during the blast, observation of the formation of dust in the supernova, as well as the detection of circumstellar and interstellar material.


Image obtained with the ESO Schmidt Telescope of the Tarentula Nebula in the Large
Magellanic Cloud. The supernova is clearly visible as the very bright star in the middle
right. At the time of this image, the supernova was visible with the unaided eye. A
unique, 256 million pixel large image of the Tarantula Nebula, with SN1987A visible at
a later stage, is available on ESO PR Photo 50/06.

Today, it is exactly twenty years since the explosion of Supernova 1987A in the Large Magellanic Cloud was first observed, at a distance of 163,000 light-years. It was the first naked-eye supernova to be seen for 383 years. Few events in modern astronomy have met with such an enthusiastic response by the scientists and now, after 20 years, it continues to be an extremely exciting object that is further studied by astronomers around the world, in particular using ESO's telescopes.

When the first signs of Supernova 1987A, the first supernova of the year 1987, were noticed early on 24 February of that year, it was clear that this would be an unusual event. It was discovered by naked-eye and on a panoramic photographic plate taken with a 10-inch astrograph on Las Campanas in Chile by Oscar Duhalde and Ian Shelton, respectively. A few hours earlier, still on 23 February, two large underground detectors - in Japan and the USA - had registered the passage of high-energy neutrinos.

Since SN 1987A exploded in the Large Magellanic Cloud (LMC), it was only accessible to telescopes in the Southern Hemisphere, more particularly in Australia, South Africa, and South America. In Chile, ESO's observatory at La Silla with its armada of telescopes with sizes between 0.5 and 3.6-m, played an important role.


Light curve of the Supernova 1987A over a long period of time. Characteristic phases
in the evolution of the supernova are indicated.

Astronomers John Danziger and Patrice Bouchet, who were there at the time, recall: "When astronomers at La Silla arrived for the ritual afternoon tea at 4pm on the 24th February 1987 after the previous night's clear observing, they were greeted by the news that a supernova had been detected in the LMC the previous night. The tea-time ritual of groggy astronomers quietly sipping their tea was transformed, to be succeeded by flurries of excited but still to some extent uncoordinated planning. Nobody doubted for one second that the sky would be clear and there would be excitement galore in the days and nights ahead. And indeed there was!
A large observatory such as La Silla with its many telescopes can be considered like a naval fleet consisting of many ships from torpedo boats to cruisers and even aircraft carriers. La Silla had them all. All observers were encouraged to plan for observing SN1987A by whatever means at their disposal."

"Ironically, the supernova was too bright for the state-of-the-art 4m-class telescopes and some of them had to be stopped down, e.g. by half-closed telescope covers," says Jason Spyromilio (ESO). Some of the smaller telescopes took their chance. The 61-cm Bochum telescope on La Silla was used, on a nearly daily basis for more than a year, to measure optical spectroscopy with photometric accuracy. Since the LMC is circumpolar for most southern observatories, this also meant that there exists an uninterrupted record of the photometry and spectroscopy; else part of the peak phase, which lasted into May of 1987, would have been missed.

By July, the first conference on SN 1987A, organised by John Danziger, had already taken place at ESO in Garching to be followed by several others during that year and following years.

The optical light curve of SN 1987A was rather different from those of previously observed core-collapse supernovae. The old models of spherical explosions had to be revised. The spectroscopic evolution provided further evidence for asymmetries in the explosion. The 'Bochum event' was a rapid change in the line profile observed with the Bochum telescope on La Silla. It is the signature of a radioactive blob rising from the inner ejecta to the surface. "The picture emerging from the observations of the first several weeks was certainly more complex than what had ever been assumed of supernovae before," says Bruno Leibundgut (ESO).


Image of SN1987A obtained at different times in the near-infrared with ESO's telescopes. The two first images were taken with the 2.2-m
telescope at La Silla with the IRAC instrument, 2468 and 2865 days, respectively, after the explosion. The third image, obtained in October
2006 or 7170 days after the explosion, was taken with the NACO Adpative Optics instrument on Yepun, the fourth Unit Telescope of the
Very Large Telescope at Paranal. NACOcorrects for the blurring effect of the atmoshpere, allowing to obtain images almost as good as if
the telescope was placed in space.

The 1-m telescope at La Silla was also extensively used in daytime observing the supernova in the near- and mid-infrared for more than one year after the explosion. A clear excess emission developed in the near-infrared already 10 days after the explosion, the origin of which is still not fully understood. It was most probably due to circumstellar material that was lighted up by the explosion.

Dust condensation in the ejecta was discovered by spectroscopy about 500 days after the explosion. Macroscopic dust grains partially covered the ejecta, and most probably still do. They might explain why no compact object is seen at the location of the supernova.

In 1989, when the NTT came into operation, it imaged for the first time the circumstellar ring around SN 1987A. And, about three years after the explosion, NTT images revealed a circumstellar structure around SN 1987A which resembled the triangular hat which Napoleon wore. Napoleon's hat gave the first opportunity for a 3-dimensional view of SN 1987A.

"The existence of the ring presents an unsolved puzzle for SN 1987A," says Roberto Gilmozzi (ESO). "Even though it is not clear how to construct such a ring, it is likely that the star that exploded as SN 1987A had a companion."

When ESO's Very Large Telescope came into operation, the interest in the supernova had not faded away. Far from it! Observations were done with the VLT's many instruments, including FORS, UVES, ISAAC, and VISIR, to probe in more detail the surroundings of the explosion. More recently, adaptive optics instruments, which compensate for the blurring effect of the atmosphere, and so can see as if they were in space, have also been used. The NACO instrument has obtained amazing images of the rings, while SINFONI has been used to study the changes in the rings' appearances and the evolution of the spectral lines.

"SN 1987A was full of surprises and it remains unique amongst the known supernovae," says Leibundgut. "Not only was it the closest supernova for several centuries, it was also very peculiar, coming from a blue supergiant progenitor, with a circumstellar environment unlike any other supernova known. We will certainly continue to monitor its evolution for many years to come."

One goal will be to find the possible compact object that should have survived the dramatic explosion. But until now, this remnant has proved elusive.

More Information

Two articles in the forthcoming issue of ESO's Messenger discuss SN 1987A:
- "SN1987A at La Silla: The early days", by Ivan John Danziger and Patrice Bouchet.
- "Twenty Years of Supernova 1987A" by Claes Fransson, Roberto Gilmozzi, Per Gröningsson, Reinhard Hanuschik, Karina Kjær, Bruno Leibundgut, and Jason Spyromilio

Source: ESO Press Release pr-08-07

SN1987A's Twentieth Anniversary

Additional images

Photographic image of the Large Magellanic Cloud, before (left) and after (right) the explosion of SN1987A. The supernova is visible on the
right image just below the Tarantula nebula, in the upper part of the irregular galaxy.


Light Echoes around SN1987A.


Nebula around SN1987A.

Source: ESO Press Release pr-08-07 - Associated Images

The European Southern Observatory (ESO) press release 16-07 is reproduced below:

ESO 16/07 - Science Release

27 March 2007
For Immediate Release

The Purple Rose of Virgo

VLT Image of Bright Supernova in Spiral Galaxy

Until now NGC 5584 was just one galaxy among many others, located to the West of the Virgo Cluster. Known only as a number in galaxy surveys, its sheer beauty is now revealed in all its glory in a new VLT image. Since 1 March, this purple cosmic rose also holds the brightest stellar explosion of the year, known as SN 2007af.

Located about 75 million light years away towards the constellation Virgo ('the Virgin'), NGC 5584 is a galaxy slightly smaller than the Milky Way. It belongs, however, to the same category: both are barred spirals.

