PoS(11th EVN Symposium)040 ± 40 . http://pos.sissa.it/ ,H.J.van g c ce. asingledistanceof1 and 22 GHz water masers ttobepartofCygnusX,was ,M.J.Reid b ected region of star formation or on. We found that the distances ion by improving the accuracy of tions of five star forming regions, these EVN+Japan observations. the long baselines between the EVN tworthy distance measurements. With ,andK.Fujisawa ntheskyhasbeendebatedfordecades. d Dwingeloo, the Netherlands 11kpc, beyond the Cygnus X region. In tory of Japan (NAOJ), 2-21-1 , . eet, Cambridge, MA 02138, USA ügel 69, 53121 Bonn, Germany f 0 RA Leiden, the Netherlands Yamaguchi 753-8512, Japan ± ), Via del fosso del cavaliere 100, 33 . ,K.M.Menten b ive Commons Attribution-NonCommercial-ShareAlike Licen ,A.Sanna b ,K.J.E.Torstensson e ,M.Honma ,A.Brunthaler f a , ∗ d [email protected] 08 kpc for the Cygnus X complex. AFGL 2591, previously though . Speaker. our individual distances measurements through the focus on and the Japanese stations and the addition of another year of the future we plan to study the 3D structure of the Cygnus X reg with Very Long Baseline Array,of we W tried 75N, to DR 20, answer DR 21, this and questi IRAS 20290+4052 are consistent with Whether the Cygnus X complex consistsof of multiple independent one regions projected physically close conn together o The main reason for this puzzling scenario isthe the lack measurements of trus of trigonometric parallaxesusing and 6.7 proper GHz mo methanol masers with the European VLBI Network 0 found to be located at a much greater distance of 3 ∗ Copyright owned by the author(s) under the terms of the Creat Max-Planck-Institut für Radiostronomie (MPIfR), Auf dem H Joint Institute for VLBI in Europe (JIVE), Postbus 2, 7990 AA Harvard Smithsonian Center for Astrophysics, 60 Garden Str Mizusawa VLBI Observatory, National Astronomical Observa c toward the Cygnus X star-forming complex K. L. J. Rygl Parallaxes and proper motions of interstellar masers ! Langevelde 11th European VLBI Network Symposium & UsersOctober Meeting, 9-12, 2012 Bordeaux, France Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS 00133 Roma, Italy Osawa, Mitaka, Tokyo 181-8588, Japan Sterrewacht Leiden, Leiden University, Postbus 9513, 2300 Faculty of Science,E-mail: Yamaguchi University, 1677-1 Yoshida, f c e a b g d PoS(11th EVN Symposium)040 = ) b , l ( remnants geodetic- 2009 and K. L. J. Rygl ,andasouth- ◦ m. Water maser emission GHz water masers as as- µ ar-formation activity in the han about 80 dDR21inCygnusXNorth, in [18] already demonstrated ship of the Cygnus X region, iation, see [12],[14], hereafter r-forming regions have a small eCygOB2clusterat AFGL 2591, which is projected than the extent of the Cygnus X masers toward four star-forming ttowardthisregion.Usingthe sbeenalong-standingissue.Itis 12 hours and made use of thin the Galaxy, are not trustworthy nus X structure. sobservedtowardfourstar-forming on of interstellar gas in a high-mass ys at each antenna (see [15], [2], [16] ocity difference between the Sun and ood as 22 ed (IR) emission in our Galaxy ([13]; sty cores with embedded protoclusters ance of 1.5 kpc). Kinematic distances, ng). All phases of star formation and whether we see a projection of several 1.2 and 1.7 kpc, a difference of more Xregion,includingalargenumberof ed discussion). For example, three OB -forming regions toward the Cygnus X inese, South African, and other radio astronomy ing complex acompact HII regions ([4], [25]), hundreds 2 ,[10]). 1 − 65 O-type; [26] and references therein), and some supernova ∼ observations were carried out in eight epochs between March 1 80) into a northern region, at Galactic longitudes greater t ◦ . 0 + , The European VLBI Network is a joint facility of European, Ch The Cygnus X region is one of the most pronounced regions of st The 6.7 GHz EVN In this context, we used strong 6.7 GHz methanol masers and 22 The distance to this remarkable ”mini-starburst” region ha 22 observing blocks to calibrate the tropospheric zenith dela 1 ◦ . and IRAS 20290+4052 (which isIRAS likely 20290) part in of Cygnus the X Cygthe South. capability OB 2 of assoc the The EVN pioneering to work achieve parallax presented accuracies as g ern region, at lower longitudes.regions Methanol with the maser European emission VLBI wa Network (EVN): W 75N, DR 20, an (80 molecular clouds [21] a population of dense, massive,and and high-mass du protostellar objects ([23],of [1], OB-type [11]), stars (of ultr which Galactic plane and