APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

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APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by APOD Robot » Mon Nov 25, 2019 5:05 am

Image NGC 6995: The Bat Nebula

Explanation: Do you see the bat? It haunts this cosmic close-up of the eastern Veil Nebula. The Veil Nebula itself is a large supernova remnant, the expanding debris cloud from the death explosion of a massive star. While the Veil is roughly circular in shape and covers nearly 3 degrees on the sky toward the constellation of the Swan (Cygnus), the Bat Nebula, NGC 6995, spans only 1/2 degree, about the apparent size of the Moon. That translates to 12 light-years at the Veil's estimated distance, a reassuring 1,400 light-years from planet Earth. In the composite of image data recorded through broad and narrow band filters, emission from hydrogen atoms in the remnant is shown in red with strong emission from oxygen and nitrogen atoms shown in hues of blue. Of course, in the western part of the Veil lies another seasonal apparition: the Witch's Broom Nebula.

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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by Guest » Mon Nov 25, 2019 8:47 am

Resembles a dried up tardigrade. :)

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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by orin stepanek » Mon Nov 25, 2019 12:31 pm

OK, I'm confused! :? Which is it? 12 light years or 14,000 light years distant!
That translates to 12 light-years at the Veil's estimated distance, a reassuring 1,400 light-years from planet Earth.
Or does that mean that the Veil is 12 light years across? :!:
NGC6995_Drudis_960.jpg
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by Chris Peterson » Mon Nov 25, 2019 1:20 pm

orin stepanek wrote:
Mon Nov 25, 2019 12:31 pm
OK, I'm confused! :? Which is it? 12 light years or 14,000 light years distant!
That translates to 12 light-years at the Veil's estimated distance, a reassuring 1,400 light-years from planet Earth.
Or does that mean that the Veil is 12 light years across? :!:
An object which is 1400 light years distant and which subtends 0.5° is 12 light years across. Basic trig.
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by orin stepanek » Mon Nov 25, 2019 2:57 pm

I'm Not hep on Trig; so I'll hope it wasn't an insult! as you can see by my question that I thought it was 12 Light across! All I wanted was clarification! :oops:
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by TheOtherBruce » Mon Nov 25, 2019 3:46 pm

Note that "12 light years" only refers to the small piece in today's picture — according to the Wiki page, the whole thing is about 77 light years across. It's biiiiig...
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Angel Bat Dawid - We are Starzz

Post by neufer » Mon Nov 25, 2019 4:23 pm

https://www.youtube.com/watch?v=hiaVJp1ZISs wrote:
Click to play embedded YouTube video.
<<Angel Bat Dawid performs her own song We are Starzz.

Composer, clarinetist, singer & spiritual jazz soothsayer Angel Bat Dawid descended on Chicago's jazz & improvised music scene just a few years ago. In very short time, the potency, prowess, spirit & charisma of her cosmic musical proselytizing has taken her from relatively unknown improviser to borderline ubiquitous performer in Chicago's avant-garde.

This video was recorded in the garden of the Nutshuis in The Hague during Rewire Festival for VPRO Vrije Geluiden: music program made by the Dutch public broadcast organization VPRO.>>
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by Ann » Mon Nov 25, 2019 4:35 pm

orin stepanek wrote:
Mon Nov 25, 2019 2:57 pm
I'm Not hep on Trig; so I'll hope it wasn't an insult! as you can see by my question that I thought it was 12 Light across! All I wanted was clarification! :oops:
I'm not hep om trig either, Orin. Thanks for asking! And Chris, thanks for answering! :D

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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by MarkBour » Mon Nov 25, 2019 4:56 pm

I'm not sure I can see a bat.
I do see two locations that look like "clumps" of the material to me:
.
Capture.JPG
Capture1.jpg
I wonder what's going on in these?

