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TriAnd and its siblings : satellites of satellites in the Milky Way halo.

Deason, A.J. and Belokurov, V. and Hamren, K.M. and Koposov, S.E. and Gilbert, K.M. and Beaton, R.L. and Dorman, C.E. and Guhathakurta, P. and Majewski, S.R. and Cunningham, E.C. (2014) 'TriAnd and its siblings : satellites of satellites in the Milky Way halo.', Monthly notices of the Royal Astronomical Society., 444 (4). pp. 3975-3985.


We explore the Triangulum–Andromeda (TriAnd) overdensity in the SPLASH (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo) and SEGUE (the Sloan Extension for Galactic Understanding and Exploration) spectroscopic surveys. Milky Way main-sequence turn-off stars in the SPLASH survey reveal that the TriAnd overdensity and the recently discovered Pan-Andromeda Archaeological Survey (PAndAS) stream share a common heliocentric distance (D ∼ 20 kpc), position on the sky, and line-of-sight velocity (VGSR ∼ 50 km s−1). Similarly, A-type, giant, and main-sequence turn-off stars selected from the SEGUE survey in the vicinity of the Segue 2 satellite show that TriAnd is prevalent in these fields, with a velocity and distance similar to Segue 2. The coincidence of the PAndAS stream and Segue 2 satellite in positional and velocity space to TriAnd suggests that these substructures are all associated, and may be a fossil record of group-infall on to the Milky Way halo. In this scenario, the Segue 2 satellite and PAndAS stream are ‘satellites of satellites’, and the large, metal-rich TriAnd overdensity is the remains of the group central.

Item Type:Article
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Publisher statement:© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
Date accepted:25 August 2014
Date deposited:18 January 2019
Date of first online publication:18 September 2014
Date first made open access:No date available

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