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تسجيل مستخدم جديدSpectroscopic Confirmation of the Pisces Overdensity
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Juna A. Kollmeier
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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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