On The Unusual Variability of 2MASS J06195260-2903592: A Long-Lived Disk around a Young Ultracool Dwarf

Michael C. Liu*, Eugene A. Magnier, Zhoujian Zhang, Eric Gaidos, Trent J. Dupuy, Pengyu Liu, Beth A. Biller, Johanna M. Vos, Katelyn N. Allers, Jason T. Hinkle, Benjamin J. Shappee, Sage N. L. Constantinou, Mitchell T. Dennis, Kenji S. Emerson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

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 (ΔAV ≈ 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 AV 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 AV ≈ 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 1022 Myr and a mass of -+0.30 0.030.04 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.
Original languageEnglish
Article number165
Pages (from-to)1-14
Number of pages14
JournalAstronomical Journal
Issue number4
Publication statusPublished - 28 Sept 2022

Keywords / Materials (for Non-textual outputs)

  • astro-ph.SR
  • astro-ph.EP


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