Starship Asterisk*

Chris Peterson wrote: ↑Fri Jan 20, 2023 8:54 pm

johnnydeep wrote: ↑Fri Jan 20, 2023 8:50 pm

Francesca wrote: ↑Fri Jan 20, 2023 8:28 pm The double images of galaxies are known. See this (indicated to me by Dan Coe)

https://arxiv.org/abs/2211.13334

Isn't that article about lensed stars, not galaxies? The title is "Two lensed star candidates at z≃4.8 behind the galaxy cluster MACS J0647.7+7015"

Unless the double galaxies we've been discussing are also mentioned within. I admit I haven't read the article in detail.

Yes, but note identified object 1 from the HST images (1.1, 1.2, and 1.3).

johnnydeep wrote: ↑Fri Jan 20, 2023 8:50 pm

Francesca wrote: ↑Fri Jan 20, 2023 8:28 pm The double images of galaxies are known. See this (indicated to me by Dan Coe)

https://arxiv.org/abs/2211.13334

Isn't that article about lensed stars, not galaxies? The title is "Two lensed star candidates at z≃4.8 behind the galaxy cluster MACS J0647.7+7015"

Unless the double galaxies we've been discussing are also mentioned within. I admit I haven't read the article in detail.

Francesca wrote: ↑Fri Jan 20, 2023 8:28 pm The double images of galaxies are known. See this (indicated to me by Dan Coe)

https://arxiv.org/abs/2211.13334

Chris Peterson wrote: ↑Thu Jan 19, 2023 9:33 pm

Francesca wrote: ↑Thu Jan 19, 2023 8:53 pm I see in the picture (also in that by Hubble) two identical images of a galaxy. My question is whether this has been already noted. To see the first one, look at the star at the left of the center of the picture. It has six blue rays. Prolong the ray pointing up-right till a small red galaxy. The second image is approximately on the vertical line at the middle of the picture, just at the end of the left blue ray of another star, a bit less brilliant than that considered above.
There are two more objects that seem to be distorted mirror images one of the other.

Interesting catch. While the two objects appear very similar- really, too much for a coincidence IMO (and not mirrored)- I don't think they can be lensed images. You'd never have a pair of lensed images that look the same, given the nature of gravitational lensing distortion. Some kind of processing and stacking anomaly, maybe?
_
2gal.jpg

johnnydeep wrote: ↑Thu Jan 19, 2023 9:08 pm

Francesca wrote: ↑Thu Jan 19, 2023 8:53 pm I see in the picture (also in that by Hubble) two identical images of a galaxy. My question is whether this has been already noted. To see the first one, look at the star at the left of the center of the picture. It has six blue rays. Prolong the ray pointing up-right till a small red galaxy. The second image is approximately on the vertical line at the middle of the picture, just at the end of the left blue ray of another star, a bit less brilliant than that considered above.
There are two more objects that seem to be distorted mirror images one of the other.

I'm not sure I'm following your directions correctly. Can you post a pic with the two galaxies indicated? This are the two galaxies that I think you are referring to:


two red galaxies in jwst gravitational lensing pic.png


[ EDIT: nah, that can't be right. I give up. I need a pic! ]

Francesca wrote: ↑Thu Jan 19, 2023 8:53 pm I see in the picture (also in that by Hubble) two identical images of a galaxy. My question is whether this has been already noted. To see the first one, look at the star at the left of the center of the picture. It has six blue rays. Prolong the ray pointing up-right till a small red galaxy. The second image is approximately on the vertical line at the middle of the picture, just at the end of the left blue ray of another star, a bit less brilliant than that considered above.
There are two more objects that seem to be distorted mirror images one of the other.

