E. D. Feigelson

Pennsylvania State University, University Park, Maryland, United States

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Publications (509)1583.38 Total impact

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    ABSTRACT: The clusters of young stars in massive star-forming regions show a wide range of sizes, morphologies, and numbers of stars. Their highly subclustered structures are revealed by the MYStIX project's sample of 31,754 young stars in nearby sites of star formation (regions at distances <3.6 kpc that contain at least one O-type star.) In 17 of the regions surveyed by MYStIX, we identify subclusters of young stars using finite mixture models -- collections of isothermal ellipsoids that model individual subclusters. Maximum likelihood estimation is used to estimate the model parameters, and the Akaike Information Criterion is used to determine the number of subclusters. This procedure often successfully finds famous subclusters, such as the BN/KL complex behind the Orion Nebula Cluster and the KW-object complex in M17. A catalog of 142 subclusters is presented, with 1 to 20 subclusters per region. The subcluster core radius distribution for this sample is peaked at 0.17 pc with a standard deviation of 0.43 dex, and subcluster core radius is negatively correlated with gas/dust absorption of the stars -- a possible age effect. Based on the morphological arrangements of subclusters, we identify four classes of spatial structure: long chains of subclusters, clumpy structures, isolated clusters with a core-halo structure, and isolated clusters well fit by a single isothermal ellipsoid.
    The Astrophysical Journal 03/2014; 787(2). · 6.73 Impact Factor
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    ABSTRACT: A major impediment to understanding star formation in massive star forming regions (MSFRs) is the absence of a reliable stellar chronometer to unravel their complex star formation histories. We present a new estimation of stellar ages using a new method that employs near-infrared (NIR) and X-ray photometry, AgeJX. Stellar masses are derived from X-ray luminosities using the Lx - Mass relation from the Taurus cloud. J-band luminosities are compared to mass-dependent pre-main-sequence evolutionary models to estimate ages. AgeJX is sensitive to a wide range of evolutionary stages, from disk-bearing stars embedded in a cloud to widely dispersed older pre-main sequence stars. The MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) project characterizes 20 OB-dominated MSFRs using X-ray, mid-infrared, and NIR catalogs. The AgeJX method has been applied to 5525 out of 31,784 MYStIX Probable Complex Members. We provide a homogeneous set of median ages for over a hundred subclusters in 15 MSFRs; median subcluster ages range between 0.5 Myr and 5 Myr. The important science result is the discovery of age gradients across MYStIX regions. The wide MSFR age distribution appears as spatially segregated structures with different ages. The AgeJX ages are youngest in obscured locations in molecular clouds, intermediate in revealed stellar clusters, and oldest in distributed populations. The NIR color index J-H, a surrogate measure of extinction, can serve as an approximate age predictor for young embedded clusters.
    The Astrophysical Journal 03/2014; 787(2). · 6.73 Impact Factor
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    ABSTRACT: We analyze age distributions of two nearby rich stellar clusters, the NGC 2024 (Flame Nebula) and Orion Nebula Cluster (ONC) in the Orion molecular cloud complex. Our analysis is based on samples from the MYStIX survey and a new estimator of pre-main sequence (PMS) stellar ages, AgeJX, derived from X-ray and near-infrared photometric data. To overcome the problem of uncertain individual ages and large spreads of age distributions for entire clusters, we compute median ages and their confidence intervals of stellar samples within annular subregions of the clusters. We find core-halo age gradients in both the NGC 2024 cluster and ONC: PMS stars in cluster cores appear younger and thus were formed later than PMS stars in cluster peripheries. These findings are further supported by the spatial gradients in the disk fraction and K-band excess frequency. Our age analysis is based on AgeJX estimates for PMS stars, and is independent of any consideration of OB stars. The result has important implications for the formation of young stellar clusters. One basic implication is that clusters form slowly and the apparent age spreads in young stellar clusters, which are often controversial, are (at least in part) real. The result further implies that simple models where clusters form inside-out are incorrect, and more complex models are needed. We provide several star formation scenarios that alone or in combination may lead to the observed core-halo age gradients.
