HST, VLT, and NTT imaging search for wide companions to bona-fide and candidate brown dwarfs in the Cha I dark cloud
HST, VLT, and NTT imaging search for wide companions to bona-fide and candidate brown dwarfs in the Cha I dark cloud
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HST、VLT 和 NTT 成像在 Cha I 暗云中寻找真正的褐矮星和候选褐矮星的广泛伴星
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发表时间：
2002
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通讯作者：
F. Comerón
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作者：
R. Neuhaeuser;W. Brandner;J. Alves;V. Joergens;F. Comerón
研究人员利用HST WFPC2 （R， I, H α）、VLT FORS1 （VRI）和NTT SofI （JHK s）对Cha I暗云中年轻的真棕矮星和候选棕矮星Cha H α 1至12周围的伴星进行了深度成像搜索。我们在5个主星系周围发现了16个暗淡的伴星候选者，它们之间的距离在1.5$^{prime prime}$和7$^{prime prime}$之间，R & I中的星等从19到25等不等，即比主星系暗8等。虽然这些伴星中的大多数可能是无关的背景天体，但有一个很有希望的候选者，即6矮星Cha H α 5的$1.5^{prime prime}$ SW。这颗候选星比原星暗3.8到4.7等，它的颜色与早期到中l光谱型一致。假设距离（140 pc）和吸收（A I = 0.47 mag）与主恒星相同，则伴星的log$ ($L_{
m bol}/L_{odot}) = -3.0 pm 0.3$。根据Burrows等人（[引用]）和Chabrier & Baraffe（[引用]）的模型，在主星系（1到5兆赫）的年龄，这个微弱的天体的质量将是3到15个木星的质量。这个伴星候选人是一个不相关的前背景天体或背景天体的概率≤0.7%，它的颜色与强烈变红的背景K巨星的颜色略微一致。另一个伴星候选者的红外颜色与早期的t型矮星一致。此外，我们还指出Cha H α 2是一个接近（~$ 0.2^{prime prime}$）的双星，其两个分量都非常接近亚恒星极限。我们的检测限是这样的，我们应该以$ $2^{素数素数}$（≥$ 320$ AU）和$ $ 5$ M以上的所有跳跃≥$ 0.35^{素数素数}$（≥$ 50$ AU）检测到跳跃大于1 M的所有同伴。
We present results from a deep imaging search for companions around the young bona-fide and candidate brown dwarfs Cha H α 1 to 12 in the Cha I dark cloud, performed with HST WFPC2 ( R , I , H α ), VLT FORS1 ( VRI ), and NTT SofI ( JHK s ). We find 16 faint companion candidates around five primaries with separations between 1.5$^{prime prime}$ and 7$^{prime prime}$ and magnitudes in R & I from 19 to 25 mag, i.e. up to 8 mag fainter than the primaries. While most of these companion candidates are probably unrelated background objects, there is one promising candidate, namely $1.5^{prime prime}$ SW off the M6-dwarf Cha H α 5. This candidate is 3.8 to 4.7 mag fainter than the primary and its colors are consistent with an early- to mid-L spectral type. Assuming the same distance (140 pc) and absorption ( A I = 0.47 mag) as towards the primary, the companion candidate has $log$ ($L_{
m bol}/L_{odot}) = -3.0 pm 0.3$. At the age of the primary (1 to 5 Myrs), the faint object would have a mass of 3 to 15 Jupiter masses according to Burrows et al. ([CITE]) and Chabrier & Baraffe ([CITE]) models. The probability for this companion candidate to be an unrelated fore- or background object is ≤ $ 0.7\%$, its colors are marginally consistent with a strongly reddened background K giant. One other companion candidate has infrared colors consistent with an early T-dwarf. In addition, we present indications for Cha H α 2 being a close (~$ 0.2^{prime prime}$) binary with both components very close to the sub-stellar limit. Our detection limits are such that we should have detected all companions above ∼ 1 M jup with separations $ge $ $2^{prime prime}$ ( ≥ $ 320$ AU) and all above ~$ 5$ M jup at ≥ $ 0.35^{prime prime}$ ( ≥ $ 50$ AU).