APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

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APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby APOD Robot » Wed Jun 14, 2017 4:07 am

Image M89: Elliptical Galaxy with Outer Shells and Plumes

Explanation: Can you see them? This famous Messier object M89, a seemingly simple elliptical galaxy, is surrounded by faint shells and plumes. The cause of the shells is currently unknown, but possibly tidal tails related to debris left over from absorbing numerous small galaxies in the past billion years. Alternatively the shells may be like ripples in a pond, where a recent collision with another large galaxy created density waves that ripple through this galactic giant. Regardless of the actual cause, the featured image highlights the increasing consensus that at least some elliptical galaxies have formed in the recent past, and that the outer halos of most large galaxies are not really smooth but have complexities induced by frequent interactions with -- and accretions of -- smaller nearby galaxies. The halo of our own Milky Way Galaxy is one example of such unexpected complexity. M89 is a member of the nearby Virgo cluster of galaxies which lies about 50 million light years distant.

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Nighteyes » Wed Jun 14, 2017 4:39 am

What an amazing and beautiful photo. Very cool Galaxy!

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Wed Jun 14, 2017 7:10 am

Ripples in a pond. Source unknown.
Today's APOD is a very fine image of a fascinating galaxy. It has something to say about the formation of large galaxies, even though M89 is not one of the largest.

Galaxies grow large by gobbling up smaller ones. The shells around M89 can be compared with ripples in a pond, when a pebble (or a larger rock) has been thrown into it. Similarly, when a smaller galaxy plunges into a larger one, waves and ripples of stars are thrown outwards from the larger galaxy. (The smaller galaxy is usually absorbed.) Some of the thrown-out stars stay in their new position and create the shells that we see around M89.



Flocculent spiral galaxy NGC 4414 with huge shells.
Photo: Adam Block.
Image
Spiral galaxy NGC 2857 with long elegant arms.
Photo: ESO/NASA/IPAC


























But why is it that we only seem to see these shells around elliptical galaxies? Actually, shells are seen around some spiral galaxies, too. But to my knowledge, they don't exist around well-formed spiral galaxies with long, elegant arms. I would be very surprised if NGC 2857 was found to be surrounded by shells. Galaxies with long elegant spiral arms have probably been mostly undisturbed for a long time. Not many pebbles have plunged into their ponds.

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Boomer12k » Wed Jun 14, 2017 8:02 am

Thanks Ann for the commentary.

It looks like there was small galaxy, left over appears to be the straight "bar" of stars in upper right area, the shells are the splayed out remains... I figure. Shock of the encounter seems to have taken care of the rest... it is interesting, many times the "colliding" galaxy is the one that gets disrupted. Not the one getting "collided with"... I think M51 is an example. Many star streams and disruption to the smaller galaxy...

Maybe the structure of the larger one makes it calm down quicker... I don't know, but fun to think about.
But NOT seeing those streams and shells, and disruptions... in other photos, make you wonder about "missing mass"... even the Hubble Shot... click on M89 link...

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby starsurfer » Wed Jun 14, 2017 8:33 am

Wow awesome image, David Malin would be proud! To think there are even more elliptical galaxies with shells around them! The only criticism of this image is that it isn't north up with north to the left. The thing that looks like a jet is actually a tidal tail and to me seem indications that a small satellite galaxy that was captured and absorbed.

A challenge for Ann: try finding M89 in this widefield image by Fabian Neyer!

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Wed Jun 14, 2017 9:47 am

starsurfer wrote:A challenge for Ann: try finding M89 in this widefield image by Fabian Neyer!


Hey, it's at 7 o'clock in the large picture! The brightest shell and the curious tidal tail are quite obvious.

Thanks for the challenge! :D

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby starsurfer » Wed Jun 14, 2017 3:54 pm

Ann wrote:
starsurfer wrote:A challenge for Ann: try finding M89 in this widefield image by Fabian Neyer!


Hey, it's at 7 o'clock in the large picture! The brightest shell and the curious tidal tal is quite obvious.

Thanks for the challenge! :D

Ann

You're right on time! :D

douglas

Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby douglas » Wed Jun 14, 2017 11:10 pm

Was wondering ..

