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The Splash Survey: A Spectroscopic Portrait of Andromeda's Giant Southern Stream

Gilbert, Karoline M. and Guhathakurta, Puragra and Kollipara, Priya and Beaton, Rachael L. and Geha, Marla C. and Kalirai, Jason S. and Kirby, Evan N. and Majewski, Steven R. and Patterson, Richard J. (2009) The Splash Survey: A Spectroscopic Portrait of Andromeda's Giant Southern Stream. Astrophysical Journal, 705 (2). pp. 1275-1297. ISSN 0004-637X.

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The giant southern stream (GSS) is the most prominent tidal debris feature in M31's stellar halo and covers a significant fraction of its southern quadrant. The GSS is a complex structure composed of a relatively metal-rich, high-surface-brightness "core" and a lower metallicity, lower-surface-brightness "envelope." We present spectroscopy of red giant stars in six fields in the vicinity of M31's GSS (including four new fields and improved spectroscopic reductions for two previously published fields) and one field on stream C, an arc-like feature seen in star-count maps on M31's southeast minor axis at R ~ 60 kpc. These data are part of our ongoing Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey of M31 using the DEIMOS instrument on the Keck II 10 m telescope. Several GSS-related findings and measurements are presented here. We present the innermost kinematical detection of the GSS core to date (R = 17 kpc). This field also contains the inner continuation of a second kinematically cold component that was originally seen in a GSS core field at R ~ 21 kpc. The velocity gradients of the GSS and the second component in the combined data set are parallel over a range of ΔR = 7 kpc, suggesting that this may represent a bifurcation in the line-of-sight velocities of GSS stars. We present the first kinematical detection of substructure in the GSS envelope (S quadrant, R ~ 58 kpc). Using kinematically identified samples, we show that the envelope debris has a ~0.7 dex lower mean photometric metallicity and possibly higher intrinsic velocity dispersion than the GSS core. The GSS is also identified in the field of the M31 dwarf spheroidal satellite And I; the GSS in this field has a metallicity distribution identical to that of the GSS core. We confirm the previous finding of two kinematically cold components in stream C, and measure intrinsic velocity dispersions of ~10 and ~4 km s^(–1). This compilation of the kinematical (mean velocity, intrinsic velocity dispersion) and chemical properties of stars in the GSS core and envelope, coupled with published surface-brightness measurements and wide-area star-count maps, will improve constraints on the orbit and internal structure of the dwarf satellite progenitor.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle Paper
Gilbert, Karoline M.0000-0003-0394-8377
Guhathakurta, Puragra0000-0001-8867-4234
Beaton, Rachael L.0000-0002-1691-8217
Geha, Marla C.0000-0002-7007-9725
Kalirai, Jason S.0000-0001-9690-4159
Kirby, Evan N.0000-0001-6196-5162
Majewski, Steven R.0000-0003-2025-3147
Additional Information:© 2009 The American Astronomical Society. Received 2008 December 15; accepted 2009 September 23; published 2009 October 20. The authors thank Mark Fardal for many useful discussions. This project was supported by NSF grants AST-0307966, AST-0507483, and AST-0607852 (K.M.G., P.G., J.S.K., P.K., and E.N.K.), NSF Graduate Student Research Fellowships (K.M.G., P.K., and E.N.K.), and NSF grants AST-0307842, AST-0307851, and AST-0607726, NASA/JPL contract 1228235, the David and Lucile Packard Foundation, and The F. H. Levinson Fund of the Peninsula Community Foundation (S.R.M., R.J.P., and R.L.B.). J.S.K. was supported by NASA through Hubble Fellowship grant HF-01185.01-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.
Group:SPLASH, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
David and Lucile Packard FoundationUNSPECIFIED
Peninsula Community FoundationUNSPECIFIED
NASA Hubble FellowshipHF-01185.01-A
Space Telescope Science InstituteUNSPECIFIED
Subject Keywords:galaxies: halos; galaxies: individual (M31); stars: kinematics; techniques: spectroscopic
Issue or Number:2
Record Number:CaltechAUTHORS:20091111-093926622
Persistent URL:
Official Citation:The Splash Survey: A Spectroscopic Portrait of Andromeda's Giant Southern Stream Karoline M. Gilbert, Puragra Guhathakurta, Priya Kollipara, Rachael L. Beaton, Marla C. Geha, Jason S. Kalirai, Evan N. Kirby, Steven R. Majewski, and Richard J. Patterson 2009 ApJ 705 1275-1297 doi: 10.1088/0004-637X/705/2/1275
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16661
Deposited By: Tony Diaz
Deposited On:16 Nov 2009 17:27
Last Modified:15 Nov 2019 03:56

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