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APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 4:08 am
by APOD Robot
Image PDS 70: Disk, Planets, and Moons

Explanation: It's not the big ring that's attracting the most attention. Although the big planet-forming ring around the star PDS 70 is clearly imaged and itself quite interesting. It's also not the planet on the right, just inside the big disk, that’s being talked about the most. Although the planet PDS 70c is a newly formed and, interestingly, similar in size and mass to Jupiter. It's the fuzzy patch around the planet PDS 70c that's causing the commotion. That fuzzy patch is thought to be a dusty disk that is now forming into moons -- and that had never been seen before. The featured image was taken in 2021 by the Atacama Large Millimeter Array (ALMA) of 66 radio telescopes in the high Atacama Desert of northern Chile. Based on ALMA data, astronomers infer that the moon-forming exoplanetary disk has a radius similar to our Earth's orbit, and may one day form three or so Luna-sized moons -- not very different from our Jupiter's four.

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Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 12:42 pm
by shaileshs
I wonder why planet forming ring is seen brightest, even planet is seen brighter than the actual star? Is it the way the image is taken and processed to show most interesting things blocking/diffusing star's light/brightness ? I'm guessing so. Also I wonder how many planets one can expect to form in this disk and what's the width of disk and would it be similar in size (width) so that planets can form at wide distances around the star as we have in our solar system (and not bunched up at same distance) ? Why one planet is formed already (and getting it's own moons) and others haven't (i mean what was special that that planet is in advanced stage compared to others) ? Thanks in advance for all answers.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 2:00 pm
by Chris Peterson
shaileshs wrote: Tue Oct 17, 2023 12:42 pm I wonder why planet forming ring is seen brightest, even planet is seen brighter than the actual star? Is it the way the image is taken and processed to show most interesting things blocking/diffusing star's light/brightness ? I'm guessing so. Also I wonder how many planets one can expect to form in this disk and what's the width of disk and would it be similar in size (width) so that planets can form at wide distances around the star as we have in our solar system (and not bunched up at same distance) ? Why one planet is formed already (and getting it's own moons) and others haven't (i mean what was special that that planet is in advanced stage compared to others) ? Thanks in advance for all answers.
At the long wavelengths this instrument operates at, the warm dust and planet are brighter than the star.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 2:37 pm
by madtom1999
Chris Peterson wrote: Tue Oct 17, 2023 2:00 pm
shaileshs wrote: Tue Oct 17, 2023 12:42 pm I wonder why planet forming ring is seen brightest, even planet is seen brighter than the actual star? Is it the way the image is taken and processed to show most interesting things blocking/diffusing star's light/brightness ? I'm guessing so. Also I wonder how many planets one can expect to form in this disk and what's the width of disk and would it be similar in size (width) so that planets can form at wide distances around the star as we have in our solar system (and not bunched up at same distance) ? Why one planet is formed already (and getting it's own moons) and others haven't (i mean what was special that that planet is in advanced stage compared to others) ? Thanks in advance for all answers.
At the long wavelengths this instrument operates at, the warm dust and planet are brighter than the star.
I've always wondered why it assumed that the star is the first thing to start blowing the gas away. It seems the case here of having a large cloud of hot gas failing to clear out all of the gas. It seems to me there is always the possibly in a solar system than various gas densities can cause planets to form before the star lights up and in this case it managed to make a large almost stellar object with satellites. Its easy to extend this to our solar system having more than 1 large planet in its early creation and no requirement for the complicated dances required to throw planets into different orbitals.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 2:41 pm
by Chris Peterson
madtom1999 wrote: Tue Oct 17, 2023 2:37 pm
Chris Peterson wrote: Tue Oct 17, 2023 2:00 pm
shaileshs wrote: Tue Oct 17, 2023 12:42 pm I wonder why planet forming ring is seen brightest, even planet is seen brighter than the actual star? Is it the way the image is taken and processed to show most interesting things blocking/diffusing star's light/brightness ? I'm guessing so. Also I wonder how many planets one can expect to form in this disk and what's the width of disk and would it be similar in size (width) so that planets can form at wide distances around the star as we have in our solar system (and not bunched up at same distance) ? Why one planet is formed already (and getting it's own moons) and others haven't (i mean what was special that that planet is in advanced stage compared to others) ? Thanks in advance for all answers.
At the long wavelengths this instrument operates at, the warm dust and planet are brighter than the star.
I've always wondered why it assumed that the star is the first thing to start blowing the gas away. It seems the case here of having a large cloud of hot gas failing to clear out all of the gas. It seems to me there is always the possibly in a solar system than various gas densities can cause planets to form before the star lights up and in this case it managed to make a large almost stellar object with satellites. Its easy to extend this to our solar system having more than 1 large planet in its early creation and no requirement for the complicated dances required to throw planets into different orbitals.
I don't understand. This star is fully "lit up" and is obviously clearing the system of dust. The star is, by many orders of magnitude, the most energetic thing in this system.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 4:33 pm
by Bartolo
Why "moons" and not "planets"?