.. how do elliptical galaxies "know" to be discreet after undergoing mergers sufficient to the point of hiding their newly-acquired gas and dust and appearing "dim"? :)

And "discretion"-enough to appear older, even redder? :ssmile:

" .. elliptical galaxies are dim. Spiral galaxies are hotbeds of star formation, but elliptical galaxies are deader. They contain less gas and dust, which means fewer new (and brighter) stars are born. The existing stars inside an elliptical galaxy tend to be older .. "

And after living long enough to become "older", a discretion occurs where dust, from earlier supernova events, somehow becomes less detectable, counter-intuitive to the expectation that repeated mergers would increase dust stores? Is the Cosmos playing some kind of prank on human perceptions?

This link makes a point of Centaurus A "hiding" a spiral in its core, yet the picture does not conform to "dim" and whatever is in that core is certainly not dim: is the Cosmos playing tricks, or is it the presenters of ellipticals? :wink: Should I feel 'resentment' because they didn't include a reference for that spiral in the core, /sarc ?

"The giant elliptical galaxy Centaurus A shows a split personality because it hides a gaseous spiral at its core. When Centaurus A collided with a spiral galaxy 300 million years ago, it slurped up the spiral's gases, which formed a new spiral inside the larger galaxy."

https://www.space.com/22395-elliptical-galaxies.html

douglas

Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby douglas » Thu Jun 15, 2017 12:17 am

Galaxies of the earliest epochs being studied:

https://www.space.com/29123-ancient-gal ... e-out.html

Well, well, .. looky-here: " .. In trying to study the chemistry of these "dead" galaxies, researchers have found a different chemical fingerprint than the one that dominates star-forming galaxies. To describe what they were seeing, researchers came up with the acronym LINER, which stands for "low-ionization nuclear emission-line region." Belfiore's explanation of the name is more direct: "The reason why we use this acronym is because we don't know what they are," he said.

And perhaps some relation to that uniform, diffuse glow?: "More specifically, scientists don't know what's creating the "LINER" chemical signature in the dead galaxies, and whether it might help explain why they stopped forming stars. Now, new observations by Belfiore and colleagues have added another twist to this LINER mystery: rather than coming from the black hole at the center of the dead galaxy, as researchers previously thought, the signature can be found throughout the galaxies, all the way out to their fringes.

According to Belfiore, this new finding that means the "N" in LINER (which stood for "nuclear," referring to the center of the galaxy) should be removed, and these galaxies should be called "LIERs."

" ... In many spiral galaxies, star formation does not shut off suddenly, but gradually. Some spiral galaxies develop regions (often near their centers) where star formation stops, and in those cases, it is possible for scientists to see a LIER emission from the "dead" region of the galaxy."

"In other words, Belfiore said, it's possible that most galaxies are LIERs.

The idea that LINER galaxies may actually be LIERs — that this chemical signature is not coming from the galactic center but from another source, such as dying stars throughout the galaxy — has been building for some years, Belfiore told Space.com."

https://www.space.com/31632-red-dead-ga ... liers.html

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby bystander » Thu Jun 15, 2017 3:39 am

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Thu Jun 15, 2017 5:54 am

Alpha Centauri A, Alpha Centauri B, Proxima Centauri, and the Sun.
Elliptical galaxies are "dim" in the sense that their stellar population is predominantly made up of old, low-mass and therefore very dim stars. Many of their stars are similar to the star (apart from the Sun) that is currently closest to us, Proxima Centauri. Proxima Centauri, by the way, is a member of the three-star Alpha Centauri system.

Jim Kaler wrote about Proxima Centauri:

As a mid-class M (M5.5) dwarf star, Proxima is faint indeed, to the eye 18,000 times dimmer than the Sun. (...) When infrared radiation produced by its 3040 Kelvin surface is accounted for, it is seen to be more luminous, but still only 1/600 as bright as the Sun (and 15 percent the size), the result of a mass only 12 percent solar.


So the mass of Proxima Centauri is 0.12 solar, but its luminosity is 0.00018 solar. My software, Guide, actually claims that the luminosity of Proxima Centauri is only 0.000055 solar. I'm not here to argue about decimals. The point is that Proxima Centauri is not just light-weight and small, but extremely faint for its light-weight mass and small size. This is typical of very low-mass stars.

Giant elliptical galaxy M87.
Consider giant elliptical galaxy M87. Is it faint? No, my software claims that M87 is four times brighter than the Milky Way. But while it is a luminous galaxy, it is first and foremost a massive galaxy. According to Wikipedia, the total mass of M87 may be 200 times the mass of the Milky Way. So while M87 is a bright galaxy, no question about it, you can nevertheless say that it is faint, or even dim, for its mass.

