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首页> 外文期刊>The Astrophysical journal >Star formation history and extinction in the central kiloparsec of M82-like starbursts
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Star formation history and extinction in the central kiloparsec of M82-like starbursts

机译：M82状星暴中心千分秒的恒星形成历史和灭绝

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We report on the star formation histories and extinction in the central kiloparsec region of a sample of starburst galaxies that have similar far-infrared (FIR), 10 mum, and K-band luminosities as those of the archetype starburst M82. Our study is based on new optical spectra and previously published K-band photometric data, both sampling the same area around the nucleus. Model starburst spectra were synthesized as a combination of stellar populations of distinct ages formed over the Hubble time and were fitted to the observed optical spectra and K-band flux. The model is able to reproduce simultaneously the equivalent widths of emission and absorption lines, the continuum fluxes between 3500 and 7000 Angstrom, and the K-band and FIR flux. A good fit requires a minimum of three populations: (1) a young population of age less than or equal to 8Myr, with its corresponding nebular emission, ( 2) an intermediate-age population ( age < 500 Myr), and ( 3) an old population that forms part of the underlying disk or/and bulge population. The birthrate parameter, which is defined as the ratio of the current star formation rate to the average past rate, is found to be in the range 1 - 12. The contribution of the old population to the K-band luminosity depends on the birthrate parameter and remains above 60% in the majority of the sample galaxies. Even in the blue band, the intermediate-age and old populations contribute more than 40% of the total flux in all the cases. A relatively high contribution from the old stars to the K-band nuclear flux is also apparent from the strength of the 4000 &ANGS; break and the Ca II K line. The extinction of the old population is found to be around half that of the young population. The contribution to the continuum from the relatively old stars has the effect of diluting the emission equivalent widths below the values expected for young bursts. The mean dilution factors are found to be 5 and 3 for the Hα and Hβ lines, respectively. [References: 44]
机译：我们报告了一个星爆星系样本的恒星形成历史和灭绝，该星爆星系样本具有与原型M82相似的远红外（FIR），10毫米和K波段光度。我们的研究基于新的光谱和先前发布的K波段光度数据，均采样了围绕核的相同区域。合成的模型星暴光谱是在哈勃时间内形成的不同年龄的恒星种群的组合，并与观测到的光谱和K波段通量拟合。该模型能够同时再现发射和吸收线的等效宽度，3500至7000埃之间的连续通量以及K波段和FIR通量。一个合适的人至少需要三个人口：（1）年龄小于或等于8Myr的年轻人口，并伴有相应的星状体放射;（2）中年人口（年龄<500 Myr）;和（3）构成基础磁盘或/和凸起种群一部分的旧种群。出生率参数定义为当前恒星形成率与过去平均平均率之比，范围为1-12。老年人群对K波段光度的贡献取决于出生率参数并在大多数样本星系中保持在60％以上。即使在蓝带中，在所有情况下，中年人和老年人口仍占总通量的40％以上。从4000埃的强度还可以明显地看出，老恒星对K波段核通量的贡献较高。突破和Ca II K线。发现老年人口的灭绝大约是年轻人口的一半。相对老的恒星对连续体的贡献具有将发射当量宽度稀释到低于年轻爆发预期值的作用。对于Hα和Hβ系，发现平均稀释因子分别为5和3。 [参考：44]

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