Starship Asterisk*

MarkBour wrote:So pretty much all of the radiation that ALMA is capturing in this image is from heat being generated from the initial gravitational collapse, with no significant fusion yet begun?

Is it out of the question that some fusion has already begun, in both that central region and the first ring?

I wonder what will happen to the material in that ring. Will it also collapse, eliminating the first gap, or will it all get blown away?

geckzilla wrote: . . .
Say, HL Tau is pretty bright for being a protostar. All of this visible light is emitted by the dust colliding with itself in this dense but yet-to-fuse ball?

Mad Ted wrote:I'm amazed this image is from land-based devices-one wonders how much more we'll be able to see with further advancements in land and space telescopes/cameras!

geckzilla wrote:Say, HL Tau is pretty bright for being a protostar. All of this visible light is emitted by the dust colliding with itself in this dense but yet-to-fuse ball?

Chris Peterson wrote:Dust particles are certainly not able to orbit a star like the Sun for very long before they lose energy to Poynting-Robertson drag and fall into it. I don't think a star with any appreciable energy output could sustain rings or any sort of dust disk unless it was very far away, in which case it would seem to bear no dynamical resemblance to planetary ring systems.

Nitpicker wrote:

snip snip snip 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.

I find the proposed solar system comparison image confussing. Shouldn't be like this one?

The caption for the image linked by Markus, suggests that the outermost orbit is Neptune's.

chuckster wrote:Isn't this image kind of unprecedented ? I've seen tiny, fuzzy photos described as possible nascent star systems before, but, at 450 light years distant, and using a ground-based observatory, this is an image of amazing detail. Does the Hubble have the instruments to capture a similar image from space ?

geckzilla wrote:Ok, away from accretion disks again ... How about the various ring systems in our solar system? How do they compare? Saturn's rings are obviously very robust while all other planets have much fainter ones. What keeps Saturn's going? They just started out like that and the other planets didn't?

I don't find the idea that a star could have a long-lived ring system to be out of the question unless there is something about the star that blows away the rings. Hmm.

Guest wrote:Agree about Neptune and not including Plato but planets orbits diameters relative proportion, sun size, highlighted planet suggesting to be Earth but being Mars...

Guest wrote:Agree about Neptune and not including Plato but planets orbits diameters relative proportion, sun size, highlighted planet suggesting to be Earth but being Mars...

moontrail wrote:

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.

I find the proposed solar system comparison image confussing. Shouldn't be like this one?

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.

Chris Peterson wrote:I don't see how. The disk is short lived. At the end, a new dust structure forms, possibly made up of some original material but mainly dust created in the star over its life. The early disk is accretionary; the later is some sort of ejected structure.

geckzilla wrote:I was actually asking exactly that: whether or not the protoplanetary disk could last that long under any circumstance.

geckzilla wrote:I was actually asking exactly that: whether or not the protoplanetary disk could last that long under any circumstance.

BDanielMayfield wrote:"Any possible connection between the two" what, exactly, geck? Surely someone with all your experience processing "planetary" nebula data into images and reading these discussions knows that they are generated near the end of a star's 'life', whereas protoplanetary disks come about right near the star's beginning. In our system for example these periods will have ultimately been separated by, what, 9.5 billion years? The only "connection" here would be that they occur around the same star. But that isn't what your asking about, or what?

geckzilla wrote:I'm well aware of that potential confusion. That's why I use "pre" instead of "proto" for the prefix when referring to planetary nebulas. It makes it a little harder to confuse it with protoplanetary disks. But I was wondering if there was any possible connection between the two.