J/A+A/666/A47ivo://CDS.VizieR/J/A+A/666/A47doi:10.26093/cds/vizier.36660047CDSZhang Y.Snellen I.A.G.Wyttenbach A.Nielsen L.D.Lendl M.,Casasayas-Barris N.Chaverot G.Kesseli A.Y.Lovis C.Pepe F.A.,Psaridi A.Seidel J.V.Udry S.Ulmer-Moll S.2022-10-10T15:05:22Z2022-10-04T09:35:43ZCDS support team

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

cds-question@unistra.frmultiple-starsexoplanetsphotometryvisible-astronomyradial-velocityUltra-hot Jupiters (UHJs), rendering the hottest planetary atmospheres, offer great opportunities of detailed characterisation with high-resolution spectroscopy. The extremely irradiated atmospheres are interesting laboratories for studying the mass loss through hydrodynamic escapes. MASCARA-4 b is a recently discovered close-in gas giant belonging to this category. We aim to characterise the UHJ MASCARA-4 b in detail, in particular searching for chemical species in its atmosphere and put these in the context of the growing knowledge on the atmospheric properties of UHJs. In order to refine the planet mass, we took high-resolution spectra of MASCARA-4 with the CORALIE spectrograph at the Swiss 1.2m Euler telescope, and extracted radial velocity measurements. We observed two transits of MASCARA-4 b with the high-resolution spectrograph ESPRESSO at ESO's Very Large Telescope. Simultaneous photometry was carried out with EulerCam installed at the Euler telescope to deliver updated system and planet parameters. We searched for atomic, ionic