Populations of Young Stellar Objects in Nearby Molecular Clouds

Abstract

We develop a new method to identify YSOs from star-forming regions using the photometry data from Spitzer's c2d Legacy Project. The aim is to obtain YSO lists as complete as possible for studying the statistical properties, such as Star Formation Rate (SFR) and lifetimes of YSOs in different evolutionary stages. The largest obstacle for identifying YSOs comes from background galaxies with similar SEDs to YSOs. Traditionally, selected color-color and color-magnitude criteria are used to separate YSOs and galaxies. However, since there is no obvious boundary between YSOs and galaxies in Color-Color Diagrams (CCDs) and Color-Magnitude Diagrams (CMDs), those criteria may exclude faint YSOs near the boundary. In this paper, we separate the YSOs and galaxies in multi-dimensional (Multi-D) magnitude space, which is equivalent to using all variations of CMDs simultaneously. Comparing sources from molecular clouds to Spitzer's SWIRE data, which have negligible amount of YSOs, we can naturally identify YSO candidates locating outside of the galaxy populated regions in the Multi-D space. In the five c2d-surveyed clouds, we select 322 new YSO candidates (YSOc), miss/exclude 33 YSOc compared to Evans et al. 2009 and result in 1313 YSOc in total. As a result, SFR increases 28% correspondingly, but the lifetimes of YSOs in different evolutionary stages remain unchanged. Comparing to theories Krumholz & McKee 2005, our derived SFR suggests that star formation in large scale is dominated by supersonic turbulence rather than magnetic fields. Furthermore, we identify 7 new Very Low Luminosity Objects.

19 pages, 15 figures, accepted by ApJ

References in corpus (12)

• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• Slow Star Formation in Dense Gas: Evidence and Implications
• Identifying the Low Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores
• The COMPLETE Survey of Star-Forming Regions: Phase I Data
• The Mid-Infrared Extinction Law in the Ophiuchus, Perseus, and Serpens Molecular Clouds
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. XI. Lupus Observed With IRAC and MIPS
• Current Star Formation in the Ophiuchus and Perseus Molecular Clouds: Constraints and Comparisons from Unbiased Submillimeter and Mid-Infrared Surveys. II
• Current Star Formation in the Perseus Molecular Cloud: Constraints from Unbiased Submillimeter and Mid-Infrared Surveys
• Characterizing the nature of embedded young stellar objects through silicate, ice and millimeter observations
• The enigmatic core L1451-mm: a first hydrostatic core? or a hidden VeLLO?
• The young population of the Chamaeleon II dark cloud
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds: VII. Ophiuchus Observed with MIPS

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• Chronology of Episodic Accretion in Protostars -- an ALMA survey of the CO and H${}_2$O snowlines
• Zooming in on Individual Star Formation: Low- and High-mass Stars
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds. XII. The Perseus YSO Population as Observed with IRAC and MIPS
• Embedded Binaries and Their Dense Cores
• Spectroscopic Assessment of WISE-based Young Stellar Object Selection
• The Anatomy of an Unusual Edge-on Protoplanetary Disk. II. Gas temperature and a warm outer region
• The circumstellar environment around the embedded protostar EC 53
• VLA cm-wave survey of young stellar objects in the Oph A cluster: constraining extreme UV- and X-ray-driven disk photo-evaporation -- A pathfinder for Square Kilometre Array studies
• The IGRINS YSO Survey III: Stellar parameters of pre-main sequence stars in Ophiuchus and Upper Scorpius
• Properties of the Molecular Cores of Low Luminosity Objects
• Distributed YSOs in the Perseus Molecular Cloud from the Gaia and LAMOST Surveys
• The YSO Population in the Vela-D Molecular Cloud
• Applications of Machine-Learning Algorithms for Infrared Colour Selection of Galactic Wolf-Rayet Stars
• A Novel Survey for Young Substellar Objects with the W band Filter.V. IC 348 and Barnard 5 in the Perseus Cloud
• Assessing the accuracy of the star formation rate measurements by direct star count in molecular clouds
• Estimation of Stellar Parameters and Mass Accretion Rate of Classical T Tauri Stars from LAMOST DR6
• Identification and parameter determination of F-type Herbig stars from LAMOST DR8
• Disk dissipation, giant planet formation and star-formation-rate fluctuations in the past three-million-year history of Gould's Belt