IN-SYNC. IV. THE YOUNG STELLAR POPULATION IN THE ORION A MOLECULAR CLOUD

Nicola Da Rio, Jonathan C. Tan, Kevin R. Covey, Michiel Cottaar, Jonathan B. Foster, Nicholas C. Cullen, John J. Tobin, Jinyoung S. Kim, Michael R. Meyer, David L. Nidever, Keivan G. Stassun, S. Drew Chojnowski, Kevin M. Flaherty, Steve Majewski, Michael F. Skrutskie, Gail Zasowski, Kaike Pan

Research output: Contribution to journalArticlepeer-review

70 Scopus citations

Abstract

We present the results of the Sloan Digital Sky Survey APOGEE INfrared Spectroscopy of Young Nebulous Clusters program (IN-SYNC) survey of the Orion A molecular cloud. This survey obtained high-resolution nearinfrared spectroscopy of about 2700 young pre-main-sequence stars on a ∼6° field of view. We have measured accurate stellar parameters (Teff, log g, v sin i) and extinctions and placed the sources in the Hertzsprung-Russel diagram (HRD). We have also extracted radial velocities for the kinematic characterization of the population. We compare our measurements with literature results to assess the performance and accuracy of the survey. Source extinction shows evidence for dust grains that are larger than those in the diffuse interstellar medium: we estimate an average RV = 5.5 in the region. Importantly, we find a clear correlation between HRD inferred ages and spectroscopic surface-gravity-inferred ages and between extinction and disk presence; this strongly suggests a real spread of ages larger than a few Myr. Focusing on the young population around NGC 1980/ι Ori, which has previously been suggested to be a separate, foreground, older cluster, we confirm its older (∼5 Myr) age and low AV, but considering that its radial velocity distribution is indistinguishable from Orion A's population, we suggest that NGC 1980 is part of Orion A's star formation activity. Based on their stellar parameters and kinematic properties, we identify 383 new candidate members of Orion A, most of which are diskless sources in areas of the region poorly studied by previous works.

Original languageEnglish (US)
Article number59
JournalAstrophysical Journal
Volume818
Issue number1
DOIs
StatePublished - Feb 10 2016
Externally publishedYes

Keywords

  • open clusters and associations: individual (Orion Nebula Cluster, L1641)
  • stars: formation
  • stars: kinematics and dynamics
  • stars: pre-main sequence

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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