APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

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APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by APOD Robot » Tue Apr 30, 2024 4:05 am

Image GK Per: Nova and Planetary Nebula

Explanation: The star system GK Per is known to be associated with only two of the three nebulas pictured. At 1500 light years distant, Nova Persei 1901 (GK Persei) was the second closest nova yet recorded. At the very center is a white dwarf star, the surviving core of a former Sun-like star. It is surrounded by the circular Firework nebula, gas that was ejected by a thermonuclear explosion on the white dwarf's surface -- a nova -- as recorded in 1901. The red glowing gas surrounding the Firework nebula is the atmosphere that used to surround the central star. This gas was expelled before the nova and appears as a diffuse planetary nebula. The faint gray gas running across is interstellar cirrus that seems to be just passing through coincidently. In 1901, GK Per's nova became brighter than Betelgeuse. Similarly, star system T CrB is expected to erupt in a nova later this year, but we don't know exactly when nor how bright it will become.

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by Ann » Tue Apr 30, 2024 6:57 am

I don't automatically comment on planetary nebula images, because I don't have a handle on their colors. I trust that I know the colors of stars, because I made a great effort to observe all sorts of (reasonably bright) stars to assess their colors, but I never managed to detect color in the few planetary nebulas I observed. And, to be honest, Hubble ruined the planetary nebulas for me! ☠️



How can the colors of planetary nebulas be so impossibly different from one another? Help!!! 😭

So, because I never managed to spot any color in the planetaries that I observed, and because of the crazily colored pictures of planetaries by Hubble, I lost interest in these stellar shrouds. Now I mostly think they are sad - they are dirges for dead stars!

Okay, but who can resist today's amazing APOD??? 😀


It looks crazy!! It looks pretty wonderful! It looks like a cosmic flower growing out of planetary nebula soil!

GKPerWide_DSC_960[1].jpg
GK Per: Nova and Planetary Nebula
Image Credit & Copyright: Deep Sky Collective
APOD 30 April 2024 annotated.png
A cosmic flower growing out of a planetary nebula!

The planetary nebula in the APOD - the big elongated red and blue thing - looks like a typical planetary nebula. It's red from hydrogen alpha and blue from OIII. (Yes, but is OIII really as blue as that?) :(

Whatever! The planetary nebula formed as the former red giant that is now a white dwarf cast off its swollen atmosphere and bared its scorchingly hot tiny innards, its compact core. The terrifically hot core blasted its own cast-off atmosphere with relentless ultraviolet radiation, ionizing these gas clouds and making them glow red and blue (green?), thus forming a planetary nebula.

Planetary nebula PK 164 plus 31 1 Eric Smith.png
Planetary nebula PK 164+31.1. This is a typical planetary nebula.
This is what GK Per looked like (more or less) before it became nova.
Credit: Eric Smith


But we are not done yet! The white dwarf had a companion, and the two of them lived cosily close to one another even before one of them became a white dwarf.


Okay, no! Not this close! I just wanted you to get an idea.

Anyway. One of the stars became a red giant, and then it cast off its atmosphere and became a white dwarf (with a planetary nebula). Yes, but then the other star entered its red gianthood too and started to swell, and then the white dwarf started sucking gas from its swollen companion, forming an accretion disk around itself!


This is not a perfect illustration, because the big star is blue, and we are told by the caption that the big star is Sun-like. (Really? So blue?)

In the case of GK Persei, the star that is the - well, "star" - of today's APOD, the "big star", the donor star, is a red giant. But the white dwarf is certainly sucking matter from its red giant companion and forming an accretion disk around itself.

What happens next? In one of the links in the caption of today's APOD, we are told this about the accretion disk swirling around the white dwarf:

As it loses angular momentum, the material in the disk slowly drifts inward and accretes onto the surface of the white dwarf.

An envelope or "ocean" of hydrogen-rich material builds up on the white dwarf surface. 🌊🌊🌊
The intense heat and pressure at the base of this envelope leads to a thermonuclear explosion as hydrogen is burned to helium. The explosion blows off the outer layers of the envelope. This event is the observed classical nova outburst which generally lasts for tens to hundreds of days.

