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首页> 外文期刊>The Astrophysical journal >INFRARED SPECTROSCOPY OF THE ULTRA-LOW-MASS BINARY OPH 162225-240515
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INFRARED SPECTROSCOPY OF THE ULTRA-LOW-MASS BINARY OPH 162225-240515

机译：超低质量二元OPH 162225-240515的红外光谱

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摘要

Binary properties are an important diagnostic of the star and brown dwarf formation processes. While wide binaries appear to be rare in the substellar regime, recent observations have revealed Ophiuchus 162225 — 240515 (2MASS J16222521 -2405139) as a likely young ultra-low-mass binary with an apparent separation of ≈240 AU. Here we present low-resolution near-infrared spectra of the pair from NTT/SOFI (R ～ 600) and VLT/ISAAC (R ～ 1400), covering the 1.0-2.5 μm spectral region. By comparing them to model atmospheres from Chabrier & Baraffe and Burrows et al., we confirm the surface temperatures to be T_A = 2350 ± 150 K and T_B = 2100 ± 100 K for the two components of the binary, consistent with earlier estimates from optical spectra. Using gravity-sensitive K I features, we find the surface gravity to be significantly lower than field dwarfs of the same spectral type, providing the best evidence so far that these objects are indeed young. However, we find that models are not sufficiently reliable to infer accurate ages/masses from surface gravity. Instead, we derive masses of M_A = 13_(-4)~(+8)M_J and M_B = 10_(-4)~(+5)M_J for the two objects using the well-constrained temperatures and assuming an age of 1-10 Myr, consistent with the full range of ages reported for the Oph region.
机译：二元性质是星型和棕矮星形成过程的重要诊断。尽管在星下政权中很少见到宽二进制文件，但最近的观察表明，蛇夫座162225 — 240515（2MASS J16222521 -2405139）是可能的年轻超低质量二进制文件，其明显分离为≈240AU。在这里，我们给出了来自NTT / SOFI（R〜600）和VLT / ISAAC（R〜1400）的低分辨率近红外光谱，覆盖1.0-2.5μm的光谱区域。通过将它们与Chabrier＆Baraffe和Burrows等人的模型大气进行比较，我们确定了二元组分的两个成分的表面温度分别为T_A = 2350±150 K和T_B = 2100±100 K，这与早期的光学估计一致。光谱。利用重力敏感的K I特征，我们发现表面重力显着低于相同光谱类型的场矮，从而提供了迄今为止最好的证据，证明这些物体确实很年轻。但是，我们发现模型不足以从表面重力推断准确的年龄/质量。取而代之的是，我们使用良好约束的温度并假设年龄为1-，得出两个物体的M_A = 13 _（-4）〜（+8）M_J和M_B = 10 _（-4）〜（+5）M_J的质量。 10马币，与Oph地区报道的所有年龄段一致。

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