The Sun and a modest-sized red giant star.











M87 is made up almost exclusively of old stars, and old stars are typically dim. Yes, some old stars are bright, particularly red giant stars. At left you can see a comparison between the Sun and a (very) modest red giant star. At best, the red giant in this picture is comparable to Pollux, whose radius is 9 times that of the Sun. Many if not most red giants are bigger, and some are very, very much bigger, but most of the biggest red giants are young stars. And there are virtually no young stars and therefore no super-sized red giants in typical elliptical galaxies.

So the kind of stars that you are likely to find in M87 are main-sequence stars like the Sun, very low-mass stars like Proxima Centauri, and modest red giants like Pollux and (considerably brighter) Arcturus. (Of course you are also likely to find huge numbers of main sequence stars that are fainter and smaller than the Sun, but bigger and brighter than Proxima Centauri.)

M51, the Whirlpool Galaxy.
Photo: Luis Romero.
Let's compare M87 with spiral galaxy M51. According to Wikipedia, M51 is only about 35% the size of the Milky Way. Its mass is estimated to be only 160 billion solar masses, compared with 2,400 solar masses for M87. (A new estimate of the mass of the Milky Way claims that the mass of our own galaxy is between 600 and 750 billion solar masses.) So the mass of M51 is about 7% of the mass of M87, and 21-27% the mass of the Milky Way. Yet even though M51 is small and light-weight, it is quite bright, about 1.4 times brighter than the Milky Way, according to my software.

Image
NGC 3293, a young cluster of massive bright stars.
Photo: ESO/G. Beccari.










Why is M51 bright? It is bright because it contains a lot of bright stars, and it contains a lot of bright stars because it keeps forming new stars all the time. Some of those new stars are very massive, and massive stars are very bright. Most of the massive bright stars shine with a blue light, which explains the bluish color of M51. There are not nearly as many massive young stars in the Milky Way as there are in M51, but a Milky Way example of massive stars is the bright members of cluster NGC 3293. The individual stars may be up to ~30 times as massive as the Sun, but they are thousands of times brighter. But massive stars die young, and a galaxy that contains many bright stars must keep on forming a lot of new stars (or, at the very least, it must have formed a lot of new stars very recently). The large number of bright pink emission nebulas in M51 suggests that this galaxy keeps forming new stars very vigorously.


Finally, why is the gaseous spiral in the core of Centaurus A hidden from us? It is hidden from us because there is a wall of stars in front of it, since the center of Cen A is crammed with stars. Yes, most of these stars are dim in themselves, but there are tremendous numbers of them, and there are even huge numbers of bright red giant stars near the center of Cen A. We are staring at a lot of suns and trying to see a (probably) not-so-bright gaseous spiral hidden among them. No wonder we can't see it!

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Thu Jun 15, 2017 10:14 am

I can see that I didn't answer your questions, douglas. Most of all, I think you want to know why elliptical galaxies stop forming stars and become (relatively) dim.

The short answer, I think, is a lack of gas supply.

I wrote in my previous post that M51 is a galaxy defined by a high rate of star formation. However, this apparently can't last.

Wikipedia wrote:

The center part of M51 appears to be undergoing a period of enhanced star formation. (...) It is estimated that the current high rate of star formation can last no more than another 100 million years or so.


I take that to mean that after a 100 million years, much of the available gas in M51 will have been used up in star formation, and much of the rest may well have been scattered by a lot of supernovas going off. After that, M51 will gradually become dimmer and dimmer.

Nearby starburst galaxy M82.
Image
Supernova, artist's impression.
Source unknown.
Nearby starburst galaxy M82 shows what can happen when a galaxy undergoes too much star formation. M82 displays huge outflows of hydrogen gas from its poles, and a lot of that gas may never return to M82 and thus never become available for further star formation in M82. The cause of this incredible gaseous outflow would seem to be large numbers of violent supernovas going off in a very short time as a consequence of the formation of so very many massive stars being born in the starburst.

