2MASS Observations of the Perseus, Orion A, Orion B, and Monoceros R2 Molecular Clouds

By J. Carpenter. 2000

239 citations recorded by the source corpus.

We use the 2MASS Second Incremental Release Point Source Catalog to investigate the spatial distribution of young stars in the Perseus, Orion A, Orion B, and MonR2 molecular clouds. After subtracting a semiempirical model of the field star contamination from the observed star counts, stellar surface density maps are used to identify compact clusters and any stellar population found more uniformly distributed over the molecular cloud. Each cloud contains between two and seven clusters, with at least half of the cluster population found in a single, rich cluster. In addition, a distributed stellar population is inferred in the Orion A and MonR2 molecular clouds within the uncertainties of the field star subtraction with a surface density between 0.013 and 0.083 arcmin-2. Sensitivity calculations suggest, however, that the number of stars in the distributed population may be underestimated by a factor of 2 or more if stars have been forming with a Miller-Scalo IMF at a constant star formation rate for longer than 10 Myr. After considering the possible evolutionary status of the distributed population, the global star formation efficiency implied by the sum of the distributed and cluster populations ranges between 1% and 9% among the four clouds. The fraction of the total stellar population contained in clusters for the nominal extinction model ranges from ≈50% to 100% if the distributed population is relatively young (<10 Myr), to ≈25%–70% if it is relatively old (≈100 Myr). The relatively high fraction of stars contained in clusters regardless of the age of the distributed population, in conjunction with the young ages generally inferred for embedded clusters in nearby molecular clouds, indicates that a substantial fraction of the total stellar population in these regions has formed within the past few million years in dense clusters. This suggests that either the star formation rate in each these clouds has recently peaked if one assumes clouds have ages greater than 10 Myr or molecular clouds are younger than typically thought if one assumes that the star formation rate has been approximately constant in time.

Subfields: Astronomy and Astrophysics, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/c0dd579ae609d6e6ed5a5b1d76fc68c6dc95e04a

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In Astronomy and Astrophysics

