Discovery of a Second L Subdwarf in the Two Micron All Sky Survey
Discovery of a Second L Subdwarf in the Two Micron All Sky Survey
复制标题
两微米全天巡天发现第二颗 L 亚矮星
DOI：
10.1086/425418
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
A. Burgasser
中科院分区：
文献类型：
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作者：
A. Burgasser
我报告了在2微米全天巡天（2 MASS J16262034+3925190）中发现的第二颗L亚矮星。这颗高自行天体（μ = 1.″27 ± 0.″03 yr-1）的近红外光谱特征表明太阳下金属丰度为L的矮星，包括强的金属氢化物和H2O吸收带、压力增宽的碱性谱线以及由碰撞诱导的H2吸收增强引起的蓝色近红外颜色。这个天体的类型比任何已知的M型次矮星都要晚，但看起来并不像明显的晚型sdL 2 MASS 0532+8246那么冷。2 MASS 1626+3925的径向速度（Vrad = -260 ± 35 km s-1）和估计的切向速度（Vtan = 90-210 km s-1）表明它属于银河系晕，并且这个来源可能接近或低于贫金属星星燃烧氢的最小质量。像2 MASS 1626+3925这样的L型亚矮星是低温恒星和褐矮星大气中气体和凝析化学的有用探测器，但需要更多的例子来研究这些天体作为一个群体，以及定义一个严格的分类方案。
I report the discovery of the second L subdwarf identified in the Two Micron All Sky Survey, 2MASS J16262034+3925190. This high proper motion object (μ = 1.″27 ± 0.″03 yr-1) exhibits near-infrared spectral features indicative of a subsolar metallicity L dwarf, including strong metal hydride and H2O absorption bands, pressure-broadened alkali lines, and blue near-infrared colors caused by enhanced collision-induced H2 absorption. This object is of later type than any of the known M subdwarfs but does not appear to be as cool as the apparently late-type sdL 2MASS 0532+8246. The radial velocity (Vrad = -260 ± 35 km s-1) and estimated tangential velocity (Vtan ≈ 90-210 km s-1) of 2MASS 1626+3925 indicate membership in the Galactic halo, and this source is likely near or below the hydrogen-burning minimum mass for a metal-poor star. L subdwarfs such as 2MASS 1626+3925 are useful probes of gas and condensate chemistry in low-temperature stellar and brown dwarf atmospheres, but more examples are needed to study these objects as a population as well as to define a rigorous classification scheme.