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EPoS |
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EPoS Contribution
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Spitzer Identified Protostars in the Orion A and Maddalena's Molecular Clouds
Thomas Megeath University of Toledo, Toledo, USA | |
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We present a study of infrared protostars in the Orion A Molecular
cloud detected by a 4.3 square degree survey with the Spitzer Space
Telescope. Orion A is a particularly interesting cloud for studying
the influence of initial conditions and environment on star formation: the
cloud shows a distinct gradient in gas properties (i.e. gas temperature,
turbulence and density) and a range of star formation environments
(dense clusters, small groups, isolation). The 260 candidate protostars
were identified by rising spectral energy distributions in the 3-24 um Spitzer
photometry. We will 1.) report on our effort to search for the effect of the
molecular gas properties and star forming environment on the properties of
the protostars (currently we find no effect), 2.) discuss the ratio of
protostars found in clusters vs. isolation, and 3.) show that
the protostars are often distributed in chains aligned
with the axis of the molecular cloud. To assess the sensitivity of Spitzer to the
youngest protostars, we compare the Spitzer sample to samples of submillimeter
sources identified by SCUBA in Orion A.
We also present the first detection of a cluster of protostars in the core of Maddalena's cloud, previously considered a rare example of a quiescent giant molecular cloud. These Spitzer observations provide information on protostars forming in a cloud with gas thermal temperatures much lower than that in the Orion Molecular Cloud (only 10 K), and may show the earliest stages of cluster formation before the young stars heat up their natal gas. | |