arXiv 1108.40442011-08-19astro-ph.CO

M31中HII区域的新目录

A New Catalog of HII Regions in M31

Mohaddesseh Azimlu, Ryan Marciniak, Pauline Barmby

备注：: accepted to be published at AJ
DOI：: 10.1088/0004-6256/142/4/139

摘要：

我们提出了一个新的目录中的M31的HII区。作为本星系群巡天的一部分，马赛克照相机观测到的10个视场的2.2度^2马赛克覆盖了整个星系盘。我们使用HIIphot，一个代码的HII区域的自动测光，以确定区域和测量其通量和大小。10 σ探测水平用于排除扩散气体波动和连续扣除后的恒星残留。这种选择限制可能会导致一些微弱的HII区被遗漏，但我们的3691个HII区的星表仍然是完整的，亮度为LHα = 10^34 erg/s。这是之前唯一一次基于CCD的研究的五倍，该研究在M31的东北半部分包含967个物体。我们通过对大于LHα = 10 ^36.7的光度拟合幂律来确定Hα光度函数（LF），并确定斜率为2.52 \pm 0.07。臂内和臂间LF在不同的光度下达到峰值，但它们具有相似的亮端斜率。臂间区域较少（占总探测区域的40%），仅占LHα = 5.6 /× 10^40 erg/s总光度的14%（经过消光校正，并考虑到扩散电离气体的65%贡献）。根据Hα的总光度估算出的恒星形成速率为0.44 M \odot /yr;这个数值与斯皮策8 μm图像的测定结果一致。我们排除了所有已知的和潜在的行星状星云，但我们发现了一个双峰光度函数。臂间较老的人口表明1500万至2000万年前的恒星爆发。这一结果与对M31恒星形成历史的紫外线研究一致，后者发现恒星形成速率在最近的过去有所下降。我们发现，在选定的恒星形成区的HII区域和星团之间的一个公平的空间相关性。大多数匹配区域位于臂区域内。

英文摘要：

We present a new catalog of HII regions in M31. The full disk of the galaxy is covered in a 2.2 deg^2 mosaic of 10 fields observed with the Mosaic Camera as part of the Local Group Galaxies survey. We used HIIphot, a code for automated photometry of HII regions, to identify the regions and measure their fluxes and sizes. A 10 σ detection level was used to exclude diffuse gas fluctuations and star residuals after continuum subtraction. That selection limit may result in missing some faint HII regions, but our catalog of 3691 HII regions is still complete to a luminosity of LHα = 10^34 erg/s. This is five times fainter than the only previous CCD-based study which contained 967 objects in the NE half of M31. We determined the Hα luminosity function (LF) by fitting a power law to luminosities larger than LHα = 10^36.7 and determined a slope of 2.52\pm0.07. The in-arm and inter-arm LFs peak at different luminosities but they have similar bright-end slopes. The inter- arm regions are less populated (40% of total detected regions) and constitute only 14% of the total luminosity of LHα = 5.6 /times 10^40 erg/s (after extinction correction and considering 65% contribution from diffused ionized gas). A star formation rate of 0.44 M\odot/yr was estimated from the Hα total luminosity; this value is consistent with the determination from the Spitzer 8 μm image. We removed all known and potential planetary nebulae, yet we found a double peaked luminosity function. The inter-arm older population suggests a starburst between 15 and 20 million years ago. This result is in agreement with UV studies of the star formation history in M31 which found a star formation rate decrease in the recent past. We found a fair spatial correlation between the HII regions and stellar clusters in selected star forming regions. Most of the matched regions lie within the arm regions.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文