The Wide Brown Dwarf Binary Oph 1622–2405 and Discovery of a Wide, Low-Mass Binary in Ophiuchus (Oph 1623–2402): A New Class of Young Evaporating Wide Binaries?
The Wide Brown Dwarf Binary Oph 1622–2405 and Discovery of a Wide, Low-Mass Binary in Ophiuchus (Oph 1623–2402): A New Class of Young Evaporating Wide Binaries?
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宽棕矮星双星 Oph 1622-2405 和在蛇夫座 (Oph 1623-2402) 中发现的宽低质量双星：一类新的年轻蒸发宽双星？
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发表时间：
2006
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通讯作者：
D. L. Mignant
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作者：
L. Close;B. Zuckerman;I. Song;T. Barman;C. Marois;E. Rice;N. Siegler;B. Macintosh;E. Becklin;R. Campbell;J. Lyke;A. Conrad;D. L. Mignant
我们用凯克激光制导星星AO系统拍摄了蛇夫座恒星形成云附近的五个物体。我们将来自Allers和同事的源11（Oph 16222-2405）和16（Oph 16233-2402）解析为二进制系统。源11被分解为243 Au的双星，这是已知最广泛的甚低质量（VLM）双星。源11的二元性质首先由Allers发现，在此期间，我们获得了第一个空间分辨的R ~ 2000近红外（J和K）光谱，中红外测光和轨道运动估计。我们估计了11 A和11B的重力（log g > 3.75）、年龄（5 ± 2百万年）、光度（log（L/L）= -2.77 ± 0.10和-2.96 ± 0.10）和温度（Teff = 2375 ± 175 K和2175 ± 175 K）。我们发现自洽DUSTY进化模型（Chabrier和同事）的质量为17兆焦耳和14兆焦耳，分别为11 A和11B。我们的质量高于Jayawardhana和Ivanov先前报道的质量（13-15 MJ和7-8 MJ）。因此，我们发现该系统不太可能是一个“行星质量双星”，就像Luhman和他的同事所做的那样，但它的质量和结合能在任何已知的双星中都是第二低的。Oph 11和Oph 16属于一个新发现的宽（1000 Au）、年轻（<1000万年）、质量大致相等的VLM恒星和褐矮星双星。我们推断，约6% ± 3%的年轻（<1000万年）VLM对象在这样的广泛的系统。然而，只有0.3% ± 0.1%的旧场VLM对象被发现在这样广泛的系统。因此，年轻的，宽的，VLM双星人口可能会蒸发，由于恒星在其纳塔尔集群中相遇，导致在宽VLM系统中的场人口耗尽。
We imaged five objects near the star-forming clouds of Ophiuchus with the Keck Laser Guide Star AO system. We resolved sources 11 (Oph 16222-2405) and 16 (Oph 16233-2402) from Allers and coworkers into binary systems. Source 11 is resolved into a 243 AU binary, the widest known for a very low mass (VLM) binary. The binary nature of source 11 was discovered first by Allers and independently here, during which we obtained the first spatially resolved R ~ 2000 near-infrared (J and K) spectra, mid-IR photometry, and orbital motion estimates. We estimate for 11A and 11B gravities (log g > 3.75), ages (5 ± 2 Myr), luminosities [log(L/L☉) = -2.77 ± 0.10 and -2.96 ± 0.10], and temperatures (Teff = 2375 ± 175 K and 2175 ± 175 K). We find self-consistent DUSTY evolutionary model (Chabrier and coworkers) masses of 17 MJ and 14 MJ, for 11A and 11B, respectively. Our masses are higher than those previously reported (13-15 MJ and 7-8 MJ) by Jayawardhana & Ivanov. Hence, we find that the system is unlikely a "planetary mass binary," as do Luhman and coworkers, but it has the second lowest mass and lowest binding energy of any known binary. Oph 11 and Oph 16 belong to a newly recognized population of wide (≳100 AU), young (<10 Myr), roughly equal mass, VLM stellar and brown dwarf binaries. We deduce that ~6% ± 3% of young (<10 Myr) VLM objects are in such wide systems. However, only 0.3% ± 0.1% of old field VLM objects are found in such wide systems. Thus, young, wide, VLM binary populations may be evaporating, due to stellar encounters in their natal clusters, leading to a field population depleted in wide VLM systems.