Massive Stars in the Arches Cluster
Massive Stars in the Arches Cluster
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DOI：
10.1086/344154
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发表时间：
2002-08
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通讯作者：
D. Figer;F. Najarro;D. Gilmore;M. Morris;Sungsoo S. Kim;E. Serabyn;I. McLean;A. Gilbert;J. Graham;J. Larkin;N. Levenson;H. Teplitz
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作者：
D. Figer;F. Najarro;D. Gilmore;M. Morris;Sungsoo S. Kim;E. Serabyn;I. McLean;A. Gilbert;J. Graham;J. Larkin;N. Levenson;H. Teplitz
我们展示并使用拱门星团中恒星的新光谱和窄带图像以及之前发布的宽带图像来提取光度、天体测量、等效宽度和速度信息。这些数据用风/大气代码进行解释，以确定恒星的温度、光度、质量损失率和丰度。我们已经将已知发射线恒星的数量增加了一倍，并且我们还首次对银河系中心任何星群的主序进行了光谱识别。我们得出的结论是，最大质量的恒星是真正的沃尔夫-拉叶（W-R）恒星；是已知质量最大的恒星之一，Minit > 100 M☉；并且有巨大的风，Ṁ > 10-5 M☉ yr-1，富含氦气和氮气；通过这些鉴定，拱门星团包含了银河系中所有已知 W-R 恒星的大约 5%。我们发现速度弥散的上限为 22 km s-1，这意味着 0.23 pc 半径内星团质量的上限为 7 × 104 M☉；我们还估计星团的整体日心速度为 vcluster, ☉ ≈ +95 km s-1。总而言之，这些结果表明，拱门星团是在大约 2.5 ± 0.5 Myr 前的一次短暂但大规模的恒星形成爆发中形成的，由不再存在的分子云形成。该簇恰好接近并电离背景分子云的表面，从而产生热拱形细丝。我们估计该星团产生 4 × 1051 个电离光子 s-1，足以解释观测到的来自附近云团的热射电通量，即 3 × 1049 个电离光子 s-1。相应地，它产生 107.8 L☉ 的总光度，为附近的分子云提供热源，Lcloud ≈ 107 L☉。热恒星团和任性的分子云之间的这些相互作用类似于在“五重态/镰刀”区域中看到的相互作用。银河系中心已知年轻星团的形成时间分布较小，并且相对缺乏中龄恒星（τage = 107.0-107.3 年），这表明银河系中心最近爆发了恒星形成。最后，我们对近红外源进行了新的鉴定，这些近红外源与最近鉴定的 X 射线和无线电源相对应。
We present and use new spectra and narrowband images, along with previously published broadband images, of stars in the Arches cluster to extract photometry, astrometry, equivalent width, and velocity information. The data are interpreted with a wind/atmosphere code to determine stellar temperatures, luminosities, mass-loss rates, and abundances. We have doubled the number of known emission-line stars, and we have also made the first spectroscopic identification of the main sequence for any population in the Galactic center. We conclude that the most massive stars are bona fide Wolf-Rayet (W-R) stars; are some of the most massive stars known, having Minit > 100 M☉; and have prodigious winds, Ṁ > 10-5 M☉ yr-1, that are enriched with helium and nitrogen; with these identifications, the Arches cluster contains about 5% of all known W-R stars in the Galaxy. We find an upper limit to the velocity dispersion of 22 km s-1, implying an upper limit to the cluster mass of 7 × 104 M☉ within a radius of 0.23 pc; we also estimate the bulk heliocentric velocity of the cluster to be vcluster, ☉ ≈ +95 km s-1. Taken together, these results suggest that the Arches cluster was formed in a short, but massive, burst of star formation about 2.5 ± 0.5 Myr ago, from a molecular cloud that is no longer present. The cluster happens to be approaching and ionizing the surface of a background molecular cloud, thus producing the thermal arched filaments. We estimate that the cluster produces 4 × 1051 ionizing photons s-1, more than enough to account for the observed thermal radio flux from the nearby cloud, 3 × 1049 ionizing photons s-1. Commensurately, it produces 107.8 L☉ in total luminosity, providing the heating source for the nearby molecular cloud, Lcloud ≈ 107 L☉. These interactions between a cluster of hot stars and a wayward molecular cloud are similar to those seen in the "Quintuplet/Sickle" region. The small spread of formation times for the known young clusters in the Galactic center and the relative lack of intermediate-age stars (τage = 107.0-107.3 yr) suggest that the Galactic center has recently been host to a burst of star formation. Finally, we have made new identifications of near-infrared sources that are counterparts to recently identified X-ray and radio sources.