A SPITZER SURVEY OF YOUNG STELLAR CLUSTERS WITHIN ONE KILOPARSEC OF THE SUN: CLUSTER CORE EXTRACTION AND BASIC STRUCTURAL ANALYSIS

By R. Gutermuth, S. Megeath, P. Myers, L. Allen, J. Pipher, G. Fazio. 2009

564 citations recorded by the source corpus.

We present a uniform mid-infrared imaging and photometric survey of 36 young, nearby, star-forming clusters and groups using Spitzer IRAC and MIPS. We have confidently identified and classified 2548 young stellar objects (YSOs) using recently established mid-infrared color-based methods. We have devised and applied a new algorithm for the isolation of local surface density enhancements from point source distributions, enabling us to extract the overdense cores of the observed star-forming regions for further analysis. We have compiled several basic structural measurements of these cluster cores from the data, such as mean surface densities of sources, cluster core radii, and aspect ratios, in order to characterize the ranges for these quantities. We find that a typical cluster core is 0.39 pc in radius, has 26 members with infrared excess in a ratio of Class II to Class I sources of 3.7, is embedded in a AK = 0.8 mag cloud clump, and has a surface density of 60 pc−2. We examine the nearest neighbor distances among the YSOs in several ways, demonstrating similarity in the spacings between Class II and Class I sources but large member clusters appear more dense than smaller clusters. We demonstrate that near-uniform source spacings in cluster cores are common, suggesting that simple Jeans fragmentation of parsec-scale cloud clumps may be the dominant process governing star formation in nearby clusters and groups. Finally, we compare our results to other similar surveys in the literature and discuss potential biases in the data to guide further interpretation.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/51d07c32692915ed23189630edf7a59edb8387d9

