APOD: Messier 104 (2022 Apr 23)

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APOD: Messier 104 (2022 Apr 23)

Post by APOD Robot » Sat Apr 23, 2022 4:05 am

Image Messier 104

Explanation: A gorgeous spiral galaxy, Messier 104 is famous for its nearly edge-on profile featuring a broad ring of obscuring dust lanes. Seen in silhouette against an extensive central bulge of stars, the swath of cosmic dust lends a broad brimmed hat-like appearance to the galaxy suggesting a more popular moniker, the Sombrero Galaxy. This sharp view of the well-known galaxy was made from over 10 hours of Hubble Space Telescope image data, processed to bring out faint details often lost in the overwhelming glare of M104's bright central bulge. Also known as NGC 4594, the Sombrero galaxy can be seen across the spectrum, and is host to a central supermassive black hole. About 50,000 light-years across and 28 million light-years away, M104 is one of the largest galaxies at the southern edge of the Virgo Galaxy Cluster. Still, the spiky foreground stars in this field of view lie well within our own Milky Way.

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Re: APOD: Messier 104 (2022 Apr 23)

Post by Patrick70 » Sat Apr 23, 2022 4:29 am

I noticed, about 1/3 of the way from the left, along the bottom edge, what appeared to be a pair of interacting spiral galaxies. Do they have a popular name, or just their NGC designations?

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Re: APOD: Messier 104 (2022 Apr 23)

Post by Ann » Sat Apr 23, 2022 4:57 am

Patrick70 wrote: Sat Apr 23, 2022 4:29 am I noticed, about 1/3 of the way from the left, along the bottom edge, what appeared to be a pair of interacting spiral galaxies. Do they have a popular name, or just their NGC designations?
Background spiral galaxies south of M104 Hubble.png
Background galaxies, crop from Wikipedia.
Background galaxies Sombrero crop from APOD April 23 2022.png

Yes, there is a quite lovely pair of interacting spiral galaxies south of the Sombrero galaxy. These background spiral galaxies are elegantly shaped, very similar in appearance, richly starforming, and high in surface brightness.

Do they have a designation? Of course. But I can guarantee that they don't have an NGC designation, because they are way, way too faint for that. They don't seem well known at all, either, so they probably don't have a popular name (but they may have a nickname that is not so well known).

They are undoubtedly listed in some kind of catalog, but I can't tell you which one.

Ann
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Re: APOD: Messier 104 (2022 Apr 23)

Post by Ann » Sat Apr 23, 2022 6:11 am


M104 is the Saturn of galaxies! 🪐 :D

Disk of M104 from APOD April 23 2022.png
Individual bluish stars and clusters can be seen in the disk of M104.
Cen A M82 M87 M96 M104 annotated GALEX.png
M104 is an overall very yellow galaxy. Image from GALEX.

Today's APOD reveals bluish - ish, mind you - stars and possible open clusters in the disk of M104.

But the popular Sombrero hat galaxy is really quite yellow. Take a look at the picture at right, which shows several galaxies in ultraviolet light, taken by NASA's now defunct ultraviolet-detecting GALEX space telescope.

The galaxies are ordered from left to right according to how ultraviolet they are. To the left they are more ultraviolet. To the right they are less ultraviolet. The more ultraviolet they are, the bluer they are, and the less ultraviolet they are, the yellower they are.

In the top row you can see Cen A. Cen A consists of a spiral galaxy that is crashing into an elliptical galaxy, and a lot of stars are forming along one edge of the spiral galaxy's dust lane. These hot young stars produce huge amounts of ultraviolet light, but the elliptical component of Cen A is "all yellow".

At far left in the second row is supergiant elliptical galaxy M87. But how can an elliptical galaxy be so ultraviolet, when it contains no hot blue stars? The answer is that the mighty jet launched by the accretion disk surrounding the enormous black hole of M87 contains huge amounts of energy at all sorts of wavelengths, among them ultraviolet.

The middle picture in the second row shows M82. In spite of what the apparently bluish disk of M82 seen in the Hubble image that I link to leads you to believe, the disk of M82 is basically "all yellow" with negligible amounts of star formation. This is confirmed by GALEX. But the huge two-lobed cloud of gas rising from the starbursting center of M82, which we are used to seeing as red from hydrogen alpha, is all blue in the GALEX image due to ultraviolet light from the giant clusters of hot stars in M82's center. (It could also be that the violent launching of hydrogen gas from the galaxy's center in itself creates ultraviolet light.)

