Summary: Handbook of Star Forming Regions Vol. I
Astronomical Society of the Pacific, 2008
Bo Reipurth, ed.
Low Mass Star Formation in the Lynds 1641 Molecular Cloud
Harvard-Smithsonian Center for Astrophysics
60 Garden Street, Cambridge, MA 02138, USA
Joint Astronomy Centre, 660 North A'ohŻokŻu Place, University Park, Hilo,
Hawaii 96720, USA
Abstract. The Lynds 1641 cloud makes up the bulk of Orion A south of the Orion
Nebula Cluster. Although it contains no rich clusters comparable to the ONC, it is
forming stars in numerous dense molecular cores found primarily along a ridge of gas
that extends the length of the cloud (approximately 2.5 degrees). Optical, X-ray, and
infrared surveys have detected hundreds of young, predominantly low-mass stars. Most
of the protostars are clustered in small groups or aggregates of N=540 members, but
the more evolved T Tauri stars appear to be located both in and around these aggregates.
L 1641 has thus become a case study for the relative importance of "distributed" vs.
"clustered" star formation. Recent results from the Spitzer Space Telescope survey of
L 1641 confirms the existence of a significant distributed population, in which 44% of