by Ann » Sat Aug 25, 2018 11:47 am
heehaw wrote: ↑Sat Aug 25, 2018 9:32 am
I remember seeing a similar photo of, I think, another galaxy. The thing that impresses me most about this is seeing star formation in the stripped material. These are stars that formed in the stripped material AFTER the material was stripped. Now I think that the question of exactly how and why star formation occurs in galaxies is still open: density, pressure, whatever factors. This (or these) stripped-material star-forming regions are dramatically different from traditional regions of star formation inside galaxies. I'd like to hear some discussion on this, and on what it means!
Obviously stars are forming in chains in the gassy tail left by ESO 137-001, and my amateur understanding suggests to me that the reason for the chain-like structures might be that gas is leaving this galaxy almost like heavy rainfall. Heavy rain can sometimes fall as long "chains" of water. In the picture at left, it would seem that the chains are formed when the rain hits the car. It may be the "bumpiness" of the car that turns the relatively smooth and evenly distributed rain into chains of water. Slightly similar chains may form as gas leaves a galaxy and hits concentrations of objects in the galaxy, for example star clusters and thick dust clouds.
In the "chains" of gas (and, presumably, dust) leaving ESO 137-001, temperatures may fall and ideal conditions for star formation may be created. It is known from the Milky Way that star formation often takes place in elongated dusty tendrils.
As you can see in the picture at left, the serpentine cosmic tendril known as "The Snake" is hatching a massive star in its belly and a smaller one in its snout. (Do visit the page where I found the picture, because there are more images there and you can find more facts.) My point, however, is that if stars can form in dusty tendrils in the Milky Way, why shouldn't stars be able to form in long chains of gas and dust that have been pushed out of ESO 137-001?
If you check out today's APOD, you can see that the chains of stars only stretch so far below the disk of ESO-137-001. The longest chains seem to be about equal in length to the diameter of the visible disk of the galaxy. Note, in the APOD, that the longest chains of new stars emanate from the rightmost part of the galaxy, where Chandra didn't detect any really strong X-ray signals. My interpretation is that these chains are the oldest, and that the gas in this part of the galaxy may already be mostly used up.
The Chandra X-ray data extend far beyond the chains of new stars. I take that to mean that at this distance from the galaxy, any dusty chains have been disintegrated and turned into a hot smooth soup of turbulent gas. This is an environment that is very hostile to star formation.
What will happen to the newly hatched star clusters forming from the chains of gas and dust being stripped from ESO 137-001? My guess is that they will form tiny dwarf galaxies, and then these dwarf galaxies will age, fade, disintegrate and disappear. In the end, what remains may be a number of old red stars floating freely in the intergalactic medium of galaxy cluster Abell 3627.
Dwarf galaxies are formed by other means too, not just through "ram stripping" as is the case in today's APOD. Take a look at the picture at left of star clusters forming in the longest tidal tail of the Antennae, the colliding galaxies NGC 4038 and 4039. Gas has been flung out in a long tidal stream from the gas-rich NGC 4038, and the gas has kept flowing out until it hit a bump of some sort, perhaps an intergalactic dust cloud, that stopped the outflowing gas in its tracks. Now the stalled gas has been concentrated and is forming quite a lot of new stars. The new star clusters will turn into dwarf galaxies (in fact they have already done so), and then they will fade over time. They may not necessarily disintegrate, since they don't sit in a massive cluster where tidal forces are pulling at them from all directions.
But they will become very faint in the end.
Ann
[quote=heehaw post_id=285264 time=1535189541]
I remember seeing a similar photo of, I think, another galaxy. The thing that impresses me most about this is seeing star formation in the stripped material. These are stars that formed in the stripped material AFTER the material was stripped. Now I think that the question of exactly how and why star formation occurs in galaxies is still open: density, pressure, whatever factors. This (or these) stripped-material star-forming regions are dramatically different from traditional regions of star formation inside galaxies. I'd like to hear some discussion on this, and on what it means!