At far right in the middle row is M104. It looks all yellow in the GALEX image.

At far left in the bottom row is M96. M96 is a fairly yellow galaxy, but it does indeed contain a number of hot stars in its arms and in a ring around its center.


How did M104 get the way it is?
Jason Major of Universe Today wrote:

The Sombrero galaxy has a split personalty, according to recent observations by NASA’s Spitzer Space Telescope. Infrared imaging has revealed a hazy elliptical halo of stars enveloping a dual-structured inner disk; before this, the Sombrero galaxy was thought to be only disk-shaped...

Spitzer discerned that the flat disk within the galaxy is made up of two sections — an inner disk composed almost entirely of stars with no dust, and an outer ring containing both dust and stars...

“The Sombrero is more complex than previously thought,” said Dimitri Gadotti of the European Southern Observatory in Chile and lead author of the report. “The only way to understand all we know about this galaxy is to think of it as two galaxies, one inside the other.”

Although it might seem that the Sombrero is the result of a collision between two separate galaxies, that’s actually not thought to be the case. Such an event would have destroyed the disk structure that’s seen today; instead, it’s thought that the Sombrero accumulated a lot of extra gas billions of years ago when the Universe was populated with large clouds of gas and dust. The extra gas fell into orbit around the galaxy, eventually spinning into a flattened disk and forming new stars.

So the Sombrero galaxy accumulated a lot of gas that fell into orbit around the galaxy, eventually spinning into a flattened disk (and forming new stars).

Doesn't it sound like the rings of Saturn?

Ann
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Re: APOD: Messier 104 (2022 Apr 23)

Post by AVAO » Sat Apr 23, 2022 9:47 am

Ann wrote: Sat Apr 23, 2022 4:57 am
Patrick70 wrote: Sat Apr 23, 2022 4:29 am I noticed, about 1/3 of the way from the left, along the bottom edge, what appeared to be a pair of interacting spiral galaxies. Do they have a popular name, or just their NGC designations?
They are undoubtedly listed in some kind of catalog, but I can't tell you which one.

Ann
in SIMBAD the mini-ensemble of 4 to 5 galaxies is not recorded. Under 2MASS and Gaia there are only cryptid numbers.

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Re: APOD: Messier 104 (2022 Apr 23)

Post by AVAO » Sat Apr 23, 2022 10:09 am

Ann wrote: Sat Apr 23, 2022 6:11 am
M104 is the Saturn of galaxies! 🪐 :D

Ann
Exciting comparison. Saturn has 82 moons. M104 has about 2000 globular clusters.
"Highlighted (squares) are all of the Sombrero’s brightest globular clusters, ranging in magnitudes from 17.5 to 22+."
https://secure2.pbase.com/rolfolsen/ima ... 6/original
About 20% of the globular clusters are also visible in X-ray.
About 40% of X-ray sources have an equivalent in visible light.

Image
https://live.staticflickr.com/65535/520 ... d203_k.jpg
Original data source / annotation golbular clusters [white]: Rolf Olsen
Original data source für X-ray sources [blue]: NASA / Chandra Space Telescope
Collage: jac berne (flickr)
Last edited by AVAO on Sat Apr 23, 2022 8:41 pm, edited 2 times in total.

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Re: APOD: Messier 104 (2022 Apr 23)

Post by orin stepanek » Sat Apr 23, 2022 12:40 pm

.jpg
Si, Si, Si, Sombrero!! :shock:
M104_HST_final2_4096.jpg
Love this Galaxy! Looks like it has many rings, (Arms) 8-)
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Re: APOD: Messier 104 (2022 Apr 23)

Post by johnnydeep » Sat Apr 23, 2022 8:57 pm

AVAO wrote: Sat Apr 23, 2022 9:47 am
Ann wrote: Sat Apr 23, 2022 4:57 am
Patrick70 wrote: Sat Apr 23, 2022 4:29 am I noticed, about 1/3 of the way from the left, along the bottom edge, what appeared to be a pair of interacting spiral galaxies. Do they have a popular name, or just their NGC designations?
They are undoubtedly listed in some kind of catalog, but I can't tell you which one.