ESO PR Photo 16/07 is a colour-composite of the barred spiral galaxy NGC 5584. It is based on data collected by the Paranal Science Team with the FORS1 instrument on Kueyen, the second 8.2-m Unit Telescope of ESO's Very Large Telescope. The supernova SN 2007af is the bright object seen slightly below and to the right of the galaxy's centre. The galaxy and its bright supernova were observed on the nights of 16, 19 and 22 March 2007 through a B, V, R, H-alpha and OII filter. The total exposure time is about 28 minutes. The observers are Susana Randall, Claudio Melo and Swetlana Hubrig, and the day astronomer was Dominique Naef (all ESO). Henri Boffin (ESO) processed the data and made the colour-composite, and Haennes Heyer (ESO) made the final adjustments.

Spiral galaxies are composed of a 'bulge' and a flat disc. The bulge hosts old stars and usually a central supermassive black hole. Younger stars reside in the disc, forming the characteristic spiral structures from which the galaxies get their name. Barred spirals are crossed by a bright band of stars. In 2000, using ESO's Very Large Telescope, astronomers discovered the smallest, faintest, and most massive spirals (see ESO PR 12/00 and 25/00).

In this amazing new image of NGC 5584 two dominant spiral arms are clearly visible, while the others are deformed, probably due to interactions with other galaxies. Luminous patches are spread all over the disc, indicating that stars are being formed in this gigantic rose at a frantic pace.

Something even brighter, however, catches the eye in this picture. Any image taken before the end of February would not have shown the luminous spot located at the lower right of the galaxy's centre. As can be seen, the newly found object is much brighter than the centre of the galaxy itself. Its name? SN 2007af, the 32nd supernova discovered this year. Its presence signals the dramatic death of a star with a mass comparable to that of the Sun.

SN 2007af, the brightest supernova of the year (so far), was discovered on 1 March by the Japanese supernova hunter Koichi Itagaki. He pointed his 60-centimetre telescope towards the Virgo constellation and discovered something that was not there before: SN 2007af. When it was discovered, its brightness (apparent visible magnitude of 15.4) was about seven times fainter than that of its host galaxy, NGC 5584. It has since brightened by the same factor of 7, reaching an apparent magnitude of 13.3 and making it observable by many amateur astronomers with smaller telescopes.

Observations on 4 March with ESO's New Technology Telescope at La Silla revealed that this energetic explosion is a Type Ia supernova that was observed a few days before it reached its maximal luminosity. Matter from the doomed star is ejected with velocities above 15,000 km/s.

Astronomers are observing SN2007af with ESO's VLT, with the aim of studying the geometry of the material ejected by the supernova, and thereby better understanding the explosion mechanism (see also ESO 44/06).

A Type Ia supernova is thought to be the result of the explosion of a small and dense star - a white dwarf - inside a binary system. As its companion continuously spills matter onto the white dwarf, the white dwarf reaches a critical mass, leading to a fatal instability and the supernova.

Type Ia supernovae are apparently quite similar to one another. This gives them a very useful role as 'standard candles' that can be used to measure cosmic distances. Their peak brightness rivals that of their parent galaxy, hence qualifying them as prime cosmic yardsticks. Astronomers have exploited this fortunate circumstance to study the expansion history of our Universe.

However Type Ia supernovae are rare events: a galaxy like the Milky Way may host a Type Ia supernova on average only every 400 years. Even so, SN 2007af is not the only brilliant detonation recently recorded in NGC 5584. Furthermore, it seems that Japanese amateur astronomers have a special talent for catching supernova explosions in this purple spiral. Indeed, in 1996 Aoki Masakatsu identified SN 1996aq in NGC 5584, a difficult to classify supernova subject to a hot discussion due to its ambiguous nature.

Source: ESO Press Release pr-16-07

The UC Berkley press release is reproduced below:

By Robert Sanders, Media Relations | 04 April 2007

BERKELEY – Tens of millions of years ago, in a galaxy far, far away, a massive star suffered a nasty double whammy.

Signs of the first shock reached Earth on Oct. 20, 2004, when the star was observed letting loose an outburst so enormous and bright that Japanese amateur astronomer Koichi Itagaki initially mistook it for a supernova. The star survived for nearly two years, however, until on Oct. 11, 2006, professional and amateur astronomers witnessed it blowing itself to smithereens as Supernova (SN) 2006jc.

Two years in the death of a supergiant star

Drawings of the death of a star
(Credit: Aurore Simonnet/Sonoma State University,
NASA Education & Public Outreach)

"We have never observed a stellar outburst and then later seen the star explode," said University of California, Berkeley, astronomer Ryan Foley. His group studied the 2006 event with ground-based telescopes, including the 10-meter (32.8-foot) W. M. Keck telescopes in Hawaii. Narrow helium spectral lines showed that the supernova's blast wave ran into a slow-moving shell of material, presumably the progenitor's outer layers that were ejected just two years earlier. If the spectral lines had been caused by the supernova's fast-moving blast wave, the lines would have been much broader.

Another group, led by Stefan Immler of NASA's Goddard Space Flight Center in Greenbelt, Md., monitored SN 2006jc with NASA's Swift satellite and the Chandra X-ray Observatory. By observing how the supernova brightened in X-rays, a result of the blast wave slamming into the outburst ejecta, they could measure the amount of gas blown off in the 2004 outburst: about 0.01 solar mass, the equivalent of about 10 Jupiters.

"The beautiful aspect of our SN 2006jc observations is that although they were obtained in different parts of the electromagnetic spectrum, in the optical and in X-rays, they lead to the same conclusions," said Immler.

"This event was a complete surprise," added Alex Filippenko, leader of the UC Berkeley/Keck supernova group and a member of NASA's Swift satellite team. "It opens up a fascinating new window on how some kinds of stars die."

All the observations suggest that the supernova's blast wave took only a few weeks to reach the shell of material ejected two years earlier, which did not have time to drift very far from the star. As the wave smashed into the ejecta, it heated the gas to millions of degrees, hot enough to emit copious X-rays. The Swift satellite saw the supernova continue to brighten in X-rays for 100 days, something that has never been seen before in a supernova. All supernovae previously observed in X-rays have started off bright and then quickly faded to invisibility.

"You don't need a lot of mass in the ejecta to produce a lot of X-rays," noted Immler. Swift's ability to monitor the supernova's X-ray rise and decline over six months was crucial to the mass determination by Immler's team. But he added that Chandra's sharp resolution enabled his group to resolve the supernova from a bright X-ray source that appears in the field of view of Swift's X-ray telescope.

"We could not have made this measurement without Chandra," said Immler, who will submit his team's paper next week to the Astrophysical Journal. "The synergy between Swift's fast response and its ability to observe a supernova every day for a long period, and Chandra's high spatial resolution, is leading to a lot of interesting results."

Foley and his colleagues, whose paper appears in the March 10 Astrophysical Journal Letters, propose that the star recently transitioned from a Luminous Blue Variable (LBV) star to a Wolf-Rayet star. An LBV is a massive star in a brief but unstable phase of stellar evolution. Similar to the 2004 eruption, LBVs are prone to blow off large amounts of mass in outbursts so extreme that they are frequently mistaken for supernovae, events dubbed "supernova impostors." Wolf-Rayet stars are hot, highly evolved stars that have shed their outer envelopes.

A color image of SN2006jc (center) taken by the Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory on Oct. 13, 2006. The smudge to the upper left of the supernova is the visible part of the galaxy in which it occurred, UGC 4904, located 77 million light years from Earth.
(Mohan Ganeshalingam, Alex Filippenko & Weidong Li/UC Berkeley/KAIT/Lick Observatory)

Most astronomers did not expect that a massive star would explode so soon after a major outburst, or that a Wolf-Rayet star would produce such a luminous eruption, so SN 2006jc represents a puzzle for theorists.

"It challenges some aspects of our current model of stellar evolution," said Foley. "We really don't know what caused this star to have such a large eruption so soon before it went supernova."

"SN 2006jc provides us with an important clue that LBV-style eruptions may be related to the deaths of massive stars, perhaps more closely than we used to think," added coauthor and UC Berkeley astronomer Nathan Smith. "The fact that we have no well-established theory for what actually causes these outbursts is the elephant in the living room that nobody is talking about."

