by Ann » Tue Oct 20, 2020 3:22 pm
bystander wrote: ↑Mon Oct 19, 2020 2:03 pm
Galactic Waterspout
ESA Hubble Picture of the Week | 2020 Oct 19
In this spectacular image captured by the NASA/ESA Hubble Space Telescope, the galaxy
NGC 2799 (on the left) is seemingly being pulled into the centre of the galaxy
NGC 2798 (on the right).
Interacting galaxies, such as these, are so named because of the influence they have on each other, which may eventually result in a merger or a unique formation. Already, these two galaxies have seemingly formed a sideways
waterspout, with stars from NGC 2799 appearing to fall into NGC 2798 almost like drops of water.
Galactic mergers can take place over several hundred million to over a billion years. While one might think the merger of two galaxies would be catastrophic for the stellar systems within, the sheer amount of space between stars means that
stellar collisions are unlikely and stars typically drift past each other.
I find the yellowish galaxy in the ESA/Hubble/NASA and SDSS (and Geck) picture in bystander's post, NGC 2798, very interesting. It reminds me of the nearby starburst galaxy, M82. Like NGC 2798, M82 has a "bland" yellowish disk with little or no star formation, but it displays a furious starburst in its center.
NGC 2798 looks just like that to me. The "water spout" of gas and stars from NGC 2799 appears to hit NGC 2798 right in its "solar plexus", causing a "splash" of dust and (mostly) old stars to fly up from its center. At the same time, all that fresh gas pouring into the center of NGC 2798 is apparently triggering a starburst there. We can clearly make out a large and bright blue star cluster below the dusty ring surrounding the inner bulge, and there are almost certainly massive bright young clusters much closer to the nucleus, too.
It is interesting to compare the color indexes of M82 and NGC 2798:
M82, U-B: +0.310. B-V: +0.890.
NGC 2798. U-B: -0.010. B-V: +0.720.
So in fact, NGC 2798 is a much bluer galaxy than M82, at least as seen from our vantage point. But of course, M82 contains massive amounts of dust, so that it is considerably dust-reddened, and its center is mostly hidden from our view by dust. NGC 2798 looks a lot less dusty, and we can see its center clearly.
It is interesting to consider the possibility that the "water spout" sending gas directly into the center of NGC 2798 is a relatively recent phenomenon, so that NGC 2798 has not had time to produce all the dust that is so characteristic of M82's moderately old starburst.
Ann
[quote=bystander post_id=307382 time=1603116186 user_id=112005]
[url=https://spacetelescope.org/images/potw2042a/][size=125][b][i]Galactic Waterspout[/i][/b][/size][/url]
ESA Hubble Picture of the Week | 2020 Oct 19
[quote]
[float=left][img3="Credit: ESA/Hubble & NASA, SDSS, J. Dalcanton;
Acknowledgement: Judy Schmidt (geckzilla)"]https://cdn.spacetelescope.org/archives/images/screen/potw2042a.jpg[/img3][/float]In this spectacular image captured by the NASA/ESA Hubble Space Telescope, the galaxy [url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC+2799]NGC 2799[/url] (on the left) is seemingly being pulled into the centre of the galaxy [url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=NGC+2798]NGC 2798[/url] (on the right).
[url=https://en.wikipedia.org/wiki/Interacting_galaxy]Interacting galaxies[/url], such as these, are so named because of the influence they have on each other, which may eventually result in a merger or a unique formation. Already, these two galaxies have seemingly formed a sideways [url=https://en.wikipedia.org/wiki/Waterspout]waterspout[/url], with stars from NGC 2799 appearing to fall into NGC 2798 almost like drops of water.
[url=https://en.wikipedia.org/wiki/Galaxy_merger]Galactic mergers[/url] can take place over several hundred million to over a billion years. While one might think the merger of two galaxies would be catastrophic for the stellar systems within, the sheer amount of space between stars means that [url=https://en.wikipedia.org/wiki/Stellar_collision]stellar collisions[/url] are unlikely and stars typically drift past each other. [/quote]
[/quote]
[float=right][img3="Starburst in the center of M82, seen in radio waves.
Credit: Josh Marvil (NM Tech/NRAO), Bill Saxton (NRAO/AUI/NSF), NASA."]https://scx2.b-cdn.net/gfx/news/hires/2014/imagestarbur.jpg[/img3][/float]
I find the yellowish galaxy in the ESA/Hubble/NASA and SDSS (and Geck) picture in bystander's post, NGC 2798, very interesting. It reminds me of the nearby starburst galaxy, M82. Like NGC 2798, M82 has a "bland" yellowish disk with little or no star formation, but it displays a furious starburst in its center.
NGC 2798 looks just like that to me. The "water spout" of gas and stars from NGC 2799 appears to hit NGC 2798 right in its "solar plexus", causing a "splash" of dust and (mostly) old stars to fly up from its center. At the same time, all that fresh gas pouring into the center of NGC 2798 is apparently triggering a starburst there. We can clearly make out a large and bright blue star cluster below the dusty ring surrounding the inner bulge, and there are almost certainly massive bright young clusters much closer to the nucleus, too.
It is interesting to compare the color indexes of M82 and NGC 2798:
M82, U-B: +0.310. B-V: +0.890.
NGC 2798. U-B: -0.010. B-V: +0.720.
So in fact, NGC 2798 is a much bluer galaxy than M82, at least as seen from our vantage point. But of course, M82 contains massive amounts of dust, so that it is considerably dust-reddened, and its center is mostly hidden from our view by dust. NGC 2798 looks a lot less dusty, and we can see its center clearly.
It is interesting to consider the possibility that the "water spout" sending gas directly into the center of NGC 2798 is a relatively recent phenomenon, so that NGC 2798 has not had time to produce all the dust that is so characteristic of M82's moderately old starburst.
Ann