Issue |
A&A
Volume 389, Number 2, July II 2002
|
|
---|---|---|
Page(s) | 367 - 373 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20020594 | |
Published online | 27 June 2002 |
Dynamical condition of neutral hydrogen envelopes of dwarf galaxies and their possible morphological evolution
Department of Astronomy, Faculty of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan e-mail: kamaya@kusastro.kyoto-u.ac.jp
Corresponding author: Y. Y. Tajiri, tajiri@kusastro.kyoto-u.ac.jp
Received:
29
August
2001
Accepted:
15
April
2002
We investigate the star-formation history of gas-rich dwarf
galaxies, taking account of the dynamical evolution of their neutral
hydrogen (Hi) envelope. Gas-rich dwarfs are classified into
blue compact dwarfs (BCDs) and dwarf irregulars (dIrrs). In this
paper, their Hi envelope is clearly shown not to be blown away
by their stellar feedback. This is concluded since the observed
star-formation rate (SFR) of gas-rich dwarfs is generally smaller than
a critical SFR, , at which stellar feedback
accelerates the Hi envelope to the escape velocity. From this
standpoint and the chemical property of sample BCDs, we suggest two
possibilities; (1) the Hi gas in the envelope of BCDs is
consumed to fuel their star-formation; and (2) BCDs have a similar
star-formation history. We also discuss morphological evolution among
dwarf galaxies. As long as gas-rich dwarfs are isolated, it is
difficult for them to evolve into dwarf ellipticals (dEs). When the
Hi envelope in gas-rich dwarfs is consumed in subsequent
star-formation, a morphological exchange between BCDs and dIrrs is
still expected, consistent with previous studies. If the SFR of
gas-rich dwarfs was much higher than
in the past,
interestingly, an evolutionary scenario from dEs to gas-rich dwarfs is
possible.
Key words: ISM: evolution / ISM: structure / stars: formation / galaxies: dwarf
© ESO, 2002
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