Max Planck Institute for Extraterrestrial Physics (MPE) | 2017 Jul 13
[img3="This radio image obtained with ALMA shows the intensity of the dust continuum emission of BHB07-11. The contrast between the disk and the envelope including spirals is clearly visible. (Credit: MPE/ALMA"]http://www.mpe.mpg.de/6742308/zoom-1499692689.jpg[/img3][hr][/hr]For the first time, an international team of astronomers led by the Max Planck Institute for Extraterrestrial Physics (MPE) has observed a molecular outflow being launched from beyond the disk surrounding a young stellar object. Outflows carry away excess angular momentum and it has been proposed that these disk winds should be launched from a wide region in the protoplanetary disk. The recent observations now show that the outflows are asymmetric and that they are launched beyond the edge of the disk, at the position of the landing site of the in-falling material.
A long-standing problem of star formation is how to get rid of the excess of angular momentum from in-falling material in the molecular cloud where a young star is born. In the classical picture, angular momentum is removed both by a stellar wind close to the newly formed star and by a disk wind from a wide region in the protoplanetary disk around the star. The exact location from where such disk winds are launched, however, is not well known.
Low-mass Young Stellar Objects (YSO), the precursors of Solar-type stars, have a prominent circumstellar disk surrounded by a tenuous envelope. The structure and kinematics of the environment of such young stars can be studied at radio wavelengths, where the dust in disk and envelope emits thermal radiation and where rotational transitions of some simple molecules (such as CO) can be used as tracers of gas motions. An international team of astronomers, led by the Max Planck Institute for Extraterrestrial Physics (MPE), now used the ALMA radio telescope to investigate the young stellar object BHB07-11, which is embedded in the Barnard 59 dense core in the Pipe nebula.
Molecular Outflow Launched Beyond the Disk Edge - Felipe O. Alves et al