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APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 4:05 am
by APOD Robot
NGC 1499: The California Nebula
Explanation: Drifting through the Orion Arm of the spiral Milky Way Galaxy,
this cosmic cloud by chance echoes the outline of California on the west coast of the United States. Our own
Sun also lies within the Milky Way's
Orion Arm, only about 1,500 light-years from the
California Nebula. Also known as
NGC 1499, the classic emission nebula is around 100 light-years long. The California Nebula shines with the telltale reddish glow characteristic of hydrogen atoms recombining with
long lost electrons. The electrons have been stripped away, ionized by energetic starlight. Most likely providing the
energetic starlight that ionizes much of the nebular gas is the bright, hot star
Xi Persei just to the right of the nebula. A popular target for astrophotographers, this deep image reveals the
glowing nebula, obscuring dust, and stars across a 3 degree
wide field of view. The California nebula lies toward the constellation
Perseus, not far from the
Pleiades.
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 5:20 am
by VictorBorun
it's where our earthly experience with depth and illumination may be working well
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 5:48 am
by Ann
NGC 1499: The California Nebula
Image Credit & Copyright: Stephen Kennedy
Today's APOD is a fine picture that brings out the two-ridge nature of the California Nebula. Possible runaway O7.5III-type star Menkib, Xi Persei (the only O-type star in constellation Perseus) has been plowing into higher-than-average density gas and pushing it and compressing it like a snowplow. The intense ultraviolet radiation of hot Xi Per ionizes the compressed gas and makes it glow red. Menkib is seen at upper center right in the APOD.
As a blue-loving Color Commentator, I was of course disappointed at the absolutely non-blue, almost egg-white appearance of Menkib. Yes, Menkib is certainly reddened dust, but its "apparent color" is almost as blue as Vega. I started hunting around for a picture that would appeal more to my color sensitivities and found a picture by Scott Rosen:
California Nebula and Pleiades widefield. Photo: Scott Rosen.
Do click the image to see the full size of Scott Rosen's image. I have annotated it and drawn the contours of the darkest and thickest dust in the vicinity. (And if you're wondering: Yes, Scott Rosen's image is "up-and-down"-reversed.)
Wikipedia wrote about Xi Per, the star ionizing the California Nebula:
The star has a mass of some 30 solar masses and a surface temperature of 35,000 kelvins, making it one of the hottest stars that can be seen with the naked eye. The fluorescence of the California Nebula (NGC 1499) is due to this star's prodigious radiation. It is a member of the Perseus OB2 association of co-moving stars, but may be a runaway star since it is now separated by 200 pc from the association's center and has an unusually high radial velocity.
I guess that the center of Perseus OB2 association of co-moving stars is near bright B1-type giants Zeta and Omicron Persei.
IC 348 near Omicron Persei is the only site of star formation in constellation Perseus, at least to my knowledge, and it may be the center of Perseus OB2. Xi Persei may have been born not far from IC 348 and then received a kick out of the association center so that it plowed a "double ridge of gas" in front of it, creating the California Nebula, and bathed it in ultraviolet light and made it glow red.
But, okay! I should have clicked on all the links in today's APOD caption to find the best portrait of the California Nebula, the Pleiades and IC 348. Here it is, by Rogelio Bernal Andreo!
Ann
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 8:37 am
by AVAO
Ann wrote: ↑Sat Oct 22, 2022 5:48 am
But, okay! I should have clicked on all the links in today's APOD caption to find the best portrait of the California Nebula, the Pleiades and IC 348. Here it is, by Rogelio Bernal Andreo!
Ann
Why isn't there a red glow at the Pleiades?
Like Xi Persei, these are very bright and also radiate strongly in the X-ray.
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 10:05 am
by VictorBorun
AVAO wrote: ↑Sat Oct 22, 2022 8:37 am
Ann wrote: ↑Sat Oct 22, 2022 5:48 am
But, okay! I should have clicked on all the links in today's APOD caption to find the best portrait of the California Nebula, the Pleiades and IC 348. Here it is, by Rogelio Bernal Andreo!
Ann
Why isn't there a red glow at the Pleiades?
Like Xi Persei, these are very bright and also radiate strongly in the X-ray.
My first thought is: you need a bulldozer of a star, i. e. massive and moving, to pile enough interstellar gas in this region.
