J/A+A/670/A13ivo://CDS.VizieR/J/A+A/670/A13doi:10.26093/cds/vizier.36700013CDSLiimets T.Kolka I.Kraus M.Eenmae T.Tuvikene T.Augusteijn T.,Antunes Amaral L.Djupvik A.A.Telting J.H.Deshev B.Kankare E.,Kankare J.Lindberg J.E.Amby T.M.Pursimo T.Somero A.Thygesen A.,Strom P.A.2024-11-06T20:02:29Z2023-01-27T09:48:12ZCDS support team

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

cds-question@unistra.frnovaeinfrared-photometryvisible-astronomybroad-band-photometryspectroscopyV838 Monocerotis is a peculiar binary that underwent an immense stellar explosion in 2002, leaving behind an expanding cool supergiant and a hot B3V companion. Five years after the outburst, the B3V companion disappeared from view, and so far did not recover. We investigate the changes in the light curve and spectral features to explain the behaviour of the V838 Mon during the current long-lasting minimum. A monitoring campaign has been performed during the past 13 years with the Nordic Optical Telescope to obtain optical photometric and spectroscopic data. The data sets are used to analyse the temporal evolution of the spectral features and the spectral energy distribution, and to characterise the object. Our photometric data show a steady brightening in all bands during the past 13 years, which is particularly prominent in the blue. This rise is also reflected in the spectra, showing a gradual relative increase in the continuum flux at shorter wavelengths. In addition, a slow brightening of the H{alpha} emission line starting in 2015 was detected. These changes might imply that the B3V companion is slowly reappearing. During the same time interval, our analysis reveals a considerable change in the observed colours of the object along with a steady decrease in the strength and width of molecular absorption bands in our low-resolution spectra. These changes suggest a rising temperature of the cool supergiant along with a weakening of its wind, most likely combined with a slow recovery of the secondary due to the evaporation of the dust and accretion of the material from the shell in which the hot companion is embedded. From our medium-resolution spectra, we find that the heliocentric radial velocity of the atomic absorption line of TiI 6556.06{AA} has been stable for more than a decade. We propose that Tii lines are tracing the velocity of the red supergiant in V838 Mon, and not representing the infalling matter as previously stated.2023A&A...670A..13Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/670/A13CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/PAZh/28/764 : UBVR photometry of Nova Mon 2002 (V838 Mon) (Goranskii+, 2002)J/ApJ/598/L43 : Polarimetry of V838 Mon and stars around (Wisniewski+, 2003)J/A+A/434/1107 : UBV(RI)c photometry of stars around V838 Mon (Munari+, 2005)J/AZh/84/147 : Light curves of V838 Mon and V4332 Sgr (Goranskii+, 2007)J/A+A/532/A138 : V838 Mon spectrum in 2009 (Tylenda+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/670/A13https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/670/A13http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/670/A13https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/670/A13https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/670/A13http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/670/A13GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap2.367228618189496e-19 6.118840631666147e-19OpticalInfrareddefaultJ/A+A/670/A13/table2Photometric data of V838 Mone_Vmag? Error of V-band magnitudemagstat.error;phot.magfloatnullableRmag? R-band magnitudemagphot.mag;em.opt.Rfloatnullablee_Rmag? Error of R-band magnitudemagstat.error;phot.magfloatnullableImag? I-band magnitudemagphot.mag;em.opt.Ifloatnullablee_Imag? Error of I-band magnitudemagstat.error;phot.magfloatnullableTelName of the telescope/instrument used (NOT, SAAO or TO)meta.id;instr.setupcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleUmag? U-band magnitudemagphot.mag;em.opt.Ufloatnullablee_Umag? Error of U-band magnitudemagstat.error;phot.magfloatnullableBmag? B-band magnitudemagphot.mag;em.opt.Bfloatnullablee_Bmag? Error of B-band magnitudemagstat.error;phot.magfloatnullableVmag? V-band magnitudemagphot.mag;em.opt.VfloatnullableJ/A+A/670/A13/table4Spectral measurementsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJDJulian Datedtime.epochdoubleV-IV-I colour indexmagphot.color;em.opt.V;em.opt.IfloatRd5737Relative depth of the 5737.703 linephot.flux.density;arith.ratiofloatEWB-X(1-0)Pseudo-equivalent width of the B-X(1-0)0.1nmspect.line.eqWidthfloatEWB-X(0-0)Pseudo-equivalent width of the B-X(0-0)0.1nmspect.line.eqWidthfloatJ/A+A/670/A13/listList of fits spectrarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNxNumber of pixels along X-axismeta.numberintObs.dateObservation datestime.epoch;obsnullableblambdaLower value of wavelength interval0.1nmem.wlintBlambdaUpper value of wavelength interval0.1nmem.wlfloatdlambdaWavelength resolution0.1nmspect.resolutionfloatsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitscharspShow the spectrummeta.ref.urlchar