A View of the M81 Galaxy Group via the Hα Window
A View of the M81 Galaxy Group via the Hα Window
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通过 Hα 窗口看到的 M81 星系群
DOI：
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发表时间：
2007
期刊：
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通讯作者：
S. Kaisin
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文献类型：
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作者：
I. Karachentsev;S. Kaisin
我们展示了在 Hα 线中获得的 M81 群 36 个星系的图像。现在可以对该组中所有已知成员的 Hα 通量和恒星形成率 (SFR) 进行估计，其绝对星等低至 MB = -10 星等。星系在MB、恒星形成率和总氢质量这三个参数上的分布特征，使我们能够就该族群的演化状况得出以下结论：（1）螺旋型和不规则型星系在宇宙学时间T0 = 13.7 Gyr期间有时间产生光度（重子质量），但矮球体天体只能复制~5% 他们观测到的光度。 (2) S 和 Im/蓝致密矮星 (BCD) 星系拥有的气体供应足以仅在下一个 T0 年维持其观测到的恒星形成率，而 dIrr 和 dSph 星系群的平均气体耗尽时间约为 3T0。 (3) 有间接证据表明，Im/BCD 和 dIrr 星系中的恒星形成是以剧烈爆发活动的方式进行的，而不是以缓慢过程的形式进行的。我们注意到，NGC 3077 附近的矮潮汐系统 Garland 在 150 个已知恒星形成率的本地体积星系中具有最高的单位光度恒星形成率。对 M81 周围直径为 4 Mpc 的局部“同质细胞”进行平均，该群的恒星形成速率 SFR = 0.165 M⊙ yr-1 Mpc-3，被证明比 z = 0 时的平均全球速率高 5-8 倍。
We present images for 36 galaxies of the M81 Group obtained in the Hα line. Estimates of the Hα flux and star formation rate (SFR) are now available for all the known members of the group with absolute magnitudes down to MB = -10 mag. The character of distribution of the galaxies over three parameters, MB, SFR, and total hydrogen mass, permits us to draw the following conclusions as to the evolutionary status of the group population: (1) Spiral and irregular-type galaxies have time to generate their luminosity (baryon mass) during the cosmological time T0 = 13.7 Gyr, but dwarf spheroidal objects are capable of reproducing only ∼5% of their observed luminosity. (2) S and Im/blue compact dwarf (BCD) galaxies possess a supply of gas sufficient to maintain their observed SFRs only during the next T0 yr, while dIrr and dSph populations have a mean gas depletion time of about 3T0. (3) There is indirect evidence that the star formation in Im/BCD and dIrr galaxies proceeds in a mode of vigorous burst activity rather than in the form of a sluggish process. We note that the dwarf tidal system near NGC 3077, the Garland, has the highest SFR per unit luminosity among 150 galaxies of the Local Volume with known SFRs. Being averaged over the local "cell of homogeneity" of 4 Mpc in diameter around M81, the rate of star formation of the group, SFR = 0.165 M⊙ yr-1 Mpc-3, proves to be 5-8 times higher than the average global rate at z = 0.