Starship Asterisk*

by **VictorBorun** » Sat Jul 15, 2023 6:41 am

orin stepanek wrote: ↑Thu Jul 13, 2023 5:01 pm https://webbtelescope.org/contents/medi ... M7EWDE9RSN
STScI-01_RhoOph1024.png
interesting view of RhoOph1024! I like it !

with a pair of mysterious doughnuts
...

: Click to view full size image 1 or image 2

by **VictorBorun** » Sat Jul 15, 2023 6:34 am

VictorBorun wrote: ↑Sat Jul 15, 2023 6:33 am
orin stepanek wrote: ↑Thu Jul 13, 2023 5:01 pm https://webbtelescope.org/contents/medi ... M7EWDE9RSN
STScI-01_RhoOph1024.png
interesting view of RhoOph1024! I like it !
not without shadows… and protoplanetaries are this way and that
shadows 400.jpgshadows 200.jpgshadows 100.jpg

by **VictorBorun** » Sat Jul 15, 2023 6:33 am

orin stepanek wrote: ↑Thu Jul 13, 2023 5:01 pm https://webbtelescope.org/contents/medi ... M7EWDE9RSN
STScI-01_RhoOph1024.png
interesting view of RhoOph1024! I like it !

not without shadows… and protoplanetaries are this way and that

by **johnnydeep** » Fri Jul 14, 2023 12:44 am

AVAO wrote: ↑Thu Jul 13, 2023 6:23 am
Ann wrote: ↑Thu Jul 13, 2023 5:50 am Where in the picture is Rho Ophiuchi itself?

Ann
Hi Ann

For orientation. Description a bit confusing...

Click to view full size image
Original Image: h[url]ttps://www.eso.org/public/unitedkingdom/images/eso1123a/?lang
biggg:https://live.staticflickr.com/65535/530 ... 7d17_o.jpg

Ok, I finally get it. I'm slow... AVAO is showing where this APOD fov is in relation to the much larger Rho Ophiuci Cloud Complex! And the Rho Ophiuci star system itself isn't even IN this APOD. No, it's the brightest star (system) in the center of the large blue area far above in AVAO's image!! <smacks head>

And just for some more context, here's an annotated version of the entire complex side by side with AVAO's image (rotated):

(The annotated image is from https://cdn.astrobin.com/solutions/imag ... 856258.jpg)

by **johnnydeep** » Thu Jul 13, 2023 11:59 pm

Chris Peterson wrote: ↑Thu Jul 13, 2023 9:00 pm
johnnydeep wrote: ↑Thu Jul 13, 2023 8:37 pm
Chris Peterson wrote: ↑Thu Jul 13, 2023 4:13 pm
Gravity is a very weak force. Protostars naturally form quite far from each other, so they are not gravitationally bound. Think about what 50 stars in a cubic light year actually means: an average separation of about 4 light years. About the same as the distance from the Sun to our nearest stellar neighbor.
That math isn't right. Fifty stars in a cubic light year means that ALL the stars are within sqrt(3) ly of each other (that's the length of the solid diagonal)! If the 50 stars were equally spread throughout the volume, each would be in the center of its own little sub-cube with volume 1/50 of a cubic ly, which is a cube 0.271 ly on a side. That gives a solid diagonal length for each little cube of sqrt(3) * 0.271 = 0.4 ly. Oh, I suppose you must have just left out the decimal point!
Thought I typed it! In any case, that's still very far apart. Two stars at that distance are weakly bound, and when you throw in the perturbations of a cloud of them, it's game over for any sort of stability.

Ok, thanks.

by **Chris Peterson** » Thu Jul 13, 2023 9:00 pm

johnnydeep wrote: ↑Thu Jul 13, 2023 8:37 pm
Chris Peterson wrote: ↑Thu Jul 13, 2023 4:13 pm
johnnydeep wrote: ↑Thu Jul 13, 2023 3:58 pm

