APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

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APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by APOD Robot » Thu Feb 15, 2024 5:05 am

Image NGC 253: Dusty Island Universe

Explanation: Shiny NGC 253 is one of the brightest spiral galaxies visible, and also one of the dustiest. Some call it the Silver Coin Galaxy for its appearance in small telescopes, or just the Sculptor Galaxy for its location within the boundaries of the southern constellation Sculptor. Discovered in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral dust lanes, tendrils of dust seem to be rising from its galactic disk laced with young star clusters and star forming regions in this colorful galaxy portrait. The high dust content accompanies frantic star formation, earning NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massive black holes near the galaxy's center.

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by Ann » Thu Feb 15, 2024 7:47 am

Today's APOD is very nice "classic" portrait of NGC 253 that shows us the nitty gritty of this galaxy: the perfect oval outline of the disk, the yellow inner region, the blue disk, the occasional small pink dots of emission nebulas, and the chaotic jumble of broken dust lanes and dust clouds.

And speaking of the perfect outline of NGC 253...

NGC 253 as a coin.png
NGC 253 as a coin? NGC 253 is not called
the Silver Dollar galaxy for notning.


I can't stop talking about the perfect oval outline of NGC 253 just yet, because such a perfect shape is by no means a given thing among spiral galaxies.


How do we know that the Milky Way has an S-shaped disk? We know it because astronomers monitored more than 2,400 Milky Way Cepheid stars, whose true brightness can be reliably inferred from their pulsations, to discover that the Cepheids create an S-shaped outline of our galaxy's disk. Read about it here.


Let's get back to NGC 253. There is a link in today's caption that takes us to a great Hubble image of the chaotic dust in the disk of NGC 253:

NGC253-HST-Gendler3M[1].jpg
Dust in the disk of NGC 253. Credit:
Hubble Legacy Archive, ESA, NASA; Processing and additional imaging: Robert Gendler

Yes, but I also like this picture of the core of NGC by R. Jay GaBany. Have you ever seen such an incredible number of smoking "chimneys" rising from a galactic disk?


The fact that there is such a lot of dust in the disk of NGC 53, and the fact that the dust is so chaotic, strongly suggests that some very energetic events have taken place in NGC 253. Like a lot of star formation. Indeed, NGC 253 is classified as a starburst galaxy, and yet we see no obvious signs of a huge starburst. There are no strikingly large blue star clusters in NGC 253 and no unusually big bright pink emission nebulas. And NGC 253 looks so different from many other starburst galaxies - just compare it to M61:


The reason why we see so little of the starburst in NGC 253 is that the thick of the action is taking place in the galaxy's very core:


The core starburst of NGC 253 is perhaps similar to the core starburst in M82. Obviously the core of M82 appears to be even more energetic and violent than the core of NGC 253. And in M82, the disk itself is somewhat warped, we see no visual signs of any spiral shape in the disk, and the disk is completely devoid of any blue star clusters of pink emission nebulas.


Let's get back to NGC 253 again. Unlike M82, it has not been "destroyed" a s a spiral galaxy, because we can make out a spiral shape in the disk of it - it's not easy, but we can. And we can indeed see modest amounts of star formation in the disk. And of course, NGC 253 is the king of its own gang, by far the largest of the rather sparse Sculptor group of galaxies. By contrast, M82 is taking punch after punch from the nearby big bully of its galaxy group, M81!

But I want to end my post on NGC 253 with an absolutely glorious picture of this galaxy by Mark Hanson. There may be more star formation in NGC 253 than we can readily see because of all the dust, and exposing NGC 253 through an Hα filter may bring out a lot of it for us. Mark Hanson did just that and brought out so much rosy red light in NGC 253 that the galaxy looks fit for Valentine gift, even if today is one day late! ❤️


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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by Christian G. » Thu Feb 15, 2024 2:10 pm

A glass may appear half empty or half full, and this island universe may appear dusty or starry! Way more starry to me!
(also the caption mentions the presence near its center of massive black holes - plural form! There must be some crazy dynamics over there...)

