APOD: Planetary Nebula Abell 78 (2020 Oct 16)

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APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by APOD Robot » Fri Oct 16, 2020 4:08 am

Image Planetary Nebula Abell 78

Explanation: Planetary nebula Abell 78 stands out in this colorful telescopic skyscape. In fact the colors of the spiky Milky Way stars depend on their surface temperatures, both cooler (yellowish) and hotter (bluish) than the Sun. But Abell 78 shines by the characteristic emission of ionized atoms in the tenuous shroud of material shrugged off from an intensely hot central star. The atoms are ionized, their electrons stripped away, by the central star's energetic but otherwise invisible ultraviolet light. The visible blue-green glow of loops and filaments in the nebula's central region corresponds to emission from doubly ionized oxygen atoms, surrounded by strong red emission from ionized hydrogen. Some 5,000 light-years distant toward the constellation Cygnus, Abell 78 is about three light-years across. A planetary nebula like Abell 78 represents a very brief final phase in stellar evolution that our own Sun will experience ... in about 5 billion years.

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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by orin stepanek » Fri Oct 16, 2020 1:42 pm

PN_Abell78-1_1024c1.jpg

Planetary Abell76! Beautiful photo picture framed by two lovely stars! :D 8-)
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Orin

Smile today; tomorrow's another day!

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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by shaileshs » Fri Oct 16, 2020 3:10 pm

I wonder - 1) All objects without spikes are galaxies then ? 2) What's the blue spike/colored star towards top right corner ?

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Ann
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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by Ann » Fri Oct 16, 2020 3:23 pm

shaileshs wrote:
Fri Oct 16, 2020 3:10 pm
I wonder - 1) All objects without spikes are galaxies then ? 2) What's the blue spike/colored star towards top right corner ?
The bright blue star is HD 205514. It is a star of spectral class A0, not unlike Vega. The star is located some ~ 1.000 light-years away, and at that distance, it is a faint 7th magnitude star as seen from the position of the Earth.

I'd say that most of the fainter objects in the APOD are stars even if they don't have very obvious spikes. As you can see if you look carefully, there are some obviously elongated, otherwise extended or even spiral-shaped objects in the image that are clearly galaxies. Most of the bright points in the APOD don't appear to be extended, however, and most of them are unlikely to be galaxies.

Abell 78 is located in Cygnus, a star-rich constellation with comparatively few visible background galaxies.

Ann
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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by johnnydeep » Fri Oct 16, 2020 6:31 pm

Ann wrote:
Fri Oct 16, 2020 3:23 pm
shaileshs wrote:
Fri Oct 16, 2020 3:10 pm
I wonder - 1) All objects without spikes are galaxies then ? 2) What's the blue spike/colored star towards top right corner ?
The bright blue star is HD 205514. It is a star of spectral class A0, not unlike Vega. The star is located some ~ 1.000 light-years away, and at that distance, it is a faint 7th magnitude star as seen from the position of the Earth.

I'd say that most of the fainter objects in the APOD are stars even if they don't have very obvious spikes. As you can see if you look carefully, there are some obviously elongated, otherwise extended or even spiral-shaped objects in the image that are clearly galaxies. Most of the bright points in the APOD don't appear to be extended, however, and most of them are unlikely to be galaxies.

Abell 78 is located in Cygnus, a star-rich constellation with comparatively few visible background galaxies.

Ann
Isn't the rule with diffraction spikes that the higher the magnitude of the object (that is, the dimmer it is), the less pronounced the spikes? At least, that seems to be the case for this picture. So, the dimmest stars would have barely discernible spikes.
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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by Ann » Fri Oct 16, 2020 6:33 pm

johnnydeep wrote:
Fri Oct 16, 2020 6:31 pm
Ann wrote:
Fri Oct 16, 2020 3:23 pm
shaileshs wrote:
Fri Oct 16, 2020 3:10 pm
I wonder - 1) All objects without spikes are galaxies then ? 2) What's the blue spike/colored star towards top right corner ?
The bright blue star is HD 205514. It is a star of spectral class A0, not unlike Vega. The star is located some ~ 1.000 light-years away, and at that distance, it is a faint 7th magnitude star as seen from the position of the Earth.

I'd say that most of the fainter objects in the APOD are stars even if they don't have very obvious spikes. As you can see if you look carefully, there are some obviously elongated, otherwise extended or even spiral-shaped objects in the image that are clearly galaxies. Most of the bright points in the APOD don't appear to be extended, however, and most of them are unlikely to be galaxies.

