Accretion, kinematics, and rotation in the Orion Nebula cluster: Initial results from Hectochelle

Aurora Sicilia-Aguilar (Lead / Corresponding author), Lee W. Hartmann, Andrew H. Szentgyorgyi, Daniel G. Fabricant, Gabor Furesz, John Roll, Maureen A. Conroy, Nuria Calvet, Susan Tokarz, Jesus Hernandez

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Abstract

We present results from high-resolution spectra of 237 stars in the Orion Nebula cluster ( ONC) obtained during two engineering runs with the Hectochelle multifiber echelle spectrograph on the 6.5 m MMT. The ONC is the nearest populous young (age similar to1 Myr) cluster and is therefore an important object for studies of the evolution of protoplanetary disks. Using the high spectral resolution of Hectochelle, we are able to distinguish stellar accretion and wind emission-line profiles from nebular emission lines and identify accreting members of the cluster from Halpha profiles with greater accuracy than previously possible. We find 15 new members on the basis of Li lambda6707 absorption and Halpha emission. Line profiles of Halpha of some objects that are not too contaminated by nebular emission show features characteristic of mass inflow and ejection. We also present rotational velocities as part of an initial investigation into angular momentum evolution of very young stars, confirming a difference between classical T Tauri stars and weak-line T Tauri stars that had been found from period analysis. Finally, we present an initial study of the radial velocity dispersion of the brighter stars in the central cluster. The very small dispersion derived, less than or equal to1.8 km s(-1), is in good agreement with estimates from proper motions.
Original languageEnglish
Pages (from-to)363-381
Number of pages19
JournalAstronomical Journal
Volume129
Issue number1
DOIs
Publication statusPublished - 2005

Keywords

  • accretion, accretion disks line : profiles stars : pre-main-sequence stars : rotation T-TAURI STARS EMISSION-LINE DIAGNOSTICS MAIN-SEQUENCE STARS HERBIG-HARO OBJECTS LOW-MASS STARS MAGNETOSPHERIC ACCRETION CIRCUMSTELLAR DISKS TRAPEZIUM CLUSTER CONVERTED MMT YOUNG CLUSTERS

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    Sicilia-Aguilar, A., Hartmann, L. W., Szentgyorgyi, A. H., Fabricant, D. G., Furesz, G., Roll, J., Conroy, M. A., Calvet, N., Tokarz, S., & Hernandez, J. (2005). Accretion, kinematics, and rotation in the Orion Nebula cluster: Initial results from Hectochelle. Astronomical Journal, 129(1), 363-381. https://doi.org/10.1086/426327