by johnnydeep » Mon Jan 08, 2024 10:47 pm
Ann wrote: ↑Mon Jan 08, 2024 9:21 pm
Thank you for identifying the cluster! I'm impressed that you were able to! And I'm very glad that I managed to get the cluster right.
The reason why I could tentatively identify it is that alex555 described it as a globular cluster, but johnnydeep pointed out that it doesn't contain enough stars to be a globular. So the cluster we were looking for looked like a globular in its spherical shape and typical brightness distribution, with a steeply rising brightness in the center. I could only think of one open cluster that looks like that, and that is NGC 2362. This is what it looks like in
Simbad's astronomical database:
NGC 2362 DSS.png
The reason why NGC 2362 looks like that is that the B-type members are perfectly spherically distributed around the supergiant central star, Tau Canis Majoris. I know of no other open cluster that looks like that. Compare it, for example, with NGC 3293, which is quite rich, compact and spherical as open clusters go, but not nearly as bright in the center as NGC 2362:
Ann
Nice work guys - NGC 2362 is quite an interesting - and large! - open cluster as well! From Wikipedia:
https://en.wikipedia.org/wiki/NGC_2362 wrote:The cluster is located at a distance of approximately 1.48 kpc from the Sun,[1] and appears associated with the giant nebula Sh2-310 that lies at the same distance,[7] about one degree to the east. This giant H II region is being ionized by the brighter members of the NGC 2362 cluster.[4]
NGC 2362 is a relatively young 4–5 million years in age[3] but is devoid of star-forming gas and dust, indicating that the star formation process has come to a halt.[4]
It is a massive open cluster, with more than 500 solar masses,[3] an estimated 100-150 member stars, and an additional 500 forming a halo around the cluster. Of these cluster members, only around 35 show evidence of a debris disk.[3] There is one slightly evolved O-type star, Tau Canis Majoris, and around 40 B-type stars still on the main sequence. Only one candidate classical Be star has been found, as of 2005.[4]
[quote=Ann post_id=336194 time=1704748874 user_id=129702]
[quote="Knight of Clear Skies" post_id=336190 time=1704744408 user_id=143544]
[quote=Ann post_id=336153 time=1704603281 user_id=129702]
The only cluster I can think of that bears the slightest resemblance to it is NGC 2362, the Tau Canis Majoris cluster.
...
Ann
[/quote]
Wow. Great call Ann, I was able to plate solve @johnnydeep's screengrab and that's what it came up with too.
[url]https://worldwidetelescope.org/webclient/?wtml=http%3A%2F%2Fwwtcoreapp-data-app.azurewebsites.net%3A80%2Fwwtweb%2FShowImage.aspx%3Freverseparity%3DFalse%26scale%3D6.385632%26name%3D20180322111709-22b66056-xx.png%26imageurl%3Dhttps%3A%2F%2Fnova.astrometry.net%2Fimage%2F21864267%26credits%3DAstrometry.net%2BUser%2B(All%2BRights%2BReserved)%26creditsUrl%3D%26ra%3D109.268597%26dec%3D-25.509736%26x%3D420.8%26y%3D668.0%26rotation%3D83.02%26thumb%3Dhttps%3A%2F%2Fnova.astrometry.net%2Fimage%2F21864270%26wtml%3Dtrue#/place=Open_Collections.20180322111709-22b66056-xx.png.0&ra=7.28457&dec=-25.50974&fov=5.41236[/url]
[/quote]
Thank you for identifying the cluster! I'm impressed that you were able to! And I'm very glad that I managed to get the cluster right.
The reason why I could tentatively identify it is that alex555 described it as a globular cluster, but johnnydeep pointed out that it doesn't contain enough stars to be a globular. So the cluster we were looking for looked like a globular in its spherical shape and typical brightness distribution, with a steeply rising brightness in the center. I could only think of one open cluster that looks like that, and that is NGC 2362. This is what it looks like in [url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tau+CMa&submit=SIMBAD+search]Simbad's astronomical database:[/url]
NGC 2362 DSS.png
The reason why NGC 2362 looks like that is that the B-type members are perfectly spherically distributed around the supergiant central star, Tau Canis Majoris. I know of no other open cluster that looks like that. Compare it, for example, with NGC 3293, which is quite rich, compact and spherical as open clusters go, but not nearly as bright in the center as NGC 2362:
[img3="NGC 3293. Credit: Andre.lucas.melo"]https://upload.wikimedia.org/wikipedia/commons/4/4e/NGC3293-cut.jpg[/img3]
Ann
[/quote]
Nice work guys - NGC 2362 is quite an interesting - and large! - open cluster as well! From Wikipedia:
[quote=https://en.wikipedia.org/wiki/NGC_2362]The cluster is located at a distance of approximately 1.48 kpc from the Sun,[1] and appears associated with the giant nebula Sh2-310 that lies at the same distance,[7] about one degree to the east. This giant H II region is being ionized by the brighter members of the NGC 2362 cluster.[4]
NGC 2362 is a relatively young 4–5 million years in age[3] but is devoid of star-forming gas and dust, indicating that the star formation process has come to a halt.[4] [b][color=#0040FF]It is a massive open cluster, with more than 500 solar masses,[3] an estimated 100-150 member stars, and an additional 500 forming a halo around the cluster.[/color][/b] Of these cluster members, only around 35 show evidence of a debris disk.[3] There is one slightly evolved O-type star, Tau Canis Majoris, and around 40 B-type stars still on the main sequence. Only one candidate classical Be star has been found, as of 2005.[4][/quote]