    The Astrophysical Journal 03/2014; 787(2). · 6.73 Impact Factor
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    ABSTRACT: We present the Massive Star-forming Regions (MSFRs) Omnibus X-ray Catalog (MOXC), a compendium of X-ray point sources from {\em Chandra}/ACIS observations of a selection of MSFRs across the Galaxy, plus 30 Doradus in the Large Magellanic Cloud. MOXC consists of 20,623 X-ray point sources from 12 MSFRs with distances ranging from 1.7 kpc to 50 kpc. Additionally, we show the morphology of the unresolved X-ray emission that remains after the catalogued X-ray point sources are excised from the ACIS data, in the context of \Spitzer\ and {\em WISE} observations that trace the bubbles, ionization fronts, and photon-dominated regions that characterize MSFRs. In previous work, we have found that this unresolved X-ray emission is dominated by hot plasma from massive star wind shocks. This diffuse X-ray emission is found in every MOXC MSFR, clearly demonstrating that massive star feedback (and the several-million-degree plasmas that it generates) is an integral component of MSFR physics.
    The Astrophysical Journal Supplement Series 03/2014; 213(1). · 16.24 Impact Factor
  • Eric Feigelson, J. M. Hilbe
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    ABSTRACT: The Astrostatistics and Astroinformatics Portal (ASAIP, http://asaip.psu.edu) is a Web resource started in 2012 to foster research into advanced methodologies for astronomical research, and to promulgate such methods into the broader astronomy community. It provides searchable abstracts to Recent Papers in the field, several discussion Forums, various resources for researchers, brief Articles by experts, lists of Meetings, and access to various Web resources such as on-line courses, books and blogs. The material can be electronically searched. The site will be used for public outreach by organizations associated with the AAS, IAU, ISI (International Statistical Institute), and LSST. ASAIP has nearly 700 members who can contribute material, and its resources are readable by the general Web public. This presentation gives examples of recent ASAIP entries and encourages AAS members to use its resources.
    01/2014;
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    ABSTRACT: MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray; Feigelson et al. 2013) is a recent survey of star-forming regions (d<4 kpc) in the X-ray and infrared, revealing >30,000 young stellar complex members. Overall, ~150 subclusters of young stars are found (1 to >10 per region) using a statistical cluster finding algorithm -- the finite mixture model. The spatial arrangments of clusters in different regions can be divided into four classes -- simple, isolated clusters, clusters with a core-halo structure, clumpy clusters, and linear chains of clusters. Clusters are often projected on or near molecular-cloud clumps or cores, particularly in the latter morphological case where subclusters are often located along cloud filamentary structures. Subluster size is negatively correlated with cluster central density (power-law with index slightly shallower than -3) and with gas/dust absorption; both of which may be explained as an effect of subcluster expansion. Overall, star formation appears to be non-coeval in the MYStIX regions, due to the wide range of subcluster properties within individual regions.
    01/2014;
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    ABSTRACT: The data were obtained using WFCAM, the IR wide-field camera on UKIRT in Hawaii for 11 regions (DR 21, Eagle Nebula, Lagoon Nebula, M 17, NGC 1893, NGC 2264, NGC 2362, NGC 6334, NGC 6357, Rosette Nebula and the Trifid Nebula). Roughly half the fields were observed as part of the Galactic Plane Survey (GPS; Lucas et al. 2008, Cat. II/316) component of UKIDSS with the remainder being obtained in Director's Discretionary Time (DDT) using identical observing procedures.(1 data file).