Ok. Now why would that be? I would think that if all the stars in an open cluster like this formed from the same mass of gas, that there would be a natural tendency for the stars so formed to remain bound to each other. Hmm, is the gas itself not even bound by its own gravity due to being so dispersed and subject to other forces like random collisions?
Gravity is a very weak force. Protostars naturally form quite far from each other, so they are not gravitationally bound. Think about what 50 stars in a cubic light year actually means: an average separation of about 4 light years. About the same as the distance from the Sun to our nearest stellar neighbor.
That math isn't right. Fifty stars in a cubic light year means that ALL the stars are within sqrt(3) ly of each other (that's the length of the solid diagonal)! If the 50 stars were equally spread throughout the volume, each would be in the center of its own little sub-cube with volume 1/50 of a cubic ly, which is a cube 0.271 ly on a side. That gives a solid diagonal length for each little cube of sqrt(3) * 0.271 = 0.4 ly. Oh, I suppose you must have just left out the decimal point! :)

Thought I typed it! In any case, that's still very far apart. Two stars at that distance are weakly bound, and when you throw in the perturbations of a cloud of them, it's game over for any sort of stability.

by **johnnydeep** » Thu Jul 13, 2023 8:37 pm

Chris Peterson wrote: ↑Thu Jul 13, 2023 4:13 pm
johnnydeep wrote: ↑Thu Jul 13, 2023 3:58 pm
Chris Peterson wrote: ↑Thu Jul 13, 2023 3:30 pm

Open clusters do not contain many gravitationally bound stars (by which I mean stars that are in closed orbits around each other). Open clusters are short-lived and simply dissipate.
Ok. Now why would that be? I would think that if all the stars in an open cluster like this formed from the same mass of gas, that there would be a natural tendency for the stars so formed to remain bound to each other. Hmm, is the gas itself not even bound by its own gravity due to being so dispersed and subject to other forces like random collisions?
Gravity is a very weak force. Protostars naturally form quite far from each other, so they are not gravitationally bound. Think about what 50 stars in a cubic light year actually means: an average separation of about 4 light years. About the same as the distance from the Sun to our nearest stellar neighbor.

That math isn't right. Fifty stars in a cubic light year means that ALL the stars are within sqrt(3) ly of each other (that's the length of the solid diagonal)! If the 50 stars were equally spread throughout the volume, each would be in the center of its own little sub-cube with volume 1/50 of a cubic ly, which is a cube 0.271 ly on a side. That gives a solid diagonal length for each little cube of sqrt(3) * 0.271 = 0.4 ly. Oh, I suppose you must have just left out the decimal point!

by **orin stepanek** » Thu Jul 13, 2023 5:01 pm

https://webbtelescope.org/contents/medi ... M7EWDE9RSN

interesting view of RhoOph1024! I like it !

by **Chris Peterson** » Thu Jul 13, 2023 4:13 pm

johnnydeep wrote: ↑Thu Jul 13, 2023 3:58 pm
Chris Peterson wrote: ↑Thu Jul 13, 2023 3:30 pm
johnnydeep wrote: ↑Thu Jul 13, 2023 3:14 pm Hmm, 50 young stars within a volume of about a cubic lightyear! This makes me wonder whether, if, over time, it is natural for sibling stars to migrate away from each other, which behavior would seem to be necessary to explain why most older stars - like our Sun - are found several lightyears apart. The counter case I suppose would be much larger nurseries of stars which might tend to form large clusters of stars that manage to stay together due to a stringer collective gravity?
Open clusters do not contain many gravitationally bound stars (by which I mean stars that are in closed orbits around each other). Open clusters are short-lived and simply dissipate.
Ok. Now why would that be? I would think that if all the stars in an open cluster like this formed from the same mass of gas, that there would be a natural tendency for the stars so formed to remain bound to each other. Hmm, is the gas itself not even bound by its own gravity due to being so dispersed and subject to other forces like random collisions?

Gravity is a very weak force. Protostars naturally form quite far from each other, so they are not gravitationally bound. Think about what 50 stars in a cubic light year actually means: an average separation of about 4 light years. About the same as the distance from the Sun to our nearest stellar neighbor.

by **johnnydeep** » Thu Jul 13, 2023 3:58 pm

Chris Peterson wrote: ↑Thu Jul 13, 2023 3:30 pm
johnnydeep wrote: ↑Thu Jul 13, 2023 3:14 pm Hmm, 50 young stars within a volume of about a cubic lightyear! This makes me wonder whether, if, over time, it is natural for sibling stars to migrate away from each other, which behavior would seem to be necessary to explain why most older stars - like our Sun - are found several lightyears apart. The counter case I suppose would be much larger nurseries of stars which might tend to form large clusters of stars that manage to stay together due to a stringer collective gravity?
Open clusters do not contain many gravitationally bound stars (by which I mean stars that are in closed orbits around each other). Open clusters are short-lived and simply dissipate.

