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Title: HUBBLE SPACE TELESCOPE OBSERVATIONS OF FIELD ULTRACOOL DWARFS AT HIGH GALACTIC LATITUDE

Abstract

We present a sample of 17 newly discovered ultracool dwarf candidates later than {approx}M8, drawn from 231.90 arcmin{sup 2} of Hubble Space Telescope Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5 {<=} J{sub 125} {<=} 25.5 AB mag to an exponential disk model, we estimate a vertical scale height of z{sub scl} = 290 {+-} 25 (random) {+-} 31 (systematic) pc for a binarity fraction of f{sub b} = 0. While our estimate is roughly consistent with published results, we suggest that the differences can be attributed to sample properties, with the present sample containing far more substellar objects than previous work. We predict the object counts should peak at J{sub 125} {approx} 24 AB mag due to the exponentially declining number density at the edge of the disk. We conclude by arguing that trend in scale height with spectral type may breakdown for brown dwarfs since they do not settle onto the main sequence.

Authors:
; ;  [1];  [2];  [3];  [4]; ; ;  [5]; ;  [6]
  1. Physics Department, University of California, Davis, CA 95616 (United States)
  2. Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States)
  3. Steward Observatory, Tucson, AZ 85721 (United States)
  4. Spitzer Science Center, California Institute of Technology, MS220-6, Pasadena, CA 91125 (United States)
  5. School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)
  6. Observatories of the Carnegie Institute of Washington, Pasadena, CA 91101 (United States)
Publication Date:
OSTI Identifier:
21587467
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 739; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/739/2/83; 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; GALAXIES; SCALE HEIGHT; STARS; DIMENSIONS; HEIGHT

Citation Formats

Ryan, R. E., Thorman, P. A., Wittman, D. M., Yan, H., Fan, X., Yan, L., Mechtley, M. R., Cohen, S. H., Windhorst, R. A., Hathi, N. P., and McCarthy, P. J., E-mail: rryan@physics.ucdavis.edu. HUBBLE SPACE TELESCOPE OBSERVATIONS OF FIELD ULTRACOOL DWARFS AT HIGH GALACTIC LATITUDE. United States: N. p., 2011. Web. doi:10.1088/0004-637X/739/2/83; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Ryan, R. E., Thorman, P. A., Wittman, D. M., Yan, H., Fan, X., Yan, L., Mechtley, M. R., Cohen, S. H., Windhorst, R. A., Hathi, N. P., & McCarthy, P. J., E-mail: rryan@physics.ucdavis.edu. HUBBLE SPACE TELESCOPE OBSERVATIONS OF FIELD ULTRACOOL DWARFS AT HIGH GALACTIC LATITUDE. United States. doi:10.1088/0004-637X/739/2/83; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Ryan, R. E., Thorman, P. A., Wittman, D. M., Yan, H., Fan, X., Yan, L., Mechtley, M. R., Cohen, S. H., Windhorst, R. A., Hathi, N. P., and McCarthy, P. J., E-mail: rryan@physics.ucdavis.edu. Sat . "HUBBLE SPACE TELESCOPE OBSERVATIONS OF FIELD ULTRACOOL DWARFS AT HIGH GALACTIC LATITUDE". United States. doi:10.1088/0004-637X/739/2/83; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21587467,
title = {HUBBLE SPACE TELESCOPE OBSERVATIONS OF FIELD ULTRACOOL DWARFS AT HIGH GALACTIC LATITUDE},
author = {Ryan, R. E. and Thorman, P. A. and Wittman, D. M. and Yan, H. and Fan, X. and Yan, L. and Mechtley, M. R. and Cohen, S. H. and Windhorst, R. A. and Hathi, N. P. and McCarthy, P. J., E-mail: rryan@physics.ucdavis.edu},
abstractNote = {We present a sample of 17 newly discovered ultracool dwarf candidates later than {approx}M8, drawn from 231.90 arcmin{sup 2} of Hubble Space Telescope Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5 {<=} J{sub 125} {<=} 25.5 AB mag to an exponential disk model, we estimate a vertical scale height of z{sub scl} = 290 {+-} 25 (random) {+-} 31 (systematic) pc for a binarity fraction of f{sub b} = 0. While our estimate is roughly consistent with published results, we suggest that the differences can be attributed to sample properties, with the present sample containing far more substellar objects than previous work. We predict the object counts should peak at J{sub 125} {approx} 24 AB mag due to the exponentially declining number density at the edge of the disk. We conclude by arguing that trend in scale height with spectral type may breakdown for brown dwarfs since they do not settle onto the main sequence.},
doi = {10.1088/0004-637X/739/2/83; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 739,
place = {United States},
year = {2011},
month = {10}
}