AAS #18: Two supernovae, no waiting

Contributed by
Jan 11, 2008
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This will be my last post from the actual physical location of the American Astronomical Society meeting; I've preloaded this entry to go up when I'll be on a plane winging it back to Boulder. I'll have some wrap-up stuff later (oh, just you wait) but since I'm heading back, I want to leave you with a really cool supernova remnant image. But I can't... so instead I'll leave you with two!

This object looks like a single nebula with two lobes, but new studies show that it's actually two separate object next to each other in the sky! This Gemini telescope image is of DEM L316, and it was always assumed to be what's called a bipolar nebula, a single object blowing bubbles of gas in opposite directions. However, it's now understood to be the expanding gas (called the remnant) from two separate exploding stars. The two stars blew up in the Large Magellanic Cloud, a small galaxy orbiting our Milky Way galaxy.

X-ray observations support the idea that these are two distinct objects: the X-ray emission indicates the chemical composition (the relative amount of iron, oxygen, and so on) are different in the two objects. In fact, it looks like these were two different types of supernovae altogether: the smaller lobe on the left is probably from the detonation of a white dwarf star, while the bigger one on the right is from the explosion of a star more like the Sun (though with substantially more mass -- the Sun can't go supernova). While both explosions probably happened around the same time (give or take a few tens of thousands of years), the stars were much different ages when they blew: the white dwarf was probably billions of years old, while the massive star was only a few million years old. The two stars were almost certainly totally unrelated to each other.

But through a cosmic coincidence, they both chose the same epoch of the Universe to light up the skies around them. And from our perspective they form a pretty, if somewhat lopsided, example of just how pretty death and destruction on an epic scale can be.