Also note how the violent star formation has affected the shape of M82. We can see a lot of chaotic dust lanes in the disk, which appear to be too "thin" and perhaps too turbulent or "hot" to support much star formation. A lot of dust has been formed by the starburst itself, and M82 is actually a very dusty galaxy.The starburst in M82 is confined to the center of the galaxy, but the entire disk seems to have been affected. The disk seems to have become rather chaotic, with few signs of the well-ordered spiral structures that are characteristic of many galaxies. Star formation appears to have stopped in the disk, while it has been rampant in the core of the galaxy.

My amateur guess is that too much star formation can affect an entire galaxy in such a way that its structure becomes chaotic and much of the remaining gas is simply expelled from the galaxy.

Ultraluminous infrared galaxies. Photo: Spitzer/Jason Ware.
Star formation in the universe peaked some 3.5 billion years after the Big Bang. Back then, the universe was much smaller than it is today and much more gas-rich. That is because much of the gas that was created in the Big Bang has now been used up in star formation, and the gas that ends up in low-mass stars - and that will be most of it - will not return to the universe for many, many billions or even trillions of years from now. But some 3.5 billion years ago, gas may still have been "sloshing" around in the universe, colliding and getting compressed and setting off fireworks of star formation.

And just like we see in present-day M82, but on a much grander scale, starbursts may have been set off that dwarfed anything we see in the nearby universe. The enormous starbursts would have created extreme outflows of gas, huge amounts of dust, contorted and chaotic shapes of the galaxies themselves and the loss of any spiral structure.

Artist's impression of a quasar.
Credit: NASA/ESA/G.Bacon, STScI









The huge gas flows may also easily have fed growing black holes in the centers of these ultraluminous infrared galaxies (ULIRGS), and it's not hard to imagine that at least some of these growing black holes may have emitted tremendously energetic jets. Such enormous jets would most certainly have upset the gas of these galaxies further, expelling a lot of it and making the rest of the gas thin and turbulent, unsuitable for star formation. And, hey presto, soon you will have a young elliptical galaxy, a roundish blob where stars are buzzing around chaotically like bees, and where no star formation is taking place.

So if you ask me, I would say that an insufficient gas supply will lead to "red and dead" galaxies. The only question is what actually turns the gas tap off. It could be violent starbursts or galactic mergers or the devastating effects of central black holes with jets, or something else.

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Thu Jun 15, 2017 5:57 pm

Okay. My third post in a row. Because there is a question that I haven't addressed, and I don't know how to answer it.
NGC 3344, a spiral galaxy with a small yellow bulge.
Photo: Adam Block.
M81, a spiral galaxy with a large yellow bulge.
Photo: Roberto Colombari.



















Why is it that basically all spiral galaxies are growing a yellow elliptical galaxy in their centers? Because that is what they do. They all have yellow centers that are (relatively) featureless and (mostly) lack star formation, just like elliptical galaxies. Why do they look like that? I don't know.

The Milky Way over Uluru.
Photo: Babak Tafreshi.
What about the Milky Way? Oh, the Milky Way is growing a big elliptical galaxy in its center. Just look at the picture at left. See how bright the featureless glow at 3 o'clock is? That's a part of the unreddened bulge of the Milky Way peeking through. But the bulge can be seen in other places too, both above and below the central dust lane. And the bulge, that is the elliptical galaxy growing there.

It would certainly seem that all spiral galaxies are slowly transforming themselves into ellipticals one way or another.

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Chris Peterson » Thu Jun 15, 2017 6:16 pm

Ann wrote:Why is it that basically all spiral galaxies are growing a yellow elliptical galaxy in their centers?

It would certainly seem that all spiral galaxies are slowly transforming themselves into ellipticals one way or another.

Why do you think that the bulges of spiral galaxies are evolving or changing or growing? I don't know of anything to suggest that spirals become ellipticals through any process other than tidal disruption by other galaxies.
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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby BDanielMayfield » Thu Jun 15, 2017 6:37 pm

Chris Peterson wrote:
Ann wrote:Why is it that basically all spiral galaxies are growing a yellow elliptical galaxy in their centers?

It would certainly seem that all spiral galaxies are slowly transforming themselves into ellipticals one way or another.

Why do you think that the bulges of spiral galaxies are evolving or changing or growing? I don't know of anything to suggest that spirals become ellipticals through any process other than tidal disruption by other galaxies.


Also, a fundamental difference between ellipticals and the bulges of many spirals is the shape. Instead of being simple ovals like ellipticals, the bulges of many spirals show elongation with additional bulging near the ends of bar like structures. The bulges at the ends can be larger than the central bulge, giving the overall shape one resembling an unshelled peanut.