It is this thermonuclear explosion from 1901 that formed the Fireworks Nebula, which is the "flower" inside the planetary nebula in today's APOD! 🌸

Do note that when there is a nova, the white dwarf whose surface layer explodes survives the explosion. :yes:

Not so with supernovas. And it's fascinating to think that supernovas type Ia form in much the same way as cataclysmic novas like GK Per. The difference is that so much matter builds up on the white dwarf's surface that the white dwarf reaches its Chandrasekhar limit, the maximum mass of a white dwarf before the electron degeneracy that prevents the white dwarf from collapsing buckles under, and a runaway flare of uncontrolled fusion tears the white dwarf apart in one of the brightest explosions of the Universe.


I guess most supernovas type Ia also grow out of a planetary nebula, but the planetary nebula surrounding them is completely overwhelmed by the unbelievable force of the supernova explosion. That's a big big flower indeed!!! 😮

Ann
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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by johnnydeep » Tue Apr 30, 2024 1:09 pm

Ann wrote:Not so with supernovas. And it's fascinating to think that supernovas type Ia form in much the same way as cataclysmic novas like GK Per. The difference is that so much matter builds up on the white dwarf's surface that the white dwarf reaches its Chandrasekhar limit, the maximum mass of a white dwarf before the electron degeneracy that prevents the white dwarf from collapsing buckles under, and a runaway flare of uncontrolled fusion tears the white dwarf apart in one of the brightest explosions of the Universe.
Why does the accretion of matter result in a supernova in some cases, but only a nova in others? Is it simply due to the rate of infalling matter? That is, if the matter falls in voluminously enough and in a short enough period of time, the Chandrasekhar limit is reached before a mere nova can forestall the process?
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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by mason dixon » Tue Apr 30, 2024 6:19 pm

Is there a timelapse of the Firework nebula growing in size like the Crab nebula?

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by johnnydeep » Tue Apr 30, 2024 6:31 pm

mason dixon wrote: Tue Apr 30, 2024 6:19 pm Is there a timelapse of the Firework nebula growing in size like the Crab nebula?
Sort of. Here's a succession of images taken over the years that demonstrate the growth: https://vimeo.com/31120259
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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by starsurfer » Tue Apr 30, 2024 6:40 pm

Awesome image! The outer nebula was discovered by the professional astronomer Michael Bode.

It would be cool to see a widefield image of this and the planetary nebula HDW 3 together!

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by Ann » Tue Apr 30, 2024 8:09 pm

johnnydeep wrote: Tue Apr 30, 2024 1:09 pm
Ann wrote:Not so with supernovas. And it's fascinating to think that supernovas type Ia form in much the same way as cataclysmic novas like GK Per. The difference is that so much matter builds up on the white dwarf's surface that the white dwarf reaches its Chandrasekhar limit, the maximum mass of a white dwarf before the electron degeneracy that prevents the white dwarf from collapsing buckles under, and a runaway flare of uncontrolled fusion tears the white dwarf apart in one of the brightest explosions of the Universe.
Why does the accretion of matter result in a supernova in some cases, but only a nova in others? Is it simply due to the rate of infalling matter? That is, if the matter falls in voluminously enough and in a short enough period of time, the Chandrasekhar limit is reached before a mere nova can forestall the process?
Good question. This is best answer I can come up with:

White dwarfs start out with different masses. Most white dwarfs are born with a mass that is less than the mass of the Sun. The white dwarf companion of Sirius is one of the most massive white dwarfs known, because its mass, according to Wikipedia, is 1.02 M. Also according to Wikipedia, the average mass of white dwarfs is 0.5–0.6 M. Remember that the Chandrasekhar limit, at which white dwarfs explode as supernovas, is 1.4 M. It goes without saying that a white dwarf with a mass of 0.5 M will probably never go supernova, even if it is accreting matter from a companion. It will almost certainly blow off the extra mass it has accreted before it comes close to the Chandrasekhar limit.

A white dwarf that starts out massive has a much better chance of accreting enough mass to become critical and explode as a supernova.

Why do stars create white dwarfs of different masses? Well, consider. Our own Sun has absolutely no chance of ever reaching the Chandrasekhar limit when it has become a white dwarf, because it will probably not be any more massive than 0.5–0.6 M when it becomes a tiny cinder of its former self. Also it has no companion from which it can accrete mass.

