J/ApJ/878/111ivo://CDS.VizieR/J/ApJ/878/111doi:10.26093/cds/vizier.18780111CDSHerczeg G.J.Kuhn M.A.Zhou X.Hatchell J.Manara C.F.Johnstone D.,Dunham M.Bhardwaj A.Jose J.Yuan Z.2022-01-18T15:09:42Z2021-01-04T14:14:14ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.fropen-star-clustersproper-motionsvisible-astronomytrigonometric-parallaxphotometryThe 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 380-480pc; 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 600-700pc, and behind patchy extinction, here called the Serpens Cirrus, located at ~250pc. 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 ~5Myr. 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 20-100pc and the absence of an older population together lead to speculation that an external forcing was needed to trigger the active star formation.2019ApJ...878..111Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/878/111CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2015)I/345 : Gaia DR2 (Gaia Collaboration, 2018)VIII/64 : Westerhout's Catalogue of 82 Discrete Sources (Westerhout 1958)VII/20 : Catalogue of HII Regions (Sharpless 1959)VII/7 : Lynds' Catalogue of Dark Nebulae (LDN) (Lynds 1962)J/AJ/117/354 : OB associations from Hipparcos (de Zeeuw+, 1999)J/AJ/130/188 : Young stars in Trumpler 37 & NGC 7160 (Sicilia-Aguilar+, 2005)J/A+A/450/147 : IzJHKs photometry of Collinder 359 (Lodieu+, 2006)J/A+A/463/275 : Chandra obs. of Serpens star-forming region (Giardino+, 2007)J/ApJ/686/1195 : IR photometry in the {gamma} Vel cluster (Hernandez+, 2008)J/ApJ/688/377 : Low-mass objects in Upper Scorpius. II. (Slesnick+, 2008)J/A+A/519/A27 : CO maps in Serpens (Duarte-Cabral+, 2010)J/ApJ/725/2485 : X-rays from the star-forming complex W40 (Kuhn+, 2010)J/AJ/140/266 : NGC 1333 X-ray luminous YSOs properties (Winston+, 2010)J/PASJ/63/S1 : Atlas & catalog of dark clouds based on 2MASS (Dobashi+, 2011)J/ApJS/209/29 : MYStIX: Mid-IR observations and catalogs (Kuhn+, 2013)J/ApJ/779/113 : IR photometry of YSOs in the W40 region (Mallick+, 2013)J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)J/ApJ/787/109 : Age estimates for NGC 2024 and ONC stars (Getman+, 2014)J/ApJ/787/107 : Spatial structure of young stellar clusters. I. (Kuhn+, 2014)J/ApJS/213/1 : The MSFRs Omnibus X-ray Catalog (MOXC) (Townsley+, 2014)J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)J/AJ/149/103 : Spectroscopy of candidate YSOs in Serpens (Erickson+, 2015)J/ApJ/806/231 : MISFITS survey: HCO+ obs. of Spitzer YSOs (Heiderman+, 2015)J/A+A/584/A91 : Cat. of dense cores in Aquila from Herschel (Konyves+, 2015)J/MNRAS/448/1551 : JCMT Gould Belt Survey: Serpens MWC 297 (Rumble+, 2015)J/ApJ/822/49 : Cand. YSOs in AFGL 333 with NEWFIRM & Spitzer (Jose+, 2016)J/MNRAS/461/4022 : JCMT Gould Belt Survey: Southern Orion A (Mairs+, 2016)J/ApJS/229/28 : SFiNCs: X-ray, IR and membership catalogs (Getman+, 2017)J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)J/ApJ/867/151 : YSOs in Gould Belt regions with Gaia-DR2 data (Dzib+, 2018)J/AJ/156/84 : APOGEE-2 survey of Orion Complex. II. (Kounkel+, 2018)J/AJ/156/271 : The stellar membership of the Taurus SFR (Luhman, 2018)J/A+A/610/A64 : Distance to the clouds in Chamaeleon complex (Voirin+, 2018)J/AJ/155/241 : Chandra X-ray obs. of YSOs in Serpens South (Winston+, 2018)J/A+A/620/A172 : Solar neighbourhood young stars 3D mapping (Zari+, 2018)J/A+A/626/A17 : Young population in Vela-Puppis region (Cantat-Gaudin+, 2019)J/A+A/623/A112 : The Sco OB2 population from Gaia DR2 data (Damiani+, 2019)J/ApJ/870/32 : Kinematics in young star clusters & associations (Kuhn+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/878/111https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/878/111http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/878/111https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/878/111https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/878/111http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/878/111GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/878/111/table7 (High-probability candidate members of the Serpens Star-forming Region)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/878/111/table7?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/878/111/table7?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/878/111/table7?GETtext/xml+votable180.050000true289.6909910.803270.0055555555555555564/1890-1891 1896-1897 5/7389 7391 7413 7415 7554-7555 7558 7578 7592-7593 7596-7597 7600 7602 7608 6/29533-29535 29555 29561 29563 29649 29651 29685 30228 30238-30239 30304 30306-30307 30318 30377 30380-30381 30383 30392-30393 30395-30398 30404 30406 30412 30414 30440 30620-30621 30623https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/878/111?format=asciiOpticaldefaultJ/ApJ/878/111/table7High-probability candidate members of the Serpens Star-forming RegionrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaGaia DR2 identifier (1)meta.id;meta.mainRA_ICRS[272/290.6] Right Ascension (ICRS) at Ep=2015.5 (1)degpos.eq.ra;meta.mainDE_ICRS[-8/11.4] Declination (ICRS) at Ep=2015.5 (1)degpos.eq.dec;meta.mainpmRA[-0.52/5.48] Proper motion in right ascension direction (pmRA*cosDE) (1)mas/yrpos.pm;pos.eq.rafloatpmDE[-11.4/-5.3] Proper motion in declination direction (1)mas/yrpos.pm;pos.eq.decfloatPlx[1.8/3.2] Parallax (1)maspos.parallaxfloate_Plx[0.02/0.6] Uncertainty in Plx (1)masstat.error;pos.parallaxfloatGmag[5.3/19] G-band mean magnitude (1)magphot.mag;em.optfloatBpmag[6.2/21.8]? Integrated BP mean magnitude (1)magphot.mag;em.opt.BfloatnullableRpmag[4.5/18]? Integrated RP mean magnitude (1)magphot.mag;em.opt.Rfloatnullableepsi[0/2] Excess astrometric noise of the source (1)masstat.fit.paramfloatN7[0.04/1.3] 7th nearest spatial neighbordegpos.angDistancefloatNPM7[0.07/3.34] 7th nearest proper motion neighbormas/yrpos.pmfloatRegRegion (2)meta.notecharSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decnullableindexed