By the way, it's not often that a massive star is kicked out of a stellar cluster. Mostly if two stars happen to interact closely, it's less massive of the two that soars and more massive one that sinks
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 10:15 am
by Ann
AVAO wrote: ↑Sat Oct 22, 2022 8:37 am
Ann wrote: ↑Sat Oct 22, 2022 5:48 am
But, okay! I should have clicked on all the links in today's APOD caption to find the best portrait of the California Nebula, the Pleiades and IC 348. Here it is, by Rogelio Bernal Andreo!
Ann
Why isn't there a red glow at the Pleiades?
Like Xi Persei, these are very bright and also radiate strongly in the X-ray.
The Pleiades are way too cool to ionize a red emission nebula! The brightest and hottest of them are spectral classes B6-B8. That is to say that their temperatures are likely below 16,000 K. The temperature of Menkib, Xi Per, which ionizes the California Nebula, is 35,000 K.
To ionize a nebula, a star has to be at least spectral class B1. A star that could have ionized a nebula if there had been any significant amounts of gas in its vicinity is Beta Cephei, Alfirk. Its temperature is 27,000 K.
A star that is a little cooler than Beta Cephei, so that it just borderline barely ionizes parts of its nebula, is HD 200775, a young star of spectral class B2. It is surrounded by a lot of blue reflection nebulosity and a hint of pink Hα emission nebulosity in its own nebula, the Iris Nebula:
Beta Cephei in constellation Cepheus by Will Gater.
The Iris Nebula and star HD 200775. The arrows point at weakly ionized regions.
I don't remember why I put the question mark there. Photo: Adam Block.
A star of spectral class B1 that does ionize a red emission nebula is BD+46 3474, ionizing star of the Cocoon Nebula:
Also it is not X-rays that ionize hydrogen and make it glow red. It is ultraviolet light, which is emitted in copious amounts by stars whose temperature is around 30,000 K and higher.
Ann
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 1:18 pm
by orin stepanek
Sun and California both in Orion arm! I never noticed that before! I
learned something!
![Cool 8-)](./images/smilies/icon_cool.gif)
Can it be seen with the naked eye? I'll look
for it when I view the 7 sisters!
![Wink :wink:](./images/smilies/icon_wink.gif)
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 1:29 pm
by AVAO
Ann wrote: ↑Sat Oct 22, 2022 10:15 am
AVAO wrote: ↑Sat Oct 22, 2022 8:37 am
Why isn't there a red glow at the Pleiades?
Like Xi Persei, these are very bright and also radiate strongly in the X-ray.
The Pleiades are way too cool to ionize a red emission nebula! The brightest and hottest of them are spectral classes B6-B8. That is to say that their temperatures are likely below 16,000 K. The temperature of Menkib, Xi Per, which ionizes the California Nebula, is 35,000 K.
To ionize a nebula, a star has to be at least spectral class B1. A star that could have ionized a nebula if there had been any significant amounts of gas in its vicinity is Beta Cephei, Alfirk. Its temperature is 27,000 K.
A star that is a little cooler than Beta Cephei, so that it just borderline barely ionizes parts of its nebula, is HD 200775, a young star of spectral class B2. It is surrounded by a lot of blue reflection nebulosity and a hint of pink Hα emission nebulosity in its own nebula, the Iris Nebula:
Beta Cep and constellation Cepheus Will Gater.png
Beta Cephei in constellation Cepheus by Will Gater.
Iris Nebula Adam Block annotated.png
The Iris Nebula and star HD 200775. The arrows point at weakly ionized regions.
I don't remember why I put the question mark there. Photo: Adam Block.
A star of spectral class B1 that does ionize a red emission nebula is BD+46 3474, ionizing star of the Cocoon Nebula:
Also it is not X-rays that ionize hydrogen and make it glow red. It is ultraviolet light, which is emitted in copious amounts by stars whose temperature is around 30,000 K and higher.
Ann
ThanX Ann
I was sure, you had a good answer to that.
Your explanations are always so helpful!
Jac
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 2:14 pm
by Cousin Ricky
APOD Robot wrote: ↑Sat Oct 22, 2022 4:05 am
The California Nebula shines with the telltale reddish glow characteristic of hydrogen atoms recombining with
long lost electrons... Most likely providing the
energetic starlight that ionizes much of the nebular gas is the bright, hot star
Xi Persei just to the right of the nebula.
This means that this star can ionize gas up to 50 light years away!
![Shocked :shock:](./images/smilies/icon_eek.gif)
That is impressive.