Abell 78 is located in Cygnus, a star-rich constellation with comparatively few visible background galaxies.

Ann
Isn't the rule with diffraction spikes that the higher the magnitude of the object (that is, the dimmer it is), the less pronounced the spikes? At least, that seems to be the case for this picture. So, the dimmest stars would have barely discernible spikes.
I think that is exactly right.

Ann
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Chris Peterson
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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by Chris Peterson » Fri Oct 16, 2020 8:13 pm

johnnydeep wrote:
Fri Oct 16, 2020 6:31 pm
Ann wrote:
Fri Oct 16, 2020 3:23 pm
shaileshs wrote:
Fri Oct 16, 2020 3:10 pm
I wonder - 1) All objects without spikes are galaxies then ? 2) What's the blue spike/colored star towards top right corner ?
The bright blue star is HD 205514. It is a star of spectral class A0, not unlike Vega. The star is located some ~ 1.000 light-years away, and at that distance, it is a faint 7th magnitude star as seen from the position of the Earth.

I'd say that most of the fainter objects in the APOD are stars even if they don't have very obvious spikes. As you can see if you look carefully, there are some obviously elongated, otherwise extended or even spiral-shaped objects in the image that are clearly galaxies. Most of the bright points in the APOD don't appear to be extended, however, and most of them are unlikely to be galaxies.

Abell 78 is located in Cygnus, a star-rich constellation with comparatively few visible background galaxies.

Ann
Isn't the rule with diffraction spikes that the higher the magnitude of the object (that is, the dimmer it is), the less pronounced the spikes? At least, that seems to be the case for this picture. So, the dimmest stars would have barely discernible spikes.
For any given optical system, a fixed percentage of the energy coming from the object (star or galaxy or anything else) is diverted into the diffraction spikes. So an object that is twice as bright will have diffraction spikes that are twice as bright.

In an image, however, things can be confused by non-linear intensity mapping. The high dynamic range of the original data is almost always remapped to emphasize dim structure and minimize blowing out of bright structure. Usually, but not always, relative brightness is maintained (that is, if one star appears brighter than another, it really is) even if the absolute photometric relationship is lost.
Chris

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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by VictorBorun » Fri Oct 16, 2020 10:31 pm

3) What's the orange spike/colored star towards bottom left corner ?

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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by Chris Peterson » Fri Oct 16, 2020 11:07 pm

VictorBorun wrote:
Fri Oct 16, 2020 10:31 pm
3) What's the orange spike/colored star towards bottom left corner ?
Tycho 2704-323-1. Or any of 15 other identifiers.
Chris

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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by VictorBorun » Sat Oct 17, 2020 4:54 am

I am trying to read this now:

"Spectral type: M0 D ~ "

It's red (=M, the last and the most red in the series of Oh Be A Fine Girl Kiss Me).

It's not as red as they come (M0 ≈ K9, or photospheric temperature of 3700°K).

It's prone to flares (~)

"Parallaxes (mas): 2.1622 [0.0359]"
It's 1500 light-years from us (www.translatorscafe.com/unit-converter/ ... -distance/)

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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by XgeoX » Sat Oct 17, 2020 10:03 am

Beatiful framing!

Eric

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Re: APOD: Planetary Nebula Abell 78 (2020 Oct 16)

Post by shaileshs » Sat Oct 17, 2020 3:58 pm

Ann wrote:
Fri Oct 16, 2020 3:23 pm
shaileshs wrote:
Fri Oct 16, 2020 3:10 pm
I wonder - 1) All objects without spikes are galaxies then ? 2) What's the blue spike/colored star towards top right corner ?
The bright blue star is HD 205514. It is a star of spectral class A0, not unlike Vega. The star is located some ~ 1.000 light-years away, and at that distance, it is a faint 7th magnitude star as seen from the position of the Earth.

I'd say that most of the fainter objects in the APOD are stars even if they don't have very obvious spikes. As you can see if you look carefully, there are some obviously elongated, otherwise extended or even spiral-shaped objects in the image that are clearly galaxies. Most of the bright points in the APOD don't appear to be extended, however, and most of them are unlikely to be galaxies.

Abell 78 is located in Cygnus, a star-rich constellation with comparatively few visible background galaxies.

Ann
Thank you Ann for providing answers, clarifications, insights for most of my queries..