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by johnnydeep » Thu Feb 15, 2024 2:42 pm

The "colorful galaxy portrait" link to the source image says NGC 253 is 27.5' x 6.8' in angular extent (those are arcmins). And since the full Moon is about 31 arcmins wide (0.5°), that makes NGC 253 about the same size! For comparison, the Andromeda galaxy is about 3° wide, or 6 full Moons, which makes sense since Andromeda is a quarter the distance at 2.5 Mly, and about twice as large. (Yes, technically, that should then make it appear 8 times larger, not 6, but it's close enough for astrophotographic work.😉)
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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by johnnydeep » Thu Feb 15, 2024 5:14 pm

It's not obvious to me that the "dusty pillars" "rising up" from the disk of NGC 253 are actually perpendicular to the plane of the galaxy and not simply striations within it. How is it proven that they're perpendicular? Is it just that there's no known mechanism for creating such stripes within a galaxy's arms?
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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by AVAO » Thu Feb 15, 2024 8:59 pm

Ann wrote: Thu Feb 15, 2024 7:47 am Today's APOD is very nice "classic" portrait of NGC 253 that shows us the nitty gritty of this galaxy: the perfect oval outline of the disk, the yellow inner region, the blue disk, the occasional small pink dots of emission nebulas, and the chaotic jumble of broken dust lanes and dust clouds.

And speaking of the perfect outline of NGC 253...

NGC 253 as a coin.png
NGC 253 as a coin? NGC 253 is not called
the Silver Dollar galaxy for notning.
I can't stop talking about the perfect oval outline of NGC 253 just yet, because Image is by no means a given thing among spiral galaxies.
...

Ann
ThanX Ann

I would put that into perspective a bit. In the optical wavelengths, perhaps yes. If we compare with other wavelengths like IR, the oval shape suddenly looks anything but oval and the galaxy is suddenly barred too...

Jac

NGC 253: UV_blue (GALEX), IR_green (JWST), X-Ray_red (CHANDRA) , free aristic composit jac berne (flickr)

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by johnnydeep » Thu Feb 15, 2024 10:23 pm

AVAO wrote: Thu Feb 15, 2024 8:59 pm
Ann wrote: Thu Feb 15, 2024 7:47 am Today's APOD is very nice "classic" portrait of NGC 253 that shows us the nitty gritty of this galaxy: the perfect oval outline of the disk, the yellow inner region, the blue disk, the occasional small pink dots of emission nebulas, and the chaotic jumble of broken dust lanes and dust clouds.

And speaking of the perfect outline of NGC 253...

NGC 253 as a coin.png
NGC 253 as a coin? NGC 253 is not called
the Silver Dollar galaxy for notning.
I can't stop talking about the perfect oval outline of NGC 253 just yet, because Image is by no means a given thing among spiral galaxies.
...

Ann
ThanX Ann

I would put that into perspective a bit. In the optical wavelengths, perhaps yes. If we compare with other wavelengths like IR, the oval shape suddenly looks anything but oval and the galaxy is suddenly barred too...

Jac

NGC 253: UV_blue (GALEX), IR_green (JWST), X-Ray_red (CHANDRA) , free aristic composit jac berne (flickr)
Now that's cool! There even seems to be some sort of plume of reddish "stuff" projecting perpendicular from the core.
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"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by Ann » Fri Feb 16, 2024 5:22 am

johnnydeep wrote: Thu Feb 15, 2024 10:23 pm
AVAO wrote: Thu Feb 15, 2024 8:59 pm
Ann wrote: Thu Feb 15, 2024 7:47 am Today's APOD is very nice "classic" portrait of NGC 253 that shows us the nitty gritty of this galaxy: the perfect oval outline of the disk, the yellow inner region, the blue disk, the occasional small pink dots of emission nebulas, and the chaotic jumble of broken dust lanes and dust clouds.