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Citations in the corpus

YOUNG STELLAR OBJECTS IN THE GOULD BELT (2015, methodology): “As the 24 µm MIPS band has lower resolution and sensitivity, some of the faintest and/or most clustered YSOs may be missed (e.g., Gutermuth et al. 2009, Gutermuth et al., in preparation.).”
THE TAURUS SPITZER SURVEY: NEW CANDIDATE TAURUS MEMBERS SELECTED USING SENSITIVE MID-INFRARED PHOTOMETRY (2009, methodology): “We note that this method has been recently updated in Gutermuth et al. (2009), though the changes to the method are considered relatively small by the authors, and are not implemented here.”
The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, background): “Even populations with ages of a few Myr have noticeably lower densities than stars that have just formed (Gutermuth et al. 2009), and by the time stellar populations reach an age of ∼ 10− 100 Myr their densities have dropped dramatically, with only a small fraction remaining in…”
CSI 2264: SIMULTANEOUS OPTICAL AND INFRARED LIGHT CURVES OF YOUNG DISK-BEARING STARS IN NGC 2264 WITH CoRoT and SPITZER—EVIDENCE FOR MULTIPLE ORIGINS OF VARIABILITY (2014, methodology): “Light curve production For both the mapping mode and the staring mode data, we used the Interactive Data Language (IDL) package Cluster Grinder (Gutermuth et al. 2009) to generate light curves from the basic calibrated data (BCD) images released by the Spitzer Science Center (SSC) pipeline, version…”
A CORRELATION BETWEEN SURFACE DENSITIES OF YOUNG STELLAR OBJECTS AND GAS IN EIGHT NEARBY MOLECULAR CLOUDS (2011, methodology): “A similar threshold (129 ± 14 M⊙ pc −2) was invoked by the sub-cloud-scale analysis by Heiderman et al. (2010), a follow-up to the cloudscale examination by Evans et al. (2009) mentioned above.”
THE DISK POPULATION OF THE UPPER SCORPIUS ASSOCIATION (2012, background): “…compact clusters (∼ 1 deg2, Lada et al. 2006; Sicilia-Aguilar et al. 2006; Dahm & Hillenbrand 2007; Hernández et al. 2007; Luhman et al. 2008; Gutermuth et al. 2009), it has also imaged more widely distributed populations in areas as large as∼ 50 deg2 (Evans et al. 2009; Rebull et al.…”
FILAMENTARY ACCRETION FLOWS IN THE EMBEDDED SERPENS SOUTH PROTOCLUSTER (2013, methodology): “The yellow diamonds, orange open circles, and red filled circles show the YSOs identified by Gutermuth in a re-analysis of the data in Gutermuth et al (2008) which now includes Spitzer 24 µm data, and adopts the classification scheme of Gutermuth et al (2009).”
WIDE-FIELD INFRARED SURVEY EXPLORER OBSERVATIONS OF THE EVOLUTION OF MASSIVE STAR-FORMING REGIONS (2012, background): “…Spitzer have revealed that the young stellar objects (YSOs) in massive star-forming regions often show elongated and clumpy spatial distributions that may reflect structure in their parental molecular clouds (e.g., Lada et al. 1996; Allen et al. 2002; Teixeira et al. 2006; Gutermuth et al. 2009).”
YSOVAR: THE FIRST SENSITIVE, WIDE-AREA, MID-INFRARED PHOTOMETRIC MONITORING OF THE ORION NEBULA CLUSTER (2011, methodology): “We used the IDL package Cluster Grinder (Gutermuth et al. 2009) which, starting from the BCD images released by the Spitzer Science Center, builds the combined mosaic for each epoch and performs aperture photometry on the mosaics.”
On the fraction of star formation occurring in bound stellar clusters (2012, background): “Their results imply that surface density thresholds used for the identification of stellar clusters (e.g. Lada & Lada 2003; Jørgensen et al. 2008; Gutermuth et al. 2009) are arbitrary, and do not correspond to a physical scale.”
The spatial distribution of star formation in the solar neighbourhood: do all stars form in dense clusters? (2010, methodology): “Gutermuth et al. (2009): This method employs the minimal spanning tree (MST) algorithm to define cluster cores by isolating the densest parts of larger scale overdensities.”
The APOGEE-2 Survey of the Orion Star-forming Complex. II. Six-dimensional Structure (2018, background): “These rules can be algorithmic, as with the choice of critical minimum cluster population in the widely-used single-linkage clustering procedure of Gutermuth et al. (2009).”
THE DISK POPULATION OF THE TAURUS STAR-FORMING REGION (2009, methodology): “For several clusters, Gutermuth et al. (2009) found that the distributions of nearest neighbor distances among classes I and II peaked near 0.02–0.05 pc, while the distribution in Taurus reaches a sharp maximum in the lowest bin below 15′′, or 0.01 pc, as shown in the top panel of Figure 10.”
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): “The determination of those values is described in Gutermuth et al. (2009).”
Star Formation in the Milky Way and Nearby Galaxies (2012, background): “A Spitzer study (Gutermuth et al. 2009) of 2548 YSOs in 39 nearby (d < 1.7 kpc), previously known (primarily from the compilation by Porras et al. 2003) young clusters, but excluding Orion and NGC2264, found the following median properties: 26 members, core radius of 0.39 pc, stellar surface…”
Dust Evolution and the Formation of Planetesimals (2016, background): “…with ages from 1Myr to tens of Myrs have been surveyed by various projects with Spitzer (e.g. Allen et al. 2004; Megeath et al. 2004; Luhman 2007; Evans et al. 2009; Gutermuth et al. 2009; Fang et al. 2009; Luhman et al. 2010; Megeath et al. 2012; Fang et al. 2013; Sicilia-Aguilar et al. 2015).”
The dynamical state of stellar structure in star‐forming regions (2011, background): “…be related to the use of sink particles in the simulation, although it should be noted that small stellar clusters and multiple systems within star-forming globules are actually found on scales as small as 0.005–0.015 pc (Kraus & Hillenbrand 2008; Gutermuth et al. 2009; Launhardt et al. 2010).”