by Ann » Thu May 12, 2022 5:42 am
NGC 346 is a perfect example of a bright young star cluster containing hot massive stars. Note that the stars are of different sizes (which in this photo is a consequence of pixel bleeding from the brightest stars, making them look bigger), and note that the biggest, brightest stars are bluish.
At left is what looks to me like an old cluster. Note that there are very many stars there, and note that the stars are relatively similar in size (and smallish) and that they are yellowish in color.
Of course, this yellow, star-rich patch doesn't have to be a cluster. Instead, it could simply be the star-rich background of relatively old stars peeking through a gap in the nebulosity surrounding NGC 346. But to me, it looks like a cluster.
Compare the appearance of NGC 346 and the swarm of small yellowish stars to one side of it with the
APOD of February 8, 2020, which starkly contrasts the young blue stars of NGC 2264 in Monoceros with the old yellow stars of cluster Trumpler 5:
The young blue stars of NGC 2264 and the old yellow stars of Trumpler 5 (top right).
Photo: Bray Falls.
A perfect example of what I mean by young clusters containing both "big" and "small" stars can be seen in the
other great young star cluster of the Small Magellanic Cloud, NGC 602:
Big and small stars of young star cluster NGC 602. Photo: Hubble.
NGC 346 really stands out in "the main body" of NGC 346. You can spot it at a glance in the portrait below of the Small Magellanic Cloud, because it is the largest, brightest red blob there. But where is that other bright young cluster in a nebula in the Small Magellanic Cloud, NGC 602? It is actually far outside the main body of the SMC, as it is located on the "wing" of this small galaxy:
Click to play embedded YouTube video.
Zooming into NGC 602.
Credit: NASA, ESA, and G. Bacon and the Hubble Heritage Team (STScI/AURA)
So why does the Small Magellanic Cloud have so few large nebulas and bright young clusters compared with its bigger neighbor, the Large Magellanic Cloud? It is simply because the larger bully of a galaxy is not only stealing gas, the star forming raw material, but stars, too, from its hapless smaller neighbor.
Wikipedia wrote:
The Magellanic Bridge (MBR) is a stream of neutral hydrogen that links the two Magellanic Clouds, with a few known stars inside it. It should not be confused with the Magellanic Stream, which links the Magellanic Clouds to the Milky Way. It was discovered in 1963 by J. V. Hindman et al.
There is a continuous stream of stars throughout the Bridge linking the Large Magellanic Cloud (LMC) with the Small Magellanic Cloud (SMC). This stellar bridge is of greater concentration in the western part. There are two major density clumps, one near the SMC, the other midway between the galaxies, referred to as the OGLE Island.
Note in the Wikipedia stub a fantastic animation of stars actually flowing from the Small Magellanic Cloud (elongated object at upper right) to the Large Magellanic Cloud (large round object at center).
Ann
[float=left][img3="Young Stars of NGC 346. Image Credit: NASA, ESA - acknowledgement: Antonella Nota (ESA/STScI) et al."]https://apod.nasa.gov/apod/image/2205/ngc346_hst_b1024.jpg[/img3][/float][float=right][attachment=2]APOD 12 May 2022 annotated NGC 346 young star cluster maybe old star cluster.png[/attachment][/float]
[clear][/clear]
NGC 346 is a perfect example of a bright young star cluster containing hot massive stars. Note that the stars are of different sizes (which in this photo is a consequence of pixel bleeding from the brightest stars, making them look bigger), and note that the biggest, brightest stars are bluish.
At left is what looks to me like an old cluster. Note that there are very many stars there, and note that the stars are relatively similar in size (and smallish) and that they are yellowish in color.
Of course, this yellow, star-rich patch doesn't have to be a cluster. Instead, it could simply be the star-rich background of relatively old stars peeking through a gap in the nebulosity surrounding NGC 346. But to me, it looks like a cluster.
Compare the appearance of NGC 346 and the swarm of small yellowish stars to one side of it with the [url=https://apod.nasa.gov/apod/ap200208.html]APOD of February 8, 2020[/url], which starkly contrasts the young blue stars of NGC 2264 in Monoceros with the old yellow stars of cluster Trumpler 5:
[float=left][attachment=1]15 Mon and Trumpler 5 APOD February 8 2020 Bray Falls.png[/attachment][c][size=85][color=#0040FF]The young blue stars of NGC 2264 and the old yellow stars of Trumpler 5 (top right).
Photo: Bray Falls.[/color][/size][/c][/float]
A perfect example of what I mean by young clusters containing both "big" and "small" stars can be seen in the [b][i]other[/i][/b] great young star cluster of the Small Magellanic Cloud, NGC 602:
[float=left][attachment=0]NGC 602.png[/attachment][c][size=85][color=#0040FF]Big and small stars of young star cluster NGC 602. Photo: Hubble.[/color][/size][/c][/float]
[clear][/clear]
NGC 346 really stands out in "the main body" of NGC 346. You can spot it at a glance in the portrait below of the Small Magellanic Cloud, because it is the largest, brightest red blob there. But where is that other bright young cluster in a nebula in the Small Magellanic Cloud, NGC 602? It is actually far outside the main body of the SMC, as it is located on the "wing" of this small galaxy:
[float=left][img3="The Small Magellanic Cloud. The brightest red blob (below center) is NGC 346. Image: ESA/Hubble and Digitized Sky Survey 2."]https://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Small_Magellanic_Cloud_%28Digitized_Sky_Survey_2%29.jpg/985px-Small_Magellanic_Cloud_%28Digitized_Sky_Survey_2%29.jpg[/img3][/float][float=right][youtube]https://www.youtube.com/watch?v=lEr40oQb4n0[/youtube][c][size=85][color=#0040FF]Zooming into NGC 602.
Credit: NASA, ESA, and G. Bacon and the Hubble Heritage Team (STScI/AURA)[/color][/size][/c][/float]
[clear][/clear]
So why does the Small Magellanic Cloud have so few large nebulas and bright young clusters compared with its bigger neighbor, the Large Magellanic Cloud? It is simply because the larger bully of a galaxy is not only stealing gas, the star forming raw material, but stars, too, from its hapless smaller neighbor.
[float=left][img3="The Large and Small Magellanic Clouds and the bridge connecting them. Image credit: V. Belokurov / D. Erkal / A. Mellinger."]https://room.eu.com/images/contents/Magellanic-Clouds-Bridge.jpg[/img3][/float]
[clear][/clear]
[quote][url=https://en.wikipedia.org/wiki/Magellanic_Bridge]Wikipedia[/url] wrote:
The Magellanic Bridge (MBR) is a stream of neutral hydrogen that links the two Magellanic Clouds, with a few known stars inside it. It should not be confused with the Magellanic Stream, which links the Magellanic Clouds to the Milky Way. It was discovered in 1963 by J. V. Hindman et al.
There is a continuous stream of stars throughout the Bridge linking the Large Magellanic Cloud (LMC) with the Small Magellanic Cloud (SMC). This stellar bridge is of greater concentration in the western part. There are two major density clumps, one near the SMC, the other midway between the galaxies, referred to as the OGLE Island.[/quote]
Note in the Wikipedia stub a fantastic animation of stars actually flowing from the Small Magellanic Cloud (elongated object at upper right) to the Large Magellanic Cloud (large round object at center).
Ann