Time-monitoring Observations of Br$\gamma$ Emission from Young Stars

Abstract

We present multiple epochs of near-IR spectroscopy for a sample of 25 young stars, including T Tauri, Herbig Ae/Be, and FU Ori objects. Using the FSPEC instrument on the Bok 90-inch telescope, we obtained K-band spectra of the BrGamma transition of hydrogen, with a resolution of ~3500. Epochs were taken over a span of >1 year, sampling time-spacings of roughly one day, one month, and one year. The majority of our targets show BrGamma emission, and in some cases these are the first published detections. Time-variability is seen in approximately half of the targets showing BrGamma emission. We compare the observed variability with expectations for rotationally-modulated accretion onto the central stars and time-variable continuum emission or extinction from matter in the inner disk. Our observations are not entirely consistent with models of rotationally-modulated magnetospheric accretion. Further monitoring, over a larger number of epochs, will facilitate more quantitative constraints on variability timescales and amplitudes, and a more conclusive comparison with theoretical models.

16 pages in emulateapj format. Accepted for publication in MNRAS

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• The Disk Substructures at High Angular Resolution Project (DSHARP): IV. Characterizing substructures and interactions in disks around multiple star systems
• A search for non-thermal radio emission from jets of massive young stellar objects
• Tracing Accretion onto Herbig Ae/Be Stars Using the Brγ Line
• ELT Imaging of MWC 297 from the 23-m LBTI: Complex Disk Structure and a Companion Candidate
• Evidence of Accretion Burst: The Viscously Heated Inner Disk of the Embedded Protostar IRAS 16316-1540