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 5:06 pm
by Chris Peterson
Bartolo wrote: Tue Oct 17, 2023 4:33 pm Why "moons" and not "planets"?
Because they are forming around a planet, not around a star.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 6:35 pm
by nikolira
Hi,

Please, whenever you link ALMA, like in the credits of this picture, use the ALMA website link: https://www.almaobservatory.org. Right now, it is pointing to the ESO's web page about ALMA.

Thanks!

Best regards,

Nicolás Lira Turpaud
ALMA EPO Coordinator

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 8:09 pm
by johnnydeep
Let's add some annotations to make this all more clear (hopefully):

the PDS 70 protoplanetary star system.jpg

[ EDIT: what I've circled as PDS 70b is not in fact visible in this image, and is likely not a planet at all. See discussion below. ]

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 10:04 pm
by orin stepanek
johnnydeep wrote: Tue Oct 17, 2023 8:09 pm Let's add some annotations to make this all more clear (hopefully):


the PDS 70 protoplanetary star system.jpg
Thanfs Johnnydeep!

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Tue Oct 17, 2023 11:37 pm
by alter-ego
johnnydeep wrote: Tue Oct 17, 2023 8:09 pm Let's add some annotations to make this all more clear (hopefully):


the PDS 70 protoplanetary star system.jpg
On the surface, certainly seems reasonable you've correctly labeled 70b, but according to the ESO desription, 70b is not visible this image, and nothing said about those additional blob(s) you circled as 70b.

70b is visible here

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Wed Oct 18, 2023 4:15 am
by shaileshs
Still some questions unanswered (from my original 1st post), hoping someone can provide their thoughts if not answers..

2) Also I wonder how many planets one can expect to form in this disk and
3) What's the width of disk and would it be similar in size (width) so that planets can form at wide distances around the star as we have in our solar system (and not bunched up at same distance) ?
4) Why one planet is formed already (and getting it's own moons) and others haven't (i mean what was special that that planet is in advanced stage compared to others) ? What are necessary conditions and what's right mix/quantity of dust and interactions that are needed for a planet to form ?

Thanks in advance for all answers/thought.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Wed Oct 18, 2023 1:35 pm
by Chris Peterson
shaileshs wrote: Wed Oct 18, 2023 4:15 am Still some questions unanswered (from my original 1st post), hoping someone can provide their thoughts if not answers..

2) Also I wonder how many planets one can expect to form in this disk and
Simulations of systems like this typically show hundreds of planets created, with most being ejected early in the formation of the system.
3) What's the width of disk and would it be similar in size (width) so that planets can form at wide distances around the star as we have in our solar system (and not bunched up at same distance) ?
The width or the radius? I'll assume you mean the latter. It's 140 AU, so pretty consistent with the size of the Solar System. Keep in mind that most planets probably end up in a different orbit from that where they formed.
4) Why one planet is formed already (and getting it's own moons) and others haven't (i mean what was special that that planet is in advanced stage compared to others) ? What are necessary conditions and what's right mix/quantity of dust and interactions that are needed for a planet to form?
We already have directly imaged two planets (or protoplanets) in this system. There are almost certainly more that we have not detected. The ones we see have cleared their orbits of dust, making it easier to detect them.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Wed Oct 18, 2023 2:37 pm
by shaileshs
Thank you Chris.

Re: APOD: PDS 70: Disk, Planets, and Moons (2023 Oct 17)

Posted: Wed Oct 18, 2023 2:43 pm
by johnnydeep
alter-ego wrote: Tue Oct 17, 2023 11:37 pm
johnnydeep wrote: Tue Oct 17, 2023 8:09 pm Let's add some annotations to make this all more clear (hopefully):


the PDS 70 protoplanetary star system.jpg
On the surface, certainly seems reasonable you've correctly labeled 70b, but according to the ESO desription, 70b is not visible this image, and nothing said about those additional blob(s) you circled as 70b.

70b is visible here
Hmm. Thanks for the correction. Perhaps I've discovered PDS 70d! Also, these people really need to start annotating their images! My hypothetical - but surely incorrect! - "discovery" of PDS 70d at least shows up in both images between the 12 and 1 o'clock positions very close to PDS 70.