SN 2006jc occurred in galaxy UGC 4904, located 77 million light years from Earth in the constellation Lynx. The supernova explosion, a peculiar variant of a Type Ib, was first sighted by Itagaki, American amateur astronomer Tim Puckett and Italian amateur astronomer Roberto Gorelli.

Source: UC Berkley Press Release

In a galaxy far, far away, a massive star suffered a nasty double whammy. On Oct. 20, 2004, Japanese amateur astronomer Koichi Itagaki saw the star let loose an outburst so bright that it was initially mistaken for a supernova. The star survived, but for only two years. On Oct. 11, 2006, professional and amateur astronomers witnessed the star actually blowing itself to smithereens as Supernova 2006jc.


Image above: Swift Ultraviolet/Optical Telescope image of
Supernova 2006jc in the galaxy UGC 4904 in three filters.
Click image to enlarge.
Credit: NASA/Swift/S. Immler

"We have never observed a stellar outburst and then later seen the star explode," says University of California at Berkeley astronomer Ryan Foley. His group studied the event with ground-based telescopes, including the 10-meter (32.8-foot) Keck telescope in Hawaii. Narrow helium spectral lines showed that the supernova’s blast wave ran into a slow-moving shell of material, presumably the progenitor’s upper layers ejected just two years earlier. If the spectral lines had been caused by the supernova’s fast-moving blast wave, the lines would have been much broader.

Another group, led by Stefan Immler of NASA’s Goddard Space Flight Center, Greenbelt, Md., monitored SN 2006jc with NASA’s Swift satellite and Chandra X-ray Observatory. By observing how the supernova brightened in X-rays, a result of the blast wave slamming into the outburst ejecta, they could measure the amount of gas blown off in the 2004 outburst: about 0.01 solar mass.

"The beautiful aspect of SN 2006jc is that everything makes sense," says Immler. "Even though our two teams observed the supernova with different instruments and at different wavelengths, we have reached identical conclusions about what happened."


Image above: Swift X-ray Telescope image of Supernova 2006jc.
Click image to enlarge.
Credit: NASA/Swift/S. Immler

"This event was a complete surprise," adds Alex Filippenko, leader of the University of California at Berkeley/Keck supernova group, and a coauthor on both studies. "It opens up a fascinating new window on how some kinds of stars die."

All the observations suggest that the supernova’s blast wave took only a few hours to reach the shell of material ejected two years earlier, which did not have time to drift very far from the star. As the wave smashed into the ejecta, it heated the gas to millions of degrees, hot enough to emit copious X-rays. NASA’s Swift satellite saw the supernova continue to brighten in X-rays for 100 days, something that has never been seen before in a supernova. All supernovae previously observed in X-rays have started off bright and then quickly faded to invisibility.

"You don’t need a lot of mass in the ejecta to produce a lot of X-rays," notes Immler. Swift’s ability to monitor the supernova’s X-ray rise and decline over six months was crucial to his team’s mass determination. But he adds that Chandra’s sharp resolution enabled his group to resolve the supernova from a bright X-ray source that appears in the field of view of Swift’s X-ray Telescope.


Image above: Chandra X-ray Observatory image of Supernova 2006jc.
Click image to enlarge.
Credit: NASA/CXC/S. Immler

"We could not have made this measurement without Chandra," says Immler, who is submitting his team’s paper to the Astrophysical Journal. "The synergy between Swift's fast response and its ability to observe a supernova every day for a long period, and Chandra's high spatial resolution, is leading to a lot of interesting results."

Foley and his colleagues, whose paper appears in the March 10 Astrophysical Journal Letters, propose that the star recently transitioned from a Luminous Blue Variable (LBV) star to a Wolf-Rayet star. An LBV is a massive star in a brief but unstable phase of stellar evolution. Similar to the 2004 eruption, LBVs are prone to blow off large amounts of mass in outbursts so extreme that they are frequently mistaken for supernovae, events dubbed "supernova impostors." Wolf-Rayet stars are hot, highly evolved stars that have shed their outer envelopes.

Most astronomers did not expect that a massive star would explode so soon after a major outburst, or that a Wolf-Rayet star would produce such a luminous eruption, so SN 2006jc represents a challenge for theorists. "It disrupts our current model of stellar evolution," says Foley. "We really don't know what caused this star to have such a large eruption so soon before it went supernova."

"SN 2006jc provides us with an important clue that LBV-style eruptions may be related to the deaths of massive stars, perhaps more closely than we used to think," adds coauthor Nathan Smith, also of the University of California at Berkeley. "The fact that we have no well-established theory for what actually causes these outbursts is the elephant in the living room that nobody is talking about."

SN 2006jc occurred in galaxy UGC 4904, located 77 million light-years from Earth in the constellation Lynx. The supernova explosion, a peculiar variant of a Type Ib, was first sighted by Itagaki, American amateur astronomer Tim Puckett, and Italian amateur Roberto Gorelli.

Related Links:

+ NASA Swift mission site
+ Chandra X-ray Observatory site


Robert Naeye
Goddard Space Flight Cente

Source: NASA/GSFC - News

Edit; removed redundant quote. Why would you want to copy the entire text of the message that sits just above your reply?

3 years ago, a star that is 77 Million light-years from earth blew up sending x-rays at >10 million miles an hour. How many years before the x-rays reach earth?
In those 3 years, the x-rays travelled 365 X 24 X 10 miles = >87,600 miles = >29,200 mi. / year
77 million / 29,200 = 770,000 / 292 = 2636.9 years
So, it is going to take about 2,637 years for the x-rays generated from that explosion to reach the earth.
That's alright, if that was all we had to worry about. But, we have stars exploding all over the place. Plus we have solar flares. What to do?
You know, I think we just should sit back and enjoy the show!
I mean, what could be better. Just sit in the back yard in your lounge chair and think, 'what a wonderful world we live in.'

You haven't understood this at all have you?

The xrays HAVE reached Earth otherwise how would we know about them? The star blew up not 3 years ago, but 77 million years ago. The xrays from the explosion were DETECTED 3 years ago.

Your calculations are total nonsense. X-rays travel at the speed of light, more than 186,000 mils per second. It works out at over 670 million miles per hour.

Even if you had got that right you have then divided 77 million by 29,200. ??? the 77 million is not miles, it is light years. A light year is the distance light travels in on year (this should give you a bit of a clue that x-rays travelling at the speed of light will take 77 million years to travel 77 million lys).

One light year is over 5.87x10¹² (5,870,000,000,000) miles (that's 5.87 TRILLION).

If you are going to try to do the calculations it helps if you understand the problem.

Oh yeah, it certainly does really help to understand what a "light year" means before engaging in any calculations. Another good explanation of "light year". Might help to think about it this way, light is very, very, very (add a few more "very"s) fast and a Earth based year is a fairly long time period, therefore anything that is "light years" from Earth is one heck of a long, long, long (add a few more "long"s) way away.

The brightest stellar explosion ever recorded may be a long-sought new type of supernova, according to observations by NASA's Chandra X-ray Observatory and ground-based optical telescopes. This discovery indicates that violent explosions of extremely massive stars were relatively common in the early universe, and that a similar explosion may be ready to go off in our own galaxy.

Artist's illustration of supernova SN 2006gy "This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Nathan Smith of the University of California at Berkeley, who led a team of astronomers from California and the University of Texas in Austin. "That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We've never seen that before."


Image above: Artist's illustration of supernova SN 2006gy.
Credit: NASA/CXC/M.Weiss
+ Full caption/large image

Astronomers think many of the first generation of stars were this massive, and this new supernova may thus provide a rare glimpse of how the first stars died. It is unprecedented, however, to find such a massive star and witness its death. The discovery of the supernova, known as SN 2006gy, provides evidence that the death of such massive stars is fundamentally different from theoretical predictions.