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Thu Jun 15, 2017 7:07 pm

Chris Peterson wrote:
Ann wrote:Why is it that basically all spiral galaxies are growing a yellow elliptical galaxy in their centers?

It would certainly seem that all spiral galaxies are slowly transforming themselves into ellipticals one way or another.

Why do you think that the bulges of spiral galaxies are evolving or changing or growing? I don't know of anything to suggest that spirals become ellipticals through any process other than tidal disruption by other galaxies.


I may be wrong, of course. I just think that those bulges in spiral galaxies are often very similar to elliptical galaxies. If you think that the bulges of spiral galaxies are too flat to resemble elliptical galaxies, remember that both lenticular galaxies and some elliptical galaxies are elongated and rather flat, too.

Galaxies dying from the inside out.
Credit: ESO.
NGC 3521. Photo: R Jay Gabany with David Martinez-Delgado.

















NGC 3115, a red and dead lenticular galaxy that used to be a blue spiral?
Source unknown.



bystander recently posted a link to a page which shows "proto-ellipticals" dying from the inside out. That just got me thinking about the fact that virtually all spiral galaxies have a yellow center. Why is that? Were they born that way? And if the red and dead center is spreading to the periphery in elliptical galaxies, why shouldn't we think that the same thing is happening to spiral galaxies? After all, star formation in the universe is winding down, that is a known fact. And can the spiral galaxies remain spirals if they stop forming stars?

But I don't know that I'm right about this. I just expressed my gut feeling.

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Chris Peterson » Thu Jun 15, 2017 7:30 pm

Ann wrote:
Chris Peterson wrote:
Ann wrote:Why is it that basically all spiral galaxies are growing a yellow elliptical galaxy in their centers?

It would certainly seem that all spiral galaxies are slowly transforming themselves into ellipticals one way or another.

Why do you think that the bulges of spiral galaxies are evolving or changing or growing? I don't know of anything to suggest that spirals become ellipticals through any process other than tidal disruption by other galaxies.

I may be wrong, of course. I just think that those bulges in spiral galaxies are often very similar to elliptical galaxies.

Sure. So do globular clusters (on a different scale). The lowest entropy state for a collection of stars is a spherical body with the stars orbiting at random inclinations. But that doesn't tell us anything about origins.

We don't see any sort of clear evolutionary trend from spirals to ellipticals. It's not clear that spirals depend on star formation in any way to retain their morphology. That might be a factor in how distinct their arms are, but not, I think, in their maintaining a disc. I don't think that the disc of spiral galaxies is either being lost to intergalactic space, or being consumed by the bulge.
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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby douglas » Thu Jun 15, 2017 8:31 pm

Ann wrote: " .. M82 displays huge outflows of hydrogen gas from its poles .. The cause of this incredible gaseous outflow would seem to be large numbers of violent supernovas going off in a very short time as a consequence of the formation of so very many massive stars being born in the starburst.

Also note how the violent star formation has affected the shape of M82.

.. The huge gas flows may also easily have fed growing black holes in the centers of these ultraluminous infrared galaxies (ULIRGS), and it's not hard to imagine that at least some of these growing black holes may have emitted tremendously energetic jets. Such enormous jets would most certainly have upset the gas of these galaxies further, expelling a lot of it and making the rest of the gas thin and turbulent, unsuitable for star formation.

Ann


M82 is a poor example as the angle of viewing from Earth is ambiguous, and is more suggestive of the main culprit in elliptical formation: mergers.
What you are calling "huge outflows looks to be disrupted merger remnants.

Do you have any idea how ENORMOUS outflow jets would have to be cause that much material to disperse over that volume of space??
Considering the only way outflow jets from a black hole could survive over those distances is magnetic fields physical law would simply prohibit such expansion in volume while retaining the force required to disturb that much matter at those distances from the jet's source.

The supernovas chain effect is another bugaboo that's of the paradigm that Belfiore mentioned is changing, slowly.

You know mergers are disruptive of structure, yet ignore that and posit supermassive black holes and supernovas to explain M82's appearance? That is simply an unlikely choice. Unless there is imagery at some wavelength of those "lobes" growing on human time scales, then positing that is simply not "discreet" when Belfiore has indicated interpretations of observation need greater resolution to find the true.

