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View Full Version : Discussion: Hubble Sees the Stingray Nebula



Fraser
2004-Sep-07, 06:28 PM
SUMMARY: The Hubble Space Telescope took this image of the Stingray Nebula, known to astronomers as Henize 1357. The dim star is surrounded by a halo of gas that was shed when the star became a red giant - a final stage in its life. As the nebula expanded away from the star, the remaining core got hotter and hotter, heating the gas up until it glowed. The Stingray Nebula is the youngest known planetary nebula; it wasn't visible in the sky just 25 years ago, when the gas around the central star hadn't heated up enough to glow.

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antoniseb
2004-Sep-07, 06:49 PM
I'd seen some speculation that the complex planetary nebulae are only formed by low-mass stars in close binaries, but I've never seen anything definitive about that. Generally, there has to be a reason that the cloud around these new white dwarfs are not radially symmetric. In this case it is hard to tell what's going on three-dimensionally, but it looks like there are four indented corners, and hot white bubble with a Balmer-alpha halo. Why isn't it a simple sphere, cylinder, or bipolar jet?

lswinford
2004-Sep-07, 09:11 PM
I'm wondering why we see so many red giants but not the nebulosities described in this article as being the result of entering the red giant phase. Then too, it did say that the nebulosity was not hot, and therefore not visible as now, before. But does that mean that they did not see the ejecta until after the recent shockwave heated it, or was it observable through other means (differing wavelengths, radio, etc.)?

Antoniseb, didn't we have some nebula discussion a while back where there were lop-sided ejections? Perhaps that discussion where the later shockwaves went through older ones.

It would be fun to see (from a safe distance and with suitable timing and patience) the star regaining its equilibrium and if it changes direction or speed after such disruptive events.

John L
2004-Sep-07, 09:12 PM
I read recently somewhere (but can't remember where) that they think the shape of all PN's is due to polar outflows from the dieing stars. The difference in the shapes of all of the PN's we see is actually due to our perspective on the event, not the particular shape it has taken. If it is completely bipolar, like the Ant Nebula, we are seeing along the equator of the star, and if its completely circular we are seeing it from above one of the poles. All of the more oddly shaped are from other angles between those two extremes caused by seeing bits of both halves and sometimes through one half into parts of the other.

I've read that the bi-polar nature might be caused by a close binary companion as Antoniseb suggested, but the article I read more recently suggested that this is directly related to the bi-polar outflows see in newly born stars.

Fraser
2004-Sep-08, 06:45 PM
Here's an older press release about this image when it was first taken:
http://hubblesite.org/newscenter/newsdesk/...s/1998/15/text/ (http://hubblesite.org/newscenter/newsdesk/archive/releases/1998/15/text/)

lswinford
2004-Sep-09, 08:09 PM
Thanks Fraser, that was good. Right on with what you noted John L. Good going.