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Title: A New View of the Dwarf Spheroidal Satellites of the Milky Way From VLT/FLAMES: Where are the Very Metal Poor Stars?

Abstract

As part of the Dwarf galaxies Abundances and Radial-velocities Team (DART) Programme, we have measured the metallicities of a large sample of stars in four nearby dwarf spheroidal galaxies (dSph): Sculptor, Sextans, Fornax and Carina. The low mean metal abundances and the presence of very old stellar populations in these galaxies have supported the view that they are fossils from the early Universe. However, contrary to naive expectations, we find a significant lack of stars with metallicities below [Fe/H] {approx} -3 dex in all four systems. This suggests that the gas that made up the stars in these systems had been uniformly enriched prior to their formation. Furthermore, the metal-poor tail of the dSph metallicity distribution is significantly different from that of the Galactic halo. These findings show that the progenitors of nearby dSph appear to have been fundamentally different from the building blocks of the Milky Way, even at the earliest epochs.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
895480
Report Number(s):
SLAC-PUB-12212
astro-ph/0611420; TRN: US200703%%183
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article
Journal Name:
Astrophys.J.651:L121-L124,2006
Additional Journal Information:
Journal Name: Astrophys.J.651:L121-L124,2006
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DISTRIBUTION; GALAXIES; MILKY WAY; SATELLITES; STARS; UNIVERSE; Astrophysics,ASTRO

Citation Formats

Helmi, Amina, Irwin, M J, Tolstoy, E, Battaglia, G, Hill, V, Jablonka, P, Venn, K, Shetrone, M, Letarte, B, Arimoto, N, Abel, T, Francois, P, Kaufer, A, Primas, F, Sadakane, K, Szeifert, T, and /Kapteyn Astron. Inst., Groningen /Cambridge U., Inst. of Astron. /Meudon Observ. /LASTRO Observ. /Victoria U. /Texas U., McDonald Observ./Tokyo, Astron. Observ. /KIPAC, Menlo Park /European Southern Obs., Chile /European Southern Observ. /Osaka Kyoiku U. A New View of the Dwarf Spheroidal Satellites of the Milky Way From VLT/FLAMES: Where are the Very Metal Poor Stars?. United States: N. p., 2006. Web. doi:10.1086/509784.
Helmi, Amina, Irwin, M J, Tolstoy, E, Battaglia, G, Hill, V, Jablonka, P, Venn, K, Shetrone, M, Letarte, B, Arimoto, N, Abel, T, Francois, P, Kaufer, A, Primas, F, Sadakane, K, Szeifert, T, & /Kapteyn Astron. Inst., Groningen /Cambridge U., Inst. of Astron. /Meudon Observ. /LASTRO Observ. /Victoria U. /Texas U., McDonald Observ./Tokyo, Astron. Observ. /KIPAC, Menlo Park /European Southern Obs., Chile /European Southern Observ. /Osaka Kyoiku U. A New View of the Dwarf Spheroidal Satellites of the Milky Way From VLT/FLAMES: Where are the Very Metal Poor Stars?. United States. doi:10.1086/509784.
Helmi, Amina, Irwin, M J, Tolstoy, E, Battaglia, G, Hill, V, Jablonka, P, Venn, K, Shetrone, M, Letarte, B, Arimoto, N, Abel, T, Francois, P, Kaufer, A, Primas, F, Sadakane, K, Szeifert, T, and /Kapteyn Astron. Inst., Groningen /Cambridge U., Inst. of Astron. /Meudon Observ. /LASTRO Observ. /Victoria U. /Texas U., McDonald Observ./Tokyo, Astron. Observ. /KIPAC, Menlo Park /European Southern Obs., Chile /European Southern Observ. /Osaka Kyoiku U. Mon . "A New View of the Dwarf Spheroidal Satellites of the Milky Way From VLT/FLAMES: Where are the Very Metal Poor Stars?". United States. doi:10.1086/509784. https://www.osti.gov/servlets/purl/895480.
@article{osti_895480,
title = {A New View of the Dwarf Spheroidal Satellites of the Milky Way From VLT/FLAMES: Where are the Very Metal Poor Stars?},
author = {Helmi, Amina and Irwin, M J and Tolstoy, E and Battaglia, G and Hill, V and Jablonka, P and Venn, K and Shetrone, M and Letarte, B and Arimoto, N and Abel, T and Francois, P and Kaufer, A and Primas, F and Sadakane, K and Szeifert, T and /Kapteyn Astron. Inst., Groningen /Cambridge U., Inst. of Astron. /Meudon Observ. /LASTRO Observ. /Victoria U. /Texas U., McDonald Observ./Tokyo, Astron. Observ. /KIPAC, Menlo Park /European Southern Obs., Chile /European Southern Observ. /Osaka Kyoiku U.},
abstractNote = {As part of the Dwarf galaxies Abundances and Radial-velocities Team (DART) Programme, we have measured the metallicities of a large sample of stars in four nearby dwarf spheroidal galaxies (dSph): Sculptor, Sextans, Fornax and Carina. The low mean metal abundances and the presence of very old stellar populations in these galaxies have supported the view that they are fossils from the early Universe. However, contrary to naive expectations, we find a significant lack of stars with metallicities below [Fe/H] {approx} -3 dex in all four systems. This suggests that the gas that made up the stars in these systems had been uniformly enriched prior to their formation. Furthermore, the metal-poor tail of the dSph metallicity distribution is significantly different from that of the Galactic halo. These findings show that the progenitors of nearby dSph appear to have been fundamentally different from the building blocks of the Milky Way, even at the earliest epochs.},
doi = {10.1086/509784},
journal = {Astrophys.J.651:L121-L124,2006},
number = ,
volume = ,
place = {United States},
year = {2006},
month = {11}
}