论文标题
关于2 MASS J06195260-2903592的异常变异：围绕年轻的Ultracool矮人的长期磁盘
On The Unusual Variability of 2MASS J06195260-2903592: A Long-Lived Disk around a Young Ultracool Dwarf
论文作者
论文摘要
我们介绍了低重力M6矮人2MASS J0619-2903的表征，先前根据其强大的IR过量和可变的近IR光谱而被识别为不寻常的场对象。多个低分辨率（R〜150）近IR光谱的时期显示出大幅度（〜0.1-0.5 mag）的连续性变化天数至12年的时间尺度，这与田间Ultracool Dwarfs典型的小振幅变化不同。随着相对灭绝的变化（$δ{a_v} \ oft2 $ mag），时期之间的变化被很好地模拟。同样，Pan-Starrs光学光度法在时间尺度上长达11年（可能短达一个小时），并且意味着类似的振幅$ a_v $变化。 Neowise Mid-IR光曲线还表明6个月时间尺度的变化，其振幅与光学/近IR灭绝变化一致。但是，在过去一年中获得的近IR光谱，近IR光度法和光学光度法表明，在小时和每月的时间表上，源也可以稳定。从比较与类似光谱类型的对象，2MASS J0619-2903的总灭绝似乎是$ a_v \ of4-6 $ mag，也许是较低的灭绝时代。 Gaia EDR3发现2MASS J0619-2903具有广泛分离的（1.2'= 10450 au）恒星伴侣，等距年龄为$ 31^{+22} _ { - 10} $ Myr，质量为$ 0.30^{+0.030^{+0.04} _ _ _ _ _ { - 0.03} $ mssun。采用该同伴的年龄和EDR3距离（145.2 $ \ pm $ 0.6 PC），我们估计2mass J0619-2903的质量为0.11-0.17 msun。总共，2MASS J0619-2903似乎拥有一个异常长的原始杂质磁盘，也许使其与附近年轻移动组的几个M矮人发现的“ Peter Pan”磁盘更加模糊。
We present the characterization of the low-gravity M6 dwarf 2MASS J0619-2903 previously identified as an unusual field object based on its strong IR excess and variable near-IR spectrum. Multiple epochs of low-resolution (R~150) near-IR spectra show large-amplitude (~0.1-0.5 mag) continuum variations on timescales of days to 12 years, unlike the small-amplitude variability typical for field ultracool dwarfs. The variations between epochs are well-modeled as changes in the relative extinction ($Δ{A_V}\approx2$ mag). Likewise, Pan-STARRS optical photometry varies on timescales as long as 11 years (and possibly as short as an hour) and implies similar amplitude $A_V$ changes. NEOWISE mid-IR light curves also suggest changes on 6-month timescales, with amplitudes consistent with the optical/near-IR extinction variations. However, near-IR spectra, near-IR photometry, and optical photometry obtained in the past year indicate the source can also be stable on hourly and monthly timescales. From comparison to objects of similar spectral type, the total extinction of 2MASS J0619-2903 seems to be $A_V\approx4-6$ mag, with perhaps epochs of lower extinction. Gaia EDR3 finds that 2MASS J0619-2903 has a wide-separation (1.2' = 10450 AU) stellar companion, with an isochronal age of $31^{+22}_{-10}$ Myr and a mass of $0.30^{+0.04}_{-0.03}$ Msun. Adopting this companion's age and EDR3 distance (145.2$\pm$0.6 pc), we estimate a mass of 0.11-0.17 Msun for 2MASS J0619-2903. Altogether, 2MASS J0619-2903 appears to possess an unusually long-lived primordial circumstellar disk, perhaps making it a more obscured analog to the "Peter Pan" disks found around a few M dwarfs in nearby young moving groups.
