A CORRELATION BETWEEN SURFACE DENSITIES OF YOUNG STELLAR OBJECTS AND GAS IN EIGHT NEARBY MOLECULAR CLOUDS

By R. Gutermuth, J. Pipher, S. Megeath, P. Myers, L. Allen, T. Allen. 2011

149 citations recorded by the source corpus.

We report the discovery and characterization of a power-law correlation between the local surface densities of Spitzer-identified, dusty young stellar objects (YSOs) and the column density of gas (as traced by near-IR extinction) in eight molecular clouds within 1 kpc and with 100 or more known YSOs. This correlation, which appears in data smoothed over size scales of ∼1 pc, varies in quality from cloud to cloud; those clouds with tight correlations, MonR2 and Ophiuchus, are fit with power laws of slope 2.67 and 1.87, respectively. The spread in the correlation is attributed primarily to local gas disruption by stars that formed there or to the presence of very young subregions at the onset of star formation. We explore the ratio of the number of Class II to Class I sources, a proxy for the star formation age of a region, as a function of gas column density; this analysis reveals a declining Class II to Class I ratio with increasing column density. We show that the observed star–gas correlation is consistent with a star formation law where the star formation rate per area varies with the gas column density squared. We also propose a simple picture of thermal fragmentation of dense gas in an isothermal, self-gravitating layer as an explanation for the power law. Finally, we briefly compare the star–gas correlation and its implied star formation law with other recent proposed of star formation laws at similar and larger size scales from nearby star-forming regions.

Subfields: Astronomy and Astrophysics, Fluid Flow and Transfer Processes, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/6e9eac0abdb42da95ff5d88a205cc0c8fb74e6e8

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Fluid Flow and Transfer Processes

In Spectroscopy

Citations in the corpus

Global hierarchical collapse in molecular clouds. Towards a comprehensive scenario (2019, background): “…works reporting a tight relation between the fragmentation level or young stellar objects counts and the density of their parent structures (Gutermuth et al. 2011; Palau et al. 2014, 2015, 2018; K. Lee et al. 2015; Mairs et al. 2016, 2017; Sharma et al. 2016; Hacar et al. 2017, 2018;…”
An uncertainty principle for star formation - I. Why galactic star formation relations break down below a certain spatial scale (2014, background): “For instance, SF relations measured in the solar neighbourhood (Heiderman et al. 2010; Lada, Lombardi & Alves 2010; Gutermuth et al. 2011; Lada et al. 2013) are fundamentally different from their galactic counterparts.”
THE SPITZER SPACE TELESCOPE SURVEY OF THE ORION A AND B MOLECULAR CLOUDS. I. A CENSUS OF DUSTY YOUNG STELLAR OBJECTS AND A STUDY OF THEIR MID-INFRARED VARIABILITY (2012, methodology): “This figure shows that the YSOs follow the general structure of the cloud and that there are few parts of the cloud that are completely devoid of YSOs (also see Gutermuth et al. 2011).”
STAR FORMATION RELATIONS IN NEARBY MOLECULAR CLOUDS (2014, background): “The issue of scale is also relevant to the interpretation of the continued rise of star formation rate surface density roughly proportional to the square of gas surface density, even above the threshold of AV = 8 mag, in young clusters (Gutermuth et al. 2011).”
What controls star formation in the central 500 pc of the Galaxy (2013, background): “…volume density threshold for star formationnLada ∼ 104 cm−3 above which most1 gas is converted into stars on a∼ 20 Myr time-scale (Gao & Solomon 2004; Heiderman et al. 2010; Lada, Lombardi & Alves 2010, although see Gutermuth et al. 2011 and Burkert & Hartmann 2012 for an opposing conclusion).”
THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS (2012, result): “We note that the simulation data in Figure 11 are furthermore consistent with the Galactic cloud samples in Lada et al. (2010) and Gutermuth et al. (2011), showing that ΣSFR can vary by more than an order of magnitude at any given Σgas.”
Star Formation in the Milky Way and Nearby Galaxies (2012, background): “Gutermuth et al. (2011) find a continuation of the steep increase in Σ(SFR) to higher Σgas in a study including embedded clusters.”
Physical Processes in the Interstellar Medium (2014, background): “, 2010; Gutermuth et al., 2011; Burkert & Hartmann, 2013; Lada et al., 2013; Evans et al., 2014). A complete theoretical understanding of why this correlation exists remains lacking, but in a recent study, Clark & Glover (2014) argue that it is a further consequence of dust shielding.”
The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, background): “Quantitative analysis backs up the visual impression: Gutermuth et al. (2011) find that the Pear- 14 son correlation coefficient between the logarithms of the gas and stellar surface densities is 0.87 in MonR2, but only 0.17 in CepOB3.”
ON THE STAR FORMATION EFFICIENCY OF TURBULENT MAGNETIZED CLOUDS (2012, methodology): “The YSO completeness achieved with Spitzer may only be 50% averaged over the inner 0.5 pc of the Trapezium region in Orion, and only 30% within a radius of 0.2 pc (Evans et al. 2009; Gutermuth et al. 2011).”
Inefficient star formation through turbulence, magnetic fields and feedback (2015, background): “The observational data are a collection of star-forming Milky Way clouds, molecular clumps and young stellar objects (YSOs) from Heiderman et al. (2010), Lada et al. (2010) and Gutermuth et al. (2011), as well as the Central Molecular Zone (CMZ) from Yusef-Zadeh et al. (2009).”
The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline (2014, background): “…to the cloud-scale physics of star formation (e.g. Bigiel et al. 2008; Heiderman et al. 2010; Lada, Lombardi & Alves 2010; Schruba et al. 2010; Gutermuth et al. 2011; Hopkins, Quataert & Murray 2011; Krumholz, Dekel & McKee 2012; Burkert & Hartmann 2013; Kruijssen & Longmore 2014), but the…”
On the fraction of star formation occurring in bound stellar clusters (2012, background): “Per consequence, observational and theoretical studies do not find any evidence for discrete modes of star formation in the density spectrum of stellar structure in such regions (Bressert et al. 2010; Gieles & Portegies Zwart 2011; Gutermuth et al. 2011; Kruijssen et al. 2012a).”