"Of all exploding stars ever observed, this was the king," said Alex Filippenko, leader of the ground-based observations at the Lick Observatory at Mt. Hamilton, Calif., and the Keck Observatory in Mauna Kea, Hawaii. "We were astonished to see how bright it got, and how long it lasted."

The Chandra observation allowed the team to rule out the most likely alternative explanation for the supernova: that a white dwarf star with a mass only slightly higher than the sun exploded into a dense, hydrogen-rich environment. In that event, SN 2006gy should have been 1,000 times brighter in X-rays than what Chandra detected.

"This provides strong evidence that SN 2006gy was, in fact, the death of an extremely massive star," said Dave Pooley of the University of California at Berkeley, who led the Chandra observations.

The star that produced SN 2006gy apparently expelled a large amount of mass prior to exploding. This large mass loss is similar to that seen from Eta Carinae, a massive star in our galaxy, raising suspicion that Eta Carinae may be poised to explode as a supernova. Although SN 2006gy is intrinsically the brightest supernova ever, it is in the galaxy NGC 1260, some 240 million light years away. However, Eta Carinae is only about 7,500 light years away in our own Milky Way galaxy.

"We don't know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case," said Mario Livio of the Space Telescope Science Institute in Baltimore, who was not involved in the research. "Eta Carinae's explosion could be the best star-show in the history of modern civilization."

Supernovas usually occur when massive stars exhaust their fuel and collapse under their own gravity. In the case of SN 2006gy, astronomers think that a very different effect may have triggered the explosion. Under some conditions, the core of a massive star produces so much gamma ray radiation that some of the energy from the radiation converts into particle and anti-particle pairs. The resulting drop in energy causes the star to collapse under its own huge gravity.

After this violent collapse, runaway thermonuclear reactions ensue and the star explodes, spewing the remains into space. The SN 2006gy data suggest that spectacular supernovas from the first stars - rather than completely collapsing to a black hole as theorized - may be more common than previously believed.

"In terms of the effect on the early universe, there's a huge difference between these two possibilities," said Smith. "One pollutes the galaxy with large quantities of newly made elements and the other locks them up forever in a black hole."

The results from Smith and his colleagues will appear in The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass. Additional information and images are available at:

http://www.nasa.gov/chandra/

Source: NASA - Chandra - News

According to observations by NASA's Chandra X-ray Observatory and ground-based optical telescopes, the supernova SN 2006gy is the brightest and most energetic stellar explosion ever recorded and may be a long-sought new type of explosion. The top panel of this graphic is an artist's illustration that shows what SN 2006gy may have looked like if viewed at a close distance. The fireworks-like material in white shows the explosion of an extremely massive star. This debris is pushing back two lobes of cool, red gas that were expelled in a large eruption from the star before it exploded. The green, blue and yellow regions in these lobes shows where gas is being heated in a shock front as the explosion material crashes into it and pushes it backwards. Most of the optical light generated by the supernova is thought to come from debris that has been heated by radioactivity, but some likely comes from the shocked gas.

The bottom left panel is an infrared image, using adaptive optics at the Lick Observatory, of NGC 1260, the galaxy containing SN 2006gy. The dimmer source to the lower left in that panel is the center of NGC 1260, while the much brighter source to the upper right is SN 2006gy. The panel to the right shows Chandra's X-ray image of the same field of view, again showing the nucleus of NGC 1260 and SN 2006gy. The Chandra observation allowed astronomers to determine that SN 2006gy was indeed caused by the collapse of an extremely massive star, and not the most likely alternative explanation for the explosion, the destruction of a low-mass star. If the supernova was caused by a white dwarf star exploding into a dense, hydrogen-rich environment, SN 2006gy would have been about 1,000 times brighter in X-rays than what Chandra detected.

Source: Chandra - Photo Album

Written by Linda Vu, Spitzer Science Center
June 13, 2007


Supernova remnant N132D was found to
contain molecules that may one day form life.
NASA/JPL-Caltech/A. Tappe and J. Rho (SSC-Caltech)

Astronomers suspect the early Earth was a very harsh place. Temperatures were extreme, and the planet was constantly bombarded by cosmic debris. Many scientists believe that life's starting materials, or building blocks, must have been very resilient to have survived this tumultuous environment.

Now, NASA's Spitzer Space Telescope has learned, for the first time, that organic molecules believed to be among life's building blocks, called polycyclic aromatic hydrocarbons (PAHs), can survive another type of harsh setting, an explosion called a supernova. Supernovae are the violent deaths of the most massive stars. In death, these volatile objects blast tons of energetic waves into the cosmos, destroying much of the dust surrounding them.

The fact that PAHs can survive a supernova indicates that they are incredibly tough -- like cosmic cockroaches enduring a nuclear blast. Such durability might be further proof that these molecules are indeed among life's building blocks.

Dr. Achim Tappe of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass., used Spitzer's Infrared Spectrograph (IRS) instrument to detect abundant amounts of PAHs along the ridge of supernova remnant N132D. The remnant is located 163,000 light-years away in a neighboring galaxy called, the Large Magellanic Cloud.

"The fact that we see PAHs surviving this explosion illustrates their resilience," says Tappe.

These intriguing molecules are comprised of carbon and hydrogen atoms, and have been spotted inside comets, around star-forming regions and planet-forming disks. Since all life on Earth is carbon-based, astronomers suspect that some of Earth's original carbon might have come from these molecules -- possibly from comets that smacked into the young planet.

Astronomers say there is some evidence that a massive star exploded near our solar system as it was just beginning to form almost 5 billion years ago. If so, the PAHs that survived that blast might have helped seed life on our planet.

Tappe's paper was published in the December 10, 2006, issue of Astrophysical Journal.

Source: NASA/CalTech - Spitzer- Newsroom

A Supernova's Shockwaves


NASA/JPL-Caltech/A. Tappe and J. Rho (SSC-Caltech)

Supernovae are the explosive deaths of the universe's most massive stars. In death, these volatile creatures blast tons of energetic waves into the cosmos, destroying much of the dust surrounding them.

This false-color composite from NASA's Spitzer Space Telescope and NASA's Chandra X-ray Observatory shows the remnant of one such explosion. The remnant, called N132D, is the wispy pink shell of gas at the center of this image. The pinkish color reveals a clash between the explosion's high-energy shockwaves and surrounding dust grains.

In the background, small organic molecules called polycyclic aromatic hydrocarbons are shown as tints of green. The blue spots represent stars in our galaxy along this line of sight.

N132D is located 163,000 light-years away in a neighboring galaxy called, the Large Magellanic Cloud.

In this image, infrared light at 4.5 microns is mapped to blue, 8.0 microns to green and 24 microns to red. Broadband X-ray light is mapped purple. The infrared data were taken by Spitzer's Infrared Array Camera (IRAC) and Multiband Imaging Photometer (MIPS), while the X-ray data were captured by Chandra.

Source: NASA/CalTech - Spitzer- Newsroom

Eta Carinae is a mysterious, extremely bright and unstable star located a mere stone's throw - astronomically speaking - from Earth at a distance of only about 7,500 light years. The star is thought to be consuming its nuclear fuel at an incredible rate, while quickly drawing closer to its ultimate explosive demise. When Eta Carinae does explode, it will be a spectacular fireworks display seen from Earth, perhaps rivaling the moon in brilliance. Its fate has been foreshadowed by the recent discovery of SN2006gy, a supernova in a nearby galaxy that was the brightest stellar explosion ever seen. The erratic behavior of the star that later exploded as SN2006gy suggests that Eta Carinae may explode at any time.

Eta Carinae, a star between 100 and 150 times more massive than the Sun, is near a point of unstable equilibrium where the star's gravity is almost balanced by the outward pressure of the intense radiation generated in the nuclear furnace. This means that slight perturbations of the star might cause enormous ejections of matter from its surface. In the 1840s, Eta Carinae had a massive eruption by ejecting more than 10 times the mass of the sun, to briefly become the second brightest star in the sky. This explosion would have torn most other stars to pieces but somehow Eta Carinae survived.

