First detection of methyl alcohol in a planet-forming disc

June 15, 2016, ESO
This artist's impression shows the closest known protoplanetary disc, around the star TW Hydrae in the huge constellation of Hydra (The Female Watersnake). The organic molecule methyl alcohol (methanol) has been found by the Atacama Large Millimeter/Submillimeter Array (ALMA) in this disc. This is the first such detection of the compound in a young planet-forming disc. Credit: ESO/M. Kornmesser

The organic molecule methyl alcohol (methanol) has been found by the Atacama Large Millimeter/Submillimeter Array (ALMA) in the TW Hydrae protoplanetary disc. This is the first such detection of the compound in a young planet-forming disc. Its detection helps astronomers understand the chemical processes that occur during the formation of planetary systems and that ultimately lead to the creation of the ingredients for life.

The protoplanetary disc around the young star TW Hydrae is the closest known example to Earth, at a distance of only about 170 light-years. As such it is an ideal target for astronomers to study discs. This system closely resembles what astronomers think the Solar System looked like during its formation more than four billion years ago.

The Atacama Large Millimeter/Submillimeter Array (ALMA) is the most powerful observatory in existence for mapping the chemical composition and the distribution of cold gas in nearby discs. These unique capabilities have now been exploited by a group of astronomers led by Catherine Walsh (Leiden Observatory, the Netherlands) to investigate the chemistry of the TW Hydrae protoplanetary disc.

The ALMA observations have revealed the fingerprint of gaseous methyl alcohol, or (CH3OH), in a protoplanetary disc for the first time. Methanol, a derivative of methane, is one of the largest detected in discs to date. Identifying its presence in pre-planetary objects represents a milestone for understanding how organic molecules are incorporated into nascent planets.

Furthermore, methanol is itself a building block for more complex species of fundamental prebiotic importance, like amino acid compounds. As a result, methanol plays a vital role in the creation of the rich organic chemistry needed for life.

Catherine Walsh, lead author of the study, explains: "Finding methanol in a protoplanetary disc shows the unique capability of ALMA to probe the complex organic ice reservoir in discs and so, for the first time, allows us to look back in time to the origin of chemical complexity in a planet nursery around a young Sun-like star."

Gaseous methanol in a protoplanetary disc has a unique importance in astrochemistry. While other species detected in space are formed by gas-phase chemistry alone, or by a combination of both gas and solid-phase generation, methanol is a complex organic compound which is formed solely in the ice phase via surface reactions on dust grains.

The sharp vision of ALMA has also allowed astronomers to map the gaseous methanol across the TW Hydrae disc. They discovered a ring-like pattern in addition to significant emission from close to the central star.

The observation of methanol in the gas phase, combined with information about its distribution, implies that methanol formed on the disc's icy grains, and was subsequently released in gaseous form. This first observation helps to clarify the puzzle of the methanol ice-gas transition, and more generally the in astrophysical environments.

Ryan A. Loomis, a co-author of the study, adds: "Methanol in gaseous form in the disc is an unambiguous indicator of rich organic chemical processes at an early stage of star and planet formation. This result has an impact on our understanding of how organic matter accumulates in very young planetary systems."

This successful first detection of cold gas-phase methanol in a protoplanetary disc means that the production of ice chemistry can now be explored in discs, paving the way to future studies of complex organic chemistry in planetary birthplaces. In the hunt for life-sustaining exoplanets, astronomers now have access to a powerful new tool.

Explore further: Planet formation in Earth-like orbit around a young star

More information: "First detection of gas-phase methanol in a protoplanetary disk", by Catherine Walsh et al., Astrophysical Journal, Volume 823, Number 1. iopscience.iop.org/article/10. … -8205/823/1/L10/meta

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Chris_Reeve
Jun 15, 2016
This comment has been removed by a moderator.
Da Schneib
4.2 / 5 (5) Jun 15, 2016
This is a big deal. It means they're not just speculating/hypothesizing about the formation of biochemicals on ice grains in giant molecular clouds and nascent solar systems, they've actually found it. All of the chemicals needed to form life can be formed this way.

Congratulations to the ALMA team. From here we start finding out the processes that lead to life, which will help us figure out how much of it there is out there. There will be many, many more chemicals found; we already know there are many compounds formed in giant molecular clouds, but we couldn't show them in protoplanetary disks. Now we can.
barakn
3.3 / 5 (7) Jun 16, 2016
Radial separation of elements is an expected feature of Marklund convection, a process where the ions surrounding a conducting plasma filament are approximately sorted by their ionization potential as a consequence of electricity flowing through the filament....
We should observe their reaction to these surprises. -Chris_Reeve
Methyl alcohol is neither an element nor is it an ion. No one said it was a surprise except you.
we are probably looking down the barrel of a conducting electrical filament.
Doppler broadening of a certain carbon monoxide emission line was used to determine that the outer layer around TW Hydrae is rotating in a plane inclined 7 degrees from "down the barrel." Qi, C. et al. 2004, ApJ, 616, L11 http://iopscience...1063/pdf This 7 degrees means that if it indeed were a filament, the filament is so short that it doesn't visibly alter TW Hydrae's almost perfectly round appearance.
barakn
3.3 / 5 (7) Jun 16, 2016
Go ahead, tell me where the filamentary tail is in this image of TW Hydrae : https://en.wikipe...disc.jpg
Chris_Reeve
Jun 16, 2016
This comment has been removed by a moderator.
barakn
2.6 / 5 (5) Jun 17, 2016
Re: "Doppler broadening of a certain carbon monoxide emission line was used to determine that the outer layer around TW Hydrae is rotating in a plane inclined 7 degrees from 'down the barrel.'"

My first reaction is: So what?
Just because you don't understand the geometric argument doesn't mean it didn't rip your pet theory to shreds.
Re: "This 7 degrees means that if it indeed were a filament, the filament is so short that it doesn't visibly alter TW Hydrae's almost perfectly round appearance."

But, Herschel has already validated that stars commonly form along filaments, so it's not clear what you're getting at here.
It's perfectly clear. You didn't state that TW Hydrae was a star resulting from a filament, you said it IS a filament. A filament, which because its axis is inclined 7 degrees from our line of sight, should be visible as a linear object. But it isn't.
barakn
2 / 5 (4) Jun 17, 2016
It's neither clear why you assume that filaments do not exist where we cannot image them. Why must electricity be visible to our instruments wherever it exists?
You're the one that claimed TW Hydrae is a visible filament. Presumably the end of the filament. So where is the rest of it? What magic leads to the entire filament being invisible except for one thin section?

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