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Title: THE SIZES OF THE NEAREST YOUNG STARS

Abstract

We present moderate resolution (R {approx} 3575) optical spectra of 19 known or suspected members of the AB Doradus and {beta} Pictoris Moving Groups, obtained with the DeVeny Spectrograph on the 72 inch Perkins telescope at Lowell Observatory. For four of five recently proposed members, signatures of youth such as Li I 6708 A absorption and H{alpha} emission further strengthen the case for youth and membership. The lack of detected lithium in the proposed {beta} Pic member TYC 2211-1309-1 implies that it is older than all other K-type members and weakens the case for membership. Effective temperatures are determined via line ratio analyses for the 11 F, G, and early-K stars observed, and via spectral comparisons for the eight late-K and M stars observed. We assemble updated candidate membership lists for these moving groups that account for known binarity. Currently, the AB Dor Moving Group contains 127 proposed members and the {beta} Pic Moving Group holds 77 proposed members. We then use temperature, luminosity, and distance estimates to predict angular diameters for these stars; the motivation is to identify stars that can be spatially resolved with long-baseline optical/infrared interferometers in order to improve age estimates for these groups and tomore » constrain evolutionary models at young ages. Considering the portion of the sky accessible to northern hemisphere facilities (decl. > - 30), six stars have diameters large enough to be spatially resolved ({theta} > 0.4 mas) with the CHARA Array, which currently has the world's longest baseline of 331 m; this subsample includes the low-mass M2.5 member of AB Dor, GJ 393, which is likely to still be pre-main sequence. For southern hemisphere facilities (decl. < + 30), 18 stars have diameters larger than this limiting size, including the low-mass debris disk star AU Mic (0.72 mas). However, the longest baselines of southern hemisphere interferometers (160 m) are only able to resolve the largest of these, the B6 star {alpha} Gru (1.17 mas); proposed long-baseline stations may alleviate the current limitations.« less

Authors:
;  [1]
  1. Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303-4106 (United States)
Publication Date:
OSTI Identifier:
22034452
Resource Type:
Journal Article
Journal Name:
Astronomical Journal (New York, N.Y. Online)
Additional Journal Information:
Journal Volume: 143; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1538-3881
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ASTRONOMY; ASTROPHYSICS; COMPARATIVE EVALUATIONS; DISTANCE; EMISSION SPECTRA; INTERFEROMETERS; LITHIUM; LUMINOSITY; MASS; NORTHERN HEMISPHERE; PHOTON EMISSION; SOUTHERN HEMISPHERE; STARS; VISIBLE SPECTRA

Citation Formats

McCarthy, Kyle, and White, Russel J., E-mail: kyle.mccarthy@uky.edu. THE SIZES OF THE NEAREST YOUNG STARS. United States: N. p., 2012. Web. doi:10.1088/0004-6256/143/6/134.
McCarthy, Kyle, & White, Russel J., E-mail: kyle.mccarthy@uky.edu. THE SIZES OF THE NEAREST YOUNG STARS. United States. doi:10.1088/0004-6256/143/6/134.
McCarthy, Kyle, and White, Russel J., E-mail: kyle.mccarthy@uky.edu. Fri . "THE SIZES OF THE NEAREST YOUNG STARS". United States. doi:10.1088/0004-6256/143/6/134.
@article{osti_22034452,
title = {THE SIZES OF THE NEAREST YOUNG STARS},
author = {McCarthy, Kyle and White, Russel J., E-mail: kyle.mccarthy@uky.edu},
abstractNote = {We present moderate resolution (R {approx} 3575) optical spectra of 19 known or suspected members of the AB Doradus and {beta} Pictoris Moving Groups, obtained with the DeVeny Spectrograph on the 72 inch Perkins telescope at Lowell Observatory. For four of five recently proposed members, signatures of youth such as Li I 6708 A absorption and H{alpha} emission further strengthen the case for youth and membership. The lack of detected lithium in the proposed {beta} Pic member TYC 2211-1309-1 implies that it is older than all other K-type members and weakens the case for membership. Effective temperatures are determined via line ratio analyses for the 11 F, G, and early-K stars observed, and via spectral comparisons for the eight late-K and M stars observed. We assemble updated candidate membership lists for these moving groups that account for known binarity. Currently, the AB Dor Moving Group contains 127 proposed members and the {beta} Pic Moving Group holds 77 proposed members. We then use temperature, luminosity, and distance estimates to predict angular diameters for these stars; the motivation is to identify stars that can be spatially resolved with long-baseline optical/infrared interferometers in order to improve age estimates for these groups and to constrain evolutionary models at young ages. Considering the portion of the sky accessible to northern hemisphere facilities (decl. > - 30), six stars have diameters large enough to be spatially resolved ({theta} > 0.4 mas) with the CHARA Array, which currently has the world's longest baseline of 331 m; this subsample includes the low-mass M2.5 member of AB Dor, GJ 393, which is likely to still be pre-main sequence. For southern hemisphere facilities (decl. < + 30), 18 stars have diameters larger than this limiting size, including the low-mass debris disk star AU Mic (0.72 mas). However, the longest baselines of southern hemisphere interferometers (160 m) are only able to resolve the largest of these, the B6 star {alpha} Gru (1.17 mas); proposed long-baseline stations may alleviate the current limitations.},
doi = {10.1088/0004-6256/143/6/134},
journal = {Astronomical Journal (New York, N.Y. Online)},
issn = {1538-3881},
number = 6,
volume = 143,
place = {United States},
year = {2012},
month = {6}
}