APOD: The Ghosts of Gamma Cas (2023 Oct 28)

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APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by APOD Robot » Sat Oct 28, 2023 4:06 am

Image The Ghosts of Gamma Cas

Explanation: Gamma Cassiopeiae shines high in northern autumn evening skies. It's the brightest spiky star in this telescopic field of view toward the constellation Cassiopeia. Gamma Cas shares the ethereal-looking scene with ghostly interstellar clouds of gas and dust, IC 59 (top left) and IC 63. About 600 light-years distant, the clouds aren't actually ghosts. They are slowly disappearing though, eroding under the influence of energetic radiation from hot and luminous gamma Cas. Gamma Cas is physically located only 3 to 4 light-years from the nebulae. Slightly closer to gamma Cas, IC 63 is dominated by red H-alpha light emitted as hydrogen atoms ionized by the star's ultraviolet radiation recombine with electrons. Farther from the star, IC 59 shows proportionally less H-alpha emission but more of the characteristic blue tint of dust reflected star light. The cosmic stage spans over 1 degree or 10 light-years at the estimated distance of gamma Cas and friends.

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Ann
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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by Ann » Sat Oct 28, 2023 7:16 am

IC63_GruntzBax1024[1].jpg
The Ghosts of Gamma Cas.
Image Credit & Copyright: Guillaume Gruntz, Jean-François Bax

Nice!!! Lovely blue Gamma Cas is one of my favorite stars! :D

Gamma Cas is massive, sizzling, azure, brilliant and octuple!
Wikipedia wrote:

Together with its common-proper-motion companion, HD 5408, the system could contain a total of eight stars.
Gamma Cas is an eruptive variable that throws off mass along its equator.
Gamma Cassiopeiae is a rapidly spinning star with a projected rotational velocity of 472 km s−1, giving it a pronounced equatorial bulge. When combined with the star's high luminosity, the result is the ejection of matter that forms a hot circumstellar disk of gas. The emissions and brightness variations are apparently caused by this "decretion disk".
Right, Gamma Cas hasn't got an accretion disk, but a "decretion" disk! Not a disk where mass is spiraling in, but a disk where mass is cascading out!

Gamma Cas also emits X-rays! Watch out for the fireworks!


Wikipedia wrote:

Gamma Cassiopeiae is the prototype of a small group of stellar sources of X-ray radiation that is about 10 times stronger than emitted from other B or Be stars.
You dont' trifle with Gamma Cas, the blue jewel in the crown of Queen Cas! Hey, the stories of Queen Cas are ugly. Let's just enjoy her cosmic W-shaped beauty, shall we?


Finally, let's enjoy another picture of Gamma Cas and its small entourage of ghostly nebulas and a star:


So all hail Gamma Cas, royal blue-blooded star of the majestic constellation, Cassiopeia! ♕

Ann
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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by jeffbax » Sat Oct 28, 2023 9:11 am

Thank you Ann.

JF

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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by JohnD » Sat Oct 28, 2023 3:26 pm

The blurb to this APOD described the clouds of gas and dust as, "slowly disappearing, eroding under the influence of energetic radiation from hot and luminous gamma Cas." So where is it going? If the dust is being reduced to gas, why isn't that made luminous? Is the gas being reduced to protons and electrons? Which will glow if energised. More detail please.
John

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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by Chris Peterson » Sat Oct 28, 2023 3:39 pm

JohnD wrote: Sat Oct 28, 2023 3:26 pm The blurb to this APOD described the clouds of gas and dust as, "slowly disappearing, eroding under the influence of energetic radiation from hot and luminous gamma Cas." So where is it going? If the dust is being reduced to gas, why isn't that made luminous? Is the gas being reduced to protons and electrons? Which will glow if energised. More detail please.
John
The dust is not becoming gas, it is merely dissipating. The gas is already a plasma of protons and electrons, which is why we see it glowing red. As it is blown away by the hot star, it will cool and there will be less ionized hydrogen, so less red glow.
Chris

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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by JohnD » Sat Oct 28, 2023 4:31 pm

Thank you, Chris!
The blurb made it sound like some unknown chemistry was just pooouff! making it not exist!

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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by orin stepanek » Sat Oct 28, 2023 6:37 pm

IC63_GruntzBax1024.jpg
I like these spooks; they're kinda cute! :mrgreen:
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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by jeffbax » Sat Oct 28, 2023 10:01 pm

orin stepanek wrote: Sat Oct 28, 2023 6:37 pm IC63_GruntzBax1024.jpg
I like these spooks; they're kinda cute! :mrgreen:
Thank you, they are cute... :lol2:

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Re: APOD: The Ghosts of Gamma Cas (2023 Oct 28)

Post by JohnD » Thu Feb 01, 2024 1:02 pm

"Cute"?
clever or shrewd often in an underhanded manner? No.
obviously straining for effect. No
attractive or pretty especially in a childish, youthful, or delicate way. The first, perhaps, but these are millions of years old!

Please don't use 'cute' about astronomy. In fact, PLEASE don't use 'cute. at all!
John