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

[APOD Robot]

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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[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.

[Chris Peterson]

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.

[madtom1999]

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.

[Chris Peterson]

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.

[Bartolo]

Why "moons" and not "planets"?

[Chris Peterson]

Why "moons" and not "planets"?

Because they are forming around a planet, not around a star.

[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

[johnnydeep]

Let's add some annotations to make this all more clear (hopefully):

[ 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. ]

[orin stepanek]

Let's add some annotations to make this all more clear (hopefully):


the PDS 70 protoplanetary star system.jpg

Thanfs Johnnydeep!

[alter-ego]

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

[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.

[Chris Peterson]

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.

[shaileshs]

Thank you Chris.

[johnnydeep]

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.

This image, taken with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, shows the young planetary system PDS 70, located nearly 400 light-years away from Earth. The system features a star at its centre, around which the planet PDS 70b is orbiting. On the same orbit as PDS 70b, astronomers have detected a cloud of debris that could be the building blocks of a new planet or the remnants of one already formed. The ring-like structure that dominates the image is a circumstellar disc of material, out of which planets are forming. There is in fact another planet in this system: PDS 70c, seen at 3 o’clock right next to the inner rim of the disc.

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This image, taken with the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, shows the PDS 70 system, located nearly 400 light-years away and still in the process of being formed. The system features a star at its centre and at least two planets orbiting it, PDS 70b (not visible in the image) and PDS 70c, surrounded by a circumplanetary disc (the dot to the right of the star). The planets have carved a cavity in the circumstellar disc (the ring-like structure that dominates the image) as they gobbled up material from the disc itself, growing in size. It was during this process that PDS 70c acquired its own circumplanetary disc, which contributes to the growth of the planet and where moons can form.

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