L. M. Rebull, J. R. Stauffer, A. M. Cody, H. M. Guenther, L. A. Hillenbrand, K. Poppenhaeger, S. J. Wolk, J. Hora, J. Hernandez, A. Bayo, K. Covey, J. Forbrich,… 展开作者
L. M. Rebull, J. R. Stauffer, A. M. Cody, H. M. Guenther, L. A. Hillenbrand, K. Poppenhaeger, S. J. Wolk, J. Hora, J. Hernandez, A. Bayo, K. Covey, J. Forbrich, R. Gutermuth, M. Morales-Calderon, P. Plavchan, I. Song, H. Bouy, S. Terebey, J. C. Cuillandre, L. Allen
As part of the Young Stellar Object VARiability (YSOVAR) program, we monitored NGC 1333 for ~35 days at 3.6 and 4.5 um using the Spitzer Space Telescope. We report here on the mid-infrared variability of the point sources in the ~10x~20arcmin area centered on 03:29:06, +31:19:30 (J2000). Out of 701 light curves in either channel, we find 78 variables over the YSOVAR campaign. About half of the members are variable. The variable fraction for the most embedded SEDs (Class I, flat) is higher than that for less embedded SEDs (Class II), which is in turn higher than the star-like SEDs (Class III). A few objects have amplitudes (10-90th percentile brightness) in [3.6] or [4.5]>0.2 mag; a more typical amplitude is 0.1-0.15 mag. The largest color change is >0.2 mag. There are 24 periodic objects, with 40% of them being flat SED class. This may mean that the periodic signal is primarily from the disk, not the photosphere, in those cases. We find 9 variables likely to be 'dippers', where texture in the disk occults the central star, and 11 likely to be 'bursters', where accretion instabilities create brightness bursts. There are 39 objects that have significant trends in [3.6]-[4.5] color over the campaign, about evenly divided between redder-when-fainter (consistent with extinction variations) and bluer-when-fainter. About a third of the 17 Class 0 and/or jet-driving sources from the literature are variable over the YSOVAR campaign, and a larger fraction (~half) are variable between the YSOVAR campaign and the cryogenic-era Spitzer observations (6-7 years), perhaps because it takes time for the envelope to respond to changes in the central source. The NGC 1333 brown dwarfs do not stand out from the stellar light curves in any way except there is a much larger fraction of periodic objects (~60% of variable brown dwarfs are periodic, compared to ~30% of the variables overall).
A Model for (Quasi-)Periodic Multi-wavelength Photometric Variability in Young Stellar Objects
我们提出的辐射传输模型的旋转年轻恒星物体（YSO）的热点在其大气中，内部磁盘扭曲和其他3-D的影响，在附近的拱星环境。我们的模型是基于磁吸积理论所预期的几何形状，即在磁盘中向内移动的物质沿着磁场线流向恒星，并在撞击时产生恒星热点。由于恒星和磁层的旋转，圆盘被反方向照射。我们将我们的模型光变曲线与Spitzer YSOVAR项目的数据（Morales-Calderon et al. 2014，Cody et al. 2014）进行比较，以确定这些过程是否可以解释在年轻恒星中观察到的光学和中红外波长的变化。我们专注于这些变量表现出“北斗”的行为，可能是周期性的，准周期性的，或非周期性的。我们发现，恒星热点的大小和温度影响光学和近红外线曲线，而形状和垂直程度的内部磁盘扭曲影响中红外光曲线的变化。具有非均匀分形密度结构的星盘分布产生更多的随机光变曲线。我们的结论是，磁吸积理论是一致的某些方面的多波长光度变化所表现出的低质量的YSO。更详细的个别来源的建模可以用来更好地确定恒星热点和内部磁盘的几何形状的特定来源。
An FUor-like Outbursting Class I Protostar in NGC 7538
China Three Gorges University（三峡大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；University of Chinese Academy of Sciences（中国科学院大学）
NGC 7538 MIR展现巨大亮度爆发和持续高亮度状态，其近红外光变曲线分为爆发前、爆发和爆发后三个阶段，揭示原恒星早期阶段类似FUor的吸积事件的重要性。
Optical and Infrared Imaging and Spectroscopy of the Multiple-Shell Planetary Nebula NGC 6369
NGC 6369是一个双壳层行星状星云（PN），由明亮的环形内壳层和暗淡的双极扩展层组成。我们已经使用地面和空间的窄带光学和近红外图像，宽带中红外图像，光学长缝阶梯光谱，和中红外光谱来研究它的物理结构。这些观测结果表明，NGC 6369的内壳可以被描述为一个类似于桶的结构形状与极性泡状突起，并揭示了H2和强多环芳烃（PAHs）的光离解区（PDR）的证据位于明亮的内壳外的分子夹杂物。高分辨率的哈勃望远镜窄带图像揭示了一个复杂的激发结构的内壳和一个系统的“彗星”结。NGC 6369的包层看起来很棘手，缺乏壳层膨胀的运动学证据，PDR外电离物质的发射明显存在，这些都使我们认为NGC 6369的包层不是一个真正的壳层，而是赤道区域的一个扁平结构。我们报告了在低激发和分子线发射中发现的不规则的结和斑点的扩散发射，这些发射位于距离中心恒星80”的地方，在主星云壳层之外。我们还表明，与极性突起相关联的细丝具有与冲击后冷却制度相一致的空间范围，并且可能代表这些结构与周围材料相互作用的区域。
The independence of the mid-infrared RR Lyrae Period-Luminosity relation from metallicity from a study of three globular clusters in the Large Magellanic Cloud
Department of Physics, University of Bath（巴斯大学物理系）