But now consider Bellatrix, bright blue star in Orion. According to Wikipedia, its mass is 7.7 M. Stars of 8 solar masses are believed to go supernova, so Bellatrix is right at the border, and it might go supernova or not. But if it doesn't explode a s a core-collapse supernova, it will undoubtedly form a massive white dwarf, probably rather close to the critical mass of 1.4 solar. Then again, Bellatrix has no companion, so it is not going to accrete mass after it has become a white dwarf (if it hasn't already exploded as a core-collapse supernova).

I think it is safe to say that only white dwarfs that start out more massive than most have a chance of going supernova type Ia.

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by Christian G. » Tue Apr 30, 2024 8:10 pm

Be sure to click twice on the image to see the Nova up close, gorgeous object!

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by johnnydeep » Tue Apr 30, 2024 9:31 pm

Ann wrote: Tue Apr 30, 2024 8:09 pm
johnnydeep wrote: Tue Apr 30, 2024 1:09 pm
Ann wrote:Not so with supernovas. And it's fascinating to think that supernovas type Ia form in much the same way as cataclysmic novas like GK Per. The difference is that so much matter builds up on the white dwarf's surface that the white dwarf reaches its Chandrasekhar limit, the maximum mass of a white dwarf before the electron degeneracy that prevents the white dwarf from collapsing buckles under, and a runaway flare of uncontrolled fusion tears the white dwarf apart in one of the brightest explosions of the Universe.
Why does the accretion of matter result in a supernova in some cases, but only a nova in others? Is it simply due to the rate of infalling matter? That is, if the matter falls in voluminously enough and in a short enough period of time, the Chandrasekhar limit is reached before a mere nova can forestall the process?
Good question. This is best answer I can come up with:

White dwarfs start out with different masses. Most white dwarfs are born with a mass that is less than the mass of the Sun. The white dwarf companion of Sirius is one of the most massive white dwarfs known, because its mass, according to Wikipedia, is 1.02 M. Also according to Wikipedia, the average mass of white dwarfs is 0.5–0.6 M. Remember that the Chandrasekhar limit, at which white dwarfs explode as supernovas, is 1.4 M. It goes without saying that a white dwarf with a mass of 0.5 M will probably never go supernova, even if it is accreting matter from a companion. It will almost certainly blow off the extra mass it has accreted before it comes close to the Chandrasekhar limit.

A white dwarf that starts out massive has a much better chance of accreting enough mass to become critical and explode as a supernova.

Why do stars create white dwarfs of different masses? Well, consider. Our own Sun has absolutely no chance of ever reaching the Chandrasekhar limit when it has become a white dwarf, because it will probably not be any more massive than 0.5–0.6 M when it becomes a tiny cinder of its former self. Also it has no companion from which it can accrete mass.

But now consider Bellatrix, bright blue star in Orion. According to Wikipedia, its mass is 7.7 M. Stars of 8 solar masses are believed to go supernova, so Bellatrix is right at the border, and it might go supernova or not. But if it doesn't explode a s a core-collapse supernova, it will undoubtedly form a massive white dwarf, probably rather close to the critical mass of 1.4 solar. Then again, Bellatrix has no companion, so it is not going to accrete mass after it has become a white dwarf (if it hasn't already exploded as a core-collapse supernova).

I think it is safe to say that only white dwarfs that start out more massive than most have a chance of going supernova type Ia.

Ann
Thanks! That makes sense to me.
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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by AVAO » Wed May 01, 2024 2:52 am

Once again a masterpiece!
Congratulations to the Deep Sky Collective team.
Christian G. wrote: Tue Apr 30, 2024 8:10 pm Be sure to click twice on the image to see the Nova up close, gorgeous object!
I like cosmic dandelions too!

...and when you overlay older images (e.g. from Hubble) you can clearly see how the nova is developing...

Click to view full size image 1 or image 2
P1: Original data: NASA/ESA (HST1995, a.m.) P2: Cut out Credit: Deep Sky Collective

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by Avalon » Wed May 01, 2024 3:39 am

So is that little "stem" between 7:00 and 8:00 on the image a jet of some sort?

