Binaries Formed via Disk Fragmentation

Tobin et al. present observations of Class 0/I protostars acquired with the VLA and observations the Combined Array for Research in Millimeter-wave Astronomy (CARMA). They find that L1165-SMM1 and CB230 IRS1 have probable binary companions at separations of ∼100 AU from detections of secondary peaks at multiple wavelengths. The position angles of these companions are nearly orthogonal to the direction of the observed bipolar outflows, consistent with the expected protostellar disk orientations. They suggest that these companions may have formed from disk fragmentation; turbulent fragmentation would not preferentially arrange the binary companions to be orthogonal to the outflow direction. For L1165-SMM1, the 7.3 mm and 1.3 mm emission show evidence of a large (R >100 AU) disk. For the L1165-SMM1 primary protostar and the CB230 IRS1 secondary protostar, the 7.3mm emission is resolved into structures consistent with ∼20 AU radius disks. For the other protostars, including L1157-mm, the emission is unresolved, suggesting disks with radii < 20 AU.

Figure: Radio images of the L1165-SMM1 binary protostellar system. Protostar locations are marked with crosses; they are separated by ~ 100 AU. [Left panel] The shorter wavelength data (1.3 mm/230 GHz) taken with CARMA. [Middle, Right panels] The longer wavelength data (7.3 mm/41 GHz). The left and middle panels have comparable resolutions of 0.33" or 100 AU; the right panel has 0.1" (30 AU) resolution. For comparison, the orbit of Pluto around the sun has a semi-major axis of 39 AU. The blue and red arrows denote the directions of the outflowing gas from the protostars.

View publication: VLA and CARMA Observations of Protostars in the Cepheus Clouds: Sub-arcsecond Proto-Binaries Formed via Disk Fragmentation, John J. Tobin (NRAO), Claire J. Chandler (NRAO), David J. Wilner (CfA), Leslie W. Looney (Illinois), Laurent Loinard (UNAM), Hsin-Fang Chiang (Hawaii), Lee Hartmann (Michigan), Nuria Calvet (Michigan), Paolo D’Alesso (UNAM), Tyler L. Bourke (CfA), and Woojin Kwon (SRON), 2014, (20 December 2013).

View 31 December 2013 Press Release

Added 21 Jan 2014

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