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arXiv 0904.0819astro-ph.SRastro-ph.EP
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斯皮策太空望远镜发现的年轻低质量恒星周围的新碎片

New Debris Disks Around Young, Low Mass Stars Discovered With The Spitzer Space Telescope

Peter Plavchan, M. W. Werner, C. H. Chen, K. R. Stapelfeldt, K. Y. L. Su, J. R. Stauffer, I. Song

摘要:

作为斯皮策保证时间计划的一部分,我们对70颗A到M型矮星进行了24和70微米MIPS观测,估计年龄从800万年到1.1千兆年。我们的样本选自具有常见年轻指标的恒星,如锂丰度,X射线活动,色球活动和快速旋转。我们将我们的MIPS观测结果与经验推导的K-[24]颜色作为恒星有效温度的函数进行比较,以确定24和70微米的过量。我们确认之前发布的HD 92945、HD 112429和AU Mic的70微米超标。我们目前发现了五颗恒星70微米的超差:HD 7590,HD 10008,HD 59967,HD 73350和HD 135599。我们还提出了对10颗恒星的24微米超差的检测:HD 10008,GJ 3400 A,HD 73350,HD 112429,HD 123998,HD 175742,AT Mic,BO Mic,HD 358623和GI 907.1。我们发现,大70微米的过剩是不太常见的恒星周围的有效温度小于5000 K(3.7%)比周围的恒星有效温度在5000 K和6000 K(21.4%),尽管较冷的恒星有一个年轻的中位年龄在我们的样本(12与3.4亿年)。我们发现,先前报道的TWA 13 A在70微米处的过量是由于附近的背景星系。在附录中,我们提出了一个更新的分析尘埃颗粒去除时间尺度由于颗粒颗粒碰撞和辐射压力,坡印廷-罗伯逊阻力,恒星风阻力和行星尘埃动力学相互作用。

英文摘要:

(abridged) We present 24 and 70 micron MIPS observations of 70 A through M-type dwarfs with estimated ages from 8 Myr to 1.1 Gyr, as part of a Spitzer guaranteed time program. Our sample is selected from stars with common youth indicators such as lithium abundance, X-ray activity, chromospheric activity, and rapid rotation. We compare our MIPS observations to empirically derived K-[24] colors as a function of the stellar effective temperature to identify 24 and 70 micron excesses. We confirm the previously published 70 micron excesses for HD 92945, HD 112429, and AU Mic. We present the discovery of 70 micron excesses for five stars: HD 7590, HD 10008, HD 59967, HD 73350, and HD 135599. We also present the detection of 24 micron excesses for ten stars: HD 10008, GJ 3400A, HD 73350, HD 112429, HD 123998, HD 175742, AT Mic, BO Mic, HD 358623 and Gl 907.1. We find that large 70 micron excesses are less common around stars with effective temperatures of less than 5000 K (3.7%) than around stars with effective temperatures between 5000 K and 6000 K (21.4%), despite the cooler stars having a younger median age in our sample (12 vs.340 Myr). We find that the previously reported excess for TWA 13A at 70 microns is due to a nearby background galaxy. In the Appendix, we present an updated analysis of dust grain removal time-scales due to grain-grain collisions and radiation pressure, Poynting-Robertson drag, stellar wind drag and planet-dust dynamical interaction.

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。

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