HALO VELOCITY GROUPS IN THE PISCES OVERDENSITY
- Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195-1580 (United States)
- Centro de Investigaciones de Astronomia (CIDA), Apartado Postal 264, Merida 5101-A (Venezuela, Bolivarian Republic of)
- Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg, Moenchhofstrasse 12-14, D-69120 Heidelberg (Germany)
We report spectroscopic observations of five faint (V {approx} 20) RR Lyrae stars associated with the Pisces overdensity conducted with the Gemini South Telescope. At a heliocentric and galactocentric distance of {approx}80 kpc, this is the most distant substructure in the Galactic halo known to date. We combined our observations with literature data and confirmed that the substructure is composed of two different kinematic groups. The main group contains eight stars and has (V{sub gsr}) = 50 km s{sup -1}, while the second group contains four stars at a velocity of (V{sub gsr}) = -52 km s{sup -1}, where V{sub gsr} is the radial velocity in the galactocentric standard of rest. The metallicity distribution of RR Lyrae stars in the Pisces overdensity is centered on [Fe/H] = -1.5 dex and has a width of 0.3 dex. The new data allowed us to establish that both groups are spatially extended making it very unlikely that they are bound systems, and are more likely to be debris of a tidally disrupted galaxy or galaxies. Due to small sky coverage, it is still unclear whether these groups have the same or different progenitors.
- OSTI ID:
- 21452892
- Journal Information:
- Astrophysical Journal, Vol. 717, Issue 1; Other Information: DOI: 10.1088/0004-637X/717/1/133; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
THE ORIGIN OF THE VIRGO STELLAR SUBSTRUCTURE
SPECTROSCOPIC CONFIRMATION OF THE PISCES OVERDENSITY