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An Initial Overview of the Extent and Structure of Recent Star Formation within the Serpens Molecular Cloud Using Gaia Data Release 2

Herczeg, Gregory J. and Kuhn, Michael A. and Zhou, Xingyu and Hatchell, Jennifer and Manara, Carlo F. and Johnstone, Doug and Dunham, Michael and Bhardwaj, Anupam and Jose, Jessy and Yuan, Zhen (2019) An Initial Overview of the Extent and Structure of Recent Star Formation within the Serpens Molecular Cloud Using Gaia Data Release 2. Astrophysical Journal, 878 (2). Art. No. 111. ISSN 1538-4357.

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The dense clusters within the Serpens Molecular Cloud are among the most active regions of nearby star formation. In this paper, we use Gaia DR2 parallaxes and proper motions to statistically measure ~1167 kinematic members of Serpens, few of which have been previously identified, to evaluate the star formation history of the complex. The optical members of Serpens are concentrated in three distinct groups located at 380–480 pc; the densest clusters are still highly obscured by optically thick dust and have few optical members. The total population of young stars and protostars in Serpens is at least 2000 stars, including past surveys that were most sensitive to protostars and disks, and may be much higher. Distances to dark clouds measured from deficits in star counts are consistent with the distances to the optical star clusters. The Serpens Molecular Cloud is seen in the foreground of the Aquila Rift, dark clouds located at 600–700 pc, and behind patchy extinction, here called the Serpens Cirrus, located at ~250 pc. Based on the lack of a distributed population of older stars, the star formation rate throughout the Serpens Molecular Cloud increased by at least a factor of 20 within the past ~5 Myr. The optically bright stars in Serpens Northeast are visible because their natal molecular cloud has been eroded, not because they were flung outwards from a central factory of star formation. The separation between subclusters of 20–100 pc and the absence of an older population together lead to speculation that an external forcing was needed to trigger the active star formation.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Herczeg, Gregory J.0000-0002-7154-6065
Kuhn, Michael A.0000-0002-0631-7514
Hatchell, Jennifer0000-0002-4870-2760
Manara, Carlo F.0000-0003-3562-262X
Johnstone, Doug0000-0002-6773-459X
Dunham, Michael0000-0003-0749-9505
Bhardwaj, Anupam0000-0001-6147-3360
Yuan, Zhen0000-0002-8129-5415
Additional Information:© 2019. The American Astronomical Society. Received 2018 December 22; revised 2019 April 8; accepted 2019 April 8; published 2019 June 19. We request that any citation to this paper also cite the primary papers that describe Gaia DR2 data, because our own work is at best a minimal intellectual contribution to understanding this region with Gaia. We thank the anonymous referee for clear, careful, and thoughtful comments, which have improved the quality of the paper. G.J.H. and M.K. thank Lynne Hillenbrand for discussions about Gaia and on the draft, including detailed suggestions for the figures and captions. G.J.H. also thanks Kaitlin Kratter for a discussion of star formation theory, James Lane for an initial discussion of extinction maps in comparison to Gaia star-count maps, Neal Evans for a discussion of L483, and Martin Smith for many discussions about Gaia. 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. This research has made use of the Spanish Virtual Observatory ( supported from the Spanish MINECO/FEDER through grant AyA2014-55216. G.J.H. is supported by general grants 11773002 and 11473005 awarded by the National Science Foundation of China. C.F.M. is supported by an ESO Fellowship. D.J. is supported by the National Research Council Canada and by an NSERC Discovery Grant. A.B. acknowledges the research grant #11850410434 awarded by the National Natural Science Foundation of China through a Research Fund for International Young Scientists and China post-doctoral General grant.
Funding AgencyGrant Number
Gaia Multilateral AgreementUNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)AyA2014-55216
Fondo Europeo de Desarrollo Regional (FEDER)UNSPECIFIED
National Natural Science Foundation of China11773002
National Natural Science Foundation of China11473005
European Southern Observatory (ESO)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
National Natural Science Foundation of China11850410434
Subject Keywords:open clusters and associations: general; planetary systems; protoplanetary disks; stars: low-mass; stars: pre-main sequence
Issue or Number:2
Record Number:CaltechAUTHORS:20190619-094200402
Persistent URL:
Official Citation:Gregory J. Herczeg et al 2019 ApJ 878 111
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96550
Deposited By: George Porter
Deposited On:19 Jun 2019 17:16
Last Modified:03 Oct 2019 21:23

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