Nice APOD. And a very big picture, too, 1.05 MB.
I don't usually have that much to say about planetary nebulas, but this closeup is my favorite picture of the Helix Nebula:
We have been talking about pillars lately, like the Pillars of Creation in the Eagle Nebula. Well, the filaments along the inner rim of the Helix Nebula are a kind of pillars of their own! And just like other pillars, they have been sculpted by the harsh ultraviolet light and strong stellar wind of a hot star. The difference is that the Pillars of Creation have been sculpted by big, massive O-type stars which shine due to furious fusion processes, whereas the cometary filaments of the Helix Nebula have been sculpted by a tiny planetary nebula central star, which shines because it is rapidly shrinking and exposing its extremely hot innards.
And the tiny but incredibly hot central star of a planetary nebula is making its cast-off outer layers glow and fluoresce in the process, and creating those cometary fingers pointing at the central star.
Oh, and... just because I was speaking of Sirius (and its white dwarf), I can't keep this from you. Why is Sirius some 22 times brighter than the Sun in visible light, even though it's not that much bigger? It's because its surface brightness is so much higher than the Sun's. Just look at this picture:
Wowzers!![:shock:]( "Shocked")
Ann
NGC 7293: The Helix Nebula. Image Credit & Copyright: Patrick Winkler
I don't usually have that much to say about planetary nebulas, but this closeup is my favorite picture of the Helix Nebula:
We have been talking about pillars lately, like the Pillars of Creation in the Eagle Nebula. Well, the filaments along the inner rim of the Helix Nebula are a kind of pillars of their own! And just like other pillars, they have been sculpted by the harsh ultraviolet light and strong stellar wind of a hot star. The difference is that the Pillars of Creation have been sculpted by big, massive O-type stars which shine due to furious fusion processes, whereas the cometary filaments of the Helix Nebula have been sculpted by a tiny planetary nebula central star, which shines because it is rapidly shrinking and exposing its extremely hot innards.
And the tiny but incredibly hot central star of a planetary nebula is making its cast-off outer layers glow and fluoresce in the process, and creating those cometary fingers pointing at the central star.
Oh, and... just because I was speaking of Sirius (and its white dwarf), I can't keep this from you. Why is Sirius some 22 times brighter than the Sun in visible light, even though it's not that much bigger? It's because its surface brightness is so much higher than the Sun's. Just look at this picture:
Wowzers!
Ann
Statistics: Posted by Ann — Thu Oct 24, 2024 5:27 am — Replies 1 — Views 46