stands out assee a prominent e.g., source the of infrar spectacularstellar Spitzer evolution [8] are and observed Herschel projected [6] across imagi the Cygnus Parallaxes and proper motions toward the1. Cygnus Introduction X star-form for a detailed discussion).regions: We W 75N, observed IRAS the 20290, 6.7 DR20, and GHz DR21. methanol Because these sta institutes funded by their national research councils. complex. No previousterminology parallax of measurements [21], were the carried Cygnus ou X complex is divided about th at the Galactic longitude ofthe Cygnus X, Cygnus because X the region radial isstar-forming vel region close (1–7 to km s the typical velocity dispersi trometric targets to measure distances of five distinct star still not clear whether allclouds clouds are at at different the distances same (see distanceassociations [21] or have and photometric [24] distance forthan a estimates 30%. detail between This uncertaintyregion of on the 500 sky pc (i.e., is withinthe a almost radius most 10 of common times about distance 50 larger method pc for at a estimating dist distances wi [24]. published in [19] and lay out our future plans to study the2. Cyg Observations and data reduction was observed with the Very Longwithin Baseline Cygnus Array X (VLBA) South. toward Here, we present the work on the member November 2010 under project EB039. Each observationlike lasted PoS(11th EVN Symposium)040 in or 2 with nge from 3degree). . K. L. J. Rygl 4 ,thevelocity )itsphysical b ≤ U kc3.InFig.2, 3kpc[3]. . 8 transferred to the other out with the VLBA = R much farther distance than otheCygnusOB2associa- ng regions (see Table 1) and ogram BM272H. These obser- ocal standard of rest velocity of ulated the 3D space velocities of ystem (AIPS) and ParselTongue expanding Strömgren sphere (e.g., ngular separations urces. The VLBA calibration was P). In the calculation of the space tion. nd the parallax and proper motion xofstar-formingregions,including ic plane (Fig. 1) and ( ming regions, but we also draw their rvations by fast-switching (every 30 velocity components: complex is similar to the photometric ce for these sources, within measure- ](again,moreobservationdetailscan ]andassumedaflatGalacticrotation softheCygnusXstar-formingregions r[17](Table1),whichcan,forexample, ing complex eNationalScienceFoundationoperatedundercoop- region nor any other large-scale organized II 3 and seem to have no particular orientation. More 1 − )AFGL2591isnotpartofasingleCygnusXcomplex, ,thevelocityinthedirectionoftheGalacticrotation;and a V blocks for calibrating the zenith delays at each antenna. As and a solar distance to the Galactic center kpc. This is an average of the individual distances, which ra 1 1degree)wecouldusethemasersinW75Nasaphasereferencef − . 08 08 . . 2 0 0 geodetic-like + − ≤ 40 . 239km s = using a switching cycle of 1.5 minutes and the solutions were θ 1 − The National Radio Astronomy Observatory is a facility of th The 22 GHz water maser observations of AFGL 2591 were carried We obtained parallaxes and proper motions to five star-formi AFGL 2591, projected against the Cygnus X South region, has a With the parallax and averaged proper motion results we calc 2 ,thevelocityinthedirectionoftheNorthGalacticPole(NG we show not only the distance resultsprojected of space the motion. Cygnus X One star-for can seehave that magnitudes the space between velocitie 0 up to 10 km s Parallaxes and proper motions toward theangular Cygnus separation X ( star-form erative agreement by Associated Universities, Inc. specifically, they do not remind of an expanding H the whole maser emission and the three background sources (a analysis can be found in [18] and in [19]. targets. We used the[7] NRAO’s Astronomical for reducing Image the Processing EVN S data, more details on the reduction a Hence, the data were phase-referenced7.1 to km the s W 75N maser at a l found that Cygnus X North isW75N,DR21,DR20,andIRAS20290(andthereforeprobablyals one physically connected comple tion), located at 1 seconds) between the maser andcarried each out of in the AIPS four following background thebe so procedure found described in in [19]). [16 3. Membership of the Cygnus X region the EVN observations, we performed phase-referencing obse as can be seen clearly when plotting the sources on the Galact 1.30 to 1.50 kpc. Ourment data uncertainty. are Furthermore, our consistent distance with to a thedistance Cygnus single of X distan 1.5 kpc obtained by [5] toward the Cyg OB 2previously associa assumed. This implies that ( four epochs between November 2008vations and November included 2009 under four pr [9]). A 3D space velocity vector is decomposed in three space properties change dramatically (discussed in [20]). the star-forming regions with respect tobe the used Galactic to explore cente if the Cygnus X region was formed through an in the direction of the Galactic center; velocities we used thecurve solar with peculiar motion obtained by [22 W PoS(11th EVN Symposium)040 3 8 3 1 3 . . . . . ) 4 0 1 2 1 1 − ± ± ± ± ± 1 2 6 0 1 . . . . . 