Vol. 563
In section 10. Planets and planetary systems

Warm formaldehyde in the Ophiuchus IRS 48 transitional disk

by N. van der Marel, E.F. van Dishoeck, S. Bruderer, T.A. van Kempen, A&A 563, A113


So-called transitional disks with a hole in the dust distribution around the central star are a hot topic in the study of young pre-main-sequence stars. One of the fascinating results obtained with ALMA has been the discovery that the dust distribution of the disk surrounding the YSO Oph 48 is asymmetric, with an arc of emission to the south of the central star. It is hypothesised that this is caused by a sub-stellar companion or planet at a distance of 20 AU from the central star. The article by Van der Marel et al. highlighted in this issue shows that there also is an arc of molecular line emission (caused by formaldehyde in this case) slightly closer to the star than the continuum emission. The kinematics and spatial distribution are consistent with a ring of 60 AU radius, and the formaldehyde abundance of 10-8 relative to hydrogen suggests rapid ongoing chemical evolution