A Search for RR Lyrae Stars in Segue 2 and Segue 3
| Autor: | Jay Strader, Annie Preston, Andrew P. Sturner, Tonima Tasnim Ananna, Ross Fadely, Tim Douglas, Erin Boettcher, Jacob Gilbert, Mariah Baker, Emily C. Cunningham, Beth Willman, Erica Hopkins |
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| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences Milky Way FOS: Physical sciences Astronomy and Astrophysics Astrophysics Segue RR Lyrae variable Horizontal branch 01 natural sciences Astrophysics - Astrophysics of Galaxies Star cluster Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Binary star Variable star 010303 astronomy & astrophysics 0105 earth and related environmental sciences Dwarf galaxy |
| Popis: | We present an extensive search for RR Lyrae stars in and around the ultra-faint Milky Way companions Segue 2 and Segue 3. The former (M_V = -2.5, Belokurov et al. 2009) appears to be an extremely faint dwarf galaxy companion of the Milky Way. The latter (M_V = 0.0, Fadely et al. 2011) is among the faintest star clusters known. We use B and V band time-series imaging obtained at the WIYN 0.9 meter telescope at Kitt Peak National Observatory to search for RR Lyrae in these objects. In our Segue 2 observations, we present a previously unknown fundamental mode (RRab) RR Lyrae star with a period of P_ab = 0.748 days. With this measurement, we revisit the inverse correlation between and established in the literature for Milky Way dwarf galaxies and their RR Lyrae. 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 and . 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 kpc; assuming [Fe/H] = -2.257 dex, we find d_BHB = 34.4 +/- 2.6 kpc. Although no RR Lyrae were present in the Segue 3 field, we found a candidate eclipsing binary star system. Comment: 10 pages, 5 figures, accepted for publication in the Astronomical Journal |
| Databáze: | OpenAIRE |
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