SPITZER SAGE SURVEY OF THE LARGE MAGELLANIC CLOUD. III. STAR FORMATION AND ∼1000 NEW CANDIDATE YOUNG STELLAR OBJECTS-猫眼课题宝

DOI：

10.1088/0004-6256/136/1/18

发表时间：

2008-05

期刊：

The Astronomical Journal

影响因子：

通讯作者：

中科院分区：

其他

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作者：

B. Whitney;M. Sewiło;R. Indebetouw;T. Robitaille;M. Meixner;K. Gordon;M. Meade;B. Babler;J. Harris;J. Hora;S. Bracker;M. Povich;E. Churchwell;C. Engelbracht;B. For;M. Block;K. Misselt;U. Vijh;C. Leitherer;A. Kawamura;R. Blum;M. Cohen;Y. Fukui;A. Mizuno;N. Mizuno;S. Srinivasan;A. Tielens;K. Volk;J. Bernard;F. Boulanger;J. Frogel;J. Gallagher;V. Gorjian;D. Kelly;W. Latter;S. Madden;F. Kemper;J. Mould;A. Nota;M. Oey;K. Olsen;T. Onishi;R. Paladini;N. Panagia;P. Pérez-González;W. Reach;H. Shibai;S. Sato;Linda J. Smith;L. Staveley-Smith;T. Ueta;S. V. Dyk;M. Werner;M. Wolff;D. Zaritsky

我们提出了1000个新的候选年轻恒星对象（YSO）在大麦哲伦云从斯皮策太空望远镜的数据选择，作为调查银河系演化（SAGE）遗产计划的代理人的一部分。通过其过量的红外发射探测到的YSO代表了演化的早期阶段，仍然被圆盘和/或下落的信封包围。此前，已知的此类YSO不到20个。候选YSO是从SAGE点源目录中选择的，来自与其他IR明亮种群混淆最少的颜色-星等空间区域。YSO偏向于中等到高质量和年轻的演化阶段，因为这些阶段与星系和演化恒星在色等空间中重叠较少。YSO在空间上与原子和分子气体高度相关，并且优先位于大质量恒星内部产生的壳层和气泡中。它们比一般的点源更聚集，正如预期的那样，如果星星的形成发生在星云或壳层中。我们采用了更严格的颜色幅度选择，以产生一个子集的“高概率”的YSO候选人。我们拟合了这个子集的光谱能量分布（SED），并推导出拟合良好的那些物理特性。这些拟合良好的YSO的总质量为2900 M，总光度为2.1 × 106 L。通过用标准的初始质量函数外推质量函数并积分，我们计算出当前的恒星形成速率为0.06 M yr−1，这是基于银河系总紫外和红外通量（0.05 M yr−1）的估计值的低端，与我们目前的YSO列表不完整的预期一致。后续的光谱学和进一步的数据挖掘将更好地分离不同的IR明亮群体，并可能增加YSO的估计数量。完整的YSO清单以电子表格形式提供，SEDs以电子数字形式提供，供科学界进一步使用。

We present ∼1000 new candidate Young Stellar Objects (YSOs) in the Large Magellanic Cloud selected from Spitzer Space Telescope data, as part of the Surveying the Agents of a Galaxy's Evolution (SAGE) Legacy program. The YSOs, detected by their excess infrared (IR) emission, represent early stages of evolution, still surrounded by disks and/or infalling envelopes. Previously, fewer than 20 such YSOs were known. The candidate YSOs were selected from the SAGE Point Source Catalog from regions of color–magnitude space least confused with other IR-bright populations. The YSOs are biased toward intermediate- to high-mass and young evolutionary stages, because these overlap less with galaxies and evolved stars in color–magnitude space. The YSOs are highly correlated spatially with atomic and molecular gas, and are preferentially located in the shells and bubbles created by massive stars inside. They are more clustered than generic point sources, as expected if star formation occurs in filamentary clouds or shells. We applied a more stringent color–magnitude selection to produce a subset of “high-probability” YSO candidates. We fitted the spectral-energy distributions (SEDs) of this subset and derived physical properties for those that were well fitted. The total mass of these well-fitted YSOs is ∼2900 M☉ and the total luminosity is ∼2.1 × 106L☉. By extrapolating the mass function with a standard initial mass function and integrating, we calculate a current star-formation rate of ∼0.06 M☉ yr−1, which is at the low end of estimates based on total ultraviolet and IR flux from the galaxy (∼0.05 − 0.25 M☉ yr−1), consistent with the expectation that our current YSO list is incomplete. Follow-up spectroscopy and further data mining will better separate the different IR-bright populations and likely increase the estimated number of YSOs. The full YSO list is available as electronic tables, and the SEDs are available as an electronic figure for further use by the scientific community.

SPITZER SAGE SURVEY OF THE LARGE MAGELLANIC CLOUD. III. STAR FORMATION AND ∼1000 NEW CANDIDATE YOUNG STELLAR OBJECTS

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