2013AJ....146...94B
A Search for RR Lyrae Stars in Segue 2 and Segue 3
Boettcher, Erin ( Department of Astronomy, University of Wisconsin, Madison, WI 53706, USA ; Department of Astronomy, Haverford College, Haverford, PA 19041, USA; ); Willman, Beth ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA ); Fadely, Ross ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA; Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003, USA ); Strader, Jay ( Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA ); Baker, Mariah ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA ); Hopkins, Erica ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA ); Tasnim Ananna, Tonima ( Department of Physics, Bryn Mawr College, Bryn Mawr, PA 19010, USA ); Cunningham, Emily C. ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA; Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA ); Douglas, Tim ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA; Dropbox Inc., 185 Berry Street, Suite 400, San Francisco, CA 94107, USA ); Gilbert, Jacob ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA ); Preston, Annie ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA ); Sturner, Andrew P. ( Department of Astronomy, Haverford College, Haverford, PA 19041, USA; Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA ) and 2 coauthors show affiliations
The Astronomical Journal, Volume 146, Issue 4, article id. 94, 9 pp. (2013).
Published in Oct 2013
We present an extensive search for RR Lyrae (RRL) stars in and around the ultra-faint Milky Way companions Segue 2 and Segue 3. The former (MV = -2.5) appears to be an extremely faint dwarf galaxy companion of the Milky Way. The latter (MV = 0.0) is among the faintest star clusters known. We use B and V band time-series imaging obtained at the WIYN 0.9 m telescope at Kitt Peak National Observatory to search for RRL in these objects. In our Segue 2 observations, we present a previously unknown fundamental mode (RRab) RRL star with a period of P ab = 0.748 days. With this measurement, we revisit the inverse correlation between langP abrang and lang[Fe/H]rang established in the literature for Milky Way dwarf galaxies and their RRL. In this context, the long period of Segue 2's RRab star as well as the known significant spread in metallicity in this dwarf galaxy are consistent with the observed trend in langP abrang and lang[Fe/H]rang. We derive the first robust distance to Segue 2, using both its RRab star and spectroscopically confirmed blue horizontal branch stars. Using [Fe/H] = -2.16 and -2.44 dex, we find d_{RRL} = 36.6^{+2.5}_{-2.4} and 37.7^{+2.7}_{-2.7} kpc assuming [Fe/H] = -2.257 dex, we find d BHB = 34.4 ± 2.6 kpc. Although no RRL were present in the Segue 3 field, we found a candidate eclipsing binary star system.
Keywords:
Free Keywords: Astrophysics - Galaxy Astrophysics; galaxies: dwarf; galaxies: star clusters: general; stars: distances; stars: variables: general; techniques: photometric
Astronomy: galaxies: dwarf; galaxies: star clusters: general; stars: distances; stars: variables: general; techniques: photometric
arXiv: Astrophysics - Galaxy Astrophysics
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