by Ann » Wed Jul 03, 2024 6:39 am
Today's APOD shows a long stellar stream emanating from M83. (Unfortunately, the picture is so big that I have to post it as an attachment.) Ah yes, but there is still more to M83 than meets the eye in the APOD!
M83: Star Streams and a Thousand Rubies
Image Credit & Copyright: Michael Sidonio
Note that the orientation is different in the two images. In the APOD, south is up, but in the two-panel image at right, north is up.
I believe that the "bright" disk of M83 is smallish, but with its extended arms, it becomes huge.
Other smallish galaxies also have extended arms:
With its extended arms small NGC 4625 suddenly looks as large (or larger) than its neighbor, NGC 4618.
Another interesting example of extended arms (of stars of otherwise) is dwarf galaxy NGC 4214. Hubble has shown that this galaxy has a disk of old stars and a few hotspots of starburst:
With the gas surrounding it, NGC 4214 suddenly becomes a spiral galaxy! Fancy that!
But the very opposite thing happens, too, when gas recedes from the outer parts of the galaxy and is only found near the center of the galaxy:
So in NGC 4314, a tiny ring of gas and dust is all the gas there is in this galaxy!
Click to play embedded YouTube video.
Ann
Today's APOD shows a long stellar stream emanating from M83. (Unfortunately, the picture is so big that I have to post it as an attachment.) Ah yes, but there is still more to M83 than meets the eye in the APOD!
[float=left][attachment=1]DeepM83ThousandRubyGalaxy1024[1].jpg[/attachment][c][size=85][color=#0040FF]M83: Star Streams and a Thousand Rubies
Image Credit & Copyright: Michael Sidonio[/color][/size][/c][/float][float=right][img3="In the image at left, long arms of neutral hydrogen are shown in red. In the picture at left, young ultraviolet stars are detected in M83's extended arms."]https://upload.wikimedia.org/wikipedia/commons/thumb/1/10/Extended_Disk_of_Galaxy_M83.jpg/1280px-Extended_Disk_of_Galaxy_M83.jpg[/img3][/float]
[clear][/clear]
Note that the orientation is different in the two images. In the APOD, south is up, but in the two-panel image at right, north is up.
I believe that the "bright" disk of M83 is smallish, but with its extended arms, it becomes huge.
Other smallish galaxies also have extended arms:
[float=left][img3="NGC 4618 and NGC 4625. NGC 4625 looks like a small galaxy with no remarkable features. Credit: SDSS/Donald Pelletier"]https://upload.wikimedia.org/wikipedia/commons/a/a3/NGC_4618_25_SDSS.jpg[/img3][/float][float=right][img3="But in ultraviolet light, NGC 4625 is shown to have a set of extended arms of young stars, shown in green in this composite image. Credit: NASA/JPL-Caltech/Carnegie Observatories/DSS"]https://upload.wikimedia.org/wikipedia/commons/thumb/9/9f/NGC_4625_and_NGC_4618.jpg/600px-NGC_4625_and_NGC_4618.jpg?20110630162426[/img3][/float]
[clear][/clear]
With its extended arms small NGC 4625 suddenly looks as large (or larger) than its neighbor, NGC 4618.
Another interesting example of extended arms (of stars of otherwise) is dwarf galaxy NGC 4214. Hubble has shown that this galaxy has a disk of old stars and a few hotspots of starburst:
[float=left][img3="NGC 4214. Note the large nebulas and bright blue star clusters set on a disk of small red stars. Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration Acknowledgment: R. O’Connell (University of Virginia) and the WFC3 Scientific Oversight Committee "]https://upload.wikimedia.org/wikipedia/commons/thumb/4/49/NGC_4214.jpg/1024px-NGC_4214.jpg[/img3][/float][float=right][img3="Radio image of neutral hydrogen in NGC 4214. Credit: National Radio Astronomy Observatory"]https://science.nrao.edu/science/surveys/littlethings/data/ngc4214/ngc4214_color_thumb.jpg[/img3][/float]
[clear][/clear]
With the gas surrounding it, NGC 4214 suddenly becomes a spiral galaxy! Fancy that! :D
But the very opposite thing happens, too, when gas recedes from the outer parts of the galaxy and is only found near the center of the galaxy:
[float=left][img3="NGC 4314, an all-yellow barred spiral galaxy. The blue point sources are foreground stars, or possibly background galaxies. Credit: Sloan Digital Sky Survey "]https://upload.wikimedia.org/wikipedia/commons/2/27/NGC4314_-_SDSS_DR14.jpg[/img3][/float][float=right][img3="Wait! Did I say that NGC 4314 is all-yellow? It is not, because there is a small ring of star formation encircling the galaxy's nucleus! Credit: G. Fritz Benedict, Andrew Howell, Inger Jorgensen, David Chapell (University of Texas), Jeffery Kenney (Yale University), and Beverly J. Smith (CASA, University of Colorado), and NASA"]https://upload.wikimedia.org/wikipedia/commons/3/39/NGC_4314HST1998-21-b-full.jpg[/img3][/float]
[clear][/clear]
So in NGC 4314, a tiny ring of gas and dust is all the gas there is in this galaxy!
[float=right][attachment=0]NGC 4314 as Peggy Lee SDSS.png[/attachment][/float][youtube]https://www.youtube.com/watch?v=LCRZZC-DH7M[/youtube]
[clear][/clear]
Ann