(via APOD: 2012 August 31 - Halo of the Cat’s Eye)
Image Credit & Copyright: Don Goldman
What? More Cat’s Eye? Yeah. You know why? Because that whole other picture…is the small dense bit in the middle of this one.
This is a 6-light-year-wide bubble of gas expelled from the system earlier in the end-life of the system. It is very faint, but has been boosted in this shot with a set of narrow-band filters to capture the ionized gas. Blue-green is twice ionized oxygen while hydrogen and nitrogen are in red. It’s overlaid on a background of broadband data to show the overall starfield.
While the inner, more visible planetary nebula phase of stellar evolution lasts about 10,000 years, astronomers have placed the age of the outer filaments at around 50-90,000 years.

(via APOD: 2012 August 31 - Halo of the Cat’s Eye)

Image Credit & Copyright: Don Goldman

What? More Cat’s Eye? Yeah. You know why? Because that whole other picture…is the small dense bit in the middle of this one.

This is a 6-light-year-wide bubble of gas expelled from the system earlier in the end-life of the system. It is very faint, but has been boosted in this shot with a set of narrow-band filters to capture the ionized gas. Blue-green is twice ionized oxygen while hydrogen and nitrogen are in red. It’s overlaid on a background of broadband data to show the overall starfield.

While the inner, more visible planetary nebula phase of stellar evolution lasts about 10,000 years, astronomers have placed the age of the outer filaments at around 50-90,000 years.

(via APOD: 2012 August 26 - The Cat’s Eye Nebula)
A classic shot from Hubble, the Cat’s Eye Nebula provides an interesting visual feast. The surrounding gas and dust clouds form more complex shapes than are usually found in a so-called planetary nebula. (Yeah, misleading name, but astronomers love to hold onto old designations. Messier’s 103 objects get to keep their names, for instance.)
It is suspected that the bright object in the center is actually a binary system, both stars of which, I suppose, may be undergoing their final stages of stellar evolution, throwing off gas in expanding shells, and then generating more radiation that catches up with the gas and illuminates it.
Image Credit: J. P. Harrington (U. Maryland) & K. J. Borkowski (NCSU) HST, NASA

(via APOD: 2012 August 26 - The Cat’s Eye Nebula)

A classic shot from Hubble, the Cat’s Eye Nebula provides an interesting visual feast. The surrounding gas and dust clouds form more complex shapes than are usually found in a so-called planetary nebula. (Yeah, misleading name, but astronomers love to hold onto old designations. Messier’s 103 objects get to keep their names, for instance.)

It is suspected that the bright object in the center is actually a binary system, both stars of which, I suppose, may be undergoing their final stages of stellar evolution, throwing off gas in expanding shells, and then generating more radiation that catches up with the gas and illuminates it.

Image Credit: J. P. Harrington (U. Maryland) & K. J. Borkowski (NCSUHSTNASA

(via APOD: 2012 August 16 - NGC 6888: The Crescent Nebula)
Image Credit & Copyright: J-P Metsävainio (Astro Anarchy)
The Crescent Nebula is born of the dying actions of a Wolf-Rayet star (WR 136) in Cygnus, the swan. As a star begins to die, it starts shedding matter as the nuclear reactions shut down temporarily, then start-up again as gravity provides enough pressure for the next set of fusion reactions. This creates a series of dust and gas clouds spreading out from the star, and then a bunch of stellar winds and radiation coming off the star again and interacting with the ejected material. This “catching up” of the radiation with the matter is what creates the wispy complex structure of this nebula.
Its next step will be somewhat more definite and final. As the star builds up to more complicated atomic structures in the fusion reactions, it will, at some point jump from fusing carbon atoms to fusing iron, at which point a big problem occurs. Fusing iron actually saps energy from the process, leading to a cataclysmic shutdown of the fusion reactions…with a bunch of really hot carbon around an iron core, which suddenly isn’t providing any outward pressure.
Click.
Boom.
Carbon-detonation supernova, Type Ia, the brightest nova events in the sky. As all that carbon collapses in the gravity, it suddenly ignites in one last burst of fusion, throwing off everything but the iron core.
In case you were wondering what it looks like when a WR star’s stellar wind catches up with the ejected red-giant shell in x-rays, Chandra’s got you covered:

Credit: X-ray: NASA/UIUC/Y. Chu & R. Gruendl et al. Optical: SDSU/MLO/Y. Chu et al.