Ann
in SIMBAD the mini-ensemble of 4 to 5 galaxies is not recorded. Under 2MASS and Gaia there are only cryptid numbers.
Four or five? Ok, checking more closely, you may be right! This is from the full 13500 x 8592 pixel image:

pair of interacting background galaxies near sombrero.png

Or are 4 and 5 even more distant, and I guess there might be some hints of smaller galaxies almost embedded near 2 and 3?
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Re: APOD: Messier 104 (2022 Apr 23)

Post by VictorBorun » Sun Apr 24, 2022 7:40 am

orin stepanek wrote: Sat Apr 23, 2022 12:40 pm Si, Si, Si, Sombrero!!
Love this Galaxy! Looks like it has many rings, (Arms)
I wonder why Saturn's disk is so thin and so devoid of any radial or spiral waves (arms).
Is it because the mass of Saturn's Sombrero is so well contained inside the core area?
Is it because the Saturn is so starved when it comes to devouring a blob from its disk and spitting a pair of jets in the plane of the disk?

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Re: APOD: Messier 104 (2022 Apr 23)

Post by VictorBorun » Sun Apr 24, 2022 8:07 am

Ann wrote: Sat Apr 23, 2022 6:11 am
Cen A M82 M87 M96 M104 annotated GALEX.png
Cen A M82 M87 M96 M104 annotated GALEX.png
I wish we did something better with color mapping.
I wish we could see a more telling representation of the temperature and the fluorescence.
To make Sun green, a red dwarf red, a blue giant blue.
To make far UV and its fluorescent narrow-band companions like Hα spooky purple
Like this:

near infrared → RGB red #ff0000 ███
red → RGB orange #ff8000 ███
green → RGB yellow #4000ff ███
blue → RGB green #00ff00 ███
violet → RGB cyan #00ffff ███
near ultraviolet → RGB blue #0000ff ███
far UV and its fluorescent narrow-band companions like Hα → RGB purple #8000ff ███
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Re: APOD: Messier 104 (2022 Apr 23)

Post by Chris Peterson » Sun Apr 24, 2022 1:23 pm

VictorBorun wrote: Sun Apr 24, 2022 8:07 am
Ann wrote: Sat Apr 23, 2022 6:11 am Cen A M82 M87 M96 M104 annotated GALEX.png
Cen A M82 M87 M96 M104 annotated GALEX.png
I wish we did something better with color mapping.
I wish we could see a more telling representation of the temperature and the fluorescence.
To make Sun green, a red dwarf red, a blue giant blue.
To make far UV and its fluorescent narrow-band companions like Hα spooky purple
Like this:

near infrared → RGB red #ff0000 ███
red → RGB orange #ff8000 ███
green → RGB yellow #4000ff ███
blue → RGB green #00ff00 ███
violet → RGB cyan #00ffff ███
near ultraviolet → RGB blue #0000ff ███
far UV and its fluorescent narrow-band companions like Hα → RGB purple #8000ff ███
Mostly, you can't. Because color mapped images only provide limited additional information, given that we see colors, not wavelengths. Mix your red and green and you get yellow, mix your red and blue and you get purple. How would you tell the difference between separate red and blue or pure purple?

In the end, if you want to really learn something about an object, you need to view each channel separately, as a grayscale or pseudocolor image.
Chris

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Re: APOD: Messier 104 (2022 Apr 23)

Post by Ann » Mon Apr 25, 2022 4:33 am

johnnydeep wrote: Sat Apr 23, 2022 8:57 pm
AVAO wrote: Sat Apr 23, 2022 9:47 am
Ann wrote: Sat Apr 23, 2022 4:57 am

They are undoubtedly listed in some kind of catalog, but I can't tell you which one.

Ann
in SIMBAD the mini-ensemble of 4 to 5 galaxies is not recorded. Under 2MASS and Gaia there are only cryptid numbers.
Four or five? Ok, checking more closely, you may be right! This is from the full 13500 x 8592 pixel image:


Or are 4 and 5 even more distant, and I guess there might be some hints of smaller galaxies almost embedded near 2 and 3?

