J/ApJ/909/138ivo://CDS.VizieR/J/ApJ/909/138doi:10.26093/cds/vizier.19090138CDSVega L.D.Stassun K.G.Montez R.Kaminski T.Sabin L.Schlegel E.M.,Vlemmings W.H.T.Kastner J.H.Ramstedt S.Boyd P.T.2022-09-14T06:11:15Z2022-09-12T11:31:11ZCDS support team

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

cds-question@unistra.frgiant-starsmultiple-starsvisible-astronomybroad-band-photometryWe present an X-ray through submillimeter observations of the classical RV Tauri (RVb-type) variable U Mon, a post-asymptotic giant branch (AGB) binary with a circumbinary disk (CBD). Our SMA observations indicate a CBD diameter of <~550au. Our XMM-Newton observations make U Mon the first RV Tauri variable detected in X-rays. The X-ray emission is characteristic of a hot plasma (~10MK), with L_X_=5x10^30^erg/s, and we consider its possible origin from U Mon, its companion, and/or binary system interactions. Combining DASCH and AAVSO data, we extend the time-series photometric baseline back to the late 1880s and find evidence that U Mon has secular changes that appear to recur on a timescale of ~60yr, possibly caused by a feature in the CBD. From literature radial velocities we find that the binary companion is a ~2M_{sun}_ A-type main-sequence star. The orientation of the binary's orbit lies along our line of sight ({omega}=95{deg}), such that apastron corresponds to photometric RVb minima, consistent with the post-AGB star becoming obscured by the near side of the CBD. In addition, we find the size of the inner-CBD hole (~4.5-9au) to be comparable to the binary separation, implying that one or both stars may interact with the CBD at apastron. The obscuration of the post-AGB star implicates the companion as the likely source of the enhanced H{alpha} observed at RVb minima and of the X-ray emission that may arise from accreted material.2021ApJ...909..138Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/909/138CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/MNRAS/376/313 : Carbon star in Magellanic Cloud (Groenewegen+, 2007)J/A+A/506/1277 : Modelisation of MCs C/O stars (Groenewegen+, 2009)J/A+A/513/A53 : LABOCA 870um images of evolved stars (Ladjal+, 2010)J/ApJS/194/7 : X-ray properties of O and B stars in Carina (Naze+, 2011)J/A+A/557/A104 : CO observations of post-AGB stars (Bujarrabal+, 2013)J/MNRAS/453/133 : WISE view of RV Tauri stars (Gezer+, 2015)J/A+A/607/A60 : BD+46 442 optical spectra (Bollen+, 2017)J/A+A/604/A29 : MC Type II & anomalous Cepheids PL & PR (Groenewegen+, 2017)J/A+A/599/A85 : Structure of Herbig AeBe disks at mas scale (Lazareff+, 2017)J/A+A/597/A129 : Galactic RV Tauri stars velocities (Manick+, 2017)J/AcA/67/297 : OGLE Galactic center Cepheids and RR Lyrae (Soszynski+, 2017)J/A+A/620/A85 : Binary post-AGB stars radial velocities (Oomen+, 2018)J/A+A/631/A53 : 1-D optical spectra for IRAS19135+3937 (Bollen+, 2019)J/A+A/631/A108 : Disks around post-AGB binaries fit results (Kluska+, 2019)http://dasch.rc.fas.harvard.edu/lightcurve.php : DASCH lightcurve home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/909/138https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/909/138http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/909/138https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/909/138https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/909/138http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/909/138GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/909/138/fig2AAVSO + DASCH light curve of U MonrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Day of observation (1)dtime.epoch;obsdoubleFlux[1.58e+6/6e+7] Arbitrary flux (2)phot.flux;arith.ratiodoubleRefAAVSO or DASCH catalogmeta.id;meta.datasetchar