Actually, I first wonder what the density of the gasses are; it all may be quite tenuous, even in those spots
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by TheOtherBruce » Mon Nov 25, 2019 5:54 pm

MarkBour wrote:
Mon Nov 25, 2019 4:56 pm
Actually, I first wonder what the density of the gasses are; it all may be quite tenuous, even in those spots
It is — the density even in the brighter patches isn't actually much more than the average near-vacuum you'd find in interstellar space. The main reasons we can see these nebulae at all is partly due to UV and visible light from nearby stars ionising the gas, partly (in this case) the high-speed debris from the supernova piling into surrounding gas and dust clouds, usually heating them to ridiculous temperatures.
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by neufer » Mon Nov 25, 2019 8:10 pm

TheOtherBruce wrote:
Mon Nov 25, 2019 5:54 pm
MarkBour wrote:
Mon Nov 25, 2019 4:56 pm

Actually, I first wonder what the density of the gasses are; it all may be quite tenuous, even in those spots
It is — the density even in the brighter patches isn't actually much more than the average near-vacuum you'd find in interstellar space. The main reasons we can see these nebulae at all is partly due to UV and visible light from nearby stars ionising the gas, partly (in this case) the high-speed debris from the supernova piling into surrounding gas and dust clouds, usually heating them to ridiculous temperatures.
https://en.wikipedia.org/wiki/Supernova_remnant wrote:
Click to play embedded YouTube video.

A supernova remnant (SNR) passes through the following stages:
  • Free expansion of the ejecta, until they sweep up their own weight in circumstellar or interstellar medium. This can last tens to a few hundred years depending on the density of the surrounding gas.

    Sweeping up of a shell of shocked circumstellar and interstellar gas. Strong X-ray emission traces the strong shock waves and hot shocked gas.

    Cooling of the shell, to form a thin (< 1 pc), dense (1-100 million atoms per cubic metre) shell surrounding the hot (few million kelvin) interior. This is the pressure-driven snowplow phase. The shell can be clearly seen in optical emission from recombining ionized hydrogen and ionized oxygen atoms.

    Cooling of the interior. The dense shell continues to expand from its own momentum. This stage is best seen in the radio emission from neutral hydrogen atoms.

    Merging with the surrounding interstellar medium. When the supernova remnant slows to the speed of the random velocities in the surrounding medium, after roughly 30,000 years, it will merge into the general turbulent flow, contributing its remaining kinetic energy to the turbulence.
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by ta152h0 » Mon Nov 25, 2019 11:34 pm

Is this the area where there's a contact binary that's supposed to go supernova in 5 years or less?
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by Chris Peterson » Mon Nov 25, 2019 11:43 pm

ta152h0 wrote:
Mon Nov 25, 2019 11:34 pm
Is this the area where there's a contact binary that's supposed to go supernova in 5 years or less?
KIC 9832227. It's in the same constellation (Cygnus), but farther away than the Veil. Also, when the two stars merge they will only produce a nova, not a supernova. And it turns out there are some problems with the predicted timing. So, probably no merger anytime soon ("soon" by our standards).
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Re: APOD: NGC 6995: The Bat Nebula (2019 Nov 25)

Post by TheOtherBruce » Tue Nov 26, 2019 8:38 am

Chris Peterson wrote:
Mon Nov 25, 2019 11:43 pm
ta152h0 wrote:
Mon Nov 25, 2019 11:34 pm
Is this the area where there's a contact binary that's supposed to go supernova in 5 years or less?
KIC 9832227. It's in the same constellation (Cygnus), but farther away than the Veil.
<wiki-wiki-wiki>

Good grief, an orbital period of eleven hours?!??! That's fast enough to actually see them going round!
Chris Peterson wrote:
Mon Nov 25, 2019 11:43 pm
Also, when the two stars merge they will only produce a nova, not a supernova. And it turns out there are some problems with the predicted timing. So, probably no merger anytime soon ("soon" by our standards).
Also depends on whether Luminous Red Novae are actually a thing — the data so far is wiggling its eyebrows suggestively, but with a sample size we could count without taking our socks off, some more examples would be good.
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