How irritating. I made a long post about the "twin background galaxies near M104", which I will henceforth call "the twins". 👯‍♀️
But my post disappeared. I guess I may have forgotten to submit it.

So let me try again. The interesting thing about Johnny's image is that galaxy #5 is so similar in size and shape to the twins, but its color is so strikingly different. Is #5 so redshift-reddened, because it is a lot more distant than the twins? But if so, how can #5 be almost as big as the twins if it is far in the background? Are the twins so tiny?


I think that the crop from an M104 portrait from Wikipedia gives us a better understanding.

Note in the Wikipedia crop the faintly reddish color of the extended outer arms or tidal tails of the twins. These features are made up of old yellow stars.

As for galaxy #5, its disk is clearly made up of old stars, too. This galaxy looks so red because we are looking at a redshift-reddened and rather faint stellar disk of intrinsically faint red and yellow stars. This is in stark contrast to the twins, whose inner arms are packed with brilliant blue and ultraviolet stars of an extremely high surface brightness.

But yes, I'm sure that the twins are intrinsically rather small, and smaller than galaxy #5. (Then again, I think galaxy #5 looks smaller in the Wikipedia crop than it does in Johnny's image, so that it is easier to accept that it is more distant than the twins.) I think the twins are similar to M83, if we disregard the fact that M83 is not interacting with a sibling galaxy:


According to ESO, the diameter of M83 is only 40,000 light-years, which is less than half the size of the Milky Way. I have seen another estimate that makes it larger, some 55,000 light-years, but in any case, M83 is a smallish galaxy.

I really think that the twins are small, too. Note in Johnny's picture how big the resolved clusters are, and how compact the galaxies themselves are compared with the clusters in them. I think that large galaxies are very rarely so full of great clusters "all over".


The Pinwheel Galaxy, M101, is an exception to the rule that richly starforming galaxies that are full of hot bright stars "all over" aren't large. But M101 is clearly a very different type of galaxy than the twins in the background of M104.

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Re: APOD: Messier 104 (2022 Apr 23)

Post by VictorBorun » Mon Apr 25, 2022 7:28 am

Chris Peterson wrote: Sun Apr 24, 2022 1:23 pm
VictorBorun wrote: Sun Apr 24, 2022 8:07 am I wish we did something better with color mapping.
I wish we could see a more telling representation of the temperature and the fluorescence.
To make Sun green, a red dwarf red, a blue giant blue.
To make far UV and its fluorescent narrow-band companions like Hα spooky purple
Mostly, you can't. Because color mapped images only provide limited additional information, given that we see colors, not wavelengths. Mix your red and green and you get yellow, mix your red and blue and you get purple. How would you tell the difference between separate red and blue or pure purple?

In the end, if you want to really learn something about an object, you need to view each channel separately, as a grayscale or pseudocolor image.
Well, the temperature of the stars is a scalar parameter, is not it? We have a sort of color chart for it, but it uses a short range of color hues, orange to cyan, and those colors are pale: the green peak in the spectrum of Sun is invisible altogether, and the cyan highland in the spectra of blue giants is pale and is the same even for very different temperatures, 10 thousand Kelvins or 40 thousand Kelvins.
We could compress an IR-to-UV range in a monotonic way to the red-to-blue range; then red dwarfs will be represented bright red and blue giants will be represented bright blue. And the central part of the peak in the spectrum of Sun will be complemented by the slopes in IR and UV, so Sun will be represented distinctly greenish.
All in all our color vision will be better applied to judge the temperatures.

As for Hα narrow-red, oxygen narrow-green and all the fluorescence of the gas under UV or fast matter winds, it's too complicated to put in the general view. So we better merge all the narrow-band fluorescence pics and represent them as one hue, outside the red-to-blue range. Maybe pink #ff00ff ███ rather than purple; pink is somewhat traditional for Hα

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Re: APOD: Messier 104 (2022 Apr 23)

Post by Chris Peterson » Mon Apr 25, 2022 1:19 pm

VictorBorun wrote: Mon Apr 25, 2022 7:28 am
Chris Peterson wrote: Sun Apr 24, 2022 1:23 pm
VictorBorun wrote: Sun Apr 24, 2022 8:07 am I wish we did something better with color mapping.
I wish we could see a more telling representation of the temperature and the fluorescence.
To make Sun green, a red dwarf red, a blue giant blue.
To make far UV and its fluorescent narrow-band companions like Hα spooky purple
Mostly, you can't. Because color mapped images only provide limited additional information, given that we see colors, not wavelengths. Mix your red and green and you get yellow, mix your red and blue and you get purple. How would you tell the difference between separate red and blue or pure purple?

