The Stellar Population of the M31 Spiral Arm around OB Association A24
The Stellar Population of the M31 Spiral Arm around OB Association A24
复制标题
OB 协会 A24 周围 M31 旋臂的恒星群
DOI：
10.1086/307361
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
S. Miyazaki
中科院分区：
文献类型：
--
作者：
K. Kodaira;V. Vansevičius;M. Tamura;S. Miyazaki
根据深V和JHK成像获得的光度数据，对OB星协A24周围M31旋臂的恒星星族进行了研究。通过应用对应于AV = 1的消光校正和作为（J-K）0的经验函数的测热校正BCK，获得了-7 Mbol <$-3.5的光度函数。通过比较观测到的色-光度图和根据尘埃壳效应修正的半理论等时线，我们发现了t = 3000万年的年轻星群中有Mbol-5超巨星，t = 0.2-2.5 Gyr的大部分中间星群中有明亮的渐近巨星分支（AGB）-5 Mbol-4，和老的t-13 Gyr星群，其中有AGB星和Mbol-4的红巨星分支（RGB）星。根据MV = -4.0（年龄~ 1000万年）附近的B 0 V星的数量密度和Mbol = -4.3（年龄~ 1Gyr）附近的明亮AGB星的数量密度，估计每1 kpc 2的反投影星盘面积的平均星星形成率分别为~ 1.8 × 104 m2/Myr-1和~ 0.7 × 104 m2/Myr-1。对V、J和H光度函数的局部变化的研究表明，在~ 100 pc尺度的子域中，年轻组分的布居与中间年龄组分的布居之间存在一种近似关系。这一发现表明，围绕A24区的盘域经历了一系列的星星形成事件，交替在不同的子域与几个螺旋通道周期的时间尺度。简要讨论了星际消光和明亮的AGB星和同一区域的高红色物体的寿命。
A study of the stellar population of the M31 spiral arm around OB association A24 was carried out based on the photometric data obtained from deep V and JHK imaging. The luminosity function was obtained for -7 ≲ Mbol ≲ -3.5 by applying the extinction correction corresponding to AV = 1 and the bolometric correction BCK as an empirical function of (J - K)0. In comparing the observed color-luminosity diagrams with semitheoretical isochrones modified for the dust-shell effects, we found the young population of t ≲ 30 Myr with supergiants of Mbol ≲ -5, the bulk of the intermediate-age population of t ~ 0.2-2.5 Gyr with bright asymptotic giant branch (AGB) stars of -5 ≲ Mbol ≲ -4, and old populations of t ≳ 3 Gyr with AGB and red giant branch (RGB) stars of Mbol ≳ -4. The average star formation rate was estimated to be ~ 1.8 × 104 m☉ Myr-1 and ~ 0.7 × 104 m☉ Myr-1 per deprojected disk area of 1 kpc2 from the number density of B0 V stars around MV = -4.0 (age ~ 10 Myr) and the number density of bright AGB stars around Mbol = -4.3 (age ~ 1 Gyr), respectively. A study of the local variation in the V and the J and H luminosity functions revealed a kind of anticorrelation between the population of the young component and that of the intermediate-age component when subdomains of ~ 100 pc scales were concerned. This finding suggests that the disk domain around the A24 area experienced a series of star formation episodes alternatively among different subdomains with a timescale of several spiral passage periods. Brief discussions are given about the interstellar extinction and about the lifetimes of bright AGB stars and the highly red objects in the same area.