论文标题
超速轨道（椰子）上的凉爽伴侣。 iii。一个非常红色的L6基准棕色矮人围绕年轻的M5矮人
COol Companions ON Ultrawide orbiTS (COCONUTS). III. A Very Red L6 Benchmark Brown Dwarf around a Young M5 Dwarf
论文作者
论文摘要
我们介绍了来自酷同伴超轨道（椰子）程序的第三个发现，即椰子-3系统，该系统由年轻的M5主要恒星UCAC4 374-046899和非常红色的L6 Dwarf Wisea J081322.19 $ - $ 1522020203.2组成。这两个对象的预计分离为61 $''$（1891 au），并且鉴于其共同的适当动作和估计距离，因此在物理上关联。主要恒星椰子-3A的质量为$ 0.123 \ pm0.006 $ m $ _ {\ odot} $，我们根据其运动学和分光光度计特性估计其年龄为100 MYR至1 GYR。我们使用较旧的高级重力M矮人建立的经验校准来得出其金属性为0.21 \ pm 0.07 $ dex，并根据凤凰型型号略微低估了这种[fe/h]，因为给定的椰子型模型，椰子型3A年龄较小。伴侣，椰子-3b具有近红外光谱类型的L6 $ \ pm $ 1 int-g，我们推断出$ t _ {\ rm eff} = 1362^{+48} _ { - 73} $ k，$ k，$ k，$ k，$ \ log {（g）= 4.96^$ 0.15 {+4.96^{+4.96^{+4.96^{+4.96^{+4.96^{+4.96^{+4.96^{+4.96^{+0.15 { = 1.03^{+0.12} _ { - 0.06} $ r $ _ {\ rm jup} $，$ m = 39^{+11} _ { - 18} $ M $ _ {\ rm jup} $，使用其Bolometric ser star star star star and star and star and start模型。我们在基于进化的物理参数上构建多云的大气模型光谱，并将其与椰子-3b的分光光度计进行比较。我们发现，该伴侣在其光球中具有充足的冷凝水云，其数据模型差异可能是由于模型使用了旧版本的不透明数据库而引起的。与现场时代的L6矮人相比，椰子-3b具有绝对的绝对幅度和120 K凉爽的$ t _ {\ rm eff} $。此外，该同伴的J-K颜色是超过几百Myr年龄段的超速基准的最红色。椰子-3可能以与恒星二进制相同的方式形成，鉴于伴侣与宿主质量比为0.3，并且代表了量化量子测定模型大气系统的宝贵基准。
We present the third discovery from the COol Companions ON Ultrawide orbiTS (COCONUTS) program, the COCONUTS-3 system, composed of a young M5 primary star UCAC4 374-046899 and a very red L6 dwarf WISEA J081322.19$-$152203.2. These two objects have a projected separation of 61$''$ (1891 au) and are physically associated given their common proper motions and estimated distances. The primary star, COCONUTS-3A, has a mass of $0.123\pm0.006$ M$_{\odot}$ and we estimate its age as 100 Myr to 1 Gyr based on its kinematics and spectrophotometric properties. We derive its metallicity as $0.21 \pm 0.07$ dex using empirical calibrations established by older higher-gravity M dwarfs and find this [Fe/H] could be slightly underestimated according to PHOENIX models given COCONUTS-3A's younger age. The companion, COCONUTS-3B, has a near-infrared spectral type of L6$\pm$1 INT-G, and we infer physical properties of $T_{\rm eff} = 1362^{+48}_{-73}$ K, $\log{(g)}= 4.96^{+0.15}_{-0.34}$ dex, $R = 1.03^{+0.12}_{-0.06}$ R$_{\rm Jup}$, and $M = 39^{+11}_{-18}$ M$_{\rm Jup}$, using its bolometric luminosity, its host star's age, and hot-start evolution models. We construct cloudy atmospheric model spectra at the evolution-based physical parameters and compare them to COCONUTS-3B's spectrophotometry. We find this companion possesses ample condensate clouds in its photosphere with the data-model discrepancies likely due to the models using an older version of the opacity database. Compared to field-age L6 dwarfs, COCONUTS-3B has fainter absolute magnitudes and a 120 K cooler $T_{\rm eff}$. Also, the J-K color of this companion is among the reddest for ultracool benchmarks with ages older than a few 100 Myr. COCONUTS-3 likely formed in the same fashion as stellar binaries given the companion-to-host mass ratio of 0.3 and represents a valuable benchmark to quantify the systematics of substellar model atmospheres.