In the end, if you want to really learn something about an object, you need to view each channel separately, as a grayscale or pseudocolor image.
Well, the temperature of the stars is a scalar parameter, is not it? We have a sort of color chart for it, but it uses a short range of color hues, orange to cyan, and those colors are pale: the green peak in the spectrum of Sun is invisible altogether, and the cyan highland in the spectra of blue giants is pale and is the same even for very different temperatures, 10 thousand Kelvins or 40 thousand Kelvins.
We could compress an IR-to-UV range in a monotonic way to the red-to-blue range; then red dwarfs will be represented bright red and blue giants will be represented bright blue. And the central part of the peak in the spectrum of Sun will be complemented by the slopes in IR and UV, so Sun will be represented distinctly greenish.
All in all our color vision will be better applied to judge the temperatures.

As for Hα narrow-red, oxygen narrow-green and all the fluorescence of the gas under UV or fast matter winds, it's too complicated to put in the general view. So we better merge all the narrow-band fluorescence pics and represent them as one hue, outside the red-to-blue range. Maybe pink #ff00ff ███ rather than purple; pink is somewhat traditional for Hα
Still, there's the problem that color is a physiological property, not a physical one, and we're stuck with both eyes and displays that assign that property based on just three primaries. When you mix wavelengths, you irreversibly convolve your data and lose much of the information. Mapped color produces pretty pictures, but at a high cost. Which is why mapped color images aren't generally used for scientific analysis.
Chris

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Re: APOD: Messier 104 (2022 Apr 23)

Post by johnnydeep » Mon Apr 25, 2022 2:50 pm

Ann wrote: Mon Apr 25, 2022 4:33 am
johnnydeep wrote: Sat Apr 23, 2022 8:57 pm
AVAO wrote: Sat Apr 23, 2022 9:47 am

in SIMBAD the mini-ensemble of 4 to 5 galaxies is not recorded. Under 2MASS and Gaia there are only cryptid numbers.
Four or five? Ok, checking more closely, you may be right! This is from the full 13500 x 8592 pixel image:


Or are 4 and 5 even more distant, and I guess there might be some hints of smaller galaxies almost embedded near 2 and 3?
...
So let me try again. The interesting thing about Johnny's image is that galaxy #5 is so similar in size and shape to the twins, but its color is so strikingly different. Is #5 so redshift-reddened, because it is a lot more distant than the twins? But if so, how can #5 be almost as big as the twins if it is far in the background? Are the twins so tiny?
...
Ann
Interesting reflections, Ann, but I believe that you're really talking about galaxy #4 from my crop, not #5. The #5 in mine was only a very hypothetical much smaller potential galaxy to the left of #4.
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Re: APOD: Messier 104 (2022 Apr 23)

Post by Ann » Mon Apr 25, 2022 3:07 pm

johnnydeep wrote: Mon Apr 25, 2022 2:50 pm
Ann wrote: Mon Apr 25, 2022 4:33 am
johnnydeep wrote: Sat Apr 23, 2022 8:57 pm

Four or five? Ok, checking more closely, you may be right! This is from the full 13500 x 8592 pixel image:


Or are 4 and 5 even more distant, and I guess there might be some hints of smaller galaxies almost embedded near 2 and 3?
...
So let me try again. The interesting thing about Johnny's image is that galaxy #5 is so similar in size and shape to the twins, but its color is so strikingly different. Is #5 so redshift-reddened, because it is a lot more distant than the twins? But if so, how can #5 be almost as big as the twins if it is far in the background? Are the twins so tiny?
...
Ann
Interesting reflections, Ann, but I believe that you're really talking about galaxy #4 from my crop, not #5. The #5 in mine was only a very hypothetical much smaller potential galaxy to the left of #4.
Of course. Stupid me! ☹️

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