And speaking of the perfect outline of NGC 253...

NGC 253 as a coin.png
NGC 253 as a coin? NGC 253 is not called
the Silver Dollar galaxy for notning.
I can't stop talking about the perfect oval outline of NGC 253 just yet, because Image is by no means a given thing among spiral galaxies.
...

Ann
ThanX Ann

I would put that into perspective a bit. In the optical wavelengths, perhaps yes. If we compare with other wavelengths like IR, the oval shape suddenly looks anything but oval and the galaxy is suddenly barred too...

Jac

NGC 253: UV_blue (GALEX), IR_green (JWST), X-Ray_red (CHANDRA) , free aristic composit jac berne (flickr)
Now that's cool! There even seems to be some sort of plume of reddish "stuff" projecting perpendicular from the core.
Thanks, Jac, and good catch, Johnny! That makes NGC 253 similar to M82 in one more way - it is already similar because it has a core starburst - but NGC 253 has a core outflow, too!

There is a third galaxy that is similar to NGC 253 and M82 in that it has a core starburst and a core outflow, namely NGC 1808. Its core outflow is not all that visible, but it is there, and it is also caused by a core starburst.

Wikipedia wrote about NGC 1808:

The core region contains a suspected weak active galactic nucleus plus a circumnuclear ring containing star clusters and supernova remnants at a distance of ~280 pc from the center. These form a ring of peculiar "hot spots". It was formerly identified as a possible Seyfert galaxy, but evidence now points to starburst activity in a ~500 pc radius around the center. A probable outflow of gas is directed to the north-east from the nucleus, forming prominent dust lanes.

There is actually a fourth galaxy with a very visible starburst in its center and a possible outflow, name NGC 3077. But that small elliptical galaxy has an active nucleus, or so they say, so maybe a black hole is at least partly responsible for the outflow (if there is one). But I would be surprised if the large starburst that we can see, and the supernovas that inevitably follow it, don't play a part in driving a core outflow in this galaxy.

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by AVAO » Fri Feb 16, 2024 6:11 am

Ann wrote: Fri Feb 16, 2024 5:22 am
johnnydeep wrote: Thu Feb 15, 2024 10:23 pm
AVAO wrote: Thu Feb 15, 2024 8:59 pm

ThanX Ann

I would put that into perspective a bit. In the optical wavelengths, perhaps yes. If we compare with other wavelengths like IR, the oval shape suddenly looks anything but oval and the galaxy is suddenly barred too...

Jac

NGC 253: UV_blue (GALEX), IR_green (JWST), X-Ray_red (CHANDRA) , free aristic composit jac berne (flickr)
Now that's cool! There even seems to be some sort of plume of reddish "stuff" projecting perpendicular from the core.
Thanks, Jac, and good catch, Johnny! That makes NGC 253 similar to M82 in one more way - it is already similar because it has a core starburst - but NGC 253 has a core outflow, too!

There is a third galaxy that is similar to NGC 253 and M82 in that it has a core starburst and a core outflow, namely NGC 1808. Its core outflow is not all that visible, but it is there, and it is also caused by a core starburst.

Wikipedia wrote about NGC 1808:

The core region contains a suspected weak active galactic nucleus plus a circumnuclear ring containing star clusters and supernova remnants at a distance of ~280 pc from the center. These form a ring of peculiar "hot spots". It was formerly identified as a possible Seyfert galaxy, but evidence now points to starburst activity in a ~500 pc radius around the center. A probable outflow of gas is directed to the north-east from the nucleus, forming prominent dust lanes.

There is actually a fourth galaxy with a very visible starburst in its center and a possible outflow, name NGC 3077. But that small elliptical galaxy has an active nucleus, or so they say, so maybe a black hole is at least partly responsible for the outflow (if there is one). But I would be surprised if the large starburst that we can see, and the supernovas that inevitably follow it, don't play a part in driving a core outflow in this galaxy.

