On the Unusual Variability of 2MASS J06195260–2903592: A Long-lived Disk around a Young Ultracool Dwarf
On the Unusual Variability of 2MASS J06195260–2903592: A Long-lived Disk around a Young Ultracool Dwarf
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DOI：
10.3847/1538-3881/ac8cee
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发表时间：
2022-08
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通讯作者：
Michael C. Liu;E. Magnier;Zhoujian Zhang;E. Gaidos;T. Dupuy;Pengyu Liu;B. Biller;J. Vos;K. Allers;J. Hinkle;B. Shappee;S. Constantinou;Mitchell Dennis;K. S. Emerson
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作者：
Michael C. Liu;E. Magnier;Zhoujian Zhang;E. Gaidos;T. Dupuy;Pengyu Liu;B. Biller;J. Vos;K. Allers;J. Hinkle;B. Shappee;S. Constantinou;Mitchell Dennis;K. S. Emerson
我们给出了低重力M6矮星2MASS J06195260-2903592的特征，它以前被认为是一个不寻常的外场天体，因为它有很强的红外过剩和可变的近红外光谱。多个时期的低分辨率(R≈150)近红外光谱显示出从天到12年的时间尺度上的大幅度(≈0.1MAG-0.5MAG)连续变化，这与野外超冷矮星典型的小幅度变化不同。历元之间的变化被很好地模拟为相对消光的变化(ΔA V≈2 MAG)。同样，全景勘测望远镜和快速反应系统1的光学光度测量在时间尺度上的变化长达11年(可能短至1小时)，并意味着可比的A-V变化。近地天体广域红外探测探测器中红外光曲线也表明了6个月时间尺度上的变化，其幅度与光学/近红外消光变化一致。然而，过去一年获得的近红外光谱、近红外测光和光学测光表明，震源在小时和每月的时间尺度上也可以是稳定的。与类似光谱类型的天体相比，2MASS J0619-2903的总消光似乎是A V≈4-6 MAG，可能存在较低的消光时期。GaIA早期数据发布3发现2MASS J0619-2903具有宽分离(1.‘2=10,450Au)伴星，等时年龄为31−10+22Myr，质量为0.30−0.03+0.04M☉。采用这个伴星的年龄和EDR3距离(145.2±0.6pC)，我们估计2MASJ0619-2903的质量为0.11-0.17M☉。总而言之，2MASS J0619-2903似乎拥有一个不同寻常的长寿命的原始恒星周盘，可能使它成为一个更模糊的类似于在附近年轻运动群体中的几颗M矮星周围发现的“彼得·潘”盘。
We present the characterization of the low-gravity M6 dwarf 2MASS J06195260-2903592, 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 yr, unlike the small-amplitude variability typical for field ultracool dwarfs. The variations between epochs are well-modeled as changes in the relative extinction (ΔA V ≈ 2 mag). Similarly, Panoramic Survey Telescope and Rapid Response System 1 optical photometry varies on timescales as long as 11 yr (and possibly as short as an hour) and implies comparable A V changes. Near Earth Object Wide-field Infrared Survey Explorer 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 that 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 ≈ 4–6 mag, with perhaps epochs of lower extinction. Gaia Early Data Release 3 (EDR3) finds that 2MASS J0619-2903 has a wide-separation (1.′2 = 10,450 au) stellar companion, with an isochronal age of 31−10+22 Myr and a mass of 0.30−0.03+0.04 M ☉. Adopting this companion’s age and EDR3 distance (145.2 ± 0.6 pc), we estimate a mass of 0.11–0.17 M ☉ 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.