Protoplanetary disk material found to be too sparse to form planet populations

October 3, 2018 by Bob Yirka, Phys.org report
Credit: CC0 Public Domain

A trio of researchers with the European Southern Observatory and Université Côte d'Azur has found evidence showing that the gas and dust disks that form around early stars systems do not contain enough material to form the planets that develop. In their paper published in the journal Astronomy Astrophysics, Carlo Manara, A. Morbidelli and T. Guillot describe their study of data from the Atacama Large Millimeter Array (ALMA) in Chile and what they found.

In this new effort, Manara, Morbidelli and Guillot were studying data from ALMA to learn more about protoplanetary disks. To that end, they looked at how much material is contained in such disks around that were just 1 to 3 million years old—the time period before planets had evolved. Next, they measured the masses of older star systems with mature planets. By comparing the two, they found that the matter in early star systems did not have enough mass to create the planets that would eventually develop.

Until now, space scientists have believed that star systems form due to space dust coalescing into a star. Once the star gets going, a usually forms around the star. It is believed the gas and dust that make up the disk are leftovers from material involved in creating the star. As more time passes, the material in the disk tends to clump together until gravity takes over, attracting more of the material in the disk. Eventually, most of the material from the disk is incorporated into planets that orbit the star. But this new evidence suggests that there is not enough material in the disk of the average early star system to create the average number and size of planets that come to exist a few million years later.

The researchers did not attempt to find a reason for the discrepancy, but suggest several possibilities. It could be that planet formation starts earlier than thought, or there could be larger bits of dust than those found by radio waves that were detectable by ALMA. There is also the possibility that star systems pull in more dust from the space around the system as develop.

Explore further: Little star sheds light on young planets

More information: C. F. Manara et al. Why do protoplanetary disks appear not massive enough to form the known exoplanet population?, Astronomy & Astrophysics (2018). DOI: 10.1051/0004-6361/201834076

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15 comments

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cantdrive85
2.1 / 5 (15) Oct 03, 2018
Another day, another observation, another fail for the standard theory.
rrwillsj
1.8 / 5 (4) Oct 03, 2018
Or evidence, that for many systems, planets do not form as early as astronomers have theorized.

That it may turn out to be a chaotic process of random chance opportunities. No overlaying rules or simple regulating formulas. Every star an outlier, every planet an outlaw.
rossim22
1.6 / 5 (7) Oct 03, 2018
Or evidence, that for many systems, planets do not form as early as astronomers have theorized.

That it may turn out to be a chaotic process of random chance opportunities. No overlaying rules or simple regulating formulas. Every star an outlier, every planet an outlaw.


Your confirmational bias is talking.

I completely understand the temptation to believe the current model was 'almost' valid and we just need to tweak a few things. That sounds easy.

But the very observations that led scientists to place their constraints and make predictions and develop a model on the timeline of planet formation in conjunction with star formation were well thought out. Everything worked the way they were. And they were just FALSIFIED. Well, why were the authors of all those peer-reviewed papers misled?

This is just another example of a foundational pillar of the standard model proven to be wrong OR an ad hoc hypothesis must be fabricated to explain the error.
Tuxford
1.5 / 5 (8) Oct 03, 2018
There is also the possibility that star systems pull in more dust from the space around the system as planets develop.

There is also the possibility that star systems form largely from episotic ejections of newly formed matter from the star itself, similar to the process that occurs in a more violent and frequent fashion in more supermassive core stars such as the grey hole at the galactic center.
jonesdave
2.5 / 5 (8) Oct 03, 2018


This is just another example of a foundational pillar of the standard model proven to be wrong OR an ad hoc hypothesis must be fabricated to explain the error.


EU dogma and word salad. Got any science to offer, woo boy?

https://www.aanda...-18.html

rossim22
2 / 5 (5) Oct 03, 2018


EU dogma and word salad. Got any science to offer, woo boy?

https://www.aanda...-18.html


The scientists already offered the science, as described in this article.

As for the paper you linked... ?
Disks of material around stars exist. Correct. They found there is likely a dwarf planet observed in a MASSIVE gap (~54au) of a disk around a star. This doesn't do much for explaining planetary formation.

Borrowed from the paper in this article:

"From the theoretical perspective, all models to explain the formation of planetesimals and planets are based on processes that are quite inefficient."

"This comparison shows that either planet accretion is more efficient than current models suggest or that other scenarios are needed."

This is a BIG problem if we have (still) no clue how planets are formed. You can't keep resorting to pebble accretion over eons.
Steelwolf
2.8 / 5 (6) Oct 04, 2018
I have long considered the possibility that planets can form during the same period and in the same manner, in general, as stars. However, in my scenario it is a race for the materials and some will be preferentially certain materials: rocky and metallic elements will tend to clump based on density and charge, large clouds of gasses will be attracted by charge and gravity until charge neutralizes, then it is infall and local magnetism to help the final approach to contact.

But in general it is a race to the ignition point of the first Star to light, which blows the dust and gas discs away from the other 'possible stars' which become, then, possible planets, that or they will float back towards the spawning grounds and try again to become full fledged stars.

