TY - JOUR
T1 - The APOGEE-2 Survey of the Orion Star-forming Complex. II. Six-dimensional Structure
AU - Kounkel, Marina
AU - Covey, Kevin
AU - Suárez, Genaro
AU - Román-Zúñiga, Carlos
AU - Hernandez, Jesus
AU - Stassun, Keivan
AU - Jaehnig, Karl O.
AU - Feigelson, Eric D.
AU - Ramírez, Karla Peña
AU - Roman-Lopes, Alexandre
AU - Rio, Nicola Da
AU - Stringfellow, Guy S.
AU - Kim, J. Serena
AU - Borissova, Jura
AU - Fernández-Trincado, José G.
AU - Burgasser, Adam
AU - García-Hernández, D. A.
AU - Zamora, Olga
AU - Pan, Kaike
AU - Nitschelm, Christian
N1 - Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.
PY - 2018/9
Y1 - 2018/9
N2 - We present an analysis of spectroscopic and astrometric data from APOGEE-2 and Gaia DR2 to identify structures toward the Orion Complex. By applying a hierarchical clustering algorithm to the six-dimensional stellar data, we identify spatially and/or kinematically distinct groups of young stellar objects with ages ranging from 1 to 12 Myr. We also investigate the star-forming history within the Orion Complex and identify peculiar subclusters. With this method we reconstruct the older populations in the regions that are currently largely devoid of molecular gas, such as Orion C (which includes the σ Ori cluster) and Orion D (the population that traces Ori OB1a, OB1b, and Orion X). We report on the distances, kinematics, and ages of the groups within the Complex. The Orion D group is in the process of expanding. On the other hand, Orion B is still in the process of contraction. In λ Ori the proper motions are consistent with a radial expansion due to an explosion from a supernova; the traceback age from the expansion exceeds the age of the youngest stars formed near the outer edges of the region, and their formation would have been triggered when they were halfway from the cluster center to their current positions. We also present a comparison between the parallax and proper-motion solutions obtained by Gaia DR2 and those obtained toward star-forming regions by the Very Long Baseline Array.
AB - We present an analysis of spectroscopic and astrometric data from APOGEE-2 and Gaia DR2 to identify structures toward the Orion Complex. By applying a hierarchical clustering algorithm to the six-dimensional stellar data, we identify spatially and/or kinematically distinct groups of young stellar objects with ages ranging from 1 to 12 Myr. We also investigate the star-forming history within the Orion Complex and identify peculiar subclusters. With this method we reconstruct the older populations in the regions that are currently largely devoid of molecular gas, such as Orion C (which includes the σ Ori cluster) and Orion D (the population that traces Ori OB1a, OB1b, and Orion X). We report on the distances, kinematics, and ages of the groups within the Complex. The Orion D group is in the process of expanding. On the other hand, Orion B is still in the process of contraction. In λ Ori the proper motions are consistent with a radial expansion due to an explosion from a supernova; the traceback age from the expansion exceeds the age of the youngest stars formed near the outer edges of the region, and their formation would have been triggered when they were halfway from the cluster center to their current positions. We also present a comparison between the parallax and proper-motion solutions obtained by Gaia DR2 and those obtained toward star-forming regions by the Very Long Baseline Array.
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U2 - 10.3847/1538-3881/aad1f1
DO - 10.3847/1538-3881/aad1f1
M3 - Article
AN - SCOPUS:85053112607
SN - 0004-6256
VL - 156
JO - Astronomical Journal
JF - Astronomical Journal
IS - 3
M1 - 84
ER -