A SEARCH FOR RR LYRAE STARS IN SEGUE 2 AND SEGUE 3
- Department of Astronomy, University of Wisconsin, Madison, WI 53706 (United States)
- Department of Astronomy, Haverford College, Haverford, PA 19041 (United States)
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)
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 (M{sub V} = –2.5) appears to be an extremely faint dwarf galaxy companion of the Milky Way. The latter (M{sub V} = 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 {sub ab} = 0.748 days. With this measurement, we revisit the inverse correlation between (P {sub ab}) and ([Fe/H]) 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 (P {sub ab}) and ([Fe/H]). 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{sub RRL}= 36.6{sup +2.5}{sub -2.4} and 37.7{sup +2.7}{sub -2.7} kpc; assuming [Fe/H] = –2.257 dex, we find d {sub BHB} = 34.4 ± 2.6 kpc. Although no RRL were present in the Segue 3 field, we found a candidate eclipsing binary star system.
- OSTI ID:
- 22273326
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 146, Issue 4; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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