2013AJ....146...94B

Query : 2013AJ....146...94B

2013AJ....146...94B - Astron. J., 146, 94 (2013/October-0)

A search for RR Lyrae stars in Segue 2 and Segue 3.

BOETTCHER E., WILLMAN B., FADELY R., STRADER J., BAKER M., HOPKINS E., ANANNA T.T., CUNNINGHAM E.C., DOUGLAS T., GILBERT J., PRESTON A. and STURNER A.P.

Abstract (from CDS):

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 Pab= 0.748 days. With this measurement, we revisit the inverse correlation between 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 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_RRL= 36.6+2.5–2.4 and 37.7+2.7–2.7 kpc; assuming [Fe/H] = -2.257 dex, we find dBHB= 34.4 ±2.6 kpc. Although no RRL were present in the Segue 3 field, we found a candidate eclipsing binary star system.

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Journal keyword(s): galaxies: dwarf - galaxies: star clusters: general - stars: distances - stars: variables: general - techniques: photometric

Simbad objects: 21

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Number of rows : 21
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1498 4
2 SDSS J021900.06+200635.2 RR* 02 19 00.0607839360 +20 06 35.211049164           ~ 8 0
3 NAME Segue 2 G 02 19 16.0 +20 10 31     15.2     ~ 299 0
4 MCG-06-07-001 G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1894 1
5 NAME UMa II Galaxy G 08 51 30.0 +63 07 48     13.3     ~ 410 0
6 NAME Segue 1 G 10 07 03.2 +16 04 25     15.3     ~ 517 1
7 Z 64-73 G 10 08 28.12 +12 18 23.4   11.3 10.0     ~ 1284 1
8 NAME Sextans dSph LSB 10 13 02.9 -01 36 53   12 10.4     ~ 921 0
9 NAME UMa I Galaxy G 10 34 52.80 +51 55 12.0     14.4     ~ 355 1
10 Z 126-111 G 11 13 28.13 +22 09 10.1   12.9 12.0     ~ 899 0
11 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
12 NAME Coma Dwarf Galaxy G 12 26 59.0 +23 54 15     14.1     ~ 482 1
13 NAME CVn II dSph G 12 57 09.6 +34 19 12     16.1     ~ 287 2
14 NAME CVn I dSph G 13 28 03.5 +33 33 21     13.1     ~ 352 1
15 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2593 0
16 NAME Bootes Dwarf Spheroidal Galaxy G 14 00 00.0 +14 30 00     12.8     ~ 491 0
17 Z 318-18 G 15 09 08.0 +67 13 21   13.60 10.6     ~ 1459 0
18 NAME Hercules Dwarf Galaxy G 16 31 02.0 +12 47 30     14.0     ~ 379 1
19 M 13 GlC 16 41 41.634 +36 27 40.75     5.8     ~ 2291 0
20 Z 300-12 G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1428 1
21 NAME Segue 3 Cl* 21 21 31.0 +19 07 02           ~ 75 0

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