Centaurus A also looks the way it does because it has undergone merger or mergers.

douglas

Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby douglas » Thu Jun 15, 2017 9:05 pm

Ann wrote: And, hey presto, soon you will have a young elliptical galaxy, a roundish blob where stars are buzzing around chaotically like bees, and where no star formation is taking place.

Ann


We can begin here as the path to recovery begins with retracing your steps, lol.

If stars "are buzzing around chaotically like bees", and these galaxies unquestionably formed LONG before humans gained sentience and the process has never been seen to be time-condensed, how do astronomers determine the mass of an elliptical galaxy, especially if resolutions are insufficiently able to penetrate the unform, diffuse glows of ellipticals?

Also, your mentioning of chaotic buzzing suggests you are aware of merger effects: are these allusions of yours a 'cry for help', as is said? :) :D

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Fri Jun 16, 2017 3:26 am

douglas wrote:
Ann wrote: " .. M82 displays huge outflows of hydrogen gas from its poles .. The cause of this incredible gaseous outflow would seem to be large numbers of violent supernovas going off in a very short time as a consequence of the formation of so very many massive stars being born in the starburst.

Also note how the violent star formation has affected the shape of M82.

.. The huge gas flows may also easily have fed growing black holes in the centers of these ultraluminous infrared galaxies (ULIRGS), and it's not hard to imagine that at least some of these growing black holes may have emitted tremendously energetic jets. Such enormous jets would most certainly have upset the gas of these galaxies further, expelling a lot of it and making the rest of the gas thin and turbulent, unsuitable for star formation.

Ann


M82 is a poor example as the angle of viewing from Earth is ambiguous, and is more suggestive of the main culprit in elliptical formation: mergers.
What you are calling "huge outflows looks to be disrupted merger remnants.

Do you have any idea how ENORMOUS outflow jets would have to be cause that much material to disperse over that volume of space??


I haven't mentioned jets in relation to M82.

Considering the only way outflow jets from a black hole could survive over those distances is magnetic fields physical law would simply prohibit such expansion in volume while retaining the force required to disturb that much matter at those distances from the jet's source.


Wikipedia agrees with me that there is a great outflow of gas (or "wind") from M82, and that it is caused by supernovas which themselves are a consequence of the starburst of M82.

Wikipedia wrote:

In the core of M82, the active starburst region spans a diameter of 500 pc. Four high surface brightness regions or clumps (designated A, C, D, and E) are detectable in this region at visible wavelengths.[6] These clumps correspond to known sources at X-ray, infrared, and radio frequencies.[6] Consequently, they are thought to be the least obscured starburst clusters from our vantage point.[6] M82's unique bipolar outflow (or 'superwind') appears to be concentrated on clumps A and C and is fueled by energy released by supernovae within the clumps which occur at a rate of about one every ten years.


douglas wrote:

You know mergers are disruptive of structure, yet ignore that and posit supermassive black holes and supernovas to explain M82's appearance?


I haven't mentioned supermassive black holes in relation to M82 at all. But the idea that supernovas are responsible for the bipolar outflow of M82 is the consensus view among astronomers.

That is simply an unlikely choice.


That's your opinion, and you are entitled to it.

Centaurus A also looks the way it does because it has undergone merger or mergers.


Certainly. But Centaurus A is a very different galaxy from M82.

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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Ann » Fri Jun 16, 2017 4:21 am

Chris Peterson wrote:
Ann wrote:
Chris Peterson wrote:Why do you think that the bulges of spiral galaxies are evolving or changing or growing? I don't know of anything to suggest that spirals become ellipticals through any process other than tidal disruption by other galaxies.

I may be wrong, of course. I just think that those bulges in spiral galaxies are often very similar to elliptical galaxies.

Sure. So do globular clusters (on a different scale). The lowest entropy state for a collection of stars is a spherical body with the stars orbiting at random inclinations. But that doesn't tell us anything about origins.

We don't see any sort of clear evolutionary trend from spirals to ellipticals. It's not clear that spirals depend on star formation in any way to retain their morphology. That might be a factor in how distinct their arms are, but not, I think, in their maintaining a disc. I don't think that the disc of spiral galaxies is either being lost to intergalactic space, or being consumed by the bulge.


