APOD: NGC 7822: Cosmic Question Mark (2021 Oct 13)

[APOD Robot]

NGC 7822: Cosmic Question Mark

Explanation: It may look like a huge cosmic question mark, but the big question really is how does the bright gas and dark dust tell this nebula's history of star formation. At the edge of a giant molecular cloud toward the northern constellation Cepheus, the glowing star forming region NGC 7822 lies about 3,000 light-years away. Within the nebula, bright edges and dark shapes stand out in this colorful and detailed skyscape. The 9-panel mosaic, taken over 28 nights with a small telescope in Texas, includes data from narrowband filters, mapping emission from atomic oxygen, hydrogen, and sulfur into blue, green, and red hues. The emission line and color combination has become well-known as the Hubble palette. The atomic emission is powered by energetic radiation from the central hot stars. Their powerful winds and radiation sculpt and erode the denser pillar shapes and clear out a characteristic cavity light-years across the center of the natal cloud. Stars could still be forming inside the pillars by gravitational collapse but as the pillars are eroded away, any forming stars will ultimately be cut off from their reservoir of star stuff. This field of view spans over 40 light-years across at the estimated distance of NGC 7822.

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[Ann]

NGC 7822 is a nebula that I have always dismissed, because I haven't been able to make head or tail of it. Where are the stars ionizing it? Let's try to find them!

NGC 7822: Cosmic Question Mark. Image Credit & Copyright: Yizhou Zhang

---

1) SAO 21019, spectral class O7.5V

2) BD+66 1673, spectral class O5.5V

3) A small cluster of hot stars


The hottest of these two O-type stars, BD+66 1673, is a lot hotter than than the hottest star of the Trapezium, Theta 1 C Orionis, and SAO 21019 is comparable with the luminary of the Trapezium.

Wikipedia wrote:

NGC 7822 is a young star forming complex in the constellation of Cepheus. The complex encompasses the emission region designated Sharpless 171, and the young cluster of stars named Berkeley 59. The complex is believed to be some 800–1000 pc distant, with the younger components aged no more than a few million years. The complex also includes one of the hottest stars discovered within 1 kpc of the Sun, namely BD+66 1673, which is an eclipsing binary system consisting of an O5V that exhibits a surface temperature of nearly 45,000 K and a luminosity about 100,000 times that of the Sun. The star is one of the primary sources illuminating the nebula and shaping the complex's famed pillars of creation-type formations, the elephant trunks.

"an eclipsing binary system consisting of an O5V", that sounds a bit funny, doesn't it, Wikipedia?

The ionizing star inside the "dot" of the "question mark" is much easier to spot than the ionizing stars of NGC 7822 proper, and Yizhou Zhang has done a good job of bringing the "question mark dot star" out for us. This is a star of spectral class O9.5V, so it is much more modest than the two furious powerhouses of NGC 7822 proper. Still, the O9.5V star is hot enough to ionize a nebula. But the star itself has garnered so little interest that it has only one designation that I can make any sense of, TYC 4022-1649-1. It doesn't even have a Hipparcos or a Gaia number, can you imagine? Simbad calls it LS I +64 11 -- Star. Yeah, right, sounds familiar.

Ann

[kybergreg]

Hello,
is there a Uranus or Neptune in the upper left corner of the picture?

[orin stepanek]

I tipped it to fit my needs! It does indeed look like a giant Or
maybe a giant Ear!! Amazing the shape and forms that star
forming regions come into!

Kitty makes bigger mess than my Magic!

[Hartmut]

In todays picture I discovered a blue object in the upper left part which I do not understand. The stars usually appear as bright spots with a small surrounding area of decreasing brightness. This is not the case with this blue object - it is a big disc of rather evenly brightness.
Is it a star so near that it can be seen as a disc rather than a spot? Or is it a planet (Uranus?) which happens to be in the field of view? Or is it something else? Thanks.