Ann

ThanX Ann for the exciting comparison!

I think there is a connection between the bipolar nuclear outflow (in red in the X-ray) and the rising dust column phenomenon described by Johnny, although I wouldn't go so far as to say that NGC 253 is in a preliminary phase to M82.

Click to view full size image 1 or image 2
IR (SPITZER/JWST) and X-ray (CHANDRA) jac berne (flickr)

Click to view full size image 1 or image 2
IR/X-ray (SPITZER/JWST/CHANDRA) and Optical (HST) jac berne (flickr)

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by Ann » Fri Feb 16, 2024 7:08 am

AVAO wrote: Fri Feb 16, 2024 6:11 am
Ann wrote: Fri Feb 16, 2024 5:22 am
johnnydeep wrote: Thu Feb 15, 2024 10:23 pm

Now that's cool! There even seems to be some sort of plume of reddish "stuff" projecting perpendicular from the core.
Thanks, Jac, and good catch, Johnny! That makes NGC 253 similar to M82 in one more way - it is already similar because it has a core starburst - but NGC 253 has a core outflow, too!

There is a third galaxy that is similar to NGC 253 and M82 in that it has a core starburst and a core outflow, namely NGC 1808. Its core outflow is not all that visible, but it is there, and it is also caused by a core starburst.

Wikipedia wrote about NGC 1808:

The core region contains a suspected weak active galactic nucleus plus a circumnuclear ring containing star clusters and supernova remnants at a distance of ~280 pc from the center. These form a ring of peculiar "hot spots". It was formerly identified as a possible Seyfert galaxy, but evidence now points to starburst activity in a ~500 pc radius around the center. A probable outflow of gas is directed to the north-east from the nucleus, forming prominent dust lanes.

There is actually a fourth galaxy with a very visible starburst in its center and a possible outflow, name NGC 3077. But that small elliptical galaxy has an active nucleus, or so they say, so maybe a black hole is at least partly responsible for the outflow (if there is one). But I would be surprised if the large starburst that we can see, and the supernovas that inevitably follow it, don't play a part in driving a core outflow in this galaxy.

Ann

ThanX Ann for the exciting comparison!

I think there is a connection between the bipolar nuclear outflow (in red in the X-ray) and the rising dust column phenomenon described by Johnny, although I wouldn't go so far as to say that NGC 253 is in a preliminary phase to M82.

Click to view full size image 1 or image 2
IR (SPITZER/JWST) and X-ray (CHANDRA) jac berne (flickr)

Click to view full size image 1 or image 2
IR/X-ray (SPITZER/JWST/CHANDRA) and Optical (HST) jac berne (flickr)
I just found another galaxy with a core starburst and a core outflow!

Hubblesite wrote:

The picture at left shows the bubble in the center of the galaxy's disk. The structure is more than 3,000 light-years wide and rises 3,500 light-years above the galaxy's disk. The smaller photo at right is a close-up view of the bubble. Astronomers suspect that the bubble is being blown by "winds" (high-speed streams of particles) released during a burst of star formation.
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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by Ann » Fri Feb 16, 2024 7:38 am

AVAO wrote: Fri Feb 16, 2024 6:11 am
ThanX Ann for the exciting comparison!

I think there is a connection between the bipolar nuclear outflow (in red in the X-ray) and the rising dust column phenomenon described by Johnny, although I wouldn't go so far as to say that NGC 253 is in a preliminary phase to M82.

Click to view full size image 1 or image 2
IR (SPITZER/JWST) and X-ray (CHANDRA) jac berne (flickr)

Click to view full size image 1 or image 2
IR/X-ray (SPITZER/JWST/CHANDRA) and Optical (HST) jac berne (flickr)
Thanks, Jac! :D

I agree that we have no particular reason to think that NGC 253 is evolving into a galaxy similar to M82. NGC 253 and M82 are two quite different galaxies, and they certainly "live in very different environments".