I have also wondered if some rocky planets are old Old Jovian-type or perhaps Neptune-like planetary cores with the gasses pretty much gone from a close orbiting 'Hot' gas planet. Vulcan anyone?
jonesdave
2.3 / 5 (9) Oct 04, 2018
This is a BIG problem if we have (still) no clue how planets are formed. You can't keep resorting to pebble accretion over eons.


Really? What else is on the table? Within the scientific literature?

I notice that you have read the paper, but for some reason have failed to mention sections 4.1 & 4.2. Those two sections discuss reasons why the disks they looked at may be lacking the necessary material, including earlier formation of planetary cores, within the first ~ 1 Myr.

torbjorn_b_g_larsson
3.2 / 5 (9) Oct 04, 2018
Cool! The most likely explanation is that pebble formation is more easy than earlier physics modesl suggest, which is in line with the rapid and gap leaving planet formation seen.

Obviously there is no need to respond individually to the usual irrelevant comments. Some that - despite more evidence for protoplanetary disks (moreobservcations) and our lack of understanding planet formation - claim this is somehow problematic or rejecting earlier protoplanetary disk and planet formation science. Others that propose unpublished 'own models' - spare us!

[tbctd]
torbjorn_b_g_larsson
2.5 / 5 (8) Oct 04, 2018
[ctd] But this merits a question:

This is a BIG problem if we have (still) no clue how planets are formed. You can't keep resorting to pebble accretion over eons.


We have clues, that is why they expect more visible material and propose ways that expectation is not met. Pebble formation is the contender to core accretion for gas giants, which would use up most planet mass, so it is obviously likely (see above). I am not aware of that it would failto deliver material until cores are formed, or that it would take "eons" as it seems to be the fastest pathway when modeled. Is that why you do not provide references to support your seemingly contra-factual claim?
rossim22
2.8 / 5 (6) Oct 04, 2018

Obviously there is no need to respond individually to the usual irrelevant comments.
[tbctd]

You guys crack me up with your self-proclaimed scientific righteousness.
"No need to respond individually" followed by a lengthy response. LOL

I am not arguing for anything except questions raised in this single paper described in this article. No need to "provide references" to you scholarly deities.

Every past observation by each relevant scientist resulted in a coherent model which was universally accepted and made specific predictions on the timeline. Then after some time, a direct observation was made and that timeline was proven to be wrong.

Clearly, there are elements in play that were not considered within all the efforts provided by those scientists. ALL I'm saying is maybe those misidentifications or misassumptions could lead to a different model. Nothing mysterious. Hell, nothing with EU or electromagnetism whatsoever. Just different.
jonesdave
2.7 / 5 (7) Oct 04, 2018
Every past observation by each relevant scientist resulted in a coherent model which was universally accepted and made specific predictions on the timeline. Then after some time, a direct observation was made and that timeline was proven to be wrong.


No, that is just more word salad. What observations? What models that were universally accepted? They were accepted as being the most likely model, given what we knew, or could model, at a specific time. As we get ever better instruments, then those models can be tested, and new information gained to improve the modelling. This paper seems to put constraints on the timeline. Nothing serious.
These are not religious or cult doctrines, that have to be accepted as a matter of faith (unlike EU, for instance). All of science is open to change from improved observations and data. The basic model is correct. It may need tweaking as to the timeline. That is all.

rossim22
2.6 / 5 (5) Oct 04, 2018
The basic model is correct. It may need tweaking as to the timeline. That is all.


I believe that's the flaw in your logic.

Any scientist should be trying to falsify claims, though this seems to be a field searching only for confirmations.

In general, however, nothing is ever given 100 percent certainty. You seem to be unaware of that or simply prefer to ignore it.
jonesdave
2.5 / 5 (8) Oct 04, 2018
The basic model is correct. It may need tweaking as to the timeline. That is all.


I believe that's the flaw in your logic.

Any scientist should be trying to falsify claims, though this seems to be a field searching only for confirmations.

In general, however, nothing is ever given 100 percent certainty. You seem to be unaware of that or simply prefer to ignore it.


I know that nothing is a 100% certainty. I said as much above. And much of the evidence says the model is generally correct. Just Google 'protoplanetary disk'.
To the best of my knowledge there is no other hypothesis on the table.
rrwillsj
not rated yet Oct 05, 2018
Like grains of sand, dribbling through your fingers. On a personal scale, through human vision appear similar. Each grain seen through a microscope will appear different.

On a personal scale, through Human vision, the stars and planets seem similar. Viewed through telescopes and other powerful instruments, the stars are seen to have many unexpected differences. And the same appears true for the planets.

When what you are observing does not fulfill the expectations for your speculations? Do any of you seriously advocate that the reality will bend one iota to coddle your belief system?

Sorry, no coherent explanation will encompass chaos. This spectrum of possibilities are what makes reality interesting, that there are no limits to variety. We could spend forever trying to categorize everything!

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