[johnnydeep]

NGC 7822: Cosmic Question Mark

Explanation: It may look like a huge cosmic question mark, but the big question really is how does the bright gas and dark dust tell this nebula's history of star formation. At the edge of a giant molecular cloud toward the northern constellation Cepheus, the glowing star forming region NGC 7822 lies about 3,000 light-years away. Within the nebula, bright edges and dark shapes stand out in this colorful and detailed skyscape. The 9-panel mosaic, taken over 28 nights with a small telescope in Texas, includes data from narrowband filters, mapping emission from atomic oxygen, hydrogen, and sulfur into blue, green, and red hues. The emission line and color combination has become well-known as the Hubble palette. The atomic emission is powered by energetic radiation from the central hot stars. Their powerful winds and radiation sculpt and erode the denser pillar shapes and clear out a characteristic cavity light-years across the center of the natal cloud. Stars could still be forming inside the pillars by gravitational collapse but as the pillars are eroded away, any forming stars will ultimately be cut off from their reservoir of star stuff. This field of view spans over 40 light-years across at the estimated distance of NGC 7822.

From the "star stuff" link:

DECEMBER 22, 2014 BY VANESSA JANEK
What Does It Mean To Be ‘Star Stuff’?
At one time or another, all science enthusiasts have heard the late Carl Sagan’s infamous words: “We are made of star stuff.” But what does that mean exactly?

1. "Infamous"?! I deem this the most infamous use of an adjective ever. Far better would have been 'famous', 'memorable', 'inspirational', 'insightful', etc. In fact, almost any other adjective would have been a better choice.

2. Does not the beautiful and seemingly disjoint "dot" of the question mark merit its own designation? It's so much nicer looking than the rest of the vaguely discernible question mark.

[johnnydeep]

In todays picture I discovered a blue object in the upper left part which I do not understand. The stars usually appear as bright spots with a small surrounding area of decreasing brightness. This is not the case with this blue object - it is a big disc of rather evenly brightness.
Is it a star so near that it can be seen as a disc rather than a spot? Or is it a planet (Uranus?) which happens to be in the field of view? Or is it something else? Thanks.

Fellow inquirer 'kybergreg' spotted that above as well. Yes, it's certainly odd: very remarkably blue and circular. Maybe a photographic or processing artifact. Here it is "up close":

What's this blue patch?

Perhaps it is the infamous "Planet 9" that seems likely to be far out in our own solar system, but so far not definitively confirmed (at least by means other than math )

(PS - of course, I'm joking about it being Planet 9 since there's no way it would look like that through this earth based amateur telescope, and not even through Hubble.)

[Ann]

In todays picture I discovered a blue object in the upper left part which I do not understand. The stars usually appear as bright spots with a small surrounding area of decreasing brightness. This is not the case with this blue object - it is a big disc of rather evenly brightness.
Is it a star so near that it can be seen as a disc rather than a spot? Or is it a planet (Uranus?) which happens to be in the field of view? Or is it something else? Thanks.

Fellow inquirer 'kybergreg' spotted that above as well. Yes, it's certainly odd: very remarkably blue and circular. Maybe a photographic or processing artifact. Here it is "up close":

Click to view full size image

Perhaps it is the infamous "Planet 9" that seems likely to be far out in our own solar system, but so far not definitively confirmed (at least by means other than math )

(PS - of course, I'm joking about it being Planet 9 since there's no way it would look like that through this earth based amateur telescope, and not even through Hubble.)

I don't know what that blue patch is either. I checked for a planetary nebula, and there is one reasonably nearby, NGC 40, but it is still not in the right position. Besides, there is an obvious star inside NGC 40, and none can be seen in that blue patch.

It also can't be Uranus or Neptune, because this constellation is Cepheus, and planets follow the ecliptic across the sky and can't be seen in constellations that are not on the ecliptic, such as Cepheus.

My best guess is that the blue patch is a photographic artifact.

Ann

[neufer]

In todays picture I discovered a blue object in the upper left part which I do not understand. The stars usually appear as bright spots with a small surrounding area of decreasing brightness. This is not the case with this blue object - it is a big disc of rather evenly brightness.
Is it a star so near that it can be seen as a disc rather than a spot? Or is it a planet (Uranus?) which happens to be in the field of view? Or is it something else? Thanks.