    12/2013;
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    ABSTRACT: The GLIMPSE survey is a Legacy Science Program of NASA's Spitzer Space Telescope to study star formation in the disk of the Milky Way Galaxy. It contains six MYStIX regions - the Lagoon Nebula, the Trifid Nebula, NGC 6334, the Eagle Nebula, M 17, and NGC 6357 - within the 2° wide strip along the Galactic equator (GLIMPSE I and II data releases). Furthermore, Spitzer images and photometry for RCW 38 and NGC 3576 come from the Vela-Carina survey (Majewski et al. 2007sptz.prop40791M), using a similar observing strategy with mosaicking and photometric analysis performed with the GLIMPSE pipeline.We obtained publicly available raw IRAC images from the Spitzer Heritage Archive for nine MYStIX regions without GLIMPSE coverage. The target list and details of the Astronomical Observation Requests (AORs) are provided in Table 1. The camera spatial resolutions are FWHM=1.6" to 1.9" from 3.6 to 8.0um.(3 data files).
    12/2013;
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    ABSTRACT: The Massive Young star-forming complex Study in Infrared and X-rays (MYStIX) project, described by Feigelson et al. (2013ApJS..209...26F), seeks to identify and study samples of young stars in 20 nearby (0.4
    12/2013;
  • T. Naylor, P. S. Broos, E. D. Feigelson
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    ABSTRACT: Identifying the infrared counterparts of X-ray sources in Galactic plane fields such as those of the MYStIX project presents particular difficulties due to the high density of infrared sources. This high stellar density makes it inevitable that a large fraction of X-ray positions will have a faint field star close to them, which standard matching techniques may incorrectly take to be the counterpart. Instead we use the infrared data to create a model of both the field star and counterpart magnitude distributions, which we then combine with a Bayesian technique to yield a probability that any star is the counterpart of an X-ray source. In our more crowded fields, between 10% and 20% of counterparts that would be identified on the grounds of being the closest star to an X-ray position within a 99% confidence error circle are instead identified by the Bayesian technique as field stars. These stars are preferentially concentrated at faint magnitudes. Equally importantly the technique also gives a probability that the true counterpart to the X-ray source falls beneath the magnitude limit of the infrared catalog. In deriving our method, we place it in the context of other procedures for matching astronomical catalogs.(4 data files).
    12/2013;
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    ABSTRACT: The Massive Young star-forming complex Study in Infrared and X-rays (MYStIX) project, described by Feigelson et al. (2013ApJS..209...26F), provides a comprehensive, parallel study of 20 Galactic massive star-forming regions (MSFRs; d=0.4-3.6kpc). The core data products of MYStIX are tables of "MYStIX probable complex members" (MPCMs) in each target MSFR, compiled by Broos et al. (2013ApJS..209...32B). MPCMs are identified using a combination of X-ray imaging data from the Chandra X-ray Observatory and infrared (IR) data from the United Kingdom Infrared Telescope (UKIRT), the Two-Micron All-Sky Survey (2MASS), and the Spitzer Space Telescope. The basic input data for MIRES were near-IR (NIR) and mid-IR (MIR) photometric catalogs. We also use NIR and MIR images and mosaics for visualizing the point-source populations with respect to various nebular structures. We provide high-level descriptions of each input catalog in section 2.(1 data file).
    12/2013;
  • Eric D. Feigelson
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    ABSTRACT: The Massive Young Stellar Cluster Study in Infrared and X-rays (MYStIX) is a project to develop a new census of pre-main sequence and OB members of ̃ 20 star clusters associated with giant molecular clouds. The census is based on archived observations obtained with NASA's Chandra X-ray Observatory, UKIRT's UKIDSS Galactic plane survey, and NASA's Spitzer Space Telescope. With advanced data analysis techniques and probabilistic algorithms to reduce contaminants such as field stars, we obtain the richest available census of cluster members. In addition, source-free X-ray images show 107 K plasma from shocked OB winds interacting with cold interstellar environments. MYStIX will address a variety of questions concerning the formation and early evolution of rich stellar clusters.