The latest composite image shows the remnants of that titanic event with new data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The blue regions show the cool optical emission, detected by Hubble, from the dust and gas thrown off the star. This debris forms a bipolar shell around the star, which lies near the brightest point of the optical emission. This bipolar shell is itself surrounded by a ragged cloud of fainter material. An unusual jet points from the star to the upper left.

Chandra's data, depicted in orange and yellow, shows the X-ray emission produced as material thrown off Eta Carinae rams into nearby gas and dust, heating gas to temperatures in excess of a million degrees.



Animation of
Massive Star
Explosion

This hot shroud extends far beyond the cooler, optical nebula and represents the outer edge of the interaction region. The X-ray observations show that the ejected outer material is enriched by complex atoms, especially nitrogen, cooked inside the star's nuclear furnace and dredged up onto the stellar surface. The Chandra observations also show that the inner optical nebula glows faintly due to X-ray reflection. The X-rays reflected by the optical nebula come from very close to the star itself; these X-rays are generated by the high-speed collision of wind flowing from Eta Carinae's surface (moving at about 1 million miles per hour) with the wind of the companion star (which is about five times faster).

The companion is not directly visible in these images, but variability in X-rays in the regions close to the star signals the star's presence. Astronomers don't know exactly what role the companion has played in the evolution of Eta Carinae, or what role it will play in its future.

Source: Chandra - Photo Album

NASA's Chandra X-ray Observatory presents the latest image of Eta Carinae, a mysterious, extremely bright and unstable star located only about 7,500 light years from Earth. The star is thought to be consuming its nuclear fuel at an incredible rate, while quickly drawing closer to its ultimate explosive death.
(Credit: NASA/CXC/GSFC/M.Corcoran et al.)

This optical image of Adromeda was taken by the National Science A huge, billowing pair of gas and dust clouds is captured in this Hubble telescope picture of the supermassive star Eta Carinae. Even though Eta Carinae is 7,500 light years away, features 10 billion miles across (about the diameter of our solar system) can be distinguished. Eta Carinae suffered a giant outburst about 160 years ago, when it became one of the brightest stars in the southern sky. Though the star released as much visible light as a supernova explosion, it survived the outburst. The explosion produced two lobes and a large, thin equatorial disk, all moving outward at about 1.5 million miles per hour.
More information at Hubble
(Credit: NASA/STScI)

Source: Chandra - Photo Album

When stars are more massive than about 8 times the Sun, they end their lives in a spectacular explosion called a supernova. The outer layers of the star are hurtled out into space at thousands of miles an hour, leaving a debris field of gas and dust. Where the star once was located, a small, incredibly dense object called a neutron star is often found. While only 10 miles or so across, the tightly packed neutrons in such a star contain more mass than the entire Sun.

A new X-ray image shows the 2,000 year-old-remnant of such a cosmic explosion, known as RCW 103, which occurred about 10,000 light years from Earth. In Chandra's image, the colors of red, green, and blue are mapped to low, medium, and high-energy X-rays. At the center, the bright blue dot is likely the neutron star that astronomers believe formed when the star exploded. For several years astronomers have struggled to understand the behavior of the this object, which exhibits unusually large variations in its X-ray emission over a period of years. New evidence from Chandra implies that the neutron star near the center is rotating once every 6.7 hours, confirming recent work from XMM-Newton. This is much slower than a neutron star of its age should be spinning. One possible solution to this mystery is that the massive progenitor star to RCW 103 may not have exploded in isolation. Rather, a low-mass star that is too dim to see directly may be orbiting around the neutron star. Gas flowing from this unseen neighbor onto the neutron star might be powering its X-ray emission, and the interaction of the magnetic field of the two stars could have caused the neutron star to slow its rotation.

Source: Chandra - Photo Album

That's fascinating. It's very likely that RCW103 is a binary system. That would easily explain the slow rotation of the neutron star because losing mass to it's neighbor, or even the gravitational attraction between the two would cause the neutron star to lose rotational speed. The Earth and Moon have a similar relationship, with the moon stealing some of the earth's rotational velocity over time.

August 2, 2007 04:00 PM (EDT) (EDT)

News Release Number: STScI-2007-30

ABOUT THIS IMAGE:
NASA's Hubble Space Telescope photographed three magnificent sections of the Veil Nebula — the shattered remains of a supernova that exploded thousands of years ago. This series of images provides beautifully detailed views of the delicate, wispy structure resulting from this cosmic explosion. The Veil Nebula is one of the most spectacular supernova remnants in the sky. The entire shell spans about 3 degrees on the sky, corresponding to about 6 full moons.

The Veil Nebula is a prototypical middle-aged supernova remnant, and is an ideal laboratory for studying the physics of supernova remnants because of its unobscured location in our Galaxy, its relative closeness, and its large size. Also known as the Cygnus Loop, the Veil Nebula is located in the constellation of Cygnus, the Swan. It is about 1,500 light-years away from Earth.

Stars in our Galaxy, and in other galaxies, are born and then die. How long a star lives depends on how massive it is. The more massive the star, the shorter its life. When a star significantly more massive than our Sun runs out of fuel, it collapses and blows itself apart in a catastrophic supernova explosion. A supernova releases so much light that it can outshine a whole galaxy of stars put together. The exploding star sweeps out a huge bubble in its surroundings, fringed with actual stellar debris along with material swept up by the blast wave. This glowing, brightly colored shell of gas forms a nebula that astronomers call a "supernova remnant."

Such a remnant can remain visible long after the initial explosion fades away. Scientists estimate that the Veil supernova explosion occurred some 5,000 to 10,000 years ago.

The small regions captured in these Hubble images provide stunning close-ups of the Veil. Fascinating smoke-like wisps of gas are all that remain visible of what was once a star in our Milky Way Galaxy. The intertwined rope-like filaments of gas in the Veil Nebula result from the enormous amounts of energy released as the fast-moving debris from the explosion plows into its surroundings and creates shock fronts. These shocks, driven by debris moving at 600,000 kilometers per hour, heat the gas to millions of degrees. It is the subsequent cooling of this material that produces the brilliant glowing colors.

The Hubble images of the Veil Nebula are striking examples of how processes that take place hundreds of light-years away can sometimes resemble effects we see around us in our daily life. Although caused by different forces, the structures show similarities to the patterns formed by the interplay of light and shadow on the bottom of a swimming pool, rising smoke, or a ragged cirrus cloud.

Although only about one star per century in our Galaxy will end its life in this spectacular way, these explosions are responsible for making all chemical elements heavier than iron, as well as being the main producers of oxygen in the universe. Elements such as copper, mercury, gold, and lead are forged in these violent events. The expanding shells of supernova remnants mix with other clouds in the Milky Way and become the raw material for new generations of stars and planets. The chemical elements that constitute Earth, and indeed those of which we ourselves are made, were formed deep inside ancient stars and distributed by supernova explosions in nebulae like the one we see here.

The images were taken with Hubble's Wide Field Planetary Camera 2 (WFPC2) in November 1994 and August 1997. The color is produced by creating a composite of three different images. The colors indicate emission from different kinds of atoms excited by the shock: blue shows oxygen, green shows sulfur, and red shows hydrogen.

For additional information, contact:

Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4514
villard@stsci.edu

Keith Noll
Space Telescope Science Institute, Baltimore, Md.
410-338-1828
noll@stsci.edu

Lars Lindberg Christensen
Hubble/ESA, Garching, Germany
011-49-89-3200-6306
lars@eso.org

Object Names: Veil Nebula

Image Type: Astronomical

Credits : NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

Acknowledgment: J. Hester (Arizona State University)

Source: HubbleSite - Newsdesk

The Florida State University press release is reproduced below:

By Barry Ray

How is matter created? What happens when stars die? Is the universe shrinking, or is it expanding? For decades, scientists have been looking for answers to such "big picture" questions.


Type Ia supernovas

For the past few months, members of the department of physics at Florida State University have begun using a groundbreaking new research facility to conduct experiments that may help provide answers to just such questions.

