Identifying the Low-Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores

dc.contributor.utaustinauthorDunham, Miranda M.en_US
dc.contributor.utaustinauthorCrapsi, Antonioen_US
dc.contributor.utaustinauthorEvans, Neal J., IIen_US
dc.creatorDunham, Miranda M.en_US
dc.creatorCrapsi, Antonioen_US
dc.creatorEvans, Neal J., IIen_US
dc.creatorBourke, Tyler L.en_US
dc.creatorHuard, Tracy L.en_US
dc.creatorMyers, Philip C.en_US
dc.creatorKauffmann, Jensen_US
dc.description.abstractWe present the results of a search for all embedded protostars with internal luminosities <= 1.0 L(circle dot) in the full sample of nearby, low-mass star-forming regions surveyed by the Spitzer Space Telescope Legacy Project "From Molecular Cores to Planet Forming Disks'' (c2d). The internal luminosity of a source, L(int), is the luminosity of the central source and excludes luminosity arising from external heating. On average, the Spitzer c2d data are sensitive to embedded protostars with L(int) >= 4 x 10(-3)(d/140 pc)(2) L(circle dot), a factor of 25 better than the sensitivity of the Infrared Astronomical Satellite (IRAS) to such objects. We present a set of selection criteria used to identify candidates from the Spitzer data and examine complementary data to decide whether each candidate is truly an embedded protostar. We find a tight correlation between the 70 mu m flux and internal luminosity of a protostar, an empirical result based on both observations and detailed two-dimensional radiative transfer models of protostars. We identify 50 embedded protostars with L(int) <= 1: 0 L(circle dot); 15 have L(int) <= 0: 1 L(circle dot). The intrinsic distribution of source luminosities increases to lower luminosities. While we find sources down to the above sensitivity limit, indicating that the distribution may extend to luminosities lower than probed by these observations, we are able to rule out a continued rise in the distribution below L(int) = 0.1 L(circle dot). Between 75% and 85% of cores classified as starless prior to being observed by Spitzer remain starless to our luminosity sensitivity; the remaining 15%-25% harbor low-luminosity, embedded protostars. We compile complete spectral energy distributions for all 50 objects and calculate standard evolutionary signatures (L(bol), T(bol), and L(bol)/L(smm)) and argue that these objects are inconsistent with the simplest picture of star Formation, wherein mass accretes from the core onto the protostar at a constant rate.en_US
dc.identifier.citationDunham, Michael M., Antonio Crapsi, Neal J. Evans II, Tyler L. Bourke, Tracy L. Huard, Philip C. Myers, and Jens Kauffmann. "Identifying the low-luminosity population of embedded protostars in the c2d observations of clouds and cores." The Astrophysical Journal Supplement Series, Vol. 179, No. 1 (Nov., 2008): 249.en_US
dc.relation.ispartofserialAstrophysical Journal Supplement Seriesen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectstars: Formationen_US
dc.subjectstars: low-mass, brown dwarfsen_US
dc.subjectyoung stellar objectsen_US
dc.subjectmass star-Formationen_US
dc.subjectdust continuum emissionen_US
dc.subjectnearby dense coresen_US
dc.subjectspectral energy-distributionsen_US
dc.subjectophiuchi molecularen_US
dc.subjectclass-i protostarsen_US
dc.subjectt-tauri starsen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleIdentifying the Low-Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Coresen_US

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