22 − 51 5 56 56 55 . . . . . )(kms 2 2 2 2 2 1 K. L. J. Rygl − ± ± ± ± ± 6 4 3 2 8 . . . . . 8 8 8 10 − − − − us X 03 5 8 5 4 . . . . . )(kms 1 1 1 1 3 1 − ± ± ± ± ± 5 0 9 5 8 UVW . . . . . 0 0 12 − − − wo year of EVN-only data; the mplex, clearly has very different asurements in Table 1 allowed to allow us to study its 3D structure, R. Hurt, NASA/JPL-Caltech/SSC) as oved to be more challenging since )(kms 15 22 12 54 1 26 7 tions using the EVN plus a Japanese 1 ques to exploit the extra angular res- . . . . . 0 0 0 0 0 − > ack dot. Sources with known distances are δ ions from this work, red dots are from the verlapping. To improve our distance ac- ± ± ± ± ± ot shown) located at (0,0) kpc. The Sun is µ ing complex 16 80 80 14 83 . . . . . 4 3 4 4 4 − − − − − und in the caption of Fig. 11 of [19]. 4 )(masyr 10 15 32 09 13 1 . . . . . 0 0 0 0 0 >< − α ± ± ± ± ± µ 97 84 20 84 29 . . . . . < 1 2 1 2 3 − − − − − vector is an order of magnitude larger). 07 07 08 07 11 11 12 11 09 08 ...... 0 0 0 0 0 0 0 0 0 0 W + − + − + − + − + − Sun 30 33 36 50 46 . . . . . Parallax, proper motions, and space velocities toward Cygn 042 1 010 3 062 1 035 1 038 1 . . . . . 0 0 0 0 0 ± ± ± ± ± (mas) (kpc) (mas yr 772 300 666 737 687 Table 1: . . . . . An artist’s impression of the Galactic plane (image credit: The results presented in the previous section were based on t SourceW75N Parallax 0 D DR 21 0 AFGL 2591 0 IRAS 20290 0 DR 20 0 antenna (program ER026) and will try other reduction techni calibration of the longmasers (9000 spots km) can Europe-Japan be resolvedestablish baselines at the pr these membership baselines. of thesince While Cygnus the our X distance region, me errors of they the didcuracy star-forming not we regions conducted were another o four epochs of parallax observa space motions (in particular, the 4. Structure of the Cygnus X region seen from the Northlocated Galactic at Pole (0, with 8.3) the kpcmarked and Galactic by marked center colored by (n dots: a blackliterature. green circle The dots around full show list a the of bl star-forming literature references reg can be fo structure. Also, AFGL 2591 which is not part of the Cygnus X co Figure 1: Parallaxes and proper motions toward the Cygnus X star-form PoS(11th EVN Symposium)040 kpc 12 11 . . 0 0 + − 36 K. L. J. Rygl . 08 kpc for the . 0 ± 40 . s(inkpc)andtheresulting mostly to Cygnus X North. kpc for DR 21, 1 nce than previously assumed. essary to have parallaxes and tend the 11th EVN Symposium us X region to establish if indi- nce of 1 08 07 . . BA. We report the following dis- 0 0 h. For the moment, at least one + − ymorewillcomeinthefuture. do not suggest an expanding Ström- 50 plex, based on 6.7 GHz methanol and . nes. With the increased accuracy we gregionsalongthelineofsight. ing complex 5 kpc for DR 20, 1 09 08 . . 0 0 + − kpc for AFGL 2591. While the distances of W 75N, DR 20, 46 11 11 . . . 0 0 + − 33 . mmapoftheCygnusXregionoverlaidwiththedistanceresult kpc for W 75N, 1 µ 07 07 . . 0 0 + − 30 MSX 8 . We have presented our first astrometric study toward the Cygn The Cygnus X sources covered with the EVN in this study belong KLJR thanks Radionet 3 which provided financial support to at Figure 2: Parallaxes and proper motions toward the Cygnus X star-form 22 GHz water maser parallaxes obtainedtances: with the 1 EVN and the VL source, S106 is covered by the BeSSeL survey [3] and hopefull 5. Summary vidual molecular clouds belong to the same star-forming com olution provided by the additionwant to of understand the the Europe-Japan relative baseli position of the star-formin For understanding more ofproper the motions Cygnus toward X star-forming complex, regions it in will Cygnus be X nec Sout space motions projected on the image (arrows). for IRAS 20290+4052, and 3 DR 21, and IRAS 20290+4052 are consistent with a single dista The space velocities of the star-forminggren regions in sphere. 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