A Spitzer view of the giant molecular cloud Mon OB1 East/NGC 2264

Journal Article · Mon Oct 20 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/794/2/124· OSTI ID:22370393

Rapson, V. A. ^[1]; Pipher, J. L. ^[2]; Gutermuth, R. A. ^[3]; Megeath, S. T.; Allen, T. S. ^[4]; Myers, P. C. ^[5]

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1. School of Physics and Astronomy, Rochester Institute of Technology, Rochester, NY 14623 (United States)
2. Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States)
3. Five College Astronomy Department, Smith College, Northampton, MA 01063 (United States)
4. Lowell Observatory, Flagstaff, AZ 86001 (United States)
5. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

We present Spitzer 3.6, 4.5, 5.8, 8.0, and 24 μm images of the Mon OB1 East giant molecular cloud, which contains the young star forming region NGC 2264, as well as more extended star formation. With Spitzer data and Two Micron All Sky Survey photometry, we identify and classify young stellar objects (YSOs) with dusty circumstellar disks and/or envelopes in Mon OB1 East by their infrared-excess emission and study their distribution with respect to cloud material. We find a correlation between the local surface density of YSOs and column density of molecular gas as traced by dust extinction that is roughly described as a power law in these quantities. NGC 2264 follows a power-law index of ∼2.7, exhibiting a large YSO surface density for a given gas column density. Outside of NGC 2264 where the surface density of YSOs is lower, the power law is shallower and the region exhibits a larger gas column density for a YSO surface density, suggesting the star formation is more recent. In order to measure the fraction of cloud members with circumstellar disks/envelopes, we estimate the number of diskless pre-main-sequence stars by statistical removal of background star detections. We find that the disk fraction of the NGC 2264 region is 45%, while the surrounding, more distributed regions show a disk fraction of 19%. This may be explained by the presence of an older, more dispersed population of stars. In total, the Spitzer observations provide evidence for heterogenous, non-coeval star formation throughout the Mon OB1 cloud.

• OSTI ID: 22370393
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 794; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CORRELATIONS
COSMIC GASES
DENSITY
DISTRIBUTION
DUSTS
EMISSION
IMAGES
MAIN SEQUENCE STARS
MOLECULES
PHOTOMETRY
REMOVAL