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V838 Monocerotis


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#1    Waspie_Dwarf

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Posted 27 September 2006 - 01:06 AM

Echoing Infrared Across the Milky Way

Written by Linda Vu, Spitzer Science Center
September 26, 2006


For a brief moment in 2002, an obscure star called V838 Monocerotis (nicknamed V838 Mon by astronomers) suddenly became 600,000 times brighter than our Sun and temporarily was the brightest star in our Milky Way galaxy. Within a few months, it faded back into obscurity.

user posted image
V838 Monocerotis infrared light echo at
70 microns
NASA/JPL-Caltech


While the star has fascinated astronomers worldwide ever since, the source of the star's sudden outburst remains a mystery. Determined scientists remain hopeful they will learn more about the nature this stellar eruption by pointing a variety of telescopes at V838 Mon and its surrounding environment.

In one observation, NASA's Spitzer Space Telescope discovered an infrared light echo around V838 Mon. This is only the second infrared light echo ever to be resolved, and its detection has helped astronomers gain some valuable insights into the star's "personality."

An infrared light echo occurs when light waves blasted away from an erupting star heats up clumps of surrounding dust, and causes them to glow in the infrared. Visually, the light echo resembles growing ripples in a pond. As light propagates outward over time, more of the star's surrounding environment is illuminated.

By observing the infrared light echo around V838 Mon, astronomers were able to obtain a three-dimensional view of its surrounding dust cloud. Using this unique perspective, they set a lower limit on how much dust was surrounding the star.

"Initially we didn't realize that we could resolve an infrared light echo around this source. The fact that we did is a testament to Spitzer's superb sensitivity," said Dr. Kate Su, of the University of Arizona, Tuscon, Ariz. Su is one of the authors on a paper describing Spitzer's observations of V838 Mon. The paper has been accepted for publication in Astrophysical Journal Letters.

Prior to the Spitzer observations, some scientists pegged V838 Mon as a volatile star that has erupted frequently throughout its lifetime, spewing dust and other material into its surrounding environment with each violent outburst. They argued that the 2002 eruption was most likely one of these evolutionary, or developmental, outbursts that are part of the star's "growing pains."

However, by comparing the mass of the material illuminated in the infrared echo to the mass of the star, Su and her colleagues found that all the dust surrounding V838 Mon couldn't have come from the star. Thus, the 2002 outburst was most likely an anomaly, and the star is probably a lot more docile that previously believed.

"There is just too much material," said Dr. Karl Misselt, also of the University of Arizona and another author on the paper. "From previous studies we know that stars do lose some material as they evolve, or develop. However, only a very massive star -- more than 100 times the size of our Sun -- can lose that much material as part of its evolution, and this star isn't that massive."

Team members are continuing to use Spitzer data to study dust formation around V838 Mon. The star is located approximately 20,000 light-years away in the constellation Monoceros.


Source: NASA/CalTech - Spitzer- Happenings

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#2    RollingThunder06

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Posted 27 September 2006 - 05:17 AM

Not a science person but do know that whatever it was had alot of energy to spare in order to out do the sun.

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#3    Waspie_Dwarf

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Posted 26 October 2006 - 05:21 PM

Hubble's Latest Views of Light Echo from Star V838 Monocerotis

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These are the most recent NASA Hubble Space Telescope views of an unusual phenomenon in space called a light echo. Light from a star that erupted nearly five years ago continues propagating outward through a cloud of dust surrounding the star. The light reflects or "echoes" off the dust and then travels to Earth.

Because of the extra distance the scattered light travels, it reaches the Earth long after the light from the stellar outburst itself. Therefore, a light echo is an analog of a sound echo produced, for example, when sound from an Alpine yodeler echoes off of the surrounding mountainsides.

The echo comes from the unusual variable star V838 Monocerotis (V838 Mon), located 20,000 light-years away on the periphery of our Galaxy. In early 2002, V838 Mon increased in brightness temporarily to become 600,000 times brighter than our Sun. The reason for the eruption is still unclear.

Hubble has been observing the V838 Mon light echo since 2002. Each new observation of the light echo reveals a new and unique "thin-section" through the interstellar dust around the star. The new images of the light echo were taken with Hubble's Advanced Camera for Surveys in November 2005 (left) and September 2006 (right). Particularly noticeable in the images are numerous whorls and eddies in the interstellar dust, which are possibly produced by effects of magnetic fields.

Credit: NASA, ESA, and H. Bond (STScI)

Image Type: Astronomical
STScI-PRC2006-50


Source: HubbleSite - Newsdesk

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