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Gaia stellar kinematics in the head of the Orion A cloud: runaway stellar groups and gravitational infall

Getman, K. V. and Feigelson, E. D. and Kuhn, M. A. and Garmire, G. P. (2019) Gaia stellar kinematics in the head of the Orion A cloud: runaway stellar groups and gravitational infall. Monthly Notices of the Royal Astronomical Society, 487 (3). pp. 2977-3000. ISSN 0035-8711. doi:10.1093/mnras/stz1457.

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This work extends previous kinematic studies of young stars in the head of the Orion A cloud (OMC-1/2/3/4/5). It is based on large samples of infrared, optical, and X-ray selected pre-main-sequence stars with reliable radial velocities and Gaia-derived parallaxes and proper motions. Stellar kinematic groups are identified assuming they mimic the motion of their parental gas. Several groups are found to have peculiar kinematics: the NGC 1977 cluster and two stellar groups in the extended Orion nebula (EON) cavity are caught in the act of departing their birthplaces. The abnormal motion of NGC 1977 may have been caused by a global hierarchical cloud collapse, feedback by massive Ori OB1ab stars, supersonic turbulence, cloud–cloud collision, and/or slingshot effect; the former two models are favoured by us. EON groups might have inherited anomalous motions of their parental cloudlets due to small-scale ‘rocket effects’ from nearby OB stars. We also identify sparse stellar groups to the east and west of Orion A that are drifting from the central region, possibly a slowly expanding halo of the Orion nebula cluster. We confirm previously reported findings of varying line-of-sight distances to different parts of the cloud’s Head with associated differences in gas velocity. 3D movies of star kinematics show contraction of the groups of stars in OMC-1 and global contraction of OMC-123 stars. Overall, the head of Orion A region exhibits complex motions consistent with theoretical models involving hierarchical gravitational collapse in (possibly turbulent) clouds with OB stellar feedback.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Getman, K. V.0000-0002-6137-8280
Feigelson, E. D.0000-0002-5077-6734
Kuhn, M. A.0000-0002-0631-7514
Garmire, G. P.0000-0002-7371-5416
Additional Information:© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2019 May 23. Received 2019 May 20; in original form 2019 January 23. Published: 27 May 2019. We thank the referee J. Alves for many useful suggestions that helped to improve this work. We thank J. Forbrich and T. Prusti for stimulating discussions. The MYStIX project is now supported by the Chandra archive grant AR7-18002X. The SFiNCs project is supported at Penn State by NASA grant NNX15AF42G, and the Chandra ACIS Team contract SV474018 (G. Garmire & L. Townsley, PI), issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. The Guaranteed Time Observations (GTO) data used here were selected by the ACIS Instrument Principal Investigator, Gordon P. Garmire, of the Huntingdon Institute for X-ray Astronomy, LLC, which is under contract to the Smithsonian Astrophysical Observatory; Contract SV2-82024. This research has used NASA’s Astrophysics Data System Bibliographic Services and SAOIMAGE DS9 software developed by Smithsonian Astrophysical Observatory. This work has made use of data from the European Space Agency (ESA) mission Gaia, processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
Funding AgencyGrant Number
Smithsonian Astrophysical ObservatorySV2-82024
Gaia Multilateral AgreementUNSPECIFIED
Subject Keywords:stars: early-type – stars: formation – stars: pre-main sequence – open clusters and associations: general – infrared: stars – X-rays: stars
Issue or Number:3
Record Number:CaltechAUTHORS:20190815-141439017
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Official Citation:K V Getman, E D Feigelson, M A Kuhn, G P Garmire, Gaia stellar kinematics in the head of the Orion A cloud: runaway stellar groups and gravitational infall, Monthly Notices of the Royal Astronomical Society, Volume 487, Issue 3, August 2019, Pages 2977–3000,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97930
Deposited By: Tony Diaz
Deposited On:15 Aug 2019 21:27
Last Modified:16 Nov 2021 17:35

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