Fellow inquirer 'kybergreg' spotted that above as well. Yes, it's certainly odd: very remarkably blue and circular. Maybe a photographic or processing artifact. Perhaps it is the infamous "Planet 9" that seems likely to be far out in our own solar system, but so far not definitively confirmed (at least by means other than math ) (PS - of course, I'm joking about it being Planet 9 since there's no way it would look like that through this earth based amateur telescope, and not even through Hubble.)

• NGC 7354

Hubble Space Telescope image of NGC 7354 by Judy Schmidt

---

<<NGC 7354 is a planetary nebula located in the constellation of Cepheus, at a distance of approximately 5.5 kly from the Sun. It was discovered by German-born astronomer William Herschel on November 3, 1787. John L. E. Dreyer described it as, "a planetary nebula, bright, small, round, pretty gradually a very little brighter middle".

This nebula is the result of an aging star casting off its outer atmosphere. Overall the nebula is elliptical in form, with a complex interior structure having inner and outer shells, several bright equatorial knots, and two jet-like features near the nebula poles. The rim of the inner shell is ellipsoidal with an aspect ratio of 1.6 and a major axis spanning 30″. The outer shell is more circular, and is approximately 33″ in diameter. The faint outer shell is expanding with a higher velocity than the inner shell, and the knots are moving at the same velocity as the outer shell. The outer shell has an estimated age of 2,500 years, while the inner shell is 1,600 years old.

The morphological features of the nebula may be explained by an interacting binary star system with one of the pair passing through the asymptotic giant branch phase. The jets may be generated by an accretion disk surrounding the resulting white dwarf star. Additionally, an analysis of Gaia data suggests that the central star is binary.>>

[johnnydeep]

In todays picture I discovered a blue object in the upper left part which I do not understand. The stars usually appear as bright spots with a small surrounding area of decreasing brightness. This is not the case with this blue object - it is a big disc of rather evenly brightness.
Is it a star so near that it can be seen as a disc rather than a spot? Or is it a planet (Uranus?) which happens to be in the field of view? Or is it something else? Thanks.

Fellow inquirer 'kybergreg' spotted that above as well. Yes, it's certainly odd: very remarkably blue and circular. Maybe a photographic or processing artifact. Perhaps it is the infamous "Planet 9" that seems likely to be far out in our own solar system, but so far not definitively confirmed (at least by means other than math ) (PS - of course, I'm joking about it being Planet 9 since there's no way it would look like that through this earth based amateur telescope, and not even through Hubble.)

• NGC 7354

Hubble Space Telescope image of NGC 7354 by Judy Schmidt

---

<<NGC 7354 is a planetary nebula located in the constellation of Cepheus, at a distance of approximately 5.5 kly from the Sun. It was discovered by German-born astronomer William Herschel on November 3, 1787. John L. E. Dreyer described it as, "a planetary nebula, bright, small, round, pretty gradually a very little brighter middle".

This nebula is the result of an aging star casting off its outer atmosphere. Overall the nebula is elliptical in form, with a complex interior structure having inner and outer shells, several bright equatorial knots, and two jet-like features near the nebula poles. The rim of the inner shell is ellipsoidal with an aspect ratio of 1.6 and a major axis spanning 30″. The outer shell is more circular, and is approximately 33″ in diameter. The faint outer shell is expanding with a higher velocity than the inner shell, and the knots are moving at the same velocity as the outer shell. The outer shell has an estimated age of 2,500 years, while the inner shell is 1,600 years old.

The morphological features of the nebula may be explained by an interacting binary star system with one of the pair passing through the asymptotic giant branch phase. The jets may be generated by an accretion disk surrounding the resulting white dwarf star. Additionally, an analysis of Gaia data suggests that the central star is binary.>>

Thanks, neufer! That would seem to be it, but I can't get any other less close-up pics of NGC 7354 to match the star field around the blue patch in this APOD. But of course, I suck at that game...