[/quote]
Obviously stars are forming in chains in the gassy tail left by ESO 137-001, and my amateur understanding suggests to me that the reason for the chain-like structures might be that gas is leaving this galaxy almost like heavy rainfall. Heavy rain can sometimes fall as long "chains" of water. In the picture at left, it would seem that the chains are formed when the rain hits the car. It may be the "bumpiness" of the car that turns the relatively smooth and evenly distributed rain into chains of water. Slightly similar chains may form as gas leaves a galaxy and hits concentrations of objects in the galaxy, for example star clusters and thick dust clouds.
[float=left][img2]https://images.glaciermedia.ca/polopoly_fs/1.23157855.1517252242!/fileImage/httpImage/image.jpg_gen/derivatives/landscape_804/car-heavy-rain.jpg[/img2][c][size=85]Source: https://www.vancourier.com/news/heavy-rains-to-soak-vancouver-again-today-1.23157849[/size][/c][/float] [float=right][img2]http://cdn.spacetelescope.org/archives/videos/videoframe/heic1404c.jpg[/img2][c][size=85]ESO 137-001. Source:
https://www.spacetelescope.org/videos/heic1404c/[/size][/c][/float]
In the "chains" of gas (and, presumably, dust) leaving ESO 137-001, temperatures may fall and ideal conditions for star formation may be created. It is known from the Milky Way that star formation often takes place in elongated dusty tendrils.
[float=left][img2]https://scitechdaily.com/images/SMA-Unveils-How-Small-Cosmic-Seeds-Grow-Into-Big-Stars.jpg[/img2][c][size=85]Source: https://scitechdaily.com/sma-reveals-new-insights-cosmic-seeds-grow-massive-stars/[/size][/c][/float]
As you can see in the picture at left, the serpentine cosmic tendril known as "The Snake" is hatching a massive star in its belly and a smaller one in its snout. (Do visit the page where I found the picture, because there are more images there and you can find more facts.) My point, however, is that if stars can form in dusty tendrils in the Milky Way, why shouldn't stars be able to form in long chains of gas and dust that have been pushed out of ESO 137-001?
If you check out today's APOD, you can see that the chains of stars only stretch so far below the disk of ESO-137-001. The longest chains seem to be about equal in length to the diameter of the visible disk of the galaxy. Note, in the APOD, that the longest chains of new stars emanate from the rightmost part of the galaxy, where Chandra didn't detect any really strong X-ray signals. My interpretation is that these chains are the oldest, and that the gas in this part of the galaxy may already be mostly used up.
The Chandra X-ray data extend far beyond the chains of new stars. I take that to mean that at this distance from the galaxy, any dusty chains have been disintegrated and turned into a hot smooth soup of turbulent gas. This is an environment that is very hostile to star formation.
[float=left][img2]https://www.cv.nrao.edu/~jhibbard/n4038/GALEX/n4038uv.jpg[/img2][c][size=85]Dwarf galaxies forming in the southern tidal tail
of colliding galaxies NGC 4038 and 4039.
Source: https://www.cv.nrao.edu/~jhibbard/n4038/GALEX/n4038uv.html[/size][/c][/float] [float=right][img2]https://www.sdss.org/wp-content/uploads/2014/04/leoi.jpeg[/img2][c][size=85]Ultra-faint dwarf galaxy Leo I. Source:
https://www.sdss.org/science/leoi/[/size][/c][/float]
What will happen to the newly hatched star clusters forming from the chains of gas and dust being stripped from ESO 137-001? My guess is that they will form tiny dwarf galaxies, and then these dwarf galaxies will age, fade, disintegrate and disappear. In the end, what remains may be a number of old red stars floating freely in the intergalactic medium of galaxy cluster Abell 3627.
Dwarf galaxies are formed by other means too, not just through "ram stripping" as is the case in today's APOD. Take a look at the picture at left of star clusters forming in the longest tidal tail of the Antennae, the colliding galaxies NGC 4038 and 4039. Gas has been flung out in a long tidal stream from the gas-rich NGC 4038, and the gas has kept flowing out until it hit a bump of some sort, perhaps an intergalactic dust cloud, that stopped the outflowing gas in its tracks. Now the stalled gas has been concentrated and is forming quite a lot of new stars. The new star clusters will turn into dwarf galaxies (in fact they have already done so), and then they will fade over time. They may not necessarily disintegrate, since they don't sit in a massive cluster where tidal forces are pulling at them from all directions.
But they will become very faint in the end.
Ann