Francesca wrote: ↑Thu Jan 19, 2023 8:53 pm I see in the picture (also in that by Hubble) two identical images of a galaxy. My question is whether this has been already noted. To see the first one, look at the star at the left of the center of the picture. It has six blue rays. Prolong the ray pointing up-right till a small red galaxy. The second image is approximately on the vertical line at the middle of the picture, just at the end of the left blue ray of another star, a bit less brilliant than that considered above.
There are two more objects that seem to be distorted mirror images one of the other.

johnnydeep wrote: ↑Wed Jan 18, 2023 8:23 pm

JohnD wrote: ↑Wed Jan 18, 2023 5:05 pm Spectral lines?

Was that in answer to my second question above?

bystander wrote: ↑Wed Jan 18, 2023 4:19 pm

Ann wrote: ↑Wed Jan 18, 2023 6:40 am ...
There can be no doubt that JWST is doing a better job than Hubble when it comes to resolving the extremely early and distant background galaxy, MACS0647-JD. JWST showed us three lensed versions of this galaxy, too.
...

Let's see. The Webb image is totally infrared (near (blue), mid (green), and far (red)). It is, after all, an infrared telescope.

The Hubble image was originally visible wavelengths (blue) with near infrared added on (green), and then some more (near) infrared (green and red) added with a later observation. Remember, Hubble is primarily a conventional telescope with some IR and UV capabilities.

Since the further objects are, the more they are red-shifted, Webb is doing exactly what it was designed to do. Give us a better look at the distant universe.

bystander wrote: ↑Wed Jan 18, 2023 4:19 pm

Ann wrote: ↑Wed Jan 18, 2023 6:40 am ...
(And by the way, why were the three lensed versions not labeled in the order that they appeared on the sky, which was, anti-clockwise: 3, 1, 2? Oh, wait, is the numbering of the lensed galaxies a right ascension thing?)
...

I think it has to do with magnification JD1 (8x), JD2 (5x), & JD3 (2x) (Dan Coe).

johnnydeep wrote: ↑Wed Jan 18, 2023 4:57 pm ...
1 - In the original Hubble image of this cluster, distant and ancient background galaxy MACS0647-JD was detected and "observed as an amorphous blob". Were the other two lensed versions of this background galaxy that JWST detected also detected by Hubble? (aside: all three images of MACS0647-JD are technically being "lensed" are they not?) If Hubble didn't detect the other two, why not?
...

Evenstar wrote: ↑Wed Jan 18, 2023 11:34 pm Won't say much because I am just amazed and don't understand how one ends up here with the same image lensed 3 times all of which look different to me (JD1, JD2, JD3). :ssmile:

Chris Peterson wrote: ↑Wed Jan 18, 2023 11:01 pm

johnnydeep wrote: ↑Wed Jan 18, 2023 10:51 pm

Chris Peterson wrote: ↑Wed Jan 18, 2023 10:18 pm
No. The lensed images show two or three different galaxies. With different colors.

But the text says "In particular, the background source MACS0647-JD is seen to be lensed three times by the cluster."

To me, that means that the same MACS0647-JD galaxy is shown in all three outset images.

But MACS0647-JD isn't a galaxy. It's a cluster of two or more galaxies. Did you miss this in the caption: "When first discovered with the Hubble Space Telescope, MACS0647-JD was observed as an amorphous blob. With Webb though, this single source is revealed to be a pair or small group of galaxies."

So we're seeing three images of the same group of galaxies.

johnnydeep wrote: ↑Wed Jan 18, 2023 10:51 pm

Chris Peterson wrote: ↑Wed Jan 18, 2023 10:18 pm

johnnydeep wrote: ↑Wed Jan 18, 2023 9:57 pm

Well, what does this statement in the text mean, specifically, "these galaxies"? There's only one galaxy being imaged here, right?:

No. The lensed images show two or three different galaxies. With different colors.

But the text says "In particular, the background source MACS0647-JD is seen to be lensed three times by the cluster."

To me, that means that the same MACS0647-JD galaxy is shown in all three outset images.

