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Title: THE SPLASH SURVEY: A SPECTROSCOPIC PORTRAIT OF ANDROMEDA'S GIANT SOUTHERN STREAM

Abstract

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 approx 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 approx 21 kpc. The velocity gradients of the GSS and the second component in the combined data set are parallel over a range of DELTAR = 7more » 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 approx 58 kpc). Using kinematically identified samples, we show that the envelope debris has a approx0.7 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 approx10 and approx4 km s{sup -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.« less

Authors:
 [1]; ; ; ;  [2]; ; ;  [3]
  1. Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States)
  2. UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)
  3. Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
Publication Date:
OSTI Identifier:
21378332
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 705; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/705/2/1275; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BIFURCATION; BRIGHTNESS; CHEMICAL PROPERTIES; GALAXIES; MAPS; ORBITS; RED GIANT STARS; SATELLITES; SPECTROSCOPY; TELESCOPES; VELOCITY; GIANT STARS; OPTICAL PROPERTIES; PHYSICAL PROPERTIES; STARS

Citation Formats

Gilbert, Karoline M, Guhathakurta, Puragra, Kollipara, Priya, Kalirai, Jason S, Kirby, Evan N, Beaton, Rachael L, Majewski, Steven R, Patterson, Richard J, and Geha, Marla C., E-mail: kgilbert@astro.washington.ed. THE SPLASH SURVEY: A SPECTROSCOPIC PORTRAIT OF ANDROMEDA'S GIANT SOUTHERN STREAM. United States: N. p., 2009. Web. doi:10.1088/0004-637X/705/2/1275.
Gilbert, Karoline M, Guhathakurta, Puragra, Kollipara, Priya, Kalirai, Jason S, Kirby, Evan N, Beaton, Rachael L, Majewski, Steven R, Patterson, Richard J, & Geha, Marla C., E-mail: kgilbert@astro.washington.ed. THE SPLASH SURVEY: A SPECTROSCOPIC PORTRAIT OF ANDROMEDA'S GIANT SOUTHERN STREAM. United States. https://doi.org/10.1088/0004-637X/705/2/1275
Gilbert, Karoline M, Guhathakurta, Puragra, Kollipara, Priya, Kalirai, Jason S, Kirby, Evan N, Beaton, Rachael L, Majewski, Steven R, Patterson, Richard J, and Geha, Marla C., E-mail: kgilbert@astro.washington.ed. 2009. "THE SPLASH SURVEY: A SPECTROSCOPIC PORTRAIT OF ANDROMEDA'S GIANT SOUTHERN STREAM". United States. https://doi.org/10.1088/0004-637X/705/2/1275.
@article{osti_21378332,
title = {THE SPLASH SURVEY: A SPECTROSCOPIC PORTRAIT OF ANDROMEDA'S GIANT SOUTHERN STREAM},
author = {Gilbert, Karoline M and Guhathakurta, Puragra and Kollipara, Priya and Kalirai, Jason S and Kirby, Evan N and Beaton, Rachael L and Majewski, Steven R and Patterson, Richard J and Geha, Marla C., E-mail: kgilbert@astro.washington.ed},
abstractNote = {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 approx 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 approx 21 kpc. The velocity gradients of the GSS and the second component in the combined data set are parallel over a range of DELTAR = 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 approx 58 kpc). Using kinematically identified samples, we show that the envelope debris has a approx0.7 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 approx10 and approx4 km s{sup -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.},
doi = {10.1088/0004-637X/705/2/1275},
url = {https://www.osti.gov/biblio/21378332}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 705,
place = {United States},
year = {Tue Nov 10 00:00:00 EST 2009},
month = {Tue Nov 10 00:00:00 EST 2009}
}