NAOJ: Chemical Change in Planetary System formation

[MargaritaMc]

National Astronomical Observatory of Japan:
Drastic Chemical Change Occurring in Birth of Planetary System:
Has the Solar System also Experienced it?
February 13, 2014

The international research team observed the protostar with ALMA, and discovered an unexpected chemical change.

The international research team observed the young protostar L1527 in the Taurus molecular cloud at a high spatial resolution with ALMA, and discovered an unexpected chemical change in the transition zone between the infalling envelope and the gas disk. So far, it has been believed that interstellar matter is smoothly delivered to the gas disk around the protostar without any significant chemical changes. However, it is now found to be oversimplified. The infalling gas is jammed up due to centrifugal force at the outer edge of the gas disk, where local heating causes a drastic chemical change. This chemical change highlights the outer edge of the gas disk which is still growing.
Read more at:
http://www.nao.ac.jp/en/news/science/20 ... -alma.html

The URL above gives links to a PDF download of the Press Release from the University of Tokyo and a commentary on the release at ALMA/NAOJ.

The research findings are presented in the article Sakai et al."Change in the chemical composition of infalling gas forming a disk around a protostar" published in the journal Nature, on February 12th, 2014

Alma observatory press release

Space.com

[BDanielMayfield]

At times I'm surprised, not by a new discovery, but by how the discovery is described as "surprising" or "unexpected." This is an example. People use thermal differences and centrifugal force to separate chemicals all the time, and these forces are are always going to be involved in the physics of protostellar discs. Planets also aren't the same chemically, so why would it have been assumed that the discs they form from would be?

Bruce

[geckzilla]

It's just that simple, is it, Bruce? Sometimes news articles interject surprise where none may actually be but if it is the case where people who have been studying something for a while are indeed surprised and you are not then it is probably an indication that you are misunderstanding or oversimplifying things.

[BDanielMayfield]

Was I "oversimplifying"? If so, I seem to be in good company.

National Astronomical Observatory of Japan:
The international research team observed the protostar ... So far, it has been believed that interstellar matter is smoothly delivered to the gas disk around the protostar without any significant chemical changes. However, it is now found to be oversimplified.

[Ann]

I guess I was a little bit surprised. At least it was good to have this "chemical boundary" described to me.

Ann

[BDanielMayfield]

What I wrote yesterday could and should have been stated more tactfully. As geckzilla alluded, news stories, and particularly article titles, are often jazzed up to garner more interest. That fact alone may largely explain my general point. But I don’t think this story was hyped, and I don’t want to imply that this finding isn’t important.

Upon further reflection, my guess would be that the “unexpected” discovery here wasn’t that chemical differences can occur in protostellar discs, but that the zone where chemical sorting can take place was so far out (100+or-20 AU) from the protostar. (I’m guessing because I can’t see over the top of Nature’s ginormous pay wall. Are they proud of their articles or what?) And the abstract states that it was unexpected that the chemical transition was so sharp, prompting the researchers to call this a “drastic change.”

Bruce, not wanting to come off as an arrogant s.o.b., even though I’m a Texan. (And my mother wasn't a b., but she was from New York City, where people also aren't shy about saying what they think.)

[Chris Peterson]

Upon further reflection, my guess would be that the “unexpected” discovery here wasn’t that chemical differences can occur in protostellar discs, but that the zone where chemical sorting can take place was so far out (100+or-20 AU) from the protostar.

Since most of what we think we understand about stellar system formation comes from computer models, "unexpected" probably just means any observation that isn't consistent with those models (and therefore requires that they be adjusted).

[MargaritaMc]

... (I’m guessing because I can’t see over the top of Nature's ginormous pay wall. Are they proud of their articles or what?) And the abstract states that it was unexpected that the chemical transition was so sharp, prompting the researchers to call this a “drastic change.”
...

I've found the University of Tokyo press release and the commentary from the NAOJ to be useful.
This is a link to a PDF of notes for Dr Sakai's press conference

Commentary on this press release by Masaaki Hiramatsu, the Education and Public Outreach Officer at NAOJ Chile Observatory

Not a substitute for the Nature article. But I can't afford their prices...

Margarita