ALMA: Planet Formation in Earth-like Orbit around a Young Star

[bystander]

Planet Formation in Earth-like Orbit around a Young Star
ESO | NAOJ | NRAO | ALMA | 2016 Mar 31

ALMA image of the planet-forming disk around the young, Sun-like star TW Hydrae. The inset image (upper right) zooms in on the gap nearest to the star, which is at the same distance as the Earth is from the Sun, suggesting an infant version of our home planet could be emerging from the dust and gas. The additional concentric light and dark features represent other planet-forming regions farther out in the disk. Credit: S. Andrews (CfA), ALMA (ESO/NAOJ/NRAO)

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ALMA's Best Image of a Protoplanetary Disk

The disks of dust and gas that surround young stars are the formation sites of planets. New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal never-before-seen details in the planet-forming disk around a nearby Sun-like star, including a tantalizing gap at the same distance from the star as the Earth is from the Sun.

This structure may mean that an infant version of our home planet, or possibly a more massive "super-Earth," is beginning to form there.

The star, TW Hydrae, is a popular target of study for astronomers because of its proximity to Earth (approximately 175 light-years away) and its status as a veritable newborn (about 10 million years old). It also has a face-on orientation as seen from Earth. This affords astronomers a rare, undistorted view of the complete disk.

"Previous studies with optical and radio telescopes confirm that this star hosts a prominent disk with features that strongly suggest planets are beginning to coalesce," said Sean Andrews with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author on a paper published today in Astrophysical Journal Letters. "The new ALMA images show the disk in unprecedented detail, revealing a series of concentric dusty bright rings and dark gaps, including intriguing features that suggest a planet with an Earth-like orbit is forming there."

Other pronounced gap features are located 3 billion and 6 billion kilometers from the central star, similar to the distances from the Sun to Uranus and Pluto in our own Solar System. They too are likely the result of particles that came together to form planets, which then swept their orbits clear of dust and gas and shepherded the remaining material into well-defined bands. ...

A Planet Is Forming in an Earth-like Orbit around a Young Star
Harvard Smithsonian Center for Astrophysics | 2016 Mar 31

Ringed Substructure and a Gap at 1 AU in the Nearest Protoplanetary Disk - Sean M. Andrews et al

• Astrophysical Journal Letters 820(2):L40 (2016 Apr 01) DOI: 10.3847/2041-8205/820/2/L40 (pdf)

viewtopic.php?t=29149

[bystander]

First Detection of Methyl Alcohol in a Planet-Forming Disc
ESO | NAOJ | NRAO | ALMA | 2016 Jun 15

ALMA’s best image of a protoplanetary disc to date. This picture of the nearby young star TW Hydrae reveals the classic rings and gaps that signify planets in formation. Credit: S. Andrews (CfA); B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO)

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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. Methanol is the only complex organic molecule as yet detected in discs that unambiguously derives from an icy form. 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 ALMA observations have revealed the fingerprint of gaseous methyl alcohol, or methanol (CH₃OH), in a protoplanetary disc for the first time. Methanol, a derivative of methane, is one of the largest complex organic molecules detected in discs to date. Identifying its presence in 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. ...

Detection of Methanol Shows Comets are Forming in Distant Solar System
Harvard Smithsonian Center for Astrophysics | 2016 Jun 15

First Detection of Gas-Phase Methanol in a Protoplanetary Disk - Catherine Walsh et al

• Astrophysical Journal Letters 823(1):L10 (2016 May 20) DOI: 10.3847/2041-8205/823/1/L10

[BMAONE23]

With the GAP being placed at approx. 1AU then the 2 concentric rings appear to be at distances equal to Jupiter and Saturn

[bystander]

ALMA Spots Possible Formation Site of Icy Giant Planet
ESO | NRAO | NAOJ | ALMA | 2016 Sep 14

ALMA image of the disk around the young star TW Hydrae. Several gaps are clearly depicted. Researchers found that the size of the dust particles in the inner 22 au gap is smaller than in the other bright regions and guess that a planet similar to Neptune is located in this gap. Credit: ALMA (ESO/NAOJ/NRAO), Tsukagoshi et al.

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Astronomers found signs of a growing planet around TW Hydra, a nearby young star, using the Atacama Large Millimeter/submillimeter Array (ALMA). Based on the distance from the central star and the distribution of tiny dust grains, the baby planet is thought to be an icy giant, similar to Uranus and Neptune in our Solar System. This result is another step towards understanding the origins of various types of planets.

A number of extrasolar planets have been found in the past two decades and now researchers agree that planets can have a wide variety of characteristics. However, it is still unclear how this diversity emerges. Especially, there is still debate about how the icy giant planets, such as Uranus and Neptune, form.

To take a close look at the planet formation site, a research team led by Takashi Tsukagoshi at Ibaraki University, Japan, observed the young star TW Hydrae. This star, estimated to be 10 million years old, is one of the closest young stars to the Earth. Thanks to the proximity and the fact that its axis of rotation points roughly in the Earth's direction, giving us a face-on-view of the developing planetary system, TW Hydrae is one of the most favorable targets for investigating planet formation.

Past observations have shown that TW Hydrae is surrounded by a disk made of tiny dust particles. This disk is the site of planet formation. Recent ALMA observations revealed multiple gaps in the disk [1]. Some theoretical studies suggest that the gaps are evidence of planet formation. ...

A Gap with a Deficit of Large Grains in the Protoplanetary Disk around TW Hya - Takashi Tsukagoshi et al

• arXiv.org > astro-ph > arXiv:1605.00289 > 01 May 2016 (v1), 01 Sep 2016 (v2)

ALMA Observations of a Gap and a Ring in the Protoplanetary Disk around TW Hya - Hideko Nomura et al

• Astrophysical Journal Letters 819(1):L7 (2016 Mar 01) DOI: 10.3847/2041-8205/819/1/L7
  arXiv.org > astro-ph > arXiv:1512.05440 > 17 Dec 2015 (v1), 26 Feb 2016 (v2)