1. N. Evans II
2. Mark R. Krumholz
3. P. Myers
4. K. Luhman
5. Ralf Klessen
6. L. Allen
7. L. Hartmann
8. R. Gutermuth

In Spectroscopy

1. N. Evans II
2. P. Myers
3. K. Luhman
4. L. Allen
5. R. Gutermuth
6. L. Hartmann
7. C. Lada
8. Mark R. Krumholz

Citations in the corpus

• A CORRELATION BETWEEN SURFACE DENSITIES OF YOUNG STELLAR OBJECTS AND GAS IN EIGHT NEARBY MOLECULAR CLOUDS (2011, background): “These are similar to reported values for “distributed” and “clustered” star formation (e.g. Carpenter 2000; Allen et al. 2007; Evans et al. 2009).”
• Near-Infrared Photometric Variability of Stars toward the Orion A Molecular Cloud (2001, methodology): “5@ of the ONC presented by Hillenbrand & Carpenter (2000).”
• The New Galaxy: Signatures of Its Formation (2002, background): “Most stars are born within rich clusters of many hundreds to many thousands of stars (Clarke et al. 2000; Carpenter 2000).”
• Mapping the interstellar dust with near-infrared observations: An optimized multi-band technique (2001, result): “Finally, there are already a number of studies in the literature which can be used to test our results (e.g., Carpenter 2000 uses the same data set to investigate the spatial distribution of young stars in these clouds and presents averaged J −Ks color maps of this region).”
• The Physical Conditions for Massive Star Formation: Dust Continuum Maps and Modeling (2002, background): “Since most stars form in clusters associated with high-mass stars (e.g., Carpenter 2000), many recent studies have focused on better understanding the physical conditions in these regions (e.g., van der Tak et al. 2000; Sridharan et al. 2002; Beuther et al. 2002; Hatchell et al. 2000;Walsh et al.…”
• A SPITZER SURVEY OF YOUNG STELLAR CLUSTERS WITHIN ONE KILOPARSEC OF THE SUN: CLUSTER CORE EXTRACTION AND BASIC STRUCTURAL ANALYSIS (2009, methodology): “These sizes were motivated by the cluster diameters reported in the literature compilation of Lada & Lada (2003) and the survey of Carpenter (2000); these showed typical diameters of 1 pc.”
• Star formation in Perseus - Clusters, filaments and the conditions for star formation (2005, background): “Infrared studies of embedded clusters of pre-main-sequence stars estimate the fraction of stars in clusters as 60–90% (L1630; Lada et al. 1991) and 50–100% (4 nearby clouds; Carpenter 2000), which are consistent with our findings.”
• KINEMATIC AND SPATIAL SUBSTRUCTURE IN NGC 2264 (2015, background): “Most stars form in clusters (Carpenter 2000; Lada & Lada 2003; Allen et al. 2007; Krumholz et al. 2014), and it is important to understand the processes that lead to the formation of these clusters, in addition to physics of the formation of the individual stars themselves.”
• The Large- and Small-Scale Structures of Dust in the Star-forming Perseus Molecular Cloud (2006, background): “…in CO have resulted in similar values - Bachiller & Cernicharo (1986) estimate 1.2×104 M⊙ (1.7×10 4 M⊙ with their assumed distance of 300 pc), while Carpenter (2000) estimate ∼ 0.8 ×104 M⊙ (1.3×104 M⊙ with their assumed distance of 320 pc) from Padoan et al. (1999)’s observations and H05…”
• Dynamics of stellar black holes in young star clusters with different metallicities – II. Black hole–black hole binaries (2014, background): “1 IN T RO D U C T I O N Most stars are expected to form in young star clusters (YSCs; Carpenter 2000; Lada & Lada 2003; Porras et al. 2003).”
• New infrared star clusters in the Northern and Equatorial Milky Way with 2MASS (2003, background): “Since they are in general deeply embedded in dust and/or located in heavily reddened lines of sight, the infrared domain is necessary to study them (e.g. Lada & Lada 1991; Hodapp 1994; Deharveng et al. 1997; Carpenter 2000).”
• Early Evolution of Stellar Groups and Clusters: Environmental Effects on Forming Planetary Systems (2005, unknown): “An observationally determined relation between Rc and N is shown in Figure 2, where squares represent data taken from the compilation of Lada & Lada (2003) and stars represent data from Carpenter (2000).”
• Connecting Dense Gas Tracers of Star Formation in our Galaxy to High-z Star Formation (2005, background): “In the Milky Way, star formation is dominated by clustered star formation (Carpenter 2000; Lada & Lada 2003 ).”
• The Initial Configuration of Young Stellar Clusters: A K-Band Number Counts Analysis of the Surface Density of Stars (2004, background): “There is a wide-spread (1.13 pc) stellar cluster detectable at nearIR wavelengths with an estimated 134 objects (Hodapp 1994; Carpenter 2000) and a moderate velocity bipolar molecular outflow oriented northwest-southeast centered on an H2O maser and secondary peak in 800 µm emission (Little,…”
• Embedded Clusters in Molecular Clouds (2003, methodology): “…AR194-AA41-03.sgm LaTeX2e(2002/01/18) P1: GJB Figure 11 shows a comparison of Trapezium IMFs recently derived from a number of different deep infrared imaging surveys using a variety of methods (Hillenbrand & Carpenter 2000; Lucas & Roche 2000; Luhman et al. 2000; Muench et al. 2000, 2003).”
• Clustered and Triggered Star Formation in W5: Observations with Spitzer (2008, methodology): “Carpenter (2000), in his analysis of the Orion A and B, Mon R2 and Perseus molecular clouds with 2MASS found a range of clustering fractions, different for every cloud, between 56–100%.”
• Disk Frequencies and Lifetimes in Young Clusters (2001, background): “Not only are such clusters believed to be the birth sites of most Galactic field stars (Lada 1992; Carpenter 2000), but they also individually and collectively contain statistically significant numbers (hundreds) of stars, providing a meaningful sampling of essentially the entire stellar mass…”
• On the Role of Massive Stars in the Support and Destruction of Giant Molecular Clouds (2001, background): “Also plotted (dash-dot line) is value of tg∗ appropriate to the entire inner Galaxy, and the range suggested by Carpenter (2000)’s observations of clouds around 2 × 104 M , 190-440 Myr (corresponding to the acceptable age range 3-7 Myr for the embedded population; see below).”