Dynamical condition of neutral hydrogen envelopes of dwarf galaxies and their possible morphological evolution
Dynamical condition of neutral hydrogen envelopes of dwarf galaxies and their possible morphological evolution
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矮星系中性氢包层的动力学条件及其可能的形态演化
DOI：
10.1051/0004-6361:20020594
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
H. Kamaya
中科院分区：
文献类型：
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作者：
Y. Y. Tajiri;H. Kamaya
我们研究了富气体矮星系的恒星形成历史，考虑了它们的中性氢（H{\sc i}）包层的动力学演化.富气矮星分为蓝致密矮星（BCD）和矮不规则矮星（dIrrs）。在本文中，他们的H{\sc i}包络清楚地表明，不会被吹走他们的恒星反馈。这是因为观测到的富含气体的矮星的恒星形成率（SFR）通常小于临界SFR，$\psi_{\rm crit}$，在该临界SFR下，恒星反馈将H{\sc i}包线加速到逃逸速度。从这个观点和样品BCD的化学性质，我们提出了两种可能性：（1）BCD包层中的H{\sc i}气体被消耗以促进其恒星形成;（2）BCD具有类似的恒星形成历史。我们还讨论了矮星系之间的形态演化。只要富含气体的矮星是孤立的，它们就很难演化成矮椭圆星系（dEs）。当富含气体的矮星中的H{\sc i}包层在随后的恒星形成中被消耗时，仍然可以预期BCD和dIrrs之间的形态交换，这与以前的研究一致。有趣的是，如果富气矮星的SFR在过去远高于$\psi_{\rm crit}$，那么从dEs到富气矮星的演化情景是可能的。
We investigate the star-formation history of gas-rich dwarf galaxies, taking account of the dynamical evolution of their neutral hydrogen (H{\sc i}) envelope. Gas-rich dwarfs are classified into blue compact dwarfs (BCDs) and dwarf irregulars (dIrrs). In this paper, their H{\sc i} 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, $\psi_{\rm crit}$, at which stellar feedback accelerates the H{\sc i} envelope to the escape velocity. From this standpoint and the chemical property of sample BCDs, we suggest two possibilities; (1) The H{\sc i} 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 H{\sc i} 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 $\psi_{\rm crit}$ in the past, interestingly, an evolutionary scenario from dEs to gas-rich dwarfs is possible.