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Post Info TOPIC: SN2003gd


L

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RE: SN2003gd
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SN 2003gd was a type II-P supernova occurring in the spiral galaxy Messier 74 in the constellation Pisces. SN 2003gd was discovered on 12 June 2003 by Robert Evans, using a 0.31m reflector, and its discovery was confirmed on 13 June 2003 by R. H. McNaught using the 1.0m telescope at the Siding Spring Observatory.
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Supernova 2003gd
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Title: A Spitzer Space Telescope Study of SN 2003gd: Still No Direct Evidence that Core-Collapse Supernovae are Major Dust Factories
Authors: W. P. S. Meikle (1), S. Mattila (2), A. Pastorello (2), C. L. Gerardy (1), R. Kotak (2), J. Sollerman (3), S. D. van Dyk (4), D. Farrah (5), A. V. Filippenko (6), P. Höflich (7) P. Lundqvist (8), M. Pozzo (9), J. C. Wheeler (10) ((1) Imperial College London, (2) Queen's University Belfast, (3) University of Copenhagen, (4) Spitzer Science Center/Caltech (5) Cornell University, (6) University of California, Berkeley, (7) Florida State University (8) Stockholm University (9) University College London (10) The University of Texas at Austin)

We present a new, detailed analysis of late-time mid-infrared (IR) observations of the Type II-P supernova (SN) 2003gd. At about 16 months after the explosion, the mid-IR flux is consistent with emission from 4 x 10^(-5) M(solar) of newly condensed dust in the ejecta. At 22 months emission from point-like sources close to the SN position was detected at 8 microns and 24 microns. By 42 months the 24 micron flux had faded. Considerations of luminosity and source size rule out the ejecta of SN 2003gd as the main origin of the emission at 22 months. A possible alternative explanation for the emission at this later epoch is an IR echo from pre-existing circumstellar or interstellar dust. We conclude that, contrary to the claim of Sugerman et al. (2006, Science, 313, 196), the mid-IR emission from SN 2003gd does not support the presence of 0.02 M(solar) of newly formed dust in the ejecta. There is, as yet, no direct evidence that core-collapse supernovae are major dust factories.

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SN2003gd
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When the universe was only 700 million years old, some of its galaxies were already filled with lots of dust. But where did all of this dust come from? Astronomers using NASA's Spitzer Space Telescope think they may have found the source in type II supernovae, the violent explosions of the universe's most massive stars.

Cosmic dust is an important component of galaxies, stars, planets, and even life. Until recently, astronomers knew of only two places where dust formed: in the outflows of old sun-like stars that are billions of years old, and in space through the slow condensation of molecules. The problem with these two scenarios is that neither explains how the universe got so dusty only a few hundred million years after its birth. Astronomers have theorised that the missing dust might be produced in supernova explosions, but evidence for this has been hard to find.

Using the space-based Spitzer and Hubble Space Telescopes and the ground-based Gemini North Telescope atop Mauna Kea in Hawaii, Dr. Ben Sugerman of the Space Telescope Science Institute in Baltimore, Md. and his colleagues found a significant amount of heated dust in the remains of a massive star called supernova SN 2003gd. The supernova remnant is located approximately 30 million light-years away in the spiral galaxy M74.

Position (2000): RA: 01h36m42.65s Dec: 15d44m19.90s

Stars like the progenitor of supernova SN 2003gd have relatively short lives of just tens of millions of years. Since Sugerman's work shows supernovae produce copious amounts of dust, he believes the explosions could account for much of the dust in the early universe. His findings will be published in the June 8 issue of Science Express.

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