ON THE STAR FORMATION RATES IN MOLECULAR CLOUDS

By C. Lada, Marco Lombardi, Joao F. Alves. 2010

497 citations recorded by the source corpus.

In this paper, we investigate the level of star formation activity within nearby molecular clouds. We employ a uniform set of infrared extinction maps to provide accurate assessments of cloud mass and structure and compare these with inventories of young stellar objects within the clouds. We present evidence indicating that both the yield and rate of star formation can vary considerably in local clouds, independent of their mass and size. We find that the surface density structure of such clouds appears to be important in controlling both these factors. In particular, we find that the star formation rate (SFR) in molecular clouds is linearly proportional to the cloud mass (M0.8) above an extinction threshold of AK≈ 0.8 mag, corresponding to a gas surface density threshold of Σgas ≈ 116 M☉ pc2. We argue that this surface density threshold corresponds to a gas volume density threshold which we estimate to be n(H2) ≈ 104 cm−3. Specifically, we find SFR (M☉ yr−1) = 4.6 ± 2.6 × 10−8 M0.8 (M☉) for the clouds in our sample. This relation between the rate of star formation and the amount of dense gas in molecular clouds appears to be in excellent agreement with previous observations of both galactic and extragalactic star-forming activity. It is likely the underlying physical relationship or empirical law that most directly connects star formation activity with interstellar gas over many spatial scales within and between individual galaxies. These results suggest that the key to obtaining a predictive understanding of the SFRs in molecular clouds and galaxies is to understand those physical factors which give rise to the dense components of these clouds.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4f03bcfde273bdd195dafd4974dc47dea365119f

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Citations in the corpus

RESOLVING THE LUMINOSITY PROBLEM IN LOW-MASS STAR FORMATION (2011, background): “…rather than true line-of-sight extinctions, and thus may underestimate the true extinction since current, active star formation (and thus the position of the youngest, embedded sources) is associated with the densest parts of molecu- 16 lar clouds (e.g., Heiderman et al. 2010; Lada et al. 2010).”
A CORRELATION BETWEEN SURFACE DENSITIES OF YOUNG STELLAR OBJECTS AND GAS IN EIGHT NEARBY MOLECULAR CLOUDS (2011, background): “Lada et al. (2010) estimated the star formation rate vs. cloud mass for a sample of 11 nearby clouds.”
ON THE STAR FORMATION EFFICIENCY OF TURBULENT MAGNETIZED CLOUDS (2012, methodology): “A similar estimate based on YSO counts and assuming a median mass for each YSO of 0.5M is provided in Lada et al. (2010).”
STAR FORMATION RELATIONS IN NEARBY MOLECULAR CLOUDS (2014, methodology): “Tests of Threshold Idea For the clouds as a whole, Lada et al. (2010) have already provided the evidence for a better correlation between star formation and cloud mass if the cloud mass is restricted to the mass above a threshold surface density.”
ATLASGAL - properties of a complete sample of Galactic clumps (2017, background): “We also show the minimum threshold of ∼116-129 M pc−2 (thick magenta band) proposed by Lada et al. (2010) and Heiderman et al. (2010) (hereafter referred to as the “LH threshold”) for “efficient” star formation in nearby molecular clouds (d ≤ 500 pc).”
The Formation and Destruction of Molecular Clouds and Galactic Star Formation (2015, background): “This threshold of line-mass for star formation is equivalent to the threshold of the column density of molecular gas 116M⊙pc−2 (Lada et al. 2010), if the widths of filaments are all close to 0.1pc (Arzoumanian et al. 2011; André et al. 2014).”
Molecular Clouds in the Milky Way (2015, background): “These simple, single-point statistics are effective tools to distinguish different dynamical components within molecular clouds (Kainulainen et al. 2009; Lada et al. 2010, 2012; Schneider et al. 2011, 2015; Kainulainen & Tan 2013).”
Herschel-Planck dust optical-depth and column-density maps - I. Method description and results for Orion (2014, background): “These two facts together might be the key to understanding the good correlation found by Lada et al. (2010) between the mass of dense gas and the star formation rate in local molecular clouds.”
WIDE-FIELD INFRARED SURVEY EXPLORER OBSERVATIONS OF THE EVOLUTION OF MASSIVE STAR-FORMING REGIONS (2012, methodology): “Following the example of Heiderman et al. (2010) and Lada et al. (2010), we estimate the star formation rate by adopting an average mass of 0.5 M (see, for example, Chabrier 2003) and a timescale of 2 Myr (the time between the formation and end of the Class II phase; see Evans et al. 2009).”
Feedback-regulated star formation in molecular clouds and galactic discs (2013, unknown): “C O ] 1 5 M ay 2 M pc −2 (e.g., Lada et al. 2010; Heiderman et al. 2010).”
AN IMPRINT OF MOLECULAR CLOUD MAGNETIZATION IN THE MORPHOLOGY OF THE DUST POLARIZED EMISSION (2013, background): “…filamentary structure but they do not probe the complex relationship of column density and magnetic field morphologies in the dense regions of molecular clouds, where stars predominantly form and which are fundamental to establishing a global picture of molecular cloud formation (Lada et al. 2010).”
The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, background): “The star formation rate per unit mass within a given cloud also appears to be strongly correlated with the amount of gas it possesses above some threshold volume or column density (Heiderman et al. 2010; Lada et al. 2010, 2012; Evans et al. 2014).”
MAXIMALLY STAR-FORMING GALACTIC DISKS. I. STARBURST REGULATION VIA FEEDBACK-DRIVEN TURBULENCE (2011, methodology): “This density threshold and efficiency factor are chosen based on observations of Milky Way and extragalactic gas and star formation (Krumholz & Tan 2007; Evans et al. 2009; Lada et al. 2010; Heiderman et al. 2010; see also Section 5).”
Star formation rates and efficiencies in the Galactic Centre (2017, methodology): “We find that the constraints on the SFR within the dust-ridge clouds ‘d’, ‘e’ and ‘f’ are too poor to test the Lada et al. (2010, 2012) predictions with any significance.”
A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from the Herschel Gould Belt survey (2015, background): “As pointed out by Lada et al. (2010, 2012), the nearby cloud value of the “efficiency” of the star formation process in dense gas is also very similar to the efficiency value SFR/Mdense ∼ 2 × 10−8 yr−1 found by Gao & Solomon (2004) for external galaxies, using HCN observations of dense gas and…”