Starship Asterisk*

Ann wrote: ↑Fri Jun 02, 2023 5:56 am

VictorBorun wrote: ↑Fri Jun 02, 2023 12:49 am

Ann wrote: ↑Thu Jun 01, 2023 6:08 pm A sparse and empty surroundings may be good for a galaxy that wants to do things its own way. Like UGC 1382.

At left, in optical light, UGC 1382 appears to be a simple elliptical galaxy. But spiral arms emerged when astronomers incorporated ultraviolet and deep optical data (middle). Combining that with a view of low-density hydrogen gas (shown in green at right), scientists discovered that UGC 1382 is gigantic. Credits: NASA/JPL/Caltech/SDSS/NRAO/L. Hagen and M. Seibert

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UGC 1382, living its life in splendid isolation unbothered by any big galactic bullies, has picked up passing galactic driftwood and flotsam and incorporated these pieces into itself. Now it is gigantic, with a diameter of some 718,000 light-years. That's aaa-mazing!!!
Ann

The last example seems to hint that every distant elliptic galaxy may in fact be the core of an understudied disk galaxy…

Well, there is a similar example.

Huge low-surface-brightness galaxy Malin 1. Image credit: Legacy Surveys / D. Lang (Perimeter Institute)

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A picture of Malin 1 processed to show its weak spiral arms. Credit: SDSS/Giuseppe Donatiello

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Like UGC 1382, galaxy Malin 1 has a smallish, all yellow, non-starforming and reasonably bright inner disk. But then both galaxies have a huge set of very low-surface brightness spiral arms. The approximate size of Malin 1, including its faint spiral arms, is some 650,000 light-years, which actually makes it a bit smaller than UGC 1382.

Wikipedia wrote:

Malin 1 was found later to be interacting with two other galaxies, Malin 1B and SDSS J123708.91+142253.2. Malin 1B is located 46,000 light-years (14,000 pc) away from the high surface brightness central spiral of Malin 1, which may be responsible for the formation of the galaxy's central bar. Meanwhile, SDSS J123708.91+142253.2 is located within the huge, faint halo of Malin 1 and might have caused the formation of the extended low surface brightness disc through tidal stripping.

Yeah. Whatever.

Ann

VictorBorun wrote: ↑Fri Jun 02, 2023 12:49 am

Ann wrote: ↑Thu Jun 01, 2023 6:08 pm A sparse and empty surroundings may be good for a galaxy that wants to do things its own way. Like UGC 1382.

At left, in optical light, UGC 1382 appears to be a simple elliptical galaxy. But spiral arms emerged when astronomers incorporated ultraviolet and deep optical data (middle). Combining that with a view of low-density hydrogen gas (shown in green at right), scientists discovered that UGC 1382 is gigantic. Credits: NASA/JPL/Caltech/SDSS/NRAO/L. Hagen and M. Seibert

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UGC 1382, living its life in splendid isolation unbothered by any big galactic bullies, has picked up passing galactic driftwood and flotsam and incorporated these pieces into itself. Now it is gigantic, with a diameter of some 718,000 light-years. That's aaa-mazing!!!
Ann

The last example seems to hint that every distant elliptic galaxy may in fact be the core of an understudied disk galaxy…

Wikipedia wrote:

Malin 1 was found later to be interacting with two other galaxies, Malin 1B and SDSS J123708.91+142253.2. Malin 1B is located 46,000 light-years (14,000 pc) away from the high surface brightness central spiral of Malin 1, which may be responsible for the formation of the galaxy's central bar. Meanwhile, SDSS J123708.91+142253.2 is located within the huge, faint halo of Malin 1 and might have caused the formation of the extended low surface brightness disc through tidal stripping.

Ann wrote: ↑Thu Jun 01, 2023 6:08 pm A sparse and empty surroundings may be good for a galaxy that wants to do things its own way. Like UGC 1382.