RESOLUT—short for "REsonator SOLenoid with Upscale Transmission"—is the name of the facility, which is located within the John D. Fox Superconducting Accelerator Laboratory on the FSU campus. Over the past few months, FSU researchers have begun using RESOLUT to create very rare, extremely short-lived radioactive particles similar to those that form inside exploding stars—and then using the analytical data produced in the experiments as the basis for hypotheses about the behavior of matter and the physical properties governing the universe.

"We're doing experiments that replicate, in a very controlled manner, the explosions that take place in stars," said Ingo Wiedenhöver, an associate professor of physics at FSU who heads up the RESOLUT team. "This helps us understand the nuclear processes that occur in stars, the origin of elements and how stars explode."

Getting to this point has been an arduous process that began in 2002.

"After five years of proposals, fundraising, designing, building and carefully testing RESOLUT, we are very excited that it has now come online for experiments," said Samuel L. Tabor, a professor of physics at FSU who directs the John D. Fox Superconducting Accelerator Laboratory. "To my knowledge, only one other university in the entire United States has a facility similar to RESOLUT, so our students have a pretty unique opportunity to receive hands-on experience that they can get almost nowhere else."

Weighing some 16 tons and taking up more than 450 square feet of space along a wall inside the accelerator lab, RESOLUT enables researchers to fire a beam of atomic particles through a steel tube at speeds approaching 60 million miles per hour—roughly one-tenth the speed of light—and then to observe the nuclear reactions that occur.

"When the beam strikes a target, the collision produces very exotic nuclei that contain properties similar to those occurring in stars and star explosions," Wiedenhöver said. "But perhaps RESOLUT's greatest value as a scientific instrument is its function as a mass spectrometer—a device that allows us to identify and study the short-lived particles created during these miniature explosions."

Wiedenhöver currently is overseeing several experiments using RESOLUT that create, for a fraction of a second, a specific type of radioactive nuclei that are found only in a type of exploding star known as a Type Ia supernova.

"Type Ia supernovas result when a certain type of star known as a white dwarf reaches a critical mass and burns through its nuclear fuel so quickly that it suddenly explodes," Wiedenhöver said. "What makes these explosions so useful for astrophysicists is that they always release the same amount of energy, so their peak brightness is virtually the same in all instances. This uniform level of brightness makes Type Ia supernovas useful as a 'standard candle'—a gauge for measuring distances across the universe."

Such standard candles also have helped scientists to determine in recent years that the universe is expanding, not shrinking—and that the expansion is taking place at an ever-increasing rate.

"Observations of Type Ia supernovas have greatly increased science's understanding of the workings of the universe," Tabor said. "Now, with RESOLUT, we hope to learn even more about these gigantic nuclear explosions—all from the safety of a lab in a basement on the FSU campus."

Source: FSU press release

I am confused here.... I know that our Sun will not go supernova due to its mass, but will become a red dwarf.

My understand was that a red dwarf would cool down over time to become a white dwarf, but the above statement says it can then go supernova?

How could it go supernova with less mass than when it was a star?

I am assuming I am wrong along the line here.

Initially the sun will become a red giant. All stars are undergoing a balancing act between internal pressure which is trying to make them expand and gravity which is trying to make them contract. When the Sun finishes burning Hydrogen at it's core gravity will briefly win*. The Sun will begin to contract. This in turn will cause the temperature at the core to rises dramatically. Eventually the temperature rise to the point where helium can be burnt. The internal pressure increases dramatically and the sun expands to a point where there is a new equilibrium. This is the red giant phase.


White dwarves are actually hotter than red dwarves. Once a star like our sun has finished burning the Helium at it's core it will once again begin to collapse. As it does so it will puff of it's outer layers to form a planetary nebula. This leaves the hot core of the Sun exposed and this is the white dwarf stage. This hot, dense object will only be about the size of the earth. As it is no longer burning fuel it will fade in brightness until it is no longer visible. It will then become a black dwarf. A cold, dead object made mostly of carbon and hydrogen.

A red dwarf on the other hand, is a star less massive than the sun. Because they are so small they burn hydrogen very slowly and so never become very hot, hence the red colour. They also live a very long time before finishing their lives as black dwarves.



That's the general stuff out of the way. Your confusion comes about because there are several types of supernova. The type you are think of is a Type II. This is where a very large star has extinguished it's nuclear fuel. Where as the sun can only burn hydrogen and then it dies very large stars can go through several stages of fusion. They contract and expand several times until the core is burning sulphur to form iron. When the sulphur runs out the star collapses once again. However iron is very stable and does not readily undergo nuclear fusion. The temperature of the core rises and rises until it can take no more. At that point there is a cataclysmic explosion in the layers immediately above the core. The vast majority of the star is blown outwards in a giant explosion. The core is compressed and becomes either a super dense neutron star or a black hole. this is the type of supernova people are most familiar with.

The article is about Type Ia supernovae. These occur by a totally separate mechanism. There is a maximum size at which a white dwarf can support itself. This is known as the Chandrasekhar limit. It is a process I can't really explain, mostly because I don't really understand it (I need to do some more reading). However a white dwarf can not exceed about 1.4 solar masses. If it becomes more massive than that it can not maintain it's internal pressure to support itself and will collapse rapidly. Almost instantly all the matter in the star will undergo nuclear fusion resulting in a cataclysmic explosion... a Type Ia supernova. In most cases it is believed that Type Ia supernovae occur in close binary systems. The white dwarf "steals" material from the other star in the system, causing it's mass to rise until eventually it passes the Chandrasekhar limit.

There are also Type Ib and Ic, but these are very similar to Type II.


Your logic was essentially correct, but because Type II supernovae "get all the press" it seems that you were simply not aware of Type Ia.

At a distance of only 200,000 light years, the Small Magellanic Cloud (SMC) is one of the Milky Way's closest galactic neighbors. TWith its millions of stars, the SMC offers astronomers a chance to study phenomena across the stellar life cycle. In various regions of the SMC, massive stars and supernovas are creating expanding envelopes of dust and gas. Evidence for these structures is found in optical (red) and radio (green) data in this composite image.

Chandra X-ray Image of LHa115-N19 (3-color)

Astronomers used Chandra to peer into a region of the Small Magellanic Cloud. This area, known as LHa115-N19 or N19 for short, is filled with ionized hydrogen gas and it is where many massive stars are expelling dust and gas through stellar winds. When the X-ray data are combined with the other wavelengths, researchers find evidence for the formation of a so-called superbubble. Superbubbles are formed when smaller structures from individual stars and supernovas combine into one giant cavity.
(Credit: NASA/CXC/UIUC/R.Williams et al.)

Astronomers used Chandra to peer into one particular region of clouds of gas and plasma where stars are forming. This area, known as LHa115-N19 or N19 for short, is filled with ionized hydrogen gas and it is where many massive stars are expelling dust and gas through stellar winds. When the X-ray data (blue and purple) are combined with the other wavelengths, researchers find evidence for the formation of a so-called superbubble. Superbubbles are formed when smaller structures from individual stars and supernovas combine into one giant cavity.

The Chandra data show evidence for three supernova explosions in this relatively small region. Furthermore, the Chandra observations suggest that each of these supernova remnants were caused by a similar process: the collapse of a very massive star. There are hints that these stars were members of a so-called OB association, a group of stars that formed from the same interstellar cloud.

Source: Chandra - Photo Album

The European Southern Observatory (ESO) press release is reproduced below:

ESO 39/07 - Press Photo

3 September 2007
For Immediate Release

Stellar Firework in a Whirlwind

VLT Image of Supernova in Beautiful Spiral Galaxy NGC 1288

Stars do not like to be alone. Indeed, most stars are members of a binary system, in which two stars circle around each other in an apparently never-ending cosmic ballet. But sometimes, things can go wrong. When the dancing stars are too close to each other, one of them can start devouring its partner. If the vampire star is a white dwarf – a burned-out star that was once like our Sun – this greed can lead to a cosmic catastrophe: the white dwarf explodes as a Type Ia supernova.

