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arXiv 1606.01896astro-ph.SRastro-ph.GA
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大犬座年轻星体的WISE普查

A WISE Census of Young Stellar Objects in Canis Major

William J. Fischer, Deborah L. Padgett, Karl L. Stapelfeldt, Marta Sewilo

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Accepted by ApJ, 25 pages, 28 figures
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摘要：

我们利用宽视场红外巡天探测器（WISE）在100 ° ^2的区域内搜寻年轻恒星天体（YSO），该区域以研究较少的大犬座恒星形成区为中心。应用严格的幅度削减，以排除大多数河外污染物，我们发现144 I类候选人和335 II类候选人。对II类候选者的敏感性受到它们在大犬座距离（假设为1000 pc）处的模糊度的限制。超过一半的候选人（53%）来自16个成员超过4人的团体，其中包括4个成员超过25人的团体。II类与I类天体之比N_II/N_I在最大的四个天体群中从0.4到8.3不等。我们将我们的结果与两微米全天巡天（2 MASS）和低温后斯皮策太空望远镜数据相结合，后者的方法恢复丢失的II类源。通过与赫歇尔空间天文台的原恒星特征的比较，我们提出了新的WISE颜色标准的平谱和0类原恒星，发现80和7个，分别。CMa OB 1中YSO的分布与超新星诱导的恒星形成相一致，但如果该参数追踪年龄，并且YSO是由同一颗超新星引起的，则不同的N_II/N_I比值是意料之外的。质量较小的云具有较大的N_II/N_I比值，这表明初始条件在决定这个量方面起作用。

英文摘要：

With the Wide-Field Infrared Survey Explorer (WISE), we searched for young stellar objects (YSOs) in a 100 deg^2 region centered on the lightly studied Canis Major star forming region. Applying stringent magnitude cuts to exclude the majority of extragalactic contaminants, we find 144 Class I candidates and 335 Class II candidates. The sensitivity to Class II candidates is limited by their faintness at the distance to Canis Major (assumed as 1000 pc). More than half the candidates (53%) are found in 16 groups of more than four members, including four groups with more than 25 members each. The ratio of Class II to Class I objects, N_II/N_I, varies from 0.4 to 8.3 in just the largest four groups. We compare our results to those obtainable with combined Two Micron All Sky Survey (2MASS) and post-cryogenic Spitzer Space Telescope data; the latter approach recovers missing Class II sources. Via a comparison to protostars characterized with the Herschel Space Observatory, we propose new WISE color criteria for flat-spectrum and Class 0 protostars, finding 80 and seven of these, respectively. The distribution of YSOs in CMa OB1 is consistent with supernova-induced star formation, although the diverse N_II/N_I ratios are unexpected if this parameter traces age and the YSOs are due to the same supernova. Less massive clouds feature larger N_II/N_I ratios, suggesting that initial conditions play a role in determining this quantity.

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