Enhanced dust emission in the HL Tau disc: a low-mass companion in formation?

Jane Sophia Greaves, A. M. S. Richards, W Ken M Rice, T. W. B. Muxlow

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43 Citations (Scopus)


We have imaged the disc of the young star HL Tau using the Very Large Array (VLA) at 1.3 cm, with 0.08-arcsec resolution (as small as the orbit of Jupiter). The disc is around half the stellar mass, assuming a canonical gas mass conversion from the measured mass in large dust grains. A simulation shows that such discs are gravitationally unstable, and can fragment at radii of a few tens of au to form planets. The VLA image shows a compact feature in the disc at 65 au radius (confirming the 'nebulosity' of Welch et al.), which is interpreted as a localized surface density enhancement representing a candidate protoplanet in its earliest accretion phase. If correct, this is the first image of a low-mass companion object seen together with the parent disc material out of which it is forming. The object has an inferred gas plus dust mass of approximate to 14M(Jupiter), similar to the mass of a protoplanet formed in the simulation. The disc instability may have been enhanced by a stellar flyby: the proper motion of the nearby star XZ Tau shows it could have recently passed the HL Tau disc as close as similar to 600 au.

Original languageEnglish
Pages (from-to)L74-L78
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Publication statusPublished - 21 Nov 2008


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