In July 2006, ESO’s Very Large Telescope took images of such a stellar firework in the galaxy NGC 1288. The supernova - designated SN 2006dr - was at its peak brightness, shining as bright as the entire galaxy itself, bearing witness to the amount of energy released.


Colour-composite image of the Type Ia supernova SN 2006dr in the spiral galaxy NGC 1288, as observed with ESO's Very Large Telescope. It is based on images acquired through several filters (B, V, R, I and H-alpha) for a total exposure time of 5 minutes. The supernova is the bright object visible to the left of the centre of the galaxy. Many distant galaxies are also seen in the vicinity of NGC 1288, of which some are behind. The data were acquired by ESO's Paranal Science team. The final image was made by Henri Boffin (ESO).

NGC 1288 is a rather spectacular spiral galaxy, seen almost face-on and showing multiple spiral arms pirouetting around the centre. Bearing a strong resemblance to the beautiful spiral galaxy NGC 1232, it is located 200 million light-years away from our home Galaxy, the Milky Way. Two main arms emerge from the central regions and then progressively split into other arms when moving further away. A small bar of stars and gas runs across the centre of the galaxy.

The first images of NGC 1288, obtained during the commissioning period of the FORS instrument on ESO's VLT in 1998, were of such high quality that they have allowed astronomers [1] to carry out a quantitative analysis of the morphology of the galaxy. They found that NGC 1288 is most probably surrounded by a large dark matter halo. The appearance and number of spiral arms are indeed directly related to the amount of dark matter in the galaxy's halo.

The supernova was first spotted by amateur astronomer Berto Monard. On the night of 17 July 2006, Monard used his 30-cm telescope in the suburbs of Pretoria in South Africa and discovered the supernova as an apparent 'new star' close to the centre of NGC 1288, which was then designated SN 2006dr. The supernova reached magnitude 16, that is, it was about 10 000 times fainter than what the unaided eye can see.

Using spectra obtained with the Keck telescope on 26 July 2006, astronomers from the University of California found SN 2006dr to be a Type Ia supernova [2] that expelled material with speeds up to 10 000 km/s.
Notes

[1]: "Morphological structure and colors of NGC 1232 and NGC 1288" by C. Moellenhoff et al., A&A 352, L5 (1999) and "Quantitative interpretation of the morphology of NGC 1288" by B. Fuchs and C, Moellenhoff, A&A 352, L36 (1999)

[2]: Type Ia supernovae are a sub-class of supernovae that were historically classified as not showing the signature of hydrogen in their spectra. They are currently interpreted as the disruption of small, compact stars, called white dwarfs, which acquire matter from a companion star. A white dwarf represents the penultimate stage of a solar-type star. The nuclear reactor in its core has run out of fuel a long time ago and is now inactive. However, at some point the mounting weight of the accumulating material will have increased the pressure inside the white dwarf so much that the nuclear ashes in there will ignite and start burning into even heavier elements. This process very quickly becomes uncontrolled and the entire star is blown to pieces in a dramatic event.
Type Ia supernovae play a very useful role as cosmological distance indicators, allowing astronomers to study the expansion history of our Universe, leading to the conclusion that the Universe is expanding at an accelerating rate (see e.g. ESO PR 21/98)

Source: ESO Press Release pr-39-07

The McDonald Observatory, University of Texas at Austin press release is reproduced below:

10 October 2007

FORT DAVIS, Texas —Astronomer Robert Quimby has done it again. Found the most luminous supernova ever, that is.

Quimby discovered the current record holder, supernova 2006gy, last year as part of his Texas Supernova Search project. Now he announces that a supernova he discovered earlier in the project is actually twice as luminous. Using follow-up studies to pinpoint its distance, supernova 2005ap peaked at more than 100 billion times the brightness of the Sun. The result has been accepted for publication in the October 20 edition of The Astrophysical Journal Letters.

This supernova is a Type II, Quimby said, because it contains hydrogen. Most Type II supernovae are thought to result when the cores of massive stars, those seven to eight times or more heavy than the Sun, collapse under their own weight and trigger an explosion. This particular Type II is 300 times brighter than average, Quimby said, and lies in a dwarf galaxy in the constellation Coma Berenices, well behind the famous Coma cluster of galaxies.

Left: Sloan Digital Sky Survey (SDSS) image of the field where supernova 2005ap was found, showing four nearby galaxies (A, B, C, and D) in December 2004. Right: Hobby-Eberly Telescope (HET) image of the same field about 2.5 months later, showing supernova 2005ap. The supernova’s host galaxy is too distant to appear in either image.
Credit: SDSS, R. Quimby/McDonald Obs./UT-Austin

“It’s clearly not the same as 2006gy,” Quimby’s colleague and supernova expert J. Craig Wheeler of The University of Texas at Austin said. “It’s a puzzle.”

Quimby completed his Ph.D. under Wheeler’s supervision at Texas in May, and has just begun a post-doctoral appointment at Caltech. His Texas Supernova Search uses the 18-inch ROTSE-IIIb robotic telescope on McDonald Observatory’s Mount Fowlkes, a tiny neighbor to the giant 10-meter-class Hobby-Eberly Telescope (HET).


The Robotic Optical Transient Search Experiment has placed telescopes in four locations on Earth to cover the entire sky in search of gamma-ray bursts. One of these, ROTSE IIIb, is located at McDonald Observatory. In addition to its primary mission, the telescope is used for the Texas Supernova Search.
Credit: ROTSE Collaboration.

Quimby studied 2005ap with HET just a few days after its discovery. The results were intriguing, Quimby said. The supernova’s spectrum hinted at the presence of a highly shifted absorption line of oxygen III (an oxygen atom that has lost two of its electrons). Quimby knew that if the feature was oxygen III, then 2005ap was “possibly very far away and thus very luminous.”

Follow-up observations with the Keck Telescope in Hawaii by Quimby’s colleague Greg Aldering of Lawrence Berkeley National Lab not only confirmed Quimby’s HET detection of oxygen III, but added another, equally shifted element to the spectrum: magnesium.

Together, the studies confirmed 2005ap’s distance of 4.7 billion light-years. (In astronomical terms, this equates to a redshift of z = 0.2832.)

It was this distance measurement, combined with measurements of the supernova’s apparent brightness that allowed the calculation of its intrinsic brightness, or “luminosity,” and uncovered 2005ap as the most powerful supernova yet.

“Before 2006gy, I thought this should not be plausible,” Quimby said. “There I was finding my first supernovae — I was just happy to get anything. It turned out to be the most luminous supernova ever found.”

How is that Quimby has found the brightest supernova yet, twice in a row? “I’ve worked too damn hard for this to be luck,” he said.

Quimby explained, “I’m searching a huge volume of space, comparable to all previous nearby supernova surveys combined.” Also, Quimby will find supernovae that other studies ignore: he doesn’t filter out non-Type Ia supernovae, which is what many studies do that are searching for supernovae for cosmology studies, and he does search dwarf galaxies as well as galaxies with active black holes at their centers, which other studies avoid. Others also avoid supernovae near the cores of galaxies.



In fact, 2006gy was found in the core of a galaxy, and that galaxy has a weakly active central black hole, Wheeler said.

“There’s no question that [his results] have gotten everybody’s attention,” Wheeler said. The University of Michigan-run ROTSE collaboration, whose main mission is the search for gamma-ray bursts, has decided to expand the supernova search to its entire network. Its robotic telescopes in Australia, Turkey, and Namibia will soon join the unit at McDonald Observatory in this search. The Sloan Digital Sky Survey Supernova Search, for which the HET provides confirming spectra, is also reconsidering its search filters in response to these discoveries, Wheeler said.

The Hobby-Eberly Telescope is a joint project of The University of Texas at Austin, The Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München and Georg-August-Universität Göttingen.