NGC 936, a galaxy that has given up star formation.
Source: https://skyserver.sdss.org/dr12/en/tool ... page1.aspx
Well, NGC 936 is a good example of a spiral or lenticular galaxy that has given up star formation. The NGC-IC Project, which is quoted by my software Guide, classified NGC 935 an "SB0-a" galaxy, a galaxy that is either a lenticular galaxy or an SBa-type galaxy, a barred galaxy with a large bulge and tightly wound arms.

As you said, the arms of NGC 936 are anything but distinct. They are barely visible if they are there at all. But NGC 936 is clearly a disk galaxy, and it may very well remain one if it is left in peace.

Abell 1689 galaxy cluster.
NASA/ESA/JPL-Caltech/STScI













So NGC 936 used to be a spiral and is on its way to becoming a lenticular. I can see your point, that lenticulars are a different sort of beasts than ellipticals. But consider galaxy cluster Abell 1689. I can see a confusion of yellow, non-starforming galaxies. (And there is one that is a bit bluer.) On closer inspection, it is obvious that some of the yellow galaxies have disks, bars and rings. They are not featureless, so they are not elliptical galaxies. But they sure are yellow and boring. :(

Then again, they are located in a dense cluster, and such galaxies will evolve differently than field galaxies or even differently than galaxies in small groups, like the Milky Way. So what do you think, Chris? The Milky Way is destined to collide with the Andromeda galaxy, so our galaxy's fate seems sealed. It will most likely merge with Andromeda, feed Andromeda's huge black hole, and help create a devastating jet that should destroy any features of the Milky Way-Andromeda merger product. But if the Milky Way was left alone, would it go gently into that good night and just slowly fade into a lenticular?

Ann
Color Commentator

douglas

Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby douglas » Fri Jun 16, 2017 9:44 am

Ann wrote: .. It will most likely merge with Andromeda, feed Andromeda's huge black hole, and help create a devastating jet that should destroy any features of the Milky Way-Andromeda merger product. But if the Milky Way was left alone, would it go gently into that good night and just slowly fade into a lenticular?

Ann


Utterly ludicrous, that bolded part.

We do not see these ellipticals, with their enormous masses reported, creating such stupendous jets.

A spiral, slowly fading into a lenticular, while avoiding mergers?

douglas

Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby douglas » Fri Jun 16, 2017 3:27 pm

Ann wrote:
That is simply an unlikely choice.


That's your opinion, and you are entitled to it.

Ann


It is more than an opinion, as a pattern has emerged. That pattern is suggestive of a 'cry for help', a common feature observed in those who front orthodox dogmas. I highly doubt you did not read bystander's viewtopics. If you had read it, and a 'cry for help' were not being effected, you could not state some number of things you have stated:

viewtopic.php?t=35536
http://www.sdss.org/press-releases/proo ... are-liers/

" .. Belfiore and his collaborators used the MaNGA data to map the state of gas and stars throughout more than 600 LINER galaxies. ‘By taking advantage of the fact that MaNGA can get data for an entire galaxy at once, we have revealed that the sources lighting the gas up must be distributed throughout the galaxy, even tens of thousands of light years away from the central black hole. This proves that the emission lines we see cannot all be due to central black holes,” says Belfiore."

" .. Although this mechanism was originally suggested to be important only in elliptical galaxies, the new MaNGA data reveals that it is in fact common in both elliptical and spiral galaxies. “In the spiral galaxies, the gas shining as LINERs is the dying gasp of star formation being quenched as gas reservoirs are depleted in inner regions and star formation moves to the outer suburbs. In the elliptical galaxies, where almost all star formation occurred rapidly in the early days of the Universe, this glowing gas represents a ‘rejuvenation’ of the dormant galaxy,” says Belfiore. “Donated gas, from dying stars within the galaxy or from a merging galaxy, is now able to intercept the extreme radiation and make the galaxy shine again, albeit only as a LINER.”

With the extensive mapping of low-ionization emission-line regions outside of the nuclei of galaxies, far removed from central supermassive black holes, but close to newly born white dwarfs, the ‘N’ for ‘nuclear’ in the LINER acronym must disappear."

You see, when considering topics that require intellectual engagement in the form of reading comprehension, and comprehension is not proffered in the forms of acknowledgement of concepts or even mention of reading material, a.k.a. "links", then it becomes obvious the person is not being honest or is performing a "technical" function (see last given link in this comment for "technical".

