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Unfinished Business in Astronomy March 11, 2013

Posted by admin in : Astronomy and Astrophysics (ASTRO) , trackback Bookmark and Share

JC Holbrook

My master’s thesis in astronomy at San Diego State University focused on the electron temperature structure of the ionized gas of planetary nebulae. I focused on two planetary nebulae: NGC 6572 and NGC 6543. I observed using the one meter telescope at Mt. Laguna Observatory with a CCD detector. Planetary nebula are created as low mass stars throw off their atmosphere during their transition to white dwarfs. My observations and analysis of NGC 6572 revealed a knot of high temperature gas well away from but connected to the nebula. I could not explain what the knot was but submitted the paper in 1992 to ApJ with my advisor Theodore Daub. The referee reports insisted that we take spectra of the knot. JPL’s Trina Ray took spectra but we still could not identify the hot knot. The project was left behind as I left SDSU for NASA and a doctorate. However, a week ago I looked up images of NGC 6572 and got a big surprise! The Hubble Space Telescope image showed a far bigger nebula than what we could detect twenty years ago! Though it has been several years, looking at the contours I estimate that the hot spot I found, which at that point was at the edge of the nebula, I have marked with a circle in the second image. The structure of NGC 6572 is much more complicated than what I was working with and it is clear that some of the assumptions that went into the temperature would need to be updated to fully determine if the knot was indeed as hot as calculated. Certainly, some eager young astronomy student has already unraveled this bit of unfinished business!

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