However, I suspect that core outflows from galaxies may happen from time to time, but I also think that they are transient phenomena. Consider the X-ray bubbles of the Milky Way:

X ray bubbles of the Milky Way E Rosita.png
X-ray bubbles of the Milky Way. They are clearly remnants
of a highly energetic outflow from the center of of galaxy in the past.

The core of our own galaxy is quiet now, and no major outflow is taking place (and possibly no minor outflow, either). I would guess that many galaxies may undergo short episodes of core outflows from time to time.

A special case of galactic outflows is caused by ram pressure, when a galaxy falls through the gravitational field and intergalactic gas of a galactic cluster and has its gas stripped away when it meets the "headwind" of the hot intergalactic medium.


Sci News wrote:

A long streamer of hydrogen gas is being stripped from a spiral galaxy called D100 as it plunges toward the center of the Coma cluster (also known as Abell 1656), a large group of galaxies approximately 330 million light-years away in the northern constellation of Coma Berenices. Eventually, D100 will lose all of its gas and become a dead relic, deprived of the material to create new stars and shining only by the feeble glow of old, red stars...
...
The new Hubble data show that the gas-stripping process began on D100’s outskirts and is moving in towards the center, which is typical in this type of mass loss.

Based on the Hubble images, the gas has been cleared out all the way down to the central 6,400 light-years.

Within that central region, there is still a lot of gas, as seen in a burst of star formation.

“This region is the only place in the galaxy where gas exists and star formation is taking place. But now that gas is being stripped out of the center, forming the long tail,” Dr. Cramer said.

Eventually galaxy D100, as well as, possibly, M82, will be depleted of gas altogether and turn into lenticular galaxies with very small amounts of dust and gas and no appreciable star formation.


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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by AVAO » Fri Feb 16, 2024 5:21 pm

Ann wrote: Fri Feb 16, 2024 7:38 am
...
However, I suspect that core outflows from galaxies may happen from time to time, but I also think that they are transient phenomena. Consider the X-ray bubbles of the Milky Way:
The core of our own galaxy is quiet now, and no major outflow is taking place (and possibly no minor outflow, either). I would guess that many galaxies may undergo short episodes of core outflows from time to time.
...

Ann
ThanX Ann
for your wonderful collection of galaxies with nuclear outflows.

However, I am critical when it comes to the article about the X-rax blubbles in our own galaxy.

Personally, I don't believe in a double bubble model. Many cosmic phenomena with double lobes are the result of bipolar jets in rotation or of the bipolar jets of more then one cores (black wholes, like in NGC 6240). Then the shapes are created like the calyx of a flower like the "core calyx" of NGC 3079, NGC 6240 or NGC 4438. (Also the corresponding bipolar outflow could be pulsed cyclically, but that's a hypothesis.)

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by johnnydeep » Fri Feb 16, 2024 6:13 pm

Very cool to see all the "dueling" posts with various images showing different types of "perpendicular core outflows". Thanks Ann and Jac!
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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by AVAO » Sat Feb 17, 2024 7:30 am

johnnydeep wrote: Fri Feb 16, 2024 6:13 pm Very cool to see all the "dueling" posts with various images showing different types of "perpendicular core outflows". Thanks Ann and Jac!
ThanX Johnny - “Dancing" black holes are also aesthetically beautiful to look at 8-) Jac

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Re: APOD: NGC 253: Dusty Island Universe (2024 Feb 15)

Post by Ann » Sat Feb 17, 2024 10:58 am

johnnydeep wrote: Fri Feb 16, 2024 6:13 pm Very cool to see all the "dueling" posts with various images showing different types of "perpendicular core outflows". Thanks Ann and Jac!
And I should say thank you too, just like AVAO did. I've been bad at thanking people for compliments people have given me for posts I have made.

Ironwood, if you are reading this, thank you so much for the great compliment you gave me!

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