NGC 1980 is not a foreground population of Orion

Min Fang, Jinyoung Serena Kim, Ilaria Pascucci, Daniel Apai, Lan Zhang, Aurora Sicilia-Aguilar, Miguel Alonso-Martinez, Carlos Eiroa, Hongchi Wang

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)


We perform a spectroscopic survey of the foreground population in Orion A with MMT/Hectospec. We use these data, along with archival spectroscopic data and photometric data, to derive spectral types, extinction values, and masses for 691 stars. Using the Spitzer Space Telescope data, we characterize the disk properties of these sources. We identify 37 new transition disk (TD) objects, one globally depleted disk candidate, and 7 probable young debris disks. We discover an object with a mass less than 0.018-0.030 M?, which harbors a flaring disk. Using the H? emission line, we characterize the accretion activity of the sources with disks, and confirm that fraction of accreting TDs is lower than that of optically thick disks (46� versus 73�, respectively). Using kinematic data from the Sloan Digital Sky Survey and APOGEE INfrared Spectroscopy of Young Nebulous Clusters program (IN-SYNC), we confirm that the foreground population shows similar kinematics to their local molecular clouds and other young stars in the same regions. Using the isochronal ages, we find that the foreground population has a median age around 1-2 Myr, which is similar to the one of other young stars in Orion A. Therefore, our results argue against the presence of a large and old foreground cluster in front of Orion A.
Original languageEnglish
Number of pages23
JournalAstronomical Journal
Issue number4
Publication statusPublished - 20 Mar 2017


  • Accretion, accretion disks
  • Planetary systems: protoplanetary disks
  • Stars: pre-main sequence


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