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 2:41 pm
by AVAO
Ann wrote: ↑Sat Oct 22, 2022 5:48 am
IC 348 near Omicron Persei is the only site of star formation in constellation Perseus, at least to my knowledge, and it may be the center of Perseus OB2. Xi Persei may have been born not far from IC 348 and then received a kick out of the association center so that it plowed a "double ridge of gas" in front of it, creating the California Nebula, and bathed it in ultraviolet light and made it glow red.
Ann
Bold hypothesis. But yeah, there seems to be a lot (star formation) going on at IC 348
Area in Mid-IR:
Core of IC 348 in different IR-wavelenghts (WISE/HERSCHEL):
jac berne (flickr)
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 3:29 pm
by Ann
AVAO wrote: ↑Sat Oct 22, 2022 2:41 pm
Ann wrote: ↑Sat Oct 22, 2022 5:48 am
IC 348 near Omicron Persei is the only site of star formation in constellation Perseus, at least to my knowledge, and it may be the center of Perseus OB2. Xi Persei may have been born not far from IC 348 and then received a kick out of the association center so that it plowed a "double ridge of gas" in front of it, creating the California Nebula, and bathed it in ultraviolet light and made it glow red.
Ann
Bold hypothesis. But yeah, there seems to be a lot (star formation) going on at IC 348
Isn't speculating fun?
Ann
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 4:57 pm
by DL MARTIN
By placing the California Nebula in the Orion Arm 1500 light-years from the Sun, I've newly appreciated why distance can be independent of time past. Thank you. Some of us just take a little longer.
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Sat Oct 22, 2022 5:55 pm
by Ann
AVAO wrote: ↑Sat Oct 22, 2022 2:41 pm
Ann wrote: ↑Sat Oct 22, 2022 5:48 am
IC 348 near Omicron Persei is the only site of star formation in constellation Perseus, at least to my knowledge, and it may be the center of Perseus OB2. Xi Persei may have been born not far from IC 348 and then received a kick out of the association center so that it plowed a "double ridge of gas" in front of it, creating the California Nebula, and bathed it in ultraviolet light and made it glow red.
Ann
Bold hypothesis. But yeah, there seems to be a lot (star formation) going on at IC 348
Area in Mid-IR:
Core of IC 348 in different IR-wavelenghts (WISE/HERSCHEL):
jac berne (flickr)
I was wrong!!!
![Embarassed :oops:](./images/smilies/icon_redface.gif)
IC 348 is not the only place where stars are forming in Perseus, because NGC 1333 is a well-known site of star formation in in this part of the sky!
Wikipedia wrote about NGC 1333:
The nebula region has a combined mass of approximately 450 M☉,[4] while the cluster contains around 150 stars with a median age of a million years and a combined mass of 100 M☉. The average star formation rate is 10×10−4 M☉ yr–1.[4] Within the nebular are 20 young stellar objects producing outflows, including Herbig–Haro objects. A total of 95 X-ray sources that are associated with known members of embedded star clusters.[6] In 2011 researchers reported finding 30 to 40 brown dwarf objects in the cloud and in the Rho Ophiuchi cloud complex.
Wikipedia wrote:
IC 348 is a star-forming region in the constellation Perseus located about 315 parsecs from the Sun. It consists of nebulosity and an associated 2-million-year-old cluster of roughly 400 stars within an angular diameter of 20″. The most massive stars in the cluster are the binary star system BD+31°643, which has a combined spectral class of B5.[3] Based upon infrared observations using the Spitzer Space Telescope, about half of the stars in the cluster have a circumstellar disk, of which 60% are thick or primordial disks.[4]
The age of this cluster has allowed three low mass brown dwarfs to be discovered. These objects lose heat as they age, so they are more readily discovered while they are still young.
At least IC 348 seems to be a more massive site of star formation than NGC 1333, with more stars and more massive stars forming there than in NGC 1333.
Then again, Perseus is located in the major Perseus arm of our galaxy, so clearly there is a lot more star formation there than just NGC 1333 and IC 348! Obviously! Where is the "slap-face, I'm-an-idiot" smiley? Okay, this one?
Ann
Re: APOD: NGC 1499: The California Nebula (2022 Oct 22)
Posted: Fri Feb 17, 2023 10:11 pm
by Astrofan1962
It just blows my mind that we are seeing this as it existed centuries ago. Resonating.