J/ApJ/741/94ivo://CDS.VizieR/J/ApJ/741/94doi:10.26093/cds/vizier.17410094CDSYung B.H.K.Nakashima J.-I.Imai H.Deguchi S.Diamond P.J.Kwok S.2013-05-08T04:22:18Z2013-04-17T14:46:22ZCDS support team

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

cds-question@unistra.frastrophysical-masersradio-astronomygiant-starsradio-sourcesWe report the results of multi-epoch Very Long Baseline Array observations of the 22.2GHz H_2_O maser emission associated with the "water fountain" IRAS 18286-0959. We suggest that this object is the second example of a highly collimated bipolar precessing outflow traced by H_2_O maser emission, the other is W 43A. The detected H_2_O emission peaks are distributed over a velocity range from -50km/s to 150km/s. The spatial distribution of over 70% of the identified maser features is found to be highly collimated along a spiral jet (jet 1) extended southeast to northwest; the remaining features appear to trace another spiral jet (jet 2) with a different orientation. The two jets form a "double-helix" pattern which lies across ~200mas. The maser distribution is reasonably fit by a model consisting of two bipolar precessing jets. The three-dimensional velocities of jet 1 and jet 2 are derived to be 138km/s and 99km/s, respectively. The precession period of jet 1 is about 56 years. For jet 2, three possible models are tested and they give different values for the kinematic parameters. We propose that the appearance of two jets is the result of a single driving source with significant proper motion.2011ApJ...741...94Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/741/94CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/416/1764 : H_2_O Southern Galactic Plane Survey (HOPS) (Walsh+, 2011)J/ApJ/669/424 : H2O maser emissions of IRAS 19134+2131 (Imai+, 2007)J/PASJ/59/1185 : Water maser in galactic IRAS sources (Sunada+, 2007)J/A+A/434/201 : The 35um absorption line towards 1612MHz masers (He+, 2005)J/A+A/366/481 : ATCA/VLA OH 1612 MHz survey. III. (Sevenster+, 2001)J/MNRAS/276/57 : IRAS Galactic star-forming regions. II. (Codella+ 1995)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/741/94https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/741/94http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/741/94https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/741/94https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/741/94http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/741/94GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/ApJ/741/94/table3*Coordinates of 54 H_2_O maser features that appear in any 3 consecutive epochs, selected from Table 2.recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintoRARight Ascension offset (G2)maspos.eq.ra;arith.diffdoubleoDEDeclination offset (G2)maspos.eq.dec;arith.diffdoubleIndex[1/3] Epoch index (3)meta.idintEp[A-F] Epoch maser feature found in (G1)time.epochcharJ/ApJ/741/94/table2Parameters of the brightest H_2_O maser spot from each detected maser feature in epoch A to F (see Section 3 for details)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEp[A-F] Epoch between 2008-04-21 and 2009-05-19 (G1)time.epochcharVLSRLocal Standard of Rest Velocity at intensity peakkm/sphys.veloc;pos.lsrfloatoRARight Ascension offset (G2)maspos.eq.ra;arith.difffloate_oRAUncertainty in oRA, from 2D Gaussian fittingmasstat.errorfloatoDEDeclination offset (G2)maspos.eq.dec;arith.difffloate_oDEUncertainty in oDE, from 2D Gaussian fittingmasstat.errorfloatIntH_2_O maser peak emission intensity; Jy/beamJyspect.line.intensityfloat