Juna A. Kollmeier et al 2009 ApJ 705 L158 doi:10.1088/0004-637X/705/2/L158
Juna A. Kollmeier1, Andrew Gould2, Stephen Shectman1, Ian B. Thompson1, George W. Preston1, Joshua D. Simon1, Jeffrey D. Crane1, Željko Ivezić3 and Branimir Sesar3
Show affiliationsWe present spectroscopic confirmation of the "Pisces Overdensity," also known as "Structure J," a photometric overdensity of RR Lyrae stars discovered by the Sloan Digital Sky Survey at an estimated photometric distance of ~85 kpc. We measure radial velocities for eight RR Lyrae stars within Pisces. We find that five of the eight stars have heliocentric radial velocities within a narrow range of –87 km s-1 < vr < –67 km s-1, suggesting that the photometric overdensity is mainly due to a physically associated system, probably a dwarf galaxy or a disrupted galaxy. Two of the remaining three stars differ from one another by only 9 km s–1, but it would be premature to identify them as a second system.
galaxies: dwarf; Galaxy: halo; Galaxy: structure; stars: individual (RR Lyrae)
95.75.Fg Spectroscopy and spectrophotometry
95.75.De Photography and photometry (including microlensing techniques)
97.10.Wn Proper motions and radial velocities (line-of-sight velocities); space motions
95.80.+p Astronomical catalogs, atlases, sky surveys, databases, retrieval systems, archives, etc.
98.52.Wz Dwarf galaxies (elliptical, irregular, and spheroidal)
97.30.Kn RR Lyrae stars; RV Tauri and PV Telescopii variables
Issue 2 (2009 November 10)
Received 2009 August 11, accepted for publication 2009 October 6
Published 2009 October 21
Juna A. Kollmeier et al 2009 ApJ 705 L158
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