At left, in optical light, UGC 1382 appears to be a simple elliptical galaxy. But spiral arms emerged when astronomers incorporated ultraviolet and deep optical data (middle). Combining that with a view of low-density hydrogen gas (shown in green at right), scientists discovered that UGC 1382 is gigantic. Credits: NASA/JPL/Caltech/SDSS/NRAO/L. Hagen and M. Seibert

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UGC 1382, living its life in splendid isolation unbothered by any big galactic bullies, has picked up passing galactic driftwood and flotsam and incorporated these pieces into itself. Now it is gigantic, with a diameter of some 718,000 light-years. That's aaa-mazing!!!
Ann

VictorBorun wrote: ↑Thu Jun 01, 2023 7:57 am

Ann wrote: ↑Thu Jun 01, 2023 4:18 am The simulation seems to show that the Universe likes to make spiral galaxies. So where do all the ellipticals come from?
…
And one mechanism that destroys spiral galaxies and turns them into ellipticals in large galaxy clusters is the violent outbursts of ultramassive black holes in the largest elliptical galaxies:

A Chandra (X-ray) and VLA (radio) composite image of giant elliptical galaxy M87, revealing the power of the galaxy's ultramassive black hole.

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Ann

Do I get it right:

1) If Local Leaf i. e. Local Cluster + Council of Giants has more spiral members than elliptical ones, it's just that this supercluster and clusters are small. In normal clusters like Virgo the galaxies population is mostly elliptical

2) Gravitation struggles to feed galaxies in a smooth way. Once a few billion suns BH forms, it tends to blow the hydrogen+dust interstellar media out of the galaxy and stop the star formation for good

Wikipedia wrote:

Maffei 1 is a massive elliptical galaxy in the constellation Cassiopeia. Once believed to be a member of the Local Group of galaxies, it is now known to belong to a separate group, the IC 342/Maffei Group....

Maffei 1 is situated at an estimated distance of 3–4 Mpc from the Milky Way. It may be the closest giant elliptical galaxy...

Maffei 1 lies in the Zone of Avoidance and is heavily obscured by the Milky Way's stars and dust. If it were not obscured, it would be one of the largest (about 3/4 the size of the full moon), brightest, and best-known galaxies in the sky...

The total visible absolute magnitude of Maffei 1, MV=−20.8, is comparable to that of the Milky Way.

Rauf wrote: ↑Thu Jun 01, 2023 1:04 pm

johnnydeep wrote: ↑Thu Jun 01, 2023 12:42 pm Non-sequitur: hey, where's the APOD for 6/1? Nothing at https://apod.nasa.gov/apod/ap230601.html yet...

I'm thinking the same. I hope dear editor is okay!

johnnydeep wrote: ↑Thu Jun 01, 2023 12:42 pm Non-sequitur: hey, where's the APOD for 6/1? Nothing at https://apod.nasa.gov/apod/ap230601.html yet...

madtom1999 wrote: ↑Thu Jun 01, 2023 8:37 am Is there any FLOSS software I can use to play with this stuff at home?

Ann wrote: ↑Thu Jun 01, 2023 4:18 am The simulation seems to show that the Universe likes to make spiral galaxies. So where do all the ellipticals come from?
…
And one mechanism that destroys spiral galaxies and turns them into ellipticals in large galaxy clusters is the violent outbursts of ultramassive black holes in the largest elliptical galaxies:

A Chandra (X-ray) and VLA (radio) composite image of giant elliptical galaxy M87, revealing the power of the galaxy's ultramassive black hole.

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Ann

Space.com wrote:

Astronomers have identified more spiral galaxies than ellipticals, but that's simply because the spirals are easier to spot. While spiral galaxies are bright, elliptical galaxies are dim. Spiral galaxies are hotbeds of star formation, but elliptical galaxies aren't nearly as prolific because 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, giving off more red light than younger stars.

So, why do astronomers think elliptical galaxies dominate the sky? Because when specific regions of the sky are studied in depth, more elliptical galaxies appear. Astronomers think such counts are consistent throughout the universe.
...

A supermassive black hole is thought to lie at the center of these ancient galaxies. These gluttonous giants consume gas and dust, and may play a role in the slower growth of elliptical galaxies.

