Starship Asterisk*

ALMA image of the protoplanetary disk around the young star TW Hydrae. A small clump of dust was found in the southwestern (bottom right) part of the otherwise highly symmetric disk. Credit: ALMA (ESO/NAOJ/NRAO), Tsukagoshi et al.

---

Researchers using ALMA (Atacama Large Millimeter/submillimeter Array) found a small dust concentration in the disk around TW Hydrae, the nearest young star. It is highly possible that a planet is growing or about to be formed in this concentration. This is the first time that the exact place where cold materials are forming the seed of a planet has been pinpointed in the disk around a young star.

The young star TW Hydrae, located 194 light-years away in the constellation Hydra, is the closest star around which planets may be forming. Its surrounding dust disk is the best target to study the process of planet formation.

Previous ALMA observations revealed that the disk is composed of concentric rings. Now, new higher sensitivity ALMA observations revealed a previously unknown small clump in the planet forming disk. The clump is elongated along the direction of the disk rotation, with a width approximately equal to the distance between the Sun and the Earth, and a length of about four-and-a-half times that. ...

However, the brightness and elongated shape of the structure revealed by ALMA don’t exactly match theoretical predictions for circumplanetary disks. It might be a gas vortex, which are also expected to form here and there around a young star. Finding only a single dust clump at this time is also contrary to theoretical studies. So the research team could not reach a definitive answer on the nature of the dusty clump. ...

• Astrophysical Journal Letters 878(1):L8 (2019 Jun 10) DOI: 10.3847/2041-8213/ab224c
• arXiv.org > astro-ph > arXiv:1905.07891 > 20 May 2019