The star formation law in Galactic high-mass star-forming molecular clouds

Abstract

We study the star formation (SF) law in 12 Galactic molecular clouds with ongoing high-mass star formation (HMSF) activity, as traced by the presence of a bright IRAS source and other HMSF tracers. We define the molecular cloud (MC) associated to each IRAS source using 13CO line emission, and count the young stellar objects (YSOs) within these clouds using GLIMPSE and MIPSGAL 24 micron Spitzer databases.The masses for high luminosity YSOs (Lbol>10~Lsun) are determined individually using Pre Main Sequence evolutionary tracks and the evolutionary stages of the sources, whereas a mean mass of 0.5 Msun was adopted to determine the masses in the low luminosity YSO population. The star formation rate surface density (sigsfr) corresponding to a gas surface density (siggas) in each MC is obtained by counting the number of the YSOs within successive contours of 13CO line emission. We find a break in the relation between sigsfr and siggas, with the relation being power-law (sigsfr ~ siggas^N) with the index N varying between 1.4 and 3.6 above the break. The siggas at the break is between 150-360 Msun/pc^2 for the sample clouds, which compares well with the threshold gas density found in recent studies of Galactic star-forming regions. Our clouds treated as a whole lie between the Kennicutt (1998) relation and the linear relation for Galactic and extra-galactic dense star-forming regions. We find a tendency for the high-mass YSOs to be found preferentially in dense regions at densities higher than 1200 Msun/pc^2 (~0.25 g/cm^2).

arXiv comment21 pages, To appear in ApJ

References in corpus (59)

• Galactic Stellar and Substellar Initial Mass Function
• The Global Schmidt Law in Star Forming Galaxies
• Star Formation in the Milky Way and Nearby Galaxies
• The CO-to-H2 Conversion Factor
• The Milky Way in Molecular Clouds: A New Complete CO Survey
• The Star Formation Law in Nearby Galaxies on Sub-Kpc Scales
• The Spitzer c2d Legacy Results: Star Formation Rates and Efficiencies; Evolution and Lifetimes
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
• The Star Formation Rate and Dense Molecular Gas in Galaxies
• A Universal Stellar Initial Mass Function? A Critical Look at Variations
• Interpreting Spectral Energy Distributions from Young Stellar Objects. I. A grid of 200,000 YSO model SEDs
• On the Star Formation Rates in Molecular Clouds
• A Spitzer Survey of Young Stellar Clusters within One Kiloparsec of the Sun: Cluster Core Extraction and Basic Structural Analysis
• Re-examining Larson's Scaling Relationships in Galactic Molecular Clouds
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• From Molecular Cores to Planet-forming Disks: A SIRTF Legacy Program
• High-Mass Proto-Stellar Candidates - I : The Sample and Initial Results
• The Star Formation Rate and Gas Surface Density Relation in the Milky Way: Implications for Extragalactic Studies
• The Spitzer Space Telescope Survey of the Orion A & B Molecular Clouds - Part I: A Census of Dusty Young Stellar Objects and a Study of their Mid-IR Variability
• Spitzer Observations of NGC 1333: A Study of Structure and Evolution in a Nearby Embedded Cluster
• Properties of the Youngest Protostars in Perseus, Serpens, and Ophiuchus
• Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation
• Bolocam Survey for 1.1 mm Dust Continuum Emission in the c2d Legacy Clouds. I. Perseus
• A Minimum Column Density of 1 g cm^-2 for Massive Star Formation
• An Assessment of Dynamical Mass Constraints on Pre-Main Sequence Evolutionary Tracks
• Star Formation Rates in Molecular Clouds and the Nature of the Extragalactic Scaling Relations
• CO Isotopologues in the Perseus Molecular Cloud Complex: the X-Factor and Regional Variations
• Young Stellar Objects in the Gould Belt
• The Origin of Episodic Accretion Bursts in the Early Stages of Star Formation
• IRAC Observations of Taurus Pre-Main Sequence Stars
• The Pisa pre-main sequence tracks and isochrones. A database covering a wide range of Z, Y, mass, and age values
• The Properties of Massive, Dense, Clumps: Mapping Surveys of HCN and CS
• A Correlation Between Surface Densities of Young Stellar Objects and Gas in Eight Nearby Molecular Clouds
• Imaging redshifts of BL Lac objects
• The RMS Survey: 6 cm continuum VLA observations towards candidate massive YSOs in the northern hemisphere
• A 24 Micron Point Source Catalog of the Galactic Plane from Spitzer/MIPSGAL
• The efficiency of star formation in clustered and distributed regions
• Luminosity Functions of Spitzer Identified Protostars in Nine Nearby Molecular Clouds
• Schmidt's Conjecture and Star Formation in Molecular Clouds
• Class I and Class II methanol masers in high-mass star forming regions
• The Spitzer c2d Survey of Large, Nearby, Interstellar Clouds.X. The Chamaeleon II Pre-Main Sequence Population as Observed With IRAC and MIPS
• Instantaneous starburst of the massive clusters Westerlund 1 and NGC 3603 YC
• Interstellar matter and star formation in W5-E - A Herschel view
• Star Formation Laws: the Effects of Gas Cloud Sampling
• The rate and latency of star formation in dense, massive clumps in the Milky Way
• Far Infrared Observations of Radio Quasars and FR II Radio Galaxies
• The nature of the dense core population in the pipe nebula: core and cloud kinematics from C18O observations
• The Dependence of Star Formation Efficiency on Gas Surface Density
• RCW36: characterizing the outcome of massive star formation
• The Dynamics of Dense Cores in the Perseus Molecular Cloud II: The Relationship Between Dense Cores and the Cloud
• Distributed Low-Mass Star Formation in the IRDC G34.43+00.24
• The relation between 13CO(2-1) line width in molecular clouds and bolometric luminosity of associated IRAS sources
• Mass and luminosity evolution of young stellar objects
• APEX/SABOCA observations of small-scale structure of infrared-dark clouds I. Early evolutionary stages of star-forming cores
• Young Stellar Objects in the Massive Star Forming Region W49
• Testing 24 micron and Infrared Luminosity as Star Formation Tracers for Galactic Star Forming Regions
• Protostar mass functions in young clusters
• The BLAST View of the Star Forming Region in Aquila (ell=45deg,b=0deg)

Cited by in corpus (10)

• Global Hierarchical Collapse In Molecular Clouds. Towards a Comprehensive Scenario
• On the Appearance of Thresholds in the Dynamical Model of Star Formation
• Recurrent strong outbursts of an EXor-like young eruptive star Gaia20eae
• Gaia 20eae: A newly discovered episodically accreting young star
• Infrared Dark Clouds and high-mass star formation activity in Galactic Molecular Clouds
• ALMA Observations of HCO+ and HCN Emission in a massive star forming region N55 of the Large Magellanic Cloud
• Benchmarking the IRDC G351.77-0.53: Gaia DR3 distance, mass distribution, and star formation content
• The SPHEREx Target List of Ice Sources (SPLICES)
• Predicting HCN, HCO + , multi-transition CO, and dust emission of star-forming galaxies: Constraining the properties of resolved gas and dust disks of local spiral galaxies
• Extended Ionized Fe Objects in the UWIFE Survey