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by Ann » Wed May 01, 2024 4:05 am

AVAO wrote: Wed May 01, 2024 2:52 am Once again a masterpiece!
Congratulations to the Deep Sky Collective team.
Christian G. wrote: Tue Apr 30, 2024 8:10 pm Be sure to click twice on the image to see the Nova up close, gorgeous object!
I like cosmic dandelions too!

...and when you overlay older images (e.g. from Hubble) you can clearly see how the nova is developing...

Click to view full size image 1 or image 2
P1: Original data: NASA/ESA (HST1995, a.m.) P2: Cut out Credit: Deep Sky Collective

Wow, Jac! Your version of the Hubble image sure looks like a dandelion with seeds flying all around it! :D


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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by Ann » Wed May 01, 2024 4:13 am

Avalon wrote: Wed May 01, 2024 3:39 am So is that little "stem" between 7:00 and 8:00 on the image a jet of some sort?

That's the only explanation I can think of.

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by JimB » Wed May 01, 2024 8:27 am

Ann wrote: Wed May 01, 2024 4:13 am
Avalon wrote: Wed May 01, 2024 3:39 am So is that little "stem" between 7:00 and 8:00 on the image a jet of some sort?

That's the only explanation I can think of.

Ann
I'm not so sure - on the APOD full sized image, it looks to me as though that "stem" is actually a continuation of one of the limbs of glowing bubbles of gas blasted by the stars radiation, as described so well in Ann's Tale of Two Stars.

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by Christian G. » Wed May 01, 2024 12:01 pm

AVAO wrote: Wed May 01, 2024 2:52 am Once again a masterpiece!
Congratulations to the Deep Sky Collective team.
Christian G. wrote: Tue Apr 30, 2024 8:10 pm Be sure to click twice on the image to see the Nova up close, gorgeous object!
I like cosmic dandelions too!

...and when you overlay older images (e.g. from Hubble) you can clearly see how the nova is developing...

Click to view full size image 1 or image 2
P1: Original data: NASA/ESA (HST1995, a.m.) P2: Cut out Credit: Deep Sky Collective
We're in good company, Carl Sagan too likes dandelions! https://youtu.be/KBs-Wu49sfc?t=97

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by VictorBorun » Sat May 04, 2024 1:44 am

AVAO wrote: Wed May 01, 2024 2:52 am Once again a masterpiece!
Congratulations to the Deep Sky Collective team.
Christian G. wrote: Tue Apr 30, 2024 8:10 pm Be sure to click twice on the image to see the Nova up close, gorgeous object!
I like cosmic dandelions too!

...and when you overlay older images (e.g. from Hubble) you can clearly see how the nova is developing...

Click to view full size image 1 or image 2
P1: Original data: NASA/ESA (HST1995, a.m.) P2: Cut out Credit: Deep Sky Collective
I wonder if this movement was used to assess the size of the Nova Persei 1901 Planetary Nebula.
I mean if it is possible to get Doppler's radial velocity for the dandelion rays and attribute them the same velocity distribution in the plane of the picture

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Re: APOD: GK Per: Nova and Planetary Nebula (2024 Apr 30)

Post by AVAO » Sat May 04, 2024 2:27 am

VictorBorun wrote: Sat May 04, 2024 1:44 am
AVAO wrote: Wed May 01, 2024 2:52 am Once again a masterpiece!
Congratulations to the Deep Sky Collective team.
Christian G. wrote: Tue Apr 30, 2024 8:10 pm Be sure to click twice on the image to see the Nova up close, gorgeous object!
I like cosmic dandelions too!

...and when you overlay older images (e.g. from Hubble) you can clearly see how the nova is developing...

Click to view full size image 1 or image 2
P1: Original data: NASA/ESA (HST1995, a.m.) P2: Cut out Credit: Deep Sky Collective
I wonder if this movement was used to assess the size of the Nova Persei 1901 Planetary Nebula.
I mean if it is possible to get Doppler's radial velocity for the dandelion rays and attribute them the same velocity distribution in the plane of the picture
Your suggestion is interesting. Unfortunately, there have been no follow-up observations with HST in the last 25 years,
so that no comparable data is available. Please write a research proposal :ssmile: