J/ApJ/930/114ivo://CDS.VizieR/J/ApJ/930/114doi:10.26093/cds/vizier.19300114CDSWenner N.Sarma A.P.Momjian E.2024-11-06T20:25:14Z2024-05-06T13:50:16ZCDS support team

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

cds-question@unistra.frastrophysical-masersradio-astronomystar-forming-regionsradio-sourcesastronomical-object-identificationHigh-mass stars play an important role in the interstellar medium, but much remains to be known about their formation. Class I methanol masers may be unique tracers of an early stage of high-mass star formation, and a better understanding of such masers will allow them to be used as more effective probes of the high-mass star-forming process. We present an investigation of the long-term variability of Class I methanol masers at 44GHz toward the high-mass star-forming region DR21(OH). We compare observations taken in 2017 to observations from 2012, and also to 2001 data from the literature. A total of 57 maser spots were found in the 2017 data, with center velocities ranging between -8.65 to +2.56km/s. The masers are arranged in a western and an eastern lobe with two arcs in each lobe that look like bow shocks, consistent with previous observations. The general trend is an increase in intensity from 2001 to 2012, and a decrease from 2012 to 2017. Variability appears to be more prevalent in the inner arc of the western lobe than in the outer arc. We speculate that this may be a consequence of episodic accretion, in which a later accretion event has resulted in ejection of material whose shock reached the inner arc at some point in time after 2001. We conclude that class I methanol masers are variable on long timescales (of the order of 5-10yr).2022ApJ...930..114Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/930/114CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/155/149 : CH_3_OH 7_0_-6_1_ A^+^ maser sources (Kurtz+, 2004)J/MNRAS/439/2584 : Southern methanol masers at 36 and 44GHz (Voronkov+, 2014)J/ApJ/854/170 : Methanol (CH_3_OH) and OH masers in NGC 6334I (Hunter+, 2018)J/ApJS/245/12 : 6.7GHz methanol masers & RRLs in MSX regions (Ouyang+, 2019)J/ApJS/248/18 : 44 and 95GHz obs. of class I methanol masers (Yang+, 2020)J/ApJS/256/7 : 18cm OH masers VLA obs. toward 80 SFRs (Bayandina+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/930/114https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/930/114http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/930/114https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/930/114https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/930/114http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/930/114GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/930/114/table2 (Fitted parameters of the observed 44GHz ClassI CH_3_OH masers in DR21(OH))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/930/114/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/930/114/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/930/114/table2?GETtext/xml+votable180.050000true309.743708342.38794440.005555555555555556Cone search capability for table J/ApJ/930/114/lit (Observed masers in DR21(OH) from Araya+ 2009ApJ...698.1321A (Table 5) and Momjian & Sarma 2017ApJ...834..168M (Table 6))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/930/114/lit?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/930/114/lit?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/930/114/lit?GETtext/xml+votable180.050000true309.744542.37280560.0055555555555555566/14704https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/930/114?format=asciiRadiodefaultJ/ApJ/930/114/table2Fitted parameters of the observed 44GHz ClassI CH_3_OH masers in DR21(OH)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintpIDDisplay the litterature data for the 2001 and 2012 observationsmeta.ref.urlcharID[1/57] Maser identifiermeta.id;meta.mainintprimarym_ID[a-d] Component identifier on the maser IDmeta.code.multipcharRAJ2000[20] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[42] Degree of declination (J2000)pos.eq.dec;meta.mainInt[0.09/278] IntensityJy/beamspect.line.intensityfloate_Int[0.01/9] Int uncertaintyJy/beamstat.errorfloatVel[-8.7/2.6] Center velocitykm/sphys.velocfloate_Vel[0.001/0.2] Vel uncertaintykm/sstat.errorfloatWidth[0.19/1.8] Velocity linewidthkm/sspect.line.widthfloate_Width[0.001/0.3] Width uncertaintykm/sstat.error;spect.line.widthfloatJ/ApJ/930/114/litObserved masers in DR21(OH) from Araya+ 2009ApJ...698.1321A (Table 5) and Momjian & Sarma 2017ApJ...834..168M (Table 6)NameMaser identifiermeta.id;meta.maincharID[2/56]? Corresponding 2017 masermeta.id.crossintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefA09=Araya+ 2009ApJ...698.1321A or MS17=Momjian & Sarma 2017ApJ...834..168Mmeta.bibcharm_Name[ab] Component identifier on the maser namemeta.code.multipcharRAJ2000[20] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[42] Degree of declination (J2000)pos.eq.dec;meta.mainm_ID[a-d] Component identifier on the 2017 maser IDmeta.code.multipcharInt[0.3/324]? Intensity (only for Table 6)Jy/beamspect.line.intensityfloatnullablee_Int[0.01/4]? Int uncertaintyJy/beamstat.errorfloatnullableVel[-2.4/2.6]? Center velocity (only for Table 6)km/sphys.velocfloatnullablee_Vel[0.001/0.2]? Vel uncertaintykm/sstat.errorfloatnullableWidth[0.2/0.8]? Velocity linewidth (only for Table 6)km/sspect.line.widthfloatnullablee_Width[0.001/0.2]? Width uncertaintykm/sstat.error;spect.line.widthfloatnullable