J/ApJS/275/20ivo://CDS.VizieR/J/ApJS/275/20doi:10.26093/cds/vizier/bb-8k-mCDSLim J.-H.Kim J.Cho S.-H.Kim H.Yoon D.-H.Son S.-M.Suh K.-W.2026-08-03T07:25:41Z2025-11-19T09:14:25ZCDS support team

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

cds-question@unistra.frastrophysical-masersradio-astronomygiant-starsvariable-starsinterferometryWe present the results from long-term simultaneous monitoring observations of SiO and H2O masers toward the Mira variable star WX Serpentis. This study has been conducted with 21m single-dish radio telescopes of the Korean VLBI Network from 2009 June to 2021 June. Five maser lines were considered: SiO v=1,2, J=1-0; SiO v=1, J=2-1, 3-2; and H2O 6_1,6_-5_2,3_ transitions, with the SiO maser lines distributed near the stellar velocity and the H2O maser exhibiting an asymmetric line profile with five to six peaked components. Intense H2O maser emissions suddenly appeared in 2019 September, indicating flaring. The intensity variations of SiO and H2O masers are strongly correlated with the optical light curve (OLC) of the central star, with individual phase lags; the phase lag of the H2O maser relative to the OLC is larger than that of the SiO masers. The consequent phase difference between the SiO masers and the H2O maser likely indicates that their formation regions and main driving mechanisms are different from each other. The SiO masers in WX Ser exhibit a dominant single-peak velocity distribution, similar to other Mira variable stars. However, the H2O maser displays distinct morphological features, showing a radial acceleration and preferential intensity dominance at blueshifted velocities. This suggests that the H2O maser clouds of WX Ser are moving outward, thereby developing an asymmetric outflow owing to nonuniform material ejection from the stellar atmosphere. The findings confirm that an initial asymmetric outflow structure emerged during the thermally pulsing asymptotic giant branch phase, specifically in the Mira variable star stage.2024ApJS..275...20Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/275/20CatalogResearchIsServedByTAP VizieR generic servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/ApJS/165/360 : SiO maser emission toward 10 late-type stars (Kang+, 2006)J/ApJ/669/446 : Observations of SiO masers (Nakashima+, 2007)J/ApJS/190/203 : 3.6 years of DIRBE NIR stellar light curves (Price+, 2010)J/AJ/144/129 : Properties of 83 known stellar SiO maser sources (Cho+, 2012)J/AJ/145/22 : Simultaneous SiO and H2O maser observations (Kim+, 2013)J/A+A/565/A127 : SiO masers v=1,2,3 for 4 AGB (Desmurs+, 2014)J/AJ/147/22 : Simultaneous SiO and H2O maser observations. IV. (Kim+, 2014)J/A+A/644/A45 : R Crt and RT Vir Medicina spectra (Brand+, 2020)J/ApJS/253/44 : SiO maser emission in oxygen-rich stars (Rizzo+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/275/20https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/275/20http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/275/20https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/275/20https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/275/20http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/275/20GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapRadiodefaultJ/ApJS/275/20/table3Observational results of SiO transitionsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMaserMaser Line (G1)meta.id;spect.linecharEpoch[1/50] Epoch numbermeta.idintObsDateObservation date (UT)'Y:M:D'time.epoch;obsnullablePhase[0.18/10.6] Phasedtime.phasefloatSpeakPeak Flux density, S_{nu}_, list (1)Jyphot.flux.density;em.radioSnudnu[1.7/270.7]? Integral, S{nu}*d{nu}Jy.km.s**-1phot.flux.density;em.radiofloatnullablermsJ/ApJS/275/20/table4Observational results of the H2O maser linerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpoch[1/50] Epoch numbermeta.idintObsDateObservation date (UT)'Y:M:D'time.epoch;obsnullablePhase[0.18/10.6] Phasedtime.phasefloatSpeak-B4[0.8/44]? Peak Flux density, Blue-shifted Line, 4Jyphot.flux.density;em.radiofloatnullableSpeak-B3[0.7/4.5]? Peak Flux density, Blue-shifted Line, 3Jyphot.flux.density;em.radiofloatnullableSpeak-B2[0.8/121]? Peak Flux density, Blue-shifted Line, 2Jyphot.flux.density;em.radiofloatnullableSpeak-B1[0.7/26.4]? Peak Flux density, Blue-shifted Line, 1Jyphot.flux.density;em.radiofloatnullableSpeak-R1[1/29.3]? Peak Flux density, Red-shifted Line, 1Jyphot.flux.density;em.radiofloatnullableSpeak-R2[3/18.7]? Peak Flux density, Red-shifted Line, 2Jyphot.flux.density;em.radiofloatnullableSnudnu[4/224.6] Integral, S{nu}*d{nu}Jy.km.s**-1phot.flux.density;em.radiofloatrmsJ/ApJS/275/20/table6Maser intensity ratiosrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpochEpoch number (1)meta.idcharObsDateObservation date (UT)'Y:M:D'time.epoch;obsnullablePhase[0/1]? Optical Phase, normalizedtime.phasefloatnullableRatio1[0.09/2.8] Maser Intensity Ratio, I.F.(H2O)/I.F.(SiO43) (G1)phot.flux;arith.ratio;em.radiofloatRatio2[0.27/2.2] Maser Intensity Ratio, I.F.(SiO42)/I.F.(SiO43) (G1)phot.flux;arith.ratio;em.radiofloatRatio3[0.18/1.51]? Maser Intensity Ratio, I.F.(SiO86)/I.F.(SiO43) (G1)phot.flux;arith.ratio;em.radiofloatnullableRatio4[0.01/0.31]? Maser Intensity Ratio, I.F.(SiO129)/I.F.(SiO43) (G1)phot.flux;arith.ratio;em.radiofloatnullableRatio5[0.02/0.5]? Maser Intensity Ratio, I.F.(SiO129)/I.F.(SiO86) (G1)phot.flux;arith.ratio;em.radiofloatnullableJ/ApJS/275/20/table7Velocity extents of SiO and H2O maser linesVR-SiO43[9.2/17.4] Red velocity edge, SiO43 (G1)km.s**-1phys.veloc;em.radiofloatVB-SiO42[-4.0/3.5] Blue velocity edge, SiO42 (G1)km.s**-1phys.veloc;em.radiofloatVR-SiO42[8.4/15.2] Red velocity edge, SiO42 (G1)km.s**-1phys.veloc;em.radiofloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEpoch[1/50] Epoch numbermeta.idintObsDateObservation date (UT)'Y:M:D'time.epoch;obsnullablePhase[0.18/10.6] Phasedtime.phasefloatVB-SiO43[-3.1/2.6] Blue velocity edge, SiO43 (G1)km.s**-1phys.veloc;em.radiofloatVB-SiO86[-3.1/3.4]? Blue velocity edge, SiO86 (G1)km.s**-1phys.veloc;em.radiofloatnullableVR-SiO86[10.9/15.6]? Red velocity edge, SiO86 (G1)km.s**-1phys.veloc;em.radiofloatnullableVB-SiO129[0.3/5.1]? Blue velocity edge, SiO129 (G1)km.s**-1phys.veloc;em.radiofloatnullableVR-SiO129[7.9/14.6]? Red velocity edge, SiO129 (G1)km.s**-1phys.veloc;em.radiofloatnullableVB-H2O[-8.7/2.4] Blue velocity edge, H2O (G1)km.s**-1phys.veloc;em.radiofloatVR-H2O[9.2/16.6] Red velocity edge, H2O (G1)km.s**-1phys.veloc;em.radiofloat