Starship Asterisk*

The Protoplanetary Disk of HL Tauri from ALMA

Explanation: Why does this giant disk have gaps? The exciting and probable answer is: planets. A mystery is how planets massive enough to create these gaps formed so quickly, since the HL Tauri star system is only about one million years old. The picture on which the gaps were discovered was taken with the new Atacama Large Millimeter Array (ALMA) of telescopes in Chile. ALMA imaged the protoplanetary disk, which spans about 1,500 light-minutes across, in unprecedented detail, resolving features as small as 40 light minutes. The low energy light used by ALMA was also able to peer through an intervening haze of gas and dust. The HL Tauri system lies about 450 light years from Earth. Studying HL Tauri will likely give insight into how our own Solar System formed and evolved.

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Will humans ever be able to terraform proto solar systems?

DavidGovett wrote:Will humans ever be able to terraform proto solar systems?

$10 on "no".

1500 light minutes is 25 hours diameter or 12.5 light hours radius. Voyager 2 is at approximately 14.75 light hours from the sun. Voyager 1 is at 18 light hours from the sun

I've been wondering where the dust torus that so frequently appears in pre-planetary nebulas comes from. I've been under the impression that the star itself somehow creates the dust but I'm very confused on the matter. I wonder if these stellar disks sometimes never coalesce into planets. Like maybe a binary star could have the dust disk but it never forms a planet because of the second star? Just some random conjecture.

Might it be the other way around, that the bright bands represent matter that is coagulating and will eventually become planets?

I remember that the science books I read as a child were still discussing if the solar system with its planets was unique. It's amazing that 25 years later, we know hundreds of exoplanets, have measured some of their atmospheres, and are now able to watch them forming.

This truly jaw-dropping image is the most amazing one I've seen this year in APOD - and that's saying something.

Markus Schwarz wrote:I remember that the science books I read as a child were still discussing if the solar system with its planets was unique. It's amazing that 25 years later, we know hundreds of exoplanets, have measured some of their atmospheres, and are now able to watch them forming.

There was a time when "NO other planets" existed, and not all that long ago, (even the 1970's)....except in Science Fiction stories...and in our own Solar System. This is one of the limitations of the Scientific Method...because if you cannot observe it...it does not exist....and that causes an erroneous belief.

Just because you have not observed something, does not mean it does not exist. It means, you have not observed it yet....every time humans have improved their technology, and instruments, we get more clear data...more details, and more refined images, and data, and out of that our knowledge increases. I eagerly await the next advances....so we can see, the OTHER things "that do not exist"....

:---[===] *

Boomer12k wrote:There was a time when "NO other planets" existed, and not all that long ago, (even the 1970's)....except in Science Fiction stories...and in our own Solar System. This is one of the limitations of the Scientific Method...because if you cannot observe it...it does not exist....and that causes an erroneous belief.

Just because you have not observed something, does not mean it does not exist. It means, you have not observed it yet....every time humans have improved their technology, and instruments, we get more clear data...more details, and more refined images, and data, and out of that our knowledge increases. I eagerly await the next advances....so we can see, the OTHER things "that do not exist"....

Oh, come on. This is not a problem with the scientific method. If anyone was telling you they were sure there are no planets around other stars out there, you were not listening to any credible scientist.

Nitpicker wrote:

DavidGovett wrote:Will humans ever be able to terraform proto solar systems?

$10 on "no".

I think Lexxy baby would cover that bet. He's always looking for new Real Estate. And this time the big blue bully
legally wouldn't be able to interfere. Lex would *win*. As an idea for a new movie it's better than
most of them.

But what I'd like to know is if ALMA is using long wavelength, low energy light how do they know what colour
the clouds are? They could be green and silver couldn't they?

However, without super-villains I'd agree that humans are never going to terrraform anything. They can't even
keep Earth terraformed and they'll never go anywhere else. Humans are going to die on this rock.

geckzilla wrote:I've been wondering where the dust torus that so frequently appears in pre-planetary nebulas comes from. I've been under the impression that the star itself somehow creates the dust but I'm very confused on the matter. I wonder if these stellar disks sometimes never coalesce into planets. Like maybe a binary star could have the dust disk but it never forms a planet because of the second star? Just some random conjecture.

Stars create dust when they die. Now, almost 14 billion years since the Big Bang, the remaining gas in a galaxy like the Milky Way is well mixed with the dust that has has been created by many, many generations of now-dead stars.

The way I understand it, a "dust disk" could also be described as a "gas disk". That is why such disks can give rise to gas giants complarable to Jupiter and Saturn.

The reason why we call the protoplanetary disks "dust disks" is probably because we can easily see and detect the dusk, whereas the gas is much harder to see.

Are there stellar disks that never coalesce into planets? Who knows? But from what we can see now, probably all dust disks certainly contain enough dust to give rise to, at least, asteroids and comets.

