An Association in the Aquila Star‐forming Region: High‐Resolution Infrared Spectroscopy of T Tauri Stars

We present the properties of a group of young stars associated with thewell-studied T Tauri star system AS 353, located in the Aquila star-formingregion. The association is identified using radial velocity measurements ofsample objects selected from the Herbig and Bell Catalog based on their spatialproximity to AS 353. Radial velocities of nine objects were measured frommulti-epoch high-resolution (R~30,000) H-band spectra obtained with NIRSPEC onKeck II. High-resolution K-band spectra were also obtained for most of thesample objects. Spectral types and rotational velocities are determined for allobjects in the sample. The multi-epoch H-band spectra were examined for radialvelocity variations in order to detect possible spectroscopic binaries. Eightof the nine objects have radial velocities that are consistent within the1-sigma scatter of the sample. From their mean of -8.6 km/s these eight objectshave a standard deviation of 2 km/s, which suggests that the sample stars arerelated. The ninth object shows significant radial velocity variations betweenepochs, characteristic of a spectroscopic binary. The overall multiplicity ofthe sample is high; we observed 13 stars in seven systems, identifying threenew candidate binary components in this project. Many of the spectra revealhydrogen emission lines typical of strong accretion processes, indicating thatmost of these objects harbor circumstellar disks and are less than a fewmillion years old. We discuss possible interpretations of the enigmatic pureemission line spectrum of HBC 684. This work represents the highest spectralresolution infrared observations to date of these intriguing, nearby youngstars.Comment: 7 figures, accepted to Astrophysical Journa