[Ann]

In todays picture I discovered a blue object in the upper left part which I do not understand. The stars usually appear as bright spots with a small surrounding area of decreasing brightness. This is not the case with this blue object - it is a big disc of rather evenly brightness.
Is it a star so near that it can be seen as a disc rather than a spot? Or is it a planet (Uranus?) which happens to be in the field of view? Or is it something else? Thanks.

Fellow inquirer 'kybergreg' spotted that above as well. Yes, it's certainly odd: very remarkably blue and circular. Maybe a photographic or processing artifact. Perhaps it is the infamous "Planet 9" that seems likely to be far out in our own solar system, but so far not definitively confirmed (at least by means other than math ) (PS - of course, I'm joking about it being Planet 9 since there's no way it would look like that through this earth based amateur telescope, and not even through Hubble.)

• NGC 7354

Hubble Space Telescope image of NGC 7354 by Judy Schmidt

---

<<NGC 7354 is a planetary nebula located in the constellation of Cepheus, at a distance of approximately 5.5 kly from the Sun. It was discovered by German-born astronomer William Herschel on November 3, 1787. John L. E. Dreyer described it as, "a planetary nebula, bright, small, round, pretty gradually a very little brighter middle".

This nebula is the result of an aging star casting off its outer atmosphere. Overall the nebula is elliptical in form, with a complex interior structure having inner and outer shells, several bright equatorial knots, and two jet-like features near the nebula poles. The rim of the inner shell is ellipsoidal with an aspect ratio of 1.6 and a major axis spanning 30″. The outer shell is more circular, and is approximately 33″ in diameter. The faint outer shell is expanding with a higher velocity than the inner shell, and the knots are moving at the same velocity as the outer shell. The outer shell has an estimated age of 2,500 years, while the inner shell is 1,600 years old.

The morphological features of the nebula may be explained by an interacting binary star system with one of the pair passing through the asymptotic giant branch phase. The jets may be generated by an accretion disk surrounding the resulting white dwarf star. Additionally, an analysis of Gaia data suggests that the central star is binary.>>

That can't be it. It's not in the right place.

Ann

[johnnydeep]

Fellow inquirer 'kybergreg' spotted that above as well. Yes, it's certainly odd: very remarkably blue and circular. Maybe a photographic or processing artifact. Perhaps it is the infamous "Planet 9" that seems likely to be far out in our own solar system, but so far not definitively confirmed (at least by means other than math ) (PS - of course, I'm joking about it being Planet 9 since there's no way it would look like that through this earth based amateur telescope, and not even through Hubble.)

• NGC 7354

Hubble Space Telescope image of NGC 7354 by Judy Schmidt

---

<<NGC 7354 is a planetary nebula located in the constellation of Cepheus, at a distance of approximately 5.5 kly from the Sun. It was discovered by German-born astronomer William Herschel on November 3, 1787. John L. E. Dreyer described it as, "a planetary nebula, bright, small, round, pretty gradually a very little brighter middle".

This nebula is the result of an aging star casting off its outer atmosphere. Overall the nebula is elliptical in form, with a complex interior structure having inner and outer shells, several bright equatorial knots, and two jet-like features near the nebula poles. The rim of the inner shell is ellipsoidal with an aspect ratio of 1.6 and a major axis spanning 30″. The outer shell is more circular, and is approximately 33″ in diameter. The faint outer shell is expanding with a higher velocity than the inner shell, and the knots are moving at the same velocity as the outer shell. The outer shell has an estimated age of 2,500 years, while the inner shell is 1,600 years old.

The morphological features of the nebula may be explained by an interacting binary star system with one of the pair passing through the asymptotic giant branch phase. The jets may be generated by an accretion disk surrounding the resulting white dwarf star. Additionally, an analysis of Gaia data suggests that the central star is binary.>>

That can't be it. It's not in the right place.

Ann

You're right! Instead, it seems to be Abell 1. From https://www.swagastro.com/ngc7822.html, see https://www.swagastro.com/uploads/2/3/3 ... abel_1.jpg

[neufer]

• NGC 7354

That can't be it. It's not in the right place.