Ok. Now why would that be? I would think that if all the stars in an open cluster like this formed from the same mass of gas, that there would be a natural tendency for the stars so formed to remain bound to each other. Hmm, is the gas itself not even bound by its own gravity due to being so dispersed and subject to other forces like random collisions?

by **bystander** » Thu Jul 13, 2023 3:48 pm

viewtopic.php?t=43232

by **Chris Peterson** » Thu Jul 13, 2023 3:30 pm

johnnydeep wrote: ↑Thu Jul 13, 2023 3:14 pm Hmm, 50 young stars within a volume of about a cubic lightyear! This makes me wonder whether, if, over time, it is natural for sibling stars to migrate away from each other, which behavior would seem to be necessary to explain why most older stars - like our Sun - are found several lightyears apart. The counter case I suppose would be much larger nurseries of stars which might tend to form large clusters of stars that manage to stay together due to a stringer collective gravity?

Open clusters do not contain many gravitationally bound stars (by which I mean stars that are in closed orbits around each other). Open clusters are short-lived and simply dissipate.

by **johnnydeep** » Thu Jul 13, 2023 3:14 pm

Hmm, 50 young stars within a volume of about a cubic lightyear! This makes me wonder whether, if, over time, it is natural for sibling stars to migrate away from each other, which behavior would seem to be necessary to explain why most older stars - like our Sun - are found several lightyears apart. The counter case I suppose would be much larger nurseries of stars which might tend to form large clusters of stars that manage to stay together due to a stringer collective gravity?

by **johnnydeep** » Thu Jul 13, 2023 3:09 pm

Chris Peterson wrote: ↑Thu Jul 13, 2023 3:04 pm
johnnydeep wrote: ↑Thu Jul 13, 2023 2:58 pm
Chris Peterson wrote: ↑Thu Jul 13, 2023 12:48 pm

I see this regularly with my own images (which have just typical 4-spike diffraction). Close doubles are often not apparent at their core, where all the light is together in a big blob, but are made obvious by their not quite overlapping diffraction spikes.
Interesting. So, we can see two true close doubles in this image, correct? One at upper left and one at far lower left.
That would be my assessment. If this were a processing artifact (e.g. an alignment error) we'd see it uniformly across the image. Also, note that the offsets are different in the two cases. We can estimate the position angles of the otherwise obscured binaries from that.

Ok, what does your last sentence mean? What "position angles"?

by **johnnydeep** » Thu Jul 13, 2023 3:05 pm

Ann wrote: ↑Thu Jul 13, 2023 6:38 am
AVAO wrote: ↑Thu Jul 13, 2023 6:23 am
Ann wrote: ↑Thu Jul 13, 2023 5:50 am Where in the picture is Rho Ophiuchi itself?

Ann
Hi Ann

For orientation. Description a bit confusing...

Click to view full size image
Original Image: h[url]ttps://www.eso.org/public/unitedkingdom/images/eso1123a/?lang
biggg:https://live.staticflickr.com/65535/530 ... 7d17_o.jpg
Thanks a bunch, AVAO!

Ann

I'm still confused. A wiki image from https://en.wikipedia.org/wiki/Rho_Ophiu ... ud_complex says Rho Ophiuchi is at the center of the large blue region. Though of course, it might still wrong!

: Rho Ophiuchi Region, with the main dark nebula Lynds 1688 (and further L1689) to the left, ρ Ophiuchi at the center of the large blue area (IC 4604), Antares in the large yellow area and Sigma Scorpii in the redish Sh2-9 area, with Messier 4 inbetween the latter two stars. North is up. July 2, 2019 photo by Adam Block.

by **Chris Peterson** » Thu Jul 13, 2023 3:04 pm

johnnydeep wrote: ↑Thu Jul 13, 2023 2:58 pm
Chris Peterson wrote: ↑Thu Jul 13, 2023 12:48 pm
SpaceCadet wrote: ↑Thu Jul 13, 2023 7:46 am The star in the upper left hand corner has a double star effect from the JW camera. Is this an anomaly or is it bc there are actually 2 stars really close to each other?
I see this regularly with my own images (which have just typical 4-spike diffraction). Close doubles are often not apparent at their core, where all the light is together in a big blob, but are made obvious by their not quite overlapping diffraction spikes.
Interesting. So, we can see two true close doubles in this image, correct? One at upper left and one at far lower left.