    11/2013;
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    Tim Naylor, Patrick S. Broos, Eric D. Feigelson
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    ABSTRACT: Identifying the infrared counterparts of X-ray sources in Galactic Plane fields such as those of the MYStIX project presents particular difficulties due to the high density of infrared sources. This high stellar density makes it inevitable that a large fraction of X-ray positions will have a faint field star close to them, which standard matching techniques may incorrectly take to be the counterpart. Instead we use the infrared data to create a model of both the field star and counterpart magnitude distributions, which we then combine with a Bayesian technique to yield a probability that any star is the counterpart of an X-ray source. In our more crowded fields, between 10 and 20% of counterparts that would be identified on the grounds of being the closest star to X-ray position within a 99% confidence error circle are instead identified by the Bayesian technique as field stars. These stars are preferentially concentrated at faint magnitudes. Equally importantly the technique also gives a probability that the true counterpart to the X-ray source falls beneath the magnitude limit of the infrared catalog. In deriving our method, we place it in the context of other procedures for matching astronomical catalogs.
    The Astrophysical Journal Supplement Series 09/2013; 209(2). · 16.24 Impact Factor
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    ABSTRACT: MYStIX (Massive Young Star-Forming Complex Study in Infrared and Xray) seeks to characterize 20 OB-dominated young clusters and their environs at distances d < 4 kpc using imaging detectors on the Chandra X-ray Observatory, Spitzer Space Telescope, and the United Kingdom InfraRed Telescope. The observational goals are to construct catalogs of star-forming complex stellar members with well-defined criteria, and maps of nebular gas (particularly of hot X-ray emitting plasma) and dust. A catalog of MYStIX Probable Complex Members (MPCMs) with several hundred OB stars and > 30, 000 low mass premain sequence is assembled. This sample and related data products will be used to seek new empirical constraints on theoretical models of cluster formation and dynamics, mass segregation, OB star formation, star formation triggering on the periphery of HII regions, the survivability of protoplanetary disks in HII regions. This paper give an introduction and overview of the project, covering the data analysis methodology and application to two star forming regions, NGC 2264 and the Trifid Nebula.
    The Astrophysical Journal Supplement Series 09/2013; 209(2). · 16.24 Impact Factor
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    ABSTRACT: The Massive Young star-forming complex Study in Infrared and X-ray (MYStIX) uses data from the Chandra X-ray Observatory to identify and characterize the young stellar populations in twenty Galactic (d < 4 kpc) massive star-forming regions. Here, the X-ray analysis for Chandra ACIS-I observations of ten of the MYStIX ?elds is described, and a catalog of >10,000 X-ray sources is presented. In comparison to other published Chandra source lists for the same regions, the number of MYStIX detected faint X-ray sources in a region is often doubled. While the higher catalog sensitivity increases the chance of false detections, it also increases the number of matches to infrared stars. X-ray emitting contaminants include foreground stars, background stars, and extragalactic sources. The X-ray properties of sources in these classes are discussed.
    The Astrophysical Journal Supplement Series 09/2013; 209(2). · 16.24 Impact Factor
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    ABSTRACT: We present JHK infrared data from the UK Infrared Telescope for a subset of the regions of the MYStIX (Massive Young Star-Forming Complex Study in Infrared and X-ray) survey. Some of the data were obtained specifically for the MYStIX project, and some as part of the UKIRT Infrared Deep Sky Survey's Galactic Plane Survey. In most of these fields crowding is a significant issue for aperture photometry, and so we have re-extracted the photometry from the processed images using an optimal extraction technique, and we describe how we adapt the optimal technique to mitigate the effects of crowding.
    The Astrophysical Journal Supplement Series 09/2013; 209(2). · 16.24 Impact Factor
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    ABSTRACT: Spitzer IRAC observations and stellar photometric catalogs are presented for the Massive Young Star-Forming Complex Study in the Infrared and X-ray (MYStIX). MYStIX is a multiwavelength census of young stellar members of twenty nearby (d < 4 kpc), Galactic, star-forming regions that contain at least one O star. All regions have data available from the Spitzer Space Telescope, consisting of GLIMPSE or other published catalogs for eleven regions and results of our own photometric analysis of archival data for the remaining nine regions. This paper seeks to construct deep and reliable catalogs of sources from the Spitzer images. Mid-infrared study of these regions faces challenges of crowding and high nebulosity. Our new catalogs typically contain fainter sources than existing Spitzer studies, which improves the match rate to Chandra X-ray sources that are likely to be young stars, but increases the possibility of spurious point-source detections, especially peaks in the nebulosity. IRAC color-color diagrams help distinguish spurious detections of nebular PAH emission from the infrared excess associated with dusty disks around young stars. The distributions of sources on the mid-infrared color-magnitude and color-color diagrams reflect differences between MYStIX regions, including astrophysical e?ects such as stellar ages and disk evolution.
