Discovering and Characterizing Embedded Stellar Clusters in the Near-Infrared

Persistent Link:
http://hdl.handle.net/10150/193801
Title:
Discovering and Characterizing Embedded Stellar Clusters in the Near-Infrared
Author:
Leistra, Andrea
Issue Date:
2006
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
I present a near-infrared search for new embedded stellar clusters in the Galaxy, and the results of near-infrared followup observations of a subset of newly discovered stellar clusters. I discuss the initial mass function of these embedded clusters and the implications of the apparent method-dependent systematic error in the IMF.First, I present near-infrared J, H, and K images of six embedded stellar clusters in the Galaxy, and K-band spectroscopy for two. I find a significant fraction of pre-main-sequence stars present in at least two of the clusters. For the clusters dominated by main-sequence stars, we determine the initial mass function (IMF) both by using the K luminosity function and a global extinction correction and by deriving individual extinction corrections for each star based on their placement in the K vs. H-K color-magnitude diagram. Based on our IMFs we find a significant discrepancy between the mean IMF derived via the different methods, suggesting that taking individual extinctions into account is necessary to correctly derive the IMF for an embedded cluster. I find that using the KLF alone to derive an IMF is likely to produce an overly steep slope in stellar clusters subject to variable extinction, and examine literature results to see if the same effect exists in the work of other authors.I conduct a two-phase search of the 2MASS Point Source Catalog to discover previously unknown embedded stellar clusters and construct a more complete sample than has previously been available. Based on comparisons with the sample of known embedded stellar clusters we determine the completeness of the total existing sample to be ~75% within 2 kpc. I discuss the limitations of previously employed algorithms for stellar cluster detection, and suggest possible alternatives for use in areas of high stellar background density.Finally I present a detailed look at two of the incorrectly identified embedded cluster candidates to better understand the limitations of our algorithm.
Type:
text; Electronic Dissertation
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Astronomy; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Liebert, James W.
Committee Chair:
Liebert, James W.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleDiscovering and Characterizing Embedded Stellar Clusters in the Near-Infrareden_US
dc.creatorLeistra, Andreaen_US
dc.contributor.authorLeistra, Andreaen_US
dc.date.issued2006en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractI present a near-infrared search for new embedded stellar clusters in the Galaxy, and the results of near-infrared followup observations of a subset of newly discovered stellar clusters. I discuss the initial mass function of these embedded clusters and the implications of the apparent method-dependent systematic error in the IMF.First, I present near-infrared J, H, and K images of six embedded stellar clusters in the Galaxy, and K-band spectroscopy for two. I find a significant fraction of pre-main-sequence stars present in at least two of the clusters. For the clusters dominated by main-sequence stars, we determine the initial mass function (IMF) both by using the K luminosity function and a global extinction correction and by deriving individual extinction corrections for each star based on their placement in the K vs. H-K color-magnitude diagram. Based on our IMFs we find a significant discrepancy between the mean IMF derived via the different methods, suggesting that taking individual extinctions into account is necessary to correctly derive the IMF for an embedded cluster. I find that using the KLF alone to derive an IMF is likely to produce an overly steep slope in stellar clusters subject to variable extinction, and examine literature results to see if the same effect exists in the work of other authors.I conduct a two-phase search of the 2MASS Point Source Catalog to discover previously unknown embedded stellar clusters and construct a more complete sample than has previously been available. Based on comparisons with the sample of known embedded stellar clusters we determine the completeness of the total existing sample to be ~75% within 2 kpc. I discuss the limitations of previously employed algorithms for stellar cluster detection, and suggest possible alternatives for use in areas of high stellar background density.Finally I present a detailed look at two of the incorrectly identified embedded cluster candidates to better understand the limitations of our algorithm.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAstronomyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLiebert, James W.en_US
dc.contributor.chairLiebert, James W.en_US
dc.contributor.committeememberLiebert, James W.en_US
dc.contributor.committeememberMassey, Philipen_US
dc.contributor.committeememberRieke, Georgeen_US
dc.contributor.committeememberYoung, Ericken_US
dc.identifier.proquest1744en_US
dc.identifier.oclc659747500en_US
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