I recall posting this link,
https://www.ifa.hawaii.edu/users/barnes ... /oeg1.html
which was also not commented upon by others. It also precludes the fronting of further orthodox dogmas. Preclusion notwithstanding, they were fronted, anyways: read "technical".

Is a "technical" function being performed?: https://www.vox.com/policy-and-politics ... se-twitter

That is the appearance with ignoring reading comprehensions: a "crowding-out" function.

"Technical" 'cries for help'? ... Aha! ... :wink:

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Chris Peterson
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Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby Chris Peterson » Fri Jun 16, 2017 3:56 pm

Ann wrote:So what do you think, Chris? The Milky Way is destined to collide with the Andromeda galaxy, so our galaxy's fate seems sealed. It will most likely merge with Andromeda, feed Andromeda's huge black hole, and help create a devastating jet that should destroy any features of the Milky Way-Andromeda merger product.

Well, there's no reason to think that a merger will result in either galaxy's central black hole necessarily becoming active. Of course, it's certainly possible. However, should either become active and produce a jet, I doubt it would be "devastating" or likely to have much impact on the structure taken on by the merger product. Also, the collision between the two galaxies isn't going to produce a merger, but a pair of distorted spirals each continuing along its own orbit. It will take more collisions before everything settles down into some sort of (presumably) elliptical galaxy form.

But if the Milky Way was left alone, would it go gently into that good night and just slowly fade into a lenticular?

Maybe. It's a real possibility that lenticular galaxies are what you get when spirals run out of free gas. But it's also possible that's not the case. The classifications of spiral, lenticular, and elliptical are morphological, and may not be clearly related to galaxy evolution.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

douglas

Re: APOD: M89: Elliptical Galaxy with Outer... (2017 Jun 14)

Postby douglas » Sat Jun 17, 2017 4:52 pm

Chris Peterson wrote:Well, there's no reason to think that a merger will result in either galaxy's central black hole necessarily becoming active. Of course, it's certainly possible. However, should either become active and produce a jet, I doubt it would be "devastating" or likely to have much impact on the structure taken on by the merger product. Also, the collision between the two galaxies isn't going to produce a merger, but a pair of distorted spirals each continuing along its own orbit. It will take more collisions before everything settles down into some sort of (presumably) elliptical galaxy form.

But if the Milky Way was left alone, would it go gently into that good night and just slowly fade into a lenticular?

Maybe. It's a real possibility that lenticular galaxies are what you get when spirals run out of free gas. But it's also possible that's not the case. The classifications of spiral, lenticular, and elliptical are morphological, and may not be clearly related to galaxy evolution.


The Milky Way is currently colliding with several dwarf galaxies, with streams of stars extending above & below the galactic disk. Evidence of devastation in those areas where the streams intersect with the disk? Uhh, no, but the Milky Way continues into its "good night", 'unperturbed', as it were.

Perhaps what drives such 'sentiments', that of enormous black holes 'tearing up the turf'/wreaking devastation on any that resist them, is the empowerment an 'editor' receives .. when contributing to Wikipedia? :)

And speaking of Wikipedia, Ann's link for M87 offers explanation for the bright halo. Could this be true of most ellipticals' halos, and would 'reading comprehension' require it be included when referring to ellipticals' morphologies?:

https://en.wikipedia.org/wiki/Messier_87#Properties
http://www.webcitation.org/6ZYTKlZVJ?ur ... s/eso1525/

" .. now a team of astronomers led by PhD student Alessia Longobardi at the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany has applied a clever observational trick to clearly show that the nearby giant elliptical galaxy Messier 87 merged with a smaller spiral galaxy in the last billion years.

"This result shows directly that large, luminous structures in the Universe are still growing in a substantial way — galaxies are not finished yet!" says Alessia Longobardi. "A large sector of Messier 87's outer halo now appears twice as bright as it would if the collision had not taken place."


"It is very exciting to be able to identify stars that have been scattered around hundreds of thousands of light-years in the halo of this galaxy — but still to be able to see from their velocities that they belong to a common structure."
The "chaotic buzzing' orthodoxy must not be used.

Greater resolution vs. "boring" ellipticals. Mr. Belfiore and the team of researchers quoted above would doubtless feel portraying ellipticals in the orthodox dogmatic way was "boring", if not disrespectful to their work.

Simply referring to Wikipedia without delving into wiki's provided sources is not resolute-enough.


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