Chris Peterson wrote: ↑Wed Jan 18, 2023 10:18 pm

johnnydeep wrote: ↑Wed Jan 18, 2023 9:57 pm

Chris Peterson wrote: ↑Wed Jan 18, 2023 9:11 pm

I think you misunderstand. All three images show the same colors. The observation is that the two or three individual sources that make up each image are different colors. We are seeing them all at very nearly the same time, because the light path lengths are nearly identical.

Well, what does this statement in the text mean, specifically, "these galaxies"? There's only one galaxy being imaged here, right?:

The colors of the MACS0647-JD objects are different as well -- indicating differences potentially in the age or dust content of these galaxies.

No. The lensed images show two or three different galaxies. With different colors.

johnnydeep wrote: ↑Wed Jan 18, 2023 9:57 pm

Chris Peterson wrote: ↑Wed Jan 18, 2023 9:11 pm

moconnor wrote: ↑Wed Jan 18, 2023 8:56 pm As was pointed out, the three images of the same cluster look different. Does that mean that the lensing shows them at different times (or ages), although they are captured at the same time from our viewpoint on Earth? For example, does JD-1 show the object at age Big Bang + 300 million years, whereas JD-2 shows it at age BB + 320 million years and JD-3 show it at BB + 390 million years? Can the lensing have that degree of difference that depends on which side of the foreground cluster we see it?

I think you misunderstand. All three images show the same colors. The observation is that the two or three individual sources that make up each image are different colors. We are seeing them all at very nearly the same time, because the light path lengths are nearly identical.

Well, what does this statement in the text mean, specifically, "these galaxies"? There's only one galaxy being imaged here, right?:

The colors of the MACS0647-JD objects are different as well -- indicating differences potentially in the age or dust content of these galaxies.

Chris Peterson wrote: ↑Wed Jan 18, 2023 9:11 pm

moconnor wrote: ↑Wed Jan 18, 2023 8:56 pm As was pointed out, the three images of the same cluster look different. Does that mean that the lensing shows them at different times (or ages), although they are captured at the same time from our viewpoint on Earth? For example, does JD-1 show the object at age Big Bang + 300 million years, whereas JD-2 shows it at age BB + 320 million years and JD-3 show it at BB + 390 million years? Can the lensing have that degree of difference that depends on which side of the foreground cluster we see it?

I think you misunderstand. All three images show the same colors. The observation is that the two or three individual sources that make up each image are different colors. We are seeing them all at very nearly the same time, because the light path lengths are nearly identical.

The colors of the MACS0647-JD objects are different as well -- indicating differences potentially in the age or dust content of these galaxies.

moconnor wrote: ↑Wed Jan 18, 2023 8:56 pm As was pointed out, the three images of the same cluster look different. Does that mean that the lensing shows them at different times (or ages), although they are captured at the same time from our viewpoint on Earth? For example, does JD-1 show the object at age Big Bang + 300 million years, whereas JD-2 shows it at age BB + 320 million years and JD-3 show it at BB + 390 million years? Can the lensing have that degree of difference that depends on which side of the foreground cluster we see it?

Cousin Ricky wrote: ↑Wed Jan 18, 2023 5:26 pm

De58te wrote: ↑Wed Jan 18, 2023 12:54 pm A question. In the close-up of JD 3 there is a small totally green galaxy that's even smaller than JD 3 at the bottom right corner. Could this be an even younger galaxy and why is it green? Was it really green, or that it was red shifted to green because of its distance and it was really some other color?

The short answer is that green is what fell out of the color assignments to the filters. JWST does not work with visible light, and these galaxies are all drastically red-shifted anyway.

JohnD wrote: ↑Wed Jan 18, 2023 5:05 pm Spectral lines?

De58te wrote: ↑Wed Jan 18, 2023 12:54 pm A question. In the close-up of JD 3 there is a small totally green galaxy that's even smaller than JD 3 at the bottom right corner. Could this be an even younger galaxy and why is it green? Was it really green, or that it was red shifted to green because of its distance and it was really some other color?