(via APOD: 2012 August 16 - NGC 6888: The Crescent Nebula)

Image Credit & CopyrightJ-P Metsävainio (Astro Anarchy)

The Crescent Nebula is born of the dying actions of a Wolf-Rayet star (WR 136) in Cygnus, the swan. As a star begins to die, it starts shedding matter as the nuclear reactions shut down temporarily, then start-up again as gravity provides enough pressure for the next set of fusion reactions. This creates a series of dust and gas clouds spreading out from the star, and then a bunch of stellar winds and radiation coming off the star again and interacting with the ejected material. This “catching up” of the radiation with the matter is what creates the wispy complex structure of this nebula.

Its next step will be somewhat more definite and final. As the star builds up to more complicated atomic structures in the fusion reactions, it will, at some point jump from fusing carbon atoms to fusing iron, at which point a big problem occurs. Fusing iron actually saps energy from the process, leading to a cataclysmic shutdown of the fusion reactions…with a bunch of really hot carbon around an iron core, which suddenly isn’t providing any outward pressure.

Click.

Boom.

Carbon-detonation supernova, Type Ia, the brightest nova events in the sky. As all that carbon collapses in the gravity, it suddenly ignites in one last burst of fusion, throwing off everything but the iron core.

In case you were wondering what it looks like when a WR star’s stellar wind catches up with the ejected red-giant shell in x-rays, Chandra’s got you covered:

Credit: X-ray: NASA/UIUC/Y. Chu & R. Gruendl et al. Optical: SDSU/MLO/Y. Chu et al.


(via Successful stars talk dead stars | Bad Astronomy | Discover Magazine)

Samwise Gamgee and Zaboo stop by the Spitzer Space Telescope offices to talk about star death. OK, OK, so it’s actually Sean Astin and Sandeep Parikh, because, y’know, real people here, but I love these videos. (I think I blogged the earlier one with Felicia Day talking about galaxies colliding, yes?)

Also, I love the punny name for these vlogs: “IRrelevant Astronomy”. (Get it? Because Spitzer is an infrared space telescope! Hah!)

(via APOD: 2011 September 1 - M27: Not a Comet)
M27, the Dumbbell Nebula, is the 27th object in Messier’s famous list of “things that are not comets.” It’s a gaseous emission nebula, a type of planetary nebula that is the result of a Sun-like star beginning its death-throes. First, it ejects the outer layers off into space as particle, then, the newly denser core gives off a ton of ultraviolet radiation, lighting up the particles that it just shot out. Thus, you get this ghostly halo effect.
This particular image is a massive composite from wideband and narrowband imaging with filters for sulfur, hydrogen, and oxygen.

(via APOD: 2011 September 1 - M27: Not a Comet)

M27, the Dumbbell Nebula, is the 27th object in Messier’s famous list of “things that are not comets.” It’s a gaseous emission nebula, a type of planetary nebula that is the result of a Sun-like star beginning its death-throes. First, it ejects the outer layers off into space as particle, then, the newly denser core gives off a ton of ultraviolet radiation, lighting up the particles that it just shot out. Thus, you get this ghostly halo effect.

This particular image is a massive composite from wideband and narrowband imaging with filters for sulfur, hydrogen, and oxygen.

(via Hubble sees a gaseous necklace 13 trillion km across | Bad Astronomy | Discover Magazine)
This is what happens when the larger of a binary system absorbs the smaller. It suddenly throws off some mass (outer ring) and then ends up getting super-hot from the extra spinning throwing out another sudden expansion of gasses (inner ring). Of course, as the faster inner ring moves outward and collides with the slower outer ring, you get this lovely image of the Necklace Nebula. That whole structure of star and gases (hydrogen is green, oxygen is blue, nitrogen is red) is 13 trillion kilometers across.
Note the light red blobs away to the upper right and lower left. That’s where the faster expanding gasses, constricted by the slower gas along the disc, are being blown out along the vertical axis. As they collide with interstellar matter away from the nebula, they get compressed and we see those little red bits. If this had been a gigantic explosion like Supernova 1987A, those would be more obvious as part of an hourglass nebula.

(via Hubble sees a gaseous necklace 13 trillion km across | Bad Astronomy | Discover Magazine)

This is what happens when the larger of a binary system absorbs the smaller. It suddenly throws off some mass (outer ring) and then ends up getting super-hot from the extra spinning throwing out another sudden expansion of gasses (inner ring). Of course, as the faster inner ring moves outward and collides with the slower outer ring, you get this lovely image of the Necklace Nebula. That whole structure of star and gases (hydrogen is green, oxygen is blue, nitrogen is red) is 13 trillion kilometers across.

Note the light red blobs away to the upper right and lower left. That’s where the faster expanding gasses, constricted by the slower gas along the disc, are being blown out along the vertical axis. As they collide with interstellar matter away from the nebula, they get compressed and we see those little red bits. If this had been a gigantic explosion like Supernova 1987A, those would be more obvious as part of an hourglass nebula.