A YOUNG PLANETARY-MASS OBJECT IN THE ρ OPH CLOUD CORE
A YOUNG PLANETARY-MASS OBJECT IN THE ρ OPH CLOUD CORE
复制标题
ρ OPH 云核心中的年轻行星质量天体
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
P. Plavchan
中科院分区：
文献类型：
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作者：
K. Marsh;J. Kirkpatrick;P. Plavchan
我们报告在ρ Oph云核中发现了一颗年轻的行星质量棕矮星。借助凯克一号望远镜上的NIRC仪器获得的1.5-2.4微米低分辨率光谱，该物体被确定为该物体。根据COND模型，观测到的光谱与红化（AV 15-16）棕矮星一致，其有效温度在1200-1800 K之间。假设年龄为100万年，与等时线的比较进一步将温度限制在1400 K，并建议质量为木星质量的102 -3倍。推断的温度是暗示的早期T光谱类型，这是支持光谱形态与弱甲烷吸收一致。根据它的距离推断（约100 pc）和存在重叠的视觉吸收，它很可能是一个ρ Oph星团成员。此外，考虑到估计的光谱类型，它可能是迄今为止发现的最年轻和质量最小的T矮星。它的存在表明ρ Oph恒星形成区域的初始质量函数可以很好地扩展到行星质量区域。
We report the discovery of a young planetary-mass brown dwarf in the ρ Oph cloud core. The object was identified as such with the aid of a 1.5–2.4 μm low-resolution spectrum obtained using the NIRC instrument on the Keck I telescope. Based on the COND model, the observed spectrum is consistent with a reddened (AV ∼ 15–16) brown dwarf whose effective temperature is in the range 1200–1800 K. For an assumed age of 1 Myr, comparison with isochrones further constrains the temperature to ∼1400 K and suggests a mass of ∼2–3 Jupiter masses. The inferred temperature is suggestive of an early T spectral type, which is supported by spectral morphology consistent with weak methane absorption. Based on its inferred distance (∼100 pc) and the presence of overlying visual absorption, it is very likely to be a ρ Oph cluster member. In addition, given the estimated spectral type, it may be the youngest and least massive T dwarf found so far. Its existence suggests that the initial mass function for the ρ Oph star-forming region extends well into the planetary-mass regime.