You're right! Instead, it seems to be Abell 1. From https://www.swagastro.com/ngc7822.html, see https://www.swagastro.com/uploads/2/3/3 ... abel_1.jpg

Art-i-fact: I'm right that it is a real planetary nebula (that is OIII blue in the Hubble Palette).

Ann's right that it is not NGC 7354 (but wrong that "the blue patch is a photographic artifact").

https://www.astrobin.com/3dqpn3/?nc=user

<<The Abell Catalog of Planetary Nebulae was created in 1966 by George O. Abell and was composed of 86 entries thought to be planetary nebulae that were collected from discoveries, about half by Albert George Wilson and the rest by Abell, Robert George Harrington, and Rudolph Minkowski. All were discovered before August 1955 as part of the National Geographic Society – Palomar Observatory Sky Survey on photographic plates created with the 48-inch Samuel Oschin telescope at Mount Palomar. Four are better known from previous catalogs: Abell 50 is NGC 6742, Abell 75 is NGC 7076, Abell 37 is IC 972, and Abell 81 is IC 1454. Another four were later rejected as not being planetaries: Abell 11 (reflection nebula), Abell 32 (red plate flaw), Abell 76 (ring galaxy PGC 85185), and Abell 85 (supernova remnant CTB 1 and noted as possibly such in Abell's 1966 paper). Another three were also not included in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (SEC): Abell 9, Abell 17 (red plate flaw), and Abell 64.[3] Planetaries on the list are best viewed with a large aperture telescope (e.g. 18-inch) and an OIII filter.>>

[johnnydeep]

That can't be it. It's not in the right place.

You're right! Instead, it seems to be Abell 1. From https://www.swagastro.com/ngc7822.html, see https://www.swagastro.com/uploads/2/3/3 ... abel_1.jpg

Art-i-fact: I'm right that it is a real planetary nebula (that is blue in the Hubble Palette).

Ann's right that it is not NGC 7354 (but wrong that "the blue patch is a photographic artifact").

https://www.astrobin.com/3dqpn3/?nc=user

And from http://cosmicneighbors.net/qmark.htm, the "dot" of the question mark is Sharpless 170. There's also a nice big annotated pic there - http://cosmicneighbors.net/qmark-big.jpg

[Ann]

• NGC 7354

That can't be it. It's not in the right place.

Ann

You're right! Instead, it seems to be Abell 1. From https://www.swagastro.com/ngc7822.html, see https://www.swagastro.com/uploads/2/3/3 ... abel_1.jpg

Right, thanks! I couldn't find it, because my software wouldn't show it to me. But when I asked it to take me to Abell 1, it took me to the right place, but still didn't show me anything but black space.

Well, in my defense, I did suggest that the blue patch might be a planetary, but I just couldn't find a planetary in the right position.

Ann

[kybergreg]

Hey, great! That was an impressive investigation (at least for me)! Thanks for identifying it. I was starting to think that it is a photographer's easter egg
And thanks Ann for pointing out that Cepheus is not in the ecliptic plane so the blue patch can't be Uranus or Neptune. That should have come to my mind in the first place. One is always learning.

[Hartmut]

Thank you for solving the riddle.

[yzhzhang]

Hi all,

Original author of this image here. I am flattered to be elected as the IOTD and I am happy it creating a discussion here!

I also immediately noticed "blue dot" on the upper left corner during processing, and I did my own research a bit as well. You guys are correct that it is indeed the Abell-1!

Thanks all for your interest.

Yizhou

[johnnydeep]

Ok, here's another possible riddle: what's the round fuzzy patch on the far left edge about two thirds down from the top edge? It appears to have a bright star at its center, but that might just be a coincidence:

Another mysterious object?

[alter-ego]

Ok, here's another possible riddle: what's the round fuzzy patch on the far left edge about two thirds down from the top edge? I appears to have a bright star at its center, but that might just be a coincidence:


another planetary nebula.JPG

Star with reflection nebula: VdB 2
Star ID: HIP 1077 (one of several IDs)

This image shows an area of the constellation Cassiopeia near the border with Cepheus, about 1.5 degrees southeast of the nebulous complex NGC 7822 (or Sh2 - 171), which northern part is visible in the lower right corner. In the lower left makes its appearance another Sharpless object: Sh2 - 170 (or LBN 577). VdB 2 (also known as Ced 1) is a small reflection nebula, which is illuminated by the 10 mag. blue-white main sequence star HIP 1077. The nebula reflects the blue light of the star, taking itself a bluish color; the surrounding regions show signs of darkening by non-illuminated dust. The distance to VdB 2 is estimated to be 1100 parsecs (about 3590 light years).

