Brown Dwarf Companions to G-Type Stars. I. Gliese 417B and Gliese 584C
Brown Dwarf Companions to G-Type Stars. I. Gliese 417B and Gliese 584C
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G 型恒星的褐矮星伴星。
DOI：
10.1086/321085
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发表时间：
2001
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：
J. Kirkpatrick;C. Dahn;D. Monet;I. Reid;J. Gizis;J. Liebert;A. Burgasser
我们提出的天文测量和光谱观测证实，两个邻近的G矮星系统（Gliese 417 = BD+36°2162和Gliese 584AB = η CrB AB）有一个相隔很远的L矮星伴星。利用对G矮星主星系年龄的估计，我们根据理论演化轨迹估计了这些L矮星的质量。对于L4.5矮星Gl 417B，我们估计其年龄为0.08-0.3 Gyr，质量为0.035±0.015 M⊙。对于L8矮星Gl 584C，我们估计其年龄为1.0-2.5 Gyr，质量为0.060±0.015 M⊙。后一个天体也显示出光谱变化的证据，这可能是由于表面的不均匀性旋转进入和离开了视野。这些新伴星还与之前发现的其他六颗L矮星和T矮星伴星进行了比较。对于L矮星伴星，由锂的存在或不存在所暗示的年龄与仅从初级恒星推断的年龄一致。
We present astrometric and spectroscopic observations confirming that two nearby G dwarf systems (Gliese 417 = BD+36°2162 and Gliese 584AB = η CrB AB) have a widely separated, L dwarf, substellar companion. Using age estimates of the G dwarf primaries, we estimate masses for these L dwarfs from theoretical evolutionary tracks. For the L4.5 dwarf Gl 417B we estimate an age of 0.08–0.3 Gyr and a mass of 0.035 ± 0.015 M⊙. For the L8 dwarf Gl 584C we estimate an age of 1.0–2.5 Gyr and a mass of 0.060 ± 0.015 M⊙. This latter object also shows evidence of spectrum variability, which may be due to surface inhomogeneities rotating into and out of view. These new companions are also compared to six other L dwarf and T dwarf companions previously recognized. For the L dwarf companions, ages implied by the presence or absence of lithium are consistent with ages inferred from the primaries alone.