That would be my assessment. If this were a processing artifact (e.g. an alignment error) we'd see it uniformly across the image. Also, note that the offsets are different in the two cases. We can estimate the position angles of the otherwise obscured binaries from that.

by **johnnydeep** » Thu Jul 13, 2023 2:58 pm

Chris Peterson wrote: ↑Thu Jul 13, 2023 12:48 pm
SpaceCadet wrote: ↑Thu Jul 13, 2023 7:46 am The star in the upper left hand corner has a double star effect from the JW camera. Is this an anomaly or is it bc there are actually 2 stars really close to each other?
I see this regularly with my own images (which have just typical 4-spike diffraction). Close doubles are often not apparent at their core, where all the light is together in a big blob, but are made obvious by their not quite overlapping diffraction spikes.

Interesting. So, we can see two true close doubles in this image, correct? One at upper left and one at far lower left.

by **johnnydeep** » Thu Jul 13, 2023 2:31 pm

One amazing year of JWST images and research in in the history books. May we have 20+ more! There was a great PBS Newshour segment about JWST on last night, and it actually featured Judy Schmidt, whose image processing prowess we all know well here!

See https://www.youtube.com/watch?v=xWSfc0IyuwI&t=2079s

Note: using the start time format makes the [ youtube ] tags fail to recognize it.

But you can drag the slider to 34:39 in the video below if you like.

Click to play embedded YouTube video.

by **Chris Peterson** » Thu Jul 13, 2023 12:48 pm

SpaceCadet wrote: ↑Thu Jul 13, 2023 7:46 am The star in the upper left hand corner has a double star effect from the JW camera. Is this an anomaly or is it bc there are actually 2 stars really close to each other?

I see this regularly with my own images (which have just typical 4-spike diffraction). Close doubles are often not apparent at their core, where all the light is together in a big blob, but are made obvious by their not quite overlapping diffraction spikes.

by **AVAO** » Thu Jul 13, 2023 8:22 am

SpaceCadet wrote: ↑Thu Jul 13, 2023 7:46 am The star in the upper left hand corner has a double star effect from the JW camera. Is this an anomaly or is it bc there are actually 2 stars really close to each other?

Two stars

by **Lasse H** » Thu Jul 13, 2023 8:19 am

SpaceCadet wrote: ↑Thu Jul 13, 2023 7:46 am The star in the upper left hand corner has a double star effect from the JW camera. Is this an anomaly or is it bc there are actually 2 stars really close to each other?

I just noticed that, too. It must be a double star, either an optical double or a visual binary. They seem to have about the same magnitude, judging from the spikes, and seem to be separated along a line from 10 to 4 on a clock face.

by **SpaceCadet** » Thu Jul 13, 2023 7:46 am

The star in the upper left hand corner has a double star effect from the JW camera. Is this an anomaly or is it bc there are actually 2 stars really close to each other?

by **Ann** » Thu Jul 13, 2023 6:38 am

AVAO wrote: ↑Thu Jul 13, 2023 6:23 am
Ann wrote: ↑Thu Jul 13, 2023 5:50 am Where in the picture is Rho Ophiuchi itself?

Ann
Hi Ann

For orientation. Description a bit confusing...

Click to view full size image
Original Image: h[url]ttps://www.eso.org/public/unitedkingdom/images/eso1123a/?lang
biggg:https://live.staticflickr.com/65535/530 ... 7d17_o.jpg

Thanks a bunch, AVAO!

Ann

by **AVAO** » Thu Jul 13, 2023 6:23 am

Ann wrote: ↑Thu Jul 13, 2023 5:50 am Where in the picture is Rho Ophiuchi itself?

Ann

Hi Ann

For orientation. Description a bit confusing...

: Click to view full size image

Original Image: h[url]ttps://www.eso.org/public/unitedkingdom/images/eso1123a/?lang
biggg:https://live.staticflickr.com/65535/530 ... 7d17_o.jpg

by **Ann** » Thu Jul 13, 2023 5:50 am

Where in the picture is Rho Ophiuchi itself?

Ann

Starship Asterisk*

APOD: Webb's Rho Ophiuchi (2023 Jul 13)

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