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arXiv · 0908.1381

Spectroscopic Confirmation of the Pisces Overdensity

Juna A. Kollmeier·Andrew Gould·Stephen Shectman·Ian B. Thompson·George W. Preston·Joshua D. Simon·Jeffrey D. Crane·Željko Ivezić·Branimir Sesar
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Abstract

We 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 (SDSS) at an estimated photometric distance of ~85kpc. We measure radial velocities for 8 RR Lyrae stars within Pisces. We find that 5 of the 8 stars have heliocentric radial velocities within a narrow range of -87 km/s < v < -67 km/s, 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 3 stars differ from one another by only 9 km/s, but it would be premature to identify them as a second system.

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Juna A. Kollmeier, Andrew Gould, Stephen Shectman, Ian B. Thompson, George W. Preston, Joshua D. Simon, Jeffrey D. Crane, Željko Ivezić, Branimir Sesar. 2009-08-11. Spectroscopic Confirmation of the Pisces Overdensity. https://doi.org/10.1088/0004-637x/705/2/l158

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