Born from collision, elliptical galaxies are more commonly found around clusters and groups of galaxies. They are less frequently spotted in the early universe, which supports the idea that they evolved from the collisions that came later in the life of a galaxy.

Hubblesite.org wrote about the spiral galaxy falling into galaxy cluster Abell 2667:

NASA's Hubble Space Telescope, in collaboration with several other ground- and space- based telescopes, has captured a galaxy being ripped apart by a galaxy cluster's gravitational field and harsh environment.

The finding sheds light on the mysterious process by which gas-rich spiral-shaped galaxies might evolve into gas-poor irregular- or elliptical-shaped galaxies over billions of years. The new observations also reveal one mechanism for forming the millions of "homeless" stars seen scattered throughout galaxy clusters.

There are many galaxies of different shapes and sizes around us today. Roughly half are gas-poor elliptical-shaped galaxies with little new star formation activity, and half are gas- rich spiral and irregular galaxies with high star formation activity. Observations have shown that gas-poor galaxies are most often found near the centers of crowded galaxy clusters, whereas spirals spend most of their lifetimes in less crowded circumstances.

But deep observations of the universe show that when the universe was half its present age, only one in five galaxies was a gas-poor object. So where do all of today's gas-poor galaxies come from? Scientists suspect that some kind of transformative process must have taken place, but because galaxy evolution occurs over billions of years, they previously have not been able to see this transformation at work...

AVAO wrote: ↑Wed May 31, 2023 5:27 pm

JohnD wrote: ↑Wed May 31, 2023 3:58 pm What a sparse explanation to this most involved and involving video!

Ok, it starts at "Redshift 12", which is how long ago? And ends at "Redshift 0", but no scale or mete is shown. But several do appear with no explanation; "LogM* which increases, "SFR" in "M.yr-1" which varies, "z" which falls. The video start with three subframes in the picture, but with no explanation, and goes are times in to split screen, displaying different wavelengths?? No explanation! One of these goes full screen with a scale of "Gas metallicity" - a measure of the forging of heavier elements as stars age and die, perhaps? More, better explanation, please!
John

"Formation of a single galaxy "g3", tracked through time from high redshift until the present day. This relatively "average" TNG50 galaxy will be just slightly less massive than our own Milky Way at z=0. We include a large-scale view (lower left), and zoomed in views of the central gas and stellar structures (lower right), while the main panel shows projected gas density. At z=1.5 we pause and rotate around the system, showing in order: gas metallicity, gas velocity field, and H-alpha luminosity, before continuing. What is a small dwarf at high redshift (108.3 solar masses in stars at z=4) transitions, at late times, into a large stable disk with a quasi-steady star formation rate of a few solar masses per year."

Chris Alex wrote: ↑Wed May 31, 2023 2:03 pm This video is more than fascinating, I find it emotionally moving.
(well chosen music on top of it! which I usually turn off to watch in silence but not this time)

JohnD wrote: ↑Wed May 31, 2023 3:58 pm What a sparse explanation to this most involved and involving video!

Ok, it starts at "Redshift 12", which is how long ago? And ends at "Redshift 0", but no scale or mete is shown. But several do appear with no explanation; "LogM* which increases, "SFR" in "M.yr-1" which varies, "z" which falls. The video start with three subframes in the picture, but with no explanation, and goes are times in to split screen, displaying different wavelengths?? No explanation! One of these goes full screen with a scale of "Gas metallicity" - a measure of the forging of heavier elements as stars age and die, perhaps? More, better explanation, please!
John

JohnD wrote: ↑Wed May 31, 2023 3:58 pm What a sparse explanation to this most involved and involving video!