Ann

Can somebody help put a scale to this photo?
The description just states it can resolve details as small as 40 light minutes. But 40 light minutes is ~720 million KM, or just shy of where Jupiter orbits.

Does that mean the innermost dark band is approximately where Jupiter would orbit?

Craine wrote:Can somebody help put a scale to this photo?
The description just states it can resolve details as small as 40 light minutes. But 40 light minutes is ~720 million KM, or just shy of where Jupiter orbits.

Does that mean the innermost dark band is approximately where Jupiter would orbit?

Here is a picture that shows the solar system in comparison.

Nitpicker wrote:

DavidGovett wrote:Will humans ever be able to terraform proto solar systems?

$10 on "no".

I'll take that bet. "Ever" is a very long time.

Rob

Craine wrote:Can somebody help put a scale to this photo?

4th post from top :

somebodyshort wrote:1500 light minutes is 25 hours diameter or 12.5 light hours radius. Voyager 2 is at approximately 14.75 light hours from the sun. Voyager 1 is at 18 light hours from the sun

How does this size appear in the sky, ie. how many arc ?seconds?, what would a light telescope see if it could peer through the murk ? ( and I'm not just talking about my clouds !

Ooops, I crossed in the post with Marcus ! Nice find.

That looks like remarkable resolution for millimtere waves !! Gosh.

Markus Schwarz wrote:

Craine wrote:Can somebody help put a scale to this photo?
The description just states it can resolve details as small as 40 light minutes. But 40 light minutes is ~720 million KM, or just shy of where Jupiter orbits.

Does that mean the innermost dark band is approximately where Jupiter would orbit?

Here is a picture that shows the solar system in comparison.

Thank you!
So, that inner most dark bend seems indeed somewhat comparable to Jupiter's orbit. And the entire disk is roughly comparable to our solar system including Kuiper belt.

rstevenson wrote:

Nitpicker wrote:

DavidGovett wrote:Will humans ever be able to terraform proto solar systems?

$10 on "no".

I'll take that bet. "Ever" is a very long time.

Rob

I agree Rob, but by the time the bet pays off $10 will likely be meaningless.

Rob wrote:
I'll take that bet. "Ever" is a very long time.

By the time we reach "ever", will humanity have become powerful enough to terraform protoplanetary disks, or will humanity have said good-bye to the universe before we reach that point?

Ann

Ann wrote:

Rob wrote:
I'll take that bet. "Ever" is a very long time.

By the time we reach "ever", will humanity have become powerful enough to terraform protoplanetary disks, or will humanity have said good-bye to the universe before we reach that point?

Ann

Or will the human race have evolved into something beyond Homo Sapiens? We will no longer be human; we shall be...Homo Spatius?

A minor copy edit suggestion: "The low energy light used by ALMA was also able to peer through an intervening haze of gas and dust" should probably be, "The low energy light received by ALMA was able to penetrate through an intervening haze of gas and dust."

Craine wrote:Can somebody help put a scale to this photo?
The description just states it can resolve details as small as 40 light minutes. But 40 light minutes is ~720 million KM, or just shy of where Jupiter orbits.

Does that mean the innermost dark band is approximately where Jupiter would orbit?

Well, they might have said instead the disc is "just under 200 AU's across". Easier for me to picture than light-minutes, especially since our time is not decimal/ten-based.

An issue troubling the scientific community has been the asteroid belt of the Solar System. Some sources believe that the asteroid belt is a gap in the planetary order caused by the mutual gravitational attraction of the Sun and Jupiter. However, this does not explain the numerous minor planets occupying the asteroid belt. Supposedly, the asteroids were unable to coalesce into a major planetary body due to the influence of Jupiter. If that is the case then similar asteroid belts may be expected to occur in other stellar systems where inner terrestrial planets are adjacent to gas giants. Stellar systems such as Alpha Centauri and Epsilon Eridani may offer clues as to the asteroid belt phenomenon. Likewise, Tau Ceti probably has a similar asteroid belt marking the border between terrestrial planet and gas giant given Sun-like character of this star.
Even so, the existence of minor planets such as Ceres and Vesta needs explanation.
Perhaps, at one time, there was indeed a major terrestrial planet between Mars and Jupiter at the position of the asteroid belt. The planet must have been an ice world with a rocky interior and a frozen oceanic shell which would have thousands of kilometers deep. The planet may also have had rings and a prominent moon.
It is known that the solar system has had a violent history of asteroid collisions; such as the Hellas Basin on Mars and the Caloris Crater on Mercury. It is very likely that a massive asteroid slammed into the fifth planet dispersing its watery mass and redistributing the rocky core, which eventually settled to form the asteroid belt of today. With the planet's mass thus dispersed the rocky components were unable to recombine into a major planet. Instead, the dispersed mass recombined into minor planets along the region between the Sun and Jupiter.