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Title: A NEW MILKY WAY HALO STAR CLUSTER IN THE SOUTHERN GALACTIC SKY

Abstract

We report on the discovery of a new Milky Way (MW) companion stellar system located at ({alpha}{sub J2000,}{delta}{sub J2000}) = (22{sup h}10{sup m}43{sup s}.15, 14 Degree-Sign 56 Prime 58 Double-Prime .8). The discovery was made using the eighth data release of SDSS after applying an automated method to search for overdensities in the Baryon Oscillation Spectroscopic Survey footprint. Follow-up observations were performed using Canada-France-Hawaii-Telescope/MegaCam, which reveal that this system is comprised of an old stellar population, located at a distance of 31.9{sup +1.0}{sub -1.6} kpc, with a half-light radius of r{sub h}= 7.24{sup +1.94}{sub -1.29} pc and a concentration parameter of c = log{sub 10}(r{sub t} /r{sub c} ) = 1.55. A systematic isochrone fit to its color-magnitude diagram resulted in log (age yr{sup -1}) = 10.07{sup +0.05}{sub -0.03} and [Fe/H] = -1.58{sup +0.08}{sub -0.13}. These quantities are typical of globular clusters in the MW halo. The newly found object is of low stellar mass, whose observed excess relative to the background is caused by 95 {+-} 6 stars. The direct integration of its background decontaminated luminosity function leads to an absolute magnitude of M{sub V} = -1.21 {+-} 0.66. The resulting surface brightness is {mu}{sub V} = 25.90 magmore » arcsec{sup -2}. Its position in the M{sub V} versus r{sub h} diagram lies close to AM4 and Koposov 1, which are identified as star clusters. The object is most likely a very faint star cluster-one of the faintest and lowest mass systems yet identified.« less

Authors:
;  [1]; ; ;  [2];  [3];  [4];  [5];  [6]
  1. Instituto de Fisica, UFRGS, CP 15051, Porto Alegre, RS 91501-970 (Brazil)
  2. Laboratorio Interinstitucional de e-Astronomia-LIneA, Rua Gal. Jose Cristino 77, Rio de Janeiro, RJ 20921-400 (Brazil)
  3. Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States)
  4. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109-1042 (United States)
  5. Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, Hampshire PO1 2UP (United Kingdom)
  6. Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)
Publication Date:
OSTI Identifier:
22126944
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 767; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BARYONS; BRIGHTNESS; DISTANCE; LUMINOSITY; MASS; MILKY WAY; OSCILLATIONS; SKY; STAR CLUSTERS; STARS; SURFACES

Citation Formats

Balbinot, E., Santiago, B. X., Da Costa, L., Maia, M. A. G., Rocha-Pinto, H. J., Majewski, S. R., Nidever, D., Thomas, D., Wechsler, R. H., and Yanny, B., E-mail: balbinot@if.ufrgs.br. A NEW MILKY WAY HALO STAR CLUSTER IN THE SOUTHERN GALACTIC SKY. United States: N. p., 2013. Web. doi:10.1088/0004-637X/767/2/101.
Balbinot, E., Santiago, B. X., Da Costa, L., Maia, M. A. G., Rocha-Pinto, H. J., Majewski, S. R., Nidever, D., Thomas, D., Wechsler, R. H., & Yanny, B., E-mail: balbinot@if.ufrgs.br. A NEW MILKY WAY HALO STAR CLUSTER IN THE SOUTHERN GALACTIC SKY. United States. https://doi.org/10.1088/0004-637X/767/2/101
Balbinot, E., Santiago, B. X., Da Costa, L., Maia, M. A. G., Rocha-Pinto, H. J., Majewski, S. R., Nidever, D., Thomas, D., Wechsler, R. H., and Yanny, B., E-mail: balbinot@if.ufrgs.br. Sat . "A NEW MILKY WAY HALO STAR CLUSTER IN THE SOUTHERN GALACTIC SKY". United States. https://doi.org/10.1088/0004-637X/767/2/101.
@article{osti_22126944,
title = {A NEW MILKY WAY HALO STAR CLUSTER IN THE SOUTHERN GALACTIC SKY},
author = {Balbinot, E. and Santiago, B. X. and Da Costa, L. and Maia, M. A. G. and Rocha-Pinto, H. J. and Majewski, S. R. and Nidever, D. and Thomas, D. and Wechsler, R. H. and Yanny, B., E-mail: balbinot@if.ufrgs.br},
abstractNote = {We report on the discovery of a new Milky Way (MW) companion stellar system located at ({alpha}{sub J2000,}{delta}{sub J2000}) = (22{sup h}10{sup m}43{sup s}.15, 14 Degree-Sign 56 Prime 58 Double-Prime .8). The discovery was made using the eighth data release of SDSS after applying an automated method to search for overdensities in the Baryon Oscillation Spectroscopic Survey footprint. Follow-up observations were performed using Canada-France-Hawaii-Telescope/MegaCam, which reveal that this system is comprised of an old stellar population, located at a distance of 31.9{sup +1.0}{sub -1.6} kpc, with a half-light radius of r{sub h}= 7.24{sup +1.94}{sub -1.29} pc and a concentration parameter of c = log{sub 10}(r{sub t} /r{sub c} ) = 1.55. A systematic isochrone fit to its color-magnitude diagram resulted in log (age yr{sup -1}) = 10.07{sup +0.05}{sub -0.03} and [Fe/H] = -1.58{sup +0.08}{sub -0.13}. These quantities are typical of globular clusters in the MW halo. The newly found object is of low stellar mass, whose observed excess relative to the background is caused by 95 {+-} 6 stars. The direct integration of its background decontaminated luminosity function leads to an absolute magnitude of M{sub V} = -1.21 {+-} 0.66. The resulting surface brightness is {mu}{sub V} = 25.90 mag arcsec{sup -2}. Its position in the M{sub V} versus r{sub h} diagram lies close to AM4 and Koposov 1, which are identified as star clusters. The object is most likely a very faint star cluster-one of the faintest and lowest mass systems yet identified.},
doi = {10.1088/0004-637X/767/2/101},
url = {https://www.osti.gov/biblio/22126944}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 767,
place = {United States},
year = {2013},
month = {4}
}

Works referencing / citing this record:

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