Planets form in organic soups with different ingredients
A series of new images reveals that planets form in organic soups -- and
no two soups are alike

Date:
September 15, 2021
Source:
Harvard-Smithsonian Center for Astrophysics
Summary:
Astronomers have mapped out the chemicals inside of planetary
nurseries in extraordinary detail. The newly unveiled maps reveal
the locations of dozens of molecules within five protoplanetary
disks -- regions of dust and gas where planets form around young
stars.



FULL STORY ========================================================================== [Protoplanetary disk | Credit: (c) Mopic / stock.adobe.com] Protoplanetary
disk illustration (stock image).

Credit: (c) Mopic / stock.adobe.com [Protoplanetary disk | Credit: (c)
Mopic / stock.adobe.com] Protoplanetary disk illustration (stock image).

Credit: (c) Mopic / stock.adobe.com Close Astronomers have mapped out
the chemicals inside of planetary nurseries in extraordinary detail. The
newly unveiled maps reveal the locations of dozens of molecules within
five protoplanetary disks -- regions of dust and gas where planets form
around young stars.


========================================================================== "These planet-forming disks are teeming with organic molecules, some
which are implicated in the origins of life here on Earth," explains
Karin O"berg, an astronomer at the Center for Astrophysics | Harvard
& Smithsonian (CfA) who led the map-making project. "This is really
exciting; the chemicals in each disk will ultimately affect the type of
planets that form -- and determine whether or not the planets can host
life." A series of 20 papers detailing the project, appropriately named Molecules with ALMA at Planet-forming Scales, or MAPS, was published today
in the open-access repository arXiv. The papers have also been accepted
to the Astrophysical Journal Supplementas a forthcoming special edition
series to showcase the high- resolution images and their implications.

Planets Form in Different Soups The new maps of the disks reveal that the chemicals in protoplanetary disks are not located uniformly throughout
each disk; instead, each disk is a different planet-forming soup, a
mixed bag of molecules, or planetary ingredients. The results suggest
that planet formation occurs in diverse chemical environments and that
as they form, each planet may be exposed to vastly different molecules depending on its location in a disk.

"Our maps reveal it matters a great deal where in a disk a planet forms,"
says O"berg, the lead author of MAPS I (https://arxiv.org/abs/2109.06268),
the first paper in the series. "Many of the chemicals in the disks are
organic, and the distribution of these organics varies dramatically
within a particular disk.

Two planets can form around the same star and have very different organic inventories, and therefore predispositions to life." CfA graduate student Charles Law led MAPS III (https://arxiv.org/abs/ 2109.06210), the study
that mapped out the specific locations of 18 molecules - - including
hydrogen cyanide, and other nitriles connected to the origins of life --
in each of the five disks. The images were taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in 2018 and 2019. The vast amount
of data collected required a 100-terabyte hard drive and took two years
to analyze and breakdown into separate maps of each molecule.



==========================================================================
The final maps of each disk surprised Law and showed that "understanding
the chemistry occurring even in a single disk is much more complicated
than we thought." "Each individual disk appears quite different from
the next one, with its own distinctive set of chemical substructures,"
Law explains. "The planets forming in these disks are going to experience
very different chemical environments." Fishing for Planetary Newborns
The MAPS project provided astronomers with opportunities to study more
than just the chemical environment of disks.

"Our team used these maps to show where some of the forming planets are
located within disks, enabling scientists to connect the observed chemical soups with the future compositions of specific planets," O"berg says.



==========================================================================
The effort was led by Richard Teague, a Submillimeter Array fellow at
the CfA, who used the data and imagery collected by MAPS to hunt for
newborn planets.

Astronomers are confident that planets form in protoplanetary disks,
but there is a catch: they can't directly see them. Dense gas and dust,
which will last some three million years, shields young, developing
planets from view.

"It's like trying to see a fish underwater," Teague says. "We know they're there, but we can't peer that far down. We have to look for subtle signs
on the surface of the water, like ripples and waves." In protoplanetary
disks, gas and dust naturally rotate around a central star.

The speed of the moving material, which astronomers can measure, should
remain consistent throughout the disk. But if a planet is lurking beneath
the surface, Teague believes it can slightly disturb the gas traveling
around it, causing a small deviation in velocity or the spiraling gas
to move in an unexpected way.

Using this tactic, Teague analyzed gas velocities in two of the
five protoplanetary disks -- around the young stars HD 163296 and MWC
480. Small hiccups in velocity in certain portions of the disks revealed a young Jupiter- like planet embedded in each of the disks. The observations
are detailed in MAPS XVIII (https://arxiv.org/abs/2109.06218).

As the planets grow, they will eventually "carve open gaps in the
structure of the disks" so we can see them, Teague says, but the process
will take thousands of years.

Teague hopes to confirm the discoveries sooner than that using the
forthcoming James Webb Space Telescope. "It should have the sensitivity
to pinpoint the planets," he says.

Law also hopes to confirm the results by studying more protoplanetary
disks in the future.

Law says, "If we want to see if the chemical diversity
observed in MAPS is typical, we're going to need to increase
our sample size and map out more disks in the same way." ========================================================================== Story Source: Materials provided by Harvard-Smithsonian_Center_for_Astrophysics. Note: Content may be edited
for style and length.


========================================================================== Related Multimedia:
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Artist's_conception_of_protoplanetary_disk;_composite_image_of_ALMA_data
from_young_star_HD_163296 ==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2021/09/210915111020.htm

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