SMA Research: Low Mass Star Formation

Low-mass stars like our Sun are formed in the dense cores of large molecular gas clouds. The star formation process is hidden from view at optical wavelengths due to the large amounts of gas and dust surrounding the forming star, and even at infrared wavelengths the most deeply embedded protostars are often difficult to study. Most of this gas and dust is relatively cool, and observations at submillimeter wavelengths (a few tenths to one millimeter) are the best probes of the physical conditions during star formation. Disks and bipolar outflows are now known to a be a integral part of the star formation process. Observations of the thermal dust emission and spectral lines of molecules enable the physics and kinematics of the large scale envelope and the small-scale disk surrounding the protostar, and the outflow, to be studied in detail. The magnetic field geometry can be determined through polarization observations of charged dust grains. Importantly, interferometer observations allow most of the emission from the large-scale envelope to be filtered out, enabling high-resolution studies of the disks and inner envelopes, where accretion of gas onto the protostar occurs and where the initial conditions for planet formation are determined. Such observations are important as they inform us about the conditions under which our own Solar System and exoplanetary systems formed. Astronomers are using the SMA to study dense cores before the onset of star formation and to probe the disks and outflows around protostars, in cores containing only one new star and in cores containing small groups.

Low Mass Star Formation Research


Tyler Bourke, Erin Brassfield, Philip Myers, Dawn Peterson, David Wilner, Qizhou Zhang, Izaskun Jimenez-Serra

Naomi Hirano, Chin-Fei Lee, Nagayoshi Ohashi, Ram Rao, Hsien Shang, Shigehisa Takakuwa

On-going collaborators:
Paola Caselli, Xuepeng Chen, Kevin Covey, James Di Francesco, José Miguel Girart,
Jes Jørgensen, Paula Teixeira. Tim van Kempen

  Low Mass Star Formation

The very compact outflow around the very low luminosity protostar L1014-IRS, as discovered using the SMA. The top panel shows a near-infared imaged obtained with the SAO's MMT (courtesy Tracy Huard). The bottom panel shows a zoomed in section of the infrared image (in greyscale), overlaid with blue and red contours showing high velocity emission from the CO molecule due to outflow gas in a bipolar outflow, one of the key signatures of star formation (Bourke et al. (ADS | astro-ph/0509865 2005 ApJL 633,L129).