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Dusty protoplanetary disks

Bringing some of the mysteries of the universe a little closer to home.

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Owlscrying
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Unread post Fri Dec 08, 2017 7:02 pm

Planetary systems form out of disks of gas and dust around young stars. How the formation proceeds, however, is complex and poorly understood. Many physical processes are involved including accretion onto the star, photoevaporation of material of the disk, interactions of the disk with planetary embryos, growth of the dust grains, settling of the dust to the midplane of the disk, and more. To unravel these various factors, observations of protoplanetary disks at multiple wavelengths are used; the submillimeter wavelength range in particular offers a way to peer through most of the disk to estimate dust masses directly.

Surveys of star forming regions with facilities such as Submillimeter Array (SMA) and ALMA have determined that disks have typical masses of 0.1%–0.5% of the host star. CfA astronomers Sean Andrews and David Wilner were members of a team that used these two facilities to study systematically the dust in 284 protoplanetary disks in three nearby star formation regions. They find clear evidence for grain growth from the spectral shape of the emission, at least for two of the regions. The result, which is in agreement with previous work, is indicative of the early stages of planet formation.

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Owlscrying
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Unread post Fri Dec 08, 2017 7:05 pm

Image
Credit: S. Andrews; Harvard-Smithsonian CfA, ALMA ESO/NAOJ/NRAO

An ALMA image of the planet-forming disk around the young, Sun-like star TW Hydrae. The inset image zooms in on the gap nearest to the star, which is at the same distance as the Earth is from the Sun. Astronomers have made a study of 284 disks in three nearby regions to study how they evolve.

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Owlscrying
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Unread post Fri Dec 08, 2017 7:06 pm



The artist conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Debris coalesces to create rocky 'planetesimals' that collide and grow to eventually form planets. The results of this study show that small planets form around stars with a wide range of heavy element content suggesting that their existence might be widespread in the galaxy.

 

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