[johnnydeep]

Ok, here's another possible riddle: what's the round fuzzy patch on the far left edge about two thirds down from the top edge? I appears to have a bright star at its center, but that might just be a coincidence:


another planetary nebula.JPG

Star with reflection nebula: VdB 2
Star ID: HIP 1077 (one of several IDs)

This image shows an area of the constellation Cassiopeia near the border with Cepheus, about 1.5 degrees southeast of the nebulous complex NGC 7822 (or Sh2 - 171), which northern part is visible in the lower right corner. In the lower left makes its appearance another Sharpless object: Sh2 - 170 (or LBN 577). VdB 2 (also known as Ced 1) is a small reflection nebula, which is illuminated by the 10 mag. blue-white main sequence star HIP 1077. The nebula reflects the blue light of the star, taking itself a bluish color; the surrounding regions show signs of darkening by non-illuminated dust. The distance to VdB 2 is estimated to be 1100 parsecs (about 3590 light years).

Thanks. But, as usual, I failed at trying to line the two images up.

Vdb2?

[alter-ego]

Ok, here's another possible riddle: what's the round fuzzy patch on the far left edge about two thirds down from the top edge? I appears to have a bright star at its center, but that might just be a coincidence:


another planetary nebula.JPG

Star with reflection nebula: VdB 2
Star ID: HIP 1077 (one of several IDs)

This image shows an area of the constellation Cassiopeia near the border with Cepheus, about 1.5 degrees southeast of the nebulous complex NGC 7822 (or Sh2 - 171), which northern part is visible in the lower right corner. In the lower left makes its appearance another Sharpless object: Sh2 - 170 (or LBN 577). VdB 2 (also known as Ced 1) is a small reflection nebula, which is illuminated by the 10 mag. blue-white main sequence star HIP 1077. The nebula reflects the blue light of the star, taking itself a bluish color; the surrounding regions show signs of darkening by non-illuminated dust. The distance to VdB 2 is estimated to be 1100 parsecs (about 3590 light years).

Thanks. But, as usual, I failed at trying to line the two images up.

Looks like I grabbed the brighter blue star/nebula which is wrong. The nebula your arrow points to is not obvious and I didn't see that the centralized star is the source of the nebula's glow. Simbad identifies the star as MacC E without other identifiers that I can find. I think MacC is after a Darrel MacConnell, and his 1968 paper where he identified 127 objects within the Cephius IV Association
(A Study of the Cepheus IV Association)
Anyway, a separate search around MacC E yields only one candidate nebula (HII) that's very well positioned: NAME Teutsch GN J0018.0+6549 is only 8.6" away from the star. The 2MASS view below shows the nebulosity amongst star field better. It is oriented the same as the APOD, and has a 4' x 4' FoV. (I added the dashed circle to outline the nebula)
 

The candidate HII region is the best match, at least in location.

[alter-ego]

...
The 2MASS view below shows the nebulosity amongst star field better. It is oriented the same as the APOD, and has a 4' x 4' FoV.
...

I've added a larger FoV image to help you locate stars common to the APOD. This image has ½°field of view, and like the APOD and my previously posted zoomed in image, the orientations are very close, if not the same.
 

[johnnydeep]

...
The 2MASS view below shows the nebulosity amongst star field better. It is oriented the same as the APOD, and has a 4' x 4' FoV.
...

I've added a larger FoV image to help you locate stars common to the APOD. This image has ½°field of view, and like the APOD and my previously posted zoomed in image, the orientations are very close, if not the same.
 
MacC E with Nebula_½° x ½°FoV .jpg

Thanks! That's definitely the same object.