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The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, II, III, VII, X, and XIV Dwarf Spheroidal Galaxies

Kalirai, Jason S. and Beaton, Rachael L. and Geha, Marla C. and Gilbert, Karoline M. and Guhathakurta, Puragra and Kirby, Evan N. and Majewski, Steven R. and Ostheimer, James C. and Patterson, Richard J. and Wolf, Joe (2010) The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, II, III, VII, X, and XIV Dwarf Spheroidal Galaxies. Astrophysical Journal, 711 (2). pp. 671-692. ISSN 0004-637X.

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We present new Keck/DEIMOS spectroscopic observations of hundreds of individual stars along the sightline to the first three of the Andromeda (M31) dwarf spheroidal (dSph) galaxies to be discovered, And I, II, and III, and combine them with recent spectroscopic studies by our team of three additional M31 dSphs, And VII, X, and XIV, as a part of the SPLASH Survey (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo). Member stars of each dSph are isolated from foreground Milky Way dwarf stars and M31 field contamination using a variety of photometric and spectroscopic diagnostics. Our final spectroscopic sample of member stars in each dSph, for which we measure accurate radial velocities with a median uncertainty (random plus systematic errors) of 4-5 km s^(–1), includes 80 red giants in And I, 95 in And II, 43 in And III, 18 in And VII, 22 in And X, and 38 in And XIV. The sample of confirmed members in the six dSphs is used to derive each system's mean radial velocity, intrinsic central velocity dispersion, mean abundance, abundance spread, and dynamical mass. This combined data set presents us with a unique opportunity to perform the first systematic comparison of the global properties (e.g., metallicities, sizes, and dark matter masses) of one-third of Andromeda's total known dSph population with Milky Way counterparts of the same luminosity. Our overall comparisons indicate that the family of dSphs in these two hosts have both similarities and differences. For example, we find that the luminosity-metallicity relation is very similar between L ~ 10^5 and 10^7 L_☉, suggesting that the chemical evolution histories of each group of dSphs are similar. The lowest luminosity M31 dSphs appear to deviate from the relation, possibly suggesting tidal stripping. Previous observations have noted that the sizes of M31's brightest dSphs are systematically larger than Milky Way satellites of similar luminosity. At lower luminosities between L = 10^4 and 10^6 L_☉, we find that the sizes of dSphs in the two hosts significantly overlap and that four of the faintest M31 dSphs are smaller than Milky Way counterparts. The first dynamical mass measurements of six M31 dSphs over a large range in luminosity indicate similar mass-to-light ratios compared to Milky Way dSphs among the brighter satellites, and smaller mass-to-light ratios among the fainter satellites. Combined with their similar or larger sizes at these luminosities, these results hint that the M31 dSphs are systematically less dense than Milky Way dSphs. The implications of these similarities and differences for general understanding of galaxy formation and evolution are summarized.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Kalirai, Jason S.0000-0001-9690-4159
Beaton, Rachael L.0000-0002-1691-8217
Geha, Marla C.0000-0002-7007-9725
Gilbert, Karoline M.0000-0003-0394-8377
Guhathakurta, Puragra0000-0001-8867-4234
Kirby, Evan N.0000-0001-6196-5162
Majewski, Steven R.0000-0003-2025-3147
Alternate Title:The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, II, III, VII, X, and XIV dSphs
Additional Information:© 2010 The American Astronomical Society. Issue 2 (2010 March 10); received 2009 November 11, accepted for publication 2010 January 21; published 2010 February 17. We thank Eva Grebel, Steve Vogt, and Dan Zucker for their valuable contribution to the And VII and X observations. J.S.K.’s research is supported in part by a grant from the STScI Director’s Discretionary Research Fund, and 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. This project was also supported by NSF grants AST-0307966, AST-0507483, AST-0607852, and AST-0808133 and NASA/STScI grant GO-10265.02 (J.S.K., P.G., K.M.G., and E.N.K.), an NSF Graduate Fellowship (K.M.G.), a Hubble Fellowship grant (HST-HF-01233.01) awarded by STScI (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.).
Group:SPLASH, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Space Telescope Science InstituteUNSPECIFIED
NASA Hubble FellowshipHF-01185.01-A
NSF Graduate Research FellowshipUNSPECIFIED
NASA Hubble FellowshipHST-HF-01233.01
David and Lucile Packard FoundationUNSPECIFIED
Peninsula Community FoundationUNSPECIFIED
Subject Keywords:dark matter; galaxies: abundances; galaxies: dwarf; galaxies: individual (And I, And I, And I, And I, And I, And II, And II, And II, And II, And II, And III, And III, And III, And III, And III, And VII, And VII, And VII, And VII, And VII, And X, And X, And X, And X, And X, And XIV, And XIV, And XIV, And XIV, And XIV); techniques: photometric; techniques: spectroscopic
Issue or Number:2
Record Number:CaltechAUTHORS:20100317-113720269
Persistent URL:
Official Citation:The SPLASH Survey: Internal Kinematics, Chemical Abundances, and Masses of the Andromeda I, II, III, VII, X, and XIV Dwarf Spheroidal Galaxies Jason S. Kalirai, Rachael L. Beaton, Marla C. Geha, Karoline M. Gilbert, Puragra Guhathakurta, Evan N. Kirby, Steven R. Majewski, James C. Ostheimer, Richard J. Patterson, and Joe Wolf doi: 10.1088/0004-637X/711/2/671
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17767
Deposited By: Jason Perez
Deposited On:17 Mar 2010 20:53
Last Modified:15 Nov 2019 03:56

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