    The Astrophysical Journal Supplement Series 09/2013; 209(2). · 16.24 Impact Factor
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    ABSTRACT: The Massive Young star-forming Complex Study in Infrared and X-rays (MYStIX) project requires samples of young stars that are likely members of 20 nearby Galactic massive star-forming regions. Membership is inferred from statistical classification of X-ray sources, from detection of a robust infrared excess that is best explained by circumstellar dust in a disk or infalling envelope, and from published spectral types that are unlikely to be found among field stars. We present the MYStIX membership lists here, and describe in detail the statistical classification of X-ray sources via a \Naive Bayes Classi
    The Astrophysical Journal Supplement Series 09/2013; 209(2). · 16.24 Impact Factor
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    ABSTRACT: The MYStIX project (Massive Young Star-Forming Complex Study in Infrared and X-rays) provides a comparative study of 20 Galactic massive star-forming complexes (d = 0.4 to 3.6 kpc). Probable stellar members in each target complex are identified using X-ray and/or infrared data via two pathways: (1) X-ray detections of young/massive stars with coronal activity/strong winds; or (2) infrared excess (IRE) selection of young stellar objects (YSOs) with circumstellar disks and/or protostellar envelopes. We present the methodology for the second pathway, using Spitzer/IRAC, 2MASS, and UKIRT imaging and photometry. Although IRE selection of YSOs is welltrodden territory, MYStIX presents unique challenges. We combine IR spectral energy distribution (SED) fitting with IR color cuts and spatial clustering analysis to identify IRE sources and isolate probable YSO members in each MYStIX target field from the myriad types of contaminating sources that can resemble YSOs: extragalactic sources, evolved stars, nebular knots, and even unassociated foreground/background YSOs. Applying our methodology consistently across 18 of the target complexes, we produce the MYStIX IRE Source (MIRES) Catalog comprising 20,719 sources, including 8686 probable stellar members of the MYStIX target complexes. We also classify the SEDs of 9365 IR counterparts to MYStIX X-ray sources to assist the first pathway, the identification of X-ray detected stellar members. The MIRES catalog provides a foundation for follow-up studies of diverse phenomena related to massive star cluster formation, including protostellar outflows, circumstellar disks, and sequential star formation triggered by massive star feedback processes.
    The Astrophysical Journal Supplement Series 09/2013; 209(2). · 16.24 Impact Factor
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    ABSTRACT: The full fields covered by the HST ACS/WFC and WFPC2 surveys are shown, respectively, in Figures 2 and 3. Both are approximately centered at RA=05:35:00 and DEC=-5:26:00 (J2000), approximately 200" to the SW of the Trapezium asterism and extend over about one-sixth of a square degree. In particular, the full ACS mosaic covers 627arcmin2, whereas the WFPC2 mosaic covers 570.5arcmin2. With NICMOS, our survey covered only a fraction of the ACS field due to the limited field of view of the instrument (Figure 4). A total of 102 regions were covered in both the filter F110W and F160W bands, corresponding to about 177arcmin2 and 171.5arcmin2 in the F110W and F160W filters, respectively. In order to exchange the relative position of ACS and WFPC2, we rotated by 180° the roll angle of the HST by scheduling the observations in two epochs separated by approximately 6 months. The first epoch, executed in the fall of 2004 (2004 October 11-November 7), covered strips 2, 5, and 6 with a position angle of 280°, for a total of 36 orbits. The second epoch, executed in the spring of 2005 (2005 March 3-April 26) covered strips 0, 1, 3, 4, 7, and 8 with a position angle of 100°, for a total of 68 orbits. Both epochs and position angles were optimized to schedule the observations at the peaks of the visibility periods of the Orion Nebula. Table 2 summarizes the scheduling of our observations. Figure 6 presents the overall coverage of the survey. See section 2 for further explanations about the observations. (4 data files).