Ok, it starts at "Redshift 12", which is how long ago? And ends at "Redshift 0", but no scale or mete is shown. But several do appear with no explanation; "LogM* which increases, "SFR" in "M.yr-1" which varies, "z" which falls. The video start with three subframes in the picture, but with no explanation, and goes are times in to split screen, displaying different wavelengths?? No explanation! One of these goes full screen with a scale of "Gas metallicity" - a measure of the forging of heavier elements as stars age and die, perhaps? More, better explanation, please!
John

AVAO wrote: ↑Wed May 31, 2023 5:19 am

APOD Robot wrote: ↑Wed May 31, 2023 4:08 am Simulation: A Disk Galaxy Forms

Explanation: How did we get here? We know that we live on a planet orbiting a star orbiting a galaxy, but how did all of this form? Since our universe moves too slowly to watch, faster-moving computer simulations are created to help find out. Specifically, this featured video from the IllustrisTNG collaboration tracks gas from the early universe (redshift 12) until today (redshift 0). As the simulation begins, ambient gas falls into and accumulates in a region of relatively high gravity. After a few billion years, a well-defined center materializes from a strange and fascinating cosmic dance. Gas blobs -- some representing small satellite galaxies -- continue to fall into and become absorbed by the rotating galaxy as the present epoch is reached and the video ends. For the Milky Way Galaxy, however, big mergers may not be over -- recent evidence indicates that our large spiral disk Galaxy will collide and coalesce with the slightly larger Andromeda spiral disk galaxy in the next few billion years.

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Well. The video shown is visually very high-quality and is intended to illustrate the formation of galaxies according to the cosmological standard model using a state-of-the-art simulation (supercomputing). Well. Astronomy outside of our solar system is astroarchaeology. It is based on one-way communication from the past and we will therefore never be able to carry out experiments in a single human generation. For astronomy as a science, this is a huge problem, since in all other sciences, only what can be experimentally verified or repeated is considered scientifically recognized. Simulations are trying to fill this huge gap in astronomy. For this purpose, first cosmological models are developed, such as the cosmological standard model from the big bang to the present day, and then "checked" using mathematically based simulations. Well. Scientific simulations, regardless of the computing power, are always the result of the previously defined framework parameters. This means that if we want to discuss simulations, we should always first talk about the framework parameters before we talk about the content or the result of the simulation. If I change this parameters, I can generate practically any result. Unfortunately, it is precisely this point, which is decisive for everything, that is not, or at least not comprehensively, comprehensible in many scientific papers. A scientific simulation can therefore inherently never be scientifically completely neutral or completely objective...

Wikipedia: The Illustris project is one of the world's largest continuous astrophysical simulation series, which a team of internationally collaborating scientists has been conducting since 2011. The aim is to explore the processes of formation and evolution of the galaxy in the universe using a comprehensive physical model... In 2018 the Illustris team released an update of the Illustris simulation called Illustris "The Next Generation" (TGN). The Illustris simulation framework and galaxy formation model have been used for numerous spin-off projects: Auriga (2017), IllustrisTNG (2017), Thesan (2021), MillenniumTNG (2022) and TNG-Cluster (announced for 2023). TGN50 shows a clipping of 50 Mpc TGN100 a clipping of 100 Mpc. Well.

It's 2023 and the James Webb Space Telescope is showing something else. I'm curious how the next generation of the next generation simulations will look like ;-)

https://apod.nasa.gov/apod/ap120717.html

APOD Robot wrote: ↑Wed May 31, 2023 4:08 am Simulation: A Disk Galaxy Forms

Explanation: How did we get here? We know that we live on a planet orbiting a star orbiting a galaxy, but how did all of this form? Since our universe moves too slowly to watch, faster-moving computer simulations are created to help find out. Specifically, this featured video from the IllustrisTNG collaboration tracks gas from the early universe (redshift 12) until today (redshift 0). As the simulation begins, ambient gas falls into and accumulates in a region of relatively high gravity. After a few billion years, a well-defined center materializes from a strange and fascinating cosmic dance. Gas blobs -- some representing small satellite galaxies -- continue to fall into and become absorbed by the rotating galaxy as the present epoch is reached and the video ends. For the Milky Way Galaxy, however, big mergers may not be over -- recent evidence indicates that our large spiral disk Galaxy will collide and coalesce with the slightly larger Andromeda spiral disk galaxy in the next few billion years.

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This Day in APOD

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