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Title: CHEMICAL SIGNATURE INDICATING A LACK OF MASSIVE STARS IN DWARF GALAXIES

Abstract

Growing evidence supports an unusual elemental feature appearing in nearby dwarf galaxies, especially dwarf spheroidals (dSphs), indicating a key process of galaxy evolution that is different from that of the Galaxy. In addition to the well-known deficiency of {alpha}-elements in dSphs, recent observations have clearly shown that s-process elements (Ba) are significantly enhanced relative to Fe, {alpha}-, and r-process elements. This enhancement occurs in some dSphs as well as in the Large Magellanic Cloud, but is unseen in the Galaxy. Here we report that this feature is evidence of the lack of very massive stars ({approx}>25 M{sub sun}) as predicted in the low star formation rate environment. We conclude that the unique elemental feature of dwarf galaxies including a low {alpha}/Fe ratio in some low-metallicity stars is, at least in some part, characterized by a different form of the initial mass function. We present a detailed model for the Fornax dSph galaxy and discuss its complex chemical enrichment history together with the nucleosynthesis site of the light s-process element Y.

Authors:
 [1]
  1. National Astronomical Observatory of Japan, Mitaka-shi, Tokyo 181-8588 (Japan)
Publication Date:
OSTI Identifier:
21578250
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 736; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/736/2/113; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BARIUM; ELEMENT ABUNDANCE; IRON; MAGELLANIC CLOUDS; MASS; R PROCESS; S PROCESS; STARS; ABUNDANCE; ALKALINE EARTH METALS; ELEMENTS; EVOLUTION; GALAXIES; METALS; STAR EVOLUTION; TRANSITION ELEMENTS

Citation Formats

Tsujimoto, Takuji, E-mail: taku.tsujimoto@nao.ac.jp. CHEMICAL SIGNATURE INDICATING A LACK OF MASSIVE STARS IN DWARF GALAXIES. United States: N. p., 2011. Web. doi:10.1088/0004-637X/736/2/113.
Tsujimoto, Takuji, E-mail: taku.tsujimoto@nao.ac.jp. CHEMICAL SIGNATURE INDICATING A LACK OF MASSIVE STARS IN DWARF GALAXIES. United States. doi:10.1088/0004-637X/736/2/113.
Tsujimoto, Takuji, E-mail: taku.tsujimoto@nao.ac.jp. Mon . "CHEMICAL SIGNATURE INDICATING A LACK OF MASSIVE STARS IN DWARF GALAXIES". United States. doi:10.1088/0004-637X/736/2/113.
@article{osti_21578250,
title = {CHEMICAL SIGNATURE INDICATING A LACK OF MASSIVE STARS IN DWARF GALAXIES},
author = {Tsujimoto, Takuji, E-mail: taku.tsujimoto@nao.ac.jp},
abstractNote = {Growing evidence supports an unusual elemental feature appearing in nearby dwarf galaxies, especially dwarf spheroidals (dSphs), indicating a key process of galaxy evolution that is different from that of the Galaxy. In addition to the well-known deficiency of {alpha}-elements in dSphs, recent observations have clearly shown that s-process elements (Ba) are significantly enhanced relative to Fe, {alpha}-, and r-process elements. This enhancement occurs in some dSphs as well as in the Large Magellanic Cloud, but is unseen in the Galaxy. Here we report that this feature is evidence of the lack of very massive stars ({approx}>25 M{sub sun}) as predicted in the low star formation rate environment. We conclude that the unique elemental feature of dwarf galaxies including a low {alpha}/Fe ratio in some low-metallicity stars is, at least in some part, characterized by a different form of the initial mass function. We present a detailed model for the Fornax dSph galaxy and discuss its complex chemical enrichment history together with the nucleosynthesis site of the light s-process element Y.},
doi = {10.1088/0004-637X/736/2/113},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 736,
place = {United States},
year = {2011},
month = {8}
}