— END —

Contact Information:

Dr. Robert Quimby
California Institute of Technology
626-395-5927; quimby@astro.caltech.edu

Dr. J. Craig Wheeler
The University of Texas at Austin
512-471-6407; wheel@astro.as.utexas.edu

Source: McDonald Observatory Press Release

CXC Release

Contacts:
Jennifer Morcone
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-7199)

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
(Phone: 617/496-7998)

For Release: October 17, 2007



A spectacular new image shows how complex a star's afterlife can be. By studying the details of this image made from a long observation by NASA's Chandra X-ray Observatory, astronomers can better understand how some stars die and disperse elements like oxygen into the next generation of stars and planets.

At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. The image shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen, other elements such as neon and silicon that were forged in the star before it exploded.

Hard X-ray Image of G292.0+1.8

When a massive star explodes like the one that produced G292.0+1.8, it creates a shell of hot gas that glows brightly in X-rays. Chandra is able to observe the stellar debris, revealing the dynamics of the explosion. With nearly six days of Chandra observing time devoted to studying G292.0+1.8, astronomers hope they can use this particular remnant to better understand the complicated details of such an explosion. This image shows the high-energy X-rays only (1.810-2.050 and 2.400-2.620 keV).
(Credit: NASA/CXC/Penn State/S.Park et al.)

"We are finding that, just like snowflakes, each supernova remnant is complicated and beautiful in its own way," said Sangwook Park of Penn State who led the work, released in conjunction with the "8 Years of Chandra" symposium in Huntsville, Ala.

The new, deep Chandra image - equaling nearly 6 days worth of observing time - shows an incredibly complex structure. Understanding the details of G292.0+1.8 is especially important because astronomers have considered it to be a "textbook" case of a supernova created by the death of a massive star.

Chandra X-ray Image of G292.0+1.8

A spectacular new image, made from a long observation by NASA's Chandra X-ray Observatory, shows how complex a star's afterlife can be. By studying the details of the supernova remnant, known as G292.0+1.8, astronomers can better understand how some stars die and disperse elements like oxygen into the next generation of stars and planets.
(Credit: NASA/CXC/Penn State/S.Park et al.)

By mapping the distribution of X-rays in different energy bands, the Chandra image traces the distribution of chemical elements ejected in the supernova. The results imply that the explosion was not symmetrical. For example, blue (silicon and sulfur) and green (magnesium) are seen strongly in the upper right, while yellow and orange (oxygen) dominate the lower left. These elements light up at different temperatures, indicating that the temperature is higher in the upper right portion of G292.0+1.8.

Slightly below and to the left of the center of G292.0+1.8 is a pulsar, a dense, rapidly rotating neutron star that remained behind after the original star exploded. Assuming that the pulsar was born at the center of the remnant, it is thought that recoil from the lopsided explosion may have kicked the pulsar in this direction.

Pulsar Wind Nebula in G292.0+1.8

Chandra's image of G292.0+1.8 shows remarkable complexity and structure in the debris field of this exploded star. Each color represents different elements such as oxygen, neon, magnesium, and silicon. The distribution of these elements gives astronomers clues about how the star exploded. The close-up zooms into the region around the dense core that remains of the star, seen in the highest-energy X-rays detected by Chandra.
(Credit: NASA/CXC/Penn State/S.Park et al.)

Surrounding the pulsar is a so-called pulsar wind nebula, a magnetized bubble of high-energy particles. The narrow, jet-like feature running from north to south in the image is likely parallel to the spin axis of the pulsar. This structure is most easily seen in high energy X-rays. In the case of G292.0+1.8, the spin direction and the kick direction do not appear to be aligned, in contrast to apparent spin-kick alignments in some other supernova remnants.

Another intriguing feature of this remnant is the bright equatorial belt of X-ray emission that extends across the center of the remnant. This structure is thought to have been created when the star - before it died - expelled material from around its equator via winds. The orientation of the equatorial belt suggests that the parent star maintained the same spin axis both before and after it exploded.

DSS Optical Image of G292.0+1.8

This Digitized Sky Survey optical image helps show the dramatic difference between what is seen in various wavelengths.
(Credit: Pal.Obs. DSS)

"The detection of the pulsar and its wind nebula confirms that the supernova that led to G292 produced a neutron star through the collapse of the core of a massive star," said coauthor John Hughes of Rutgers University, "The ability to study the asymmetry of the original explosion using X-ray images of the remnant gives us a powerful new technique for learning about these cataclysmic events."

These results will appear in an upcoming issue of The Astrophysical Journal Letters. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.
Additional information and images are available at:


Source: Chandra - Press Room

The Harvard-Smithsonian Center for Astrophysics press release is reproduced below:

Release No.: 2007-29
For Release: Wednesday, October 31, 2007

Cambridge, MA - Astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) have found that a supernova discovered last year was caused by two colliding white dwarf stars. The white dwarfs were siblings orbiting each other. They slowly spiraled inward until they merged, touching off a titanic explosion. CfA observations show the strongest evidence yet of what was, until now, a purely theoretical mechanism for creating a supernova.

"This finding shows that nature may be richer than we suspected, with more than one way to make a white dwarf explode," said Harvard graduate student and first author Malcolm Hicken.

The paper describing this discovery appeared in the November 1 issue of The Astrophysical Journal Letters.

This artist's conception shows two white dwarf stars spiraling in toward each other until they collide. A collision like this is believed to have spawned supernova 2006gz.
Credit: NASA/Dana Berry, Sky Works Digital

Supernova 2006gz, marked in this photo, shows the strongest evidence yet that it was caused by the merger of two white dwarfs. It was located in spiral galaxy IC 1277, located approximately 300 million light-years away in the constellation Hercules.
Credit: J.L. Prieto & M. Hicken (CfA)

Astronomers characterize an observed supernova based on whether its spectrum shows evidence of hydrogen (Type II) or not (Type I). In Type II, a massive, short-lived star undergoes core collapse and explodes. In the conventional picture for Type Ia, the most common supernovae lacking hydrogen, a white dwarf star collects gas from a companion star until it undergoes catastrophic nuclear fusion and blasts itself apart.

The new find, supernova 2006gz, was classified as a Type Ia due to the lack of hydrogen and other characteristics. However, an analysis combining CfA data with measurements from The Ohio State University suggested that SN 2006gz was unusual and deserved a closer look.

Most importantly, SN 2006gz showed the strongest spectral signature of unburned carbon ever seen. Merging white dwarfs are expected to have carbon outside their densest regions. The powerful explosion from the inside then should push off the outmost carbon-rich layers.

The spectrum of SN 2006gz also showed evidence for compressed layers of silicon. Silicon was created during the explosion and then compressed by a shock wave that rebounded from the surrounding layers of carbon and oxygen. Computer models for merging white dwarfs predict both the carbon and silicon spectral signatures.

Additionally, SN 2006gz was brighter than expected, indicating that its progenitor exceeded the 1.4 solar mass Chandrasekhar limit – the upper bound for a single white dwarf. Only one other potential example of a super-Chandrasekhar supernova has been seen: SN 2003fg. While observations of that event were suggestive, the data from SN 2006gz are much stronger.

"Our case is different. Although 2006gz is also extra bright, the chemistry we see, particularly unburned carbon, is well observed and very unusual," said Harvard astronomer Robert Kirshner, a member of the discovery team.

In addition to providing the first example of a new way to make supernovae, SN 2006gz holds implications for the field of cosmology. Type Ia supernovae typically have a narrow spread in brightness, which makes them useful as "standard candles" for calculating cosmic distances. It was the study of Type Ia supernovae that led to the discovery of dark energy, the mysterious force causing the expansion of the universe to accelerate.

If Type Ia supernovae are more varied than previously expected, then astronomers must be extra cautious when using them to study the cosmos.

"Supernova 2006gz stands out from normal Type Ia objects and wouldn’t be included in cosmology studies," commented Hicken. "But we have to be careful not to mistake a double white