    VizieR Online Data Catalog. 08/2013; 220:70010.

Publication Stats

9k Citations
1,583.38 Total Impact Points

Institutions

  • 1970–2014
    • Pennsylvania State University
      • Department of Astronomy and Astrophysics
      University Park, Maryland, United States
    • Institut de France
      Lutetia Parisorum, Île-de-France, France
    • Carnegie Mellon University
      • Department of Physics
      Pittsburgh, PA, United States
    • Hungarian Academy of Sciences
      Budapeŝto, Budapest, Hungary
    • Max Planck Institute for Extraterrestrial Physics
      Arching, Bavaria, Germany
    • Universidad de Cartagena
      Cartagena de Indias, Bolívar, Colombia
    • Johns Hopkins University
      • Department of Physics and Astronomy
      Baltimore, MD, United States
    • Nagoya University
      Nagoya, Aichi, Japan
  • 2013
    • Fisk University
      • Department of Physics
      Nashville, Tennessee, United States
    • Northwestern University
      • Center for Interdisciplinary Exploration and Research in Astrophysics
      Evanston, Illinois, United States
  • 2011
    • Universities Space Research Association
      Houston, Texas, United States
  • 1970–2010
    • Harvard-Smithsonian Center for Astrophysics
      • Smithsonian Astrophysical Observatory
      Cambridge, Massachusetts, United States
  • 2009
    • Max Planck Institute for Astronomy
      Heidelburg, Baden-Württemberg, Germany
  • 2006
    • Harvard University
      • Department of Statistics
      Cambridge, Massachusetts, United States
    • Stanford University
      • Department of Statistics
      Stanford, CA, United States
    • University of California, Irvine
      • Department of Physics and Astronomy
      Irvine, CA, United States
    • Princeton University
      • Department of Astrophysical Sciences
      Princeton, New Jersey, United States
    • Queen's University Belfast
      Béal Feirste, N Ireland, United Kingdom
    • University of Washington Seattle
      • Department of Medicine
      Seattle, WA, United States
    • Iowa State University
      Ames, Iowa, United States
    • Columbia University
      New York City, New York, United States
    • Cochin University of Science and Technology
      Fort Cochin, Kerala, India
    • Universität Basel
      Bâle, Basel-City, Switzerland
    • Boston University
      • Department of Mathematics and Statistics
      Boston, MA, United States
    • University of Calcutta
      • Department of Applied Mathematics
      Calcutta, Bengal, India
    • Cornell University
      • Department of Astronomy
      Ithaca, NY, United States
  • 1970–2006
    • University of California, Berkeley
      • • Department of Astronomy
      • • Department of Statistics
      Berkeley, CA, United States
    • Instituto de Física de Cantabria
      Santander, Cantabria, Spain
    • University of Groningen
      • Kapteyn Astronomical Institute
      Groningen, Groningen, Netherlands
    • Duke University
      Durham, North Carolina, United States
  • 2005
    • University College London
      • Department of Space and Climate Physics
      Londinium, England, United Kingdom
    • Max Planck Institute for Radio Astronomy
      Bonn, North Rhine-Westphalia, Germany
    • Academia Sinica
      • Institute of Astronomy and Astrophysics
      T’ai-pei, Taipei, Taiwan
    • Ruhr-Universität Bochum
      Bochum, North Rhine-Westphalia, Germany
  • 2001–2004
    • Massachusetts Institute of Technology
      • Kavli Institute for Astrophysics and Space Research
      Cambridge, Massachusetts, United States
    • William Penn University
      Penn Hills, Pennsylvania, United States
  • 2000
    • The University of Arizona
      • Department of Astronomy
      Tucson, Arizona, United States
  • 1984
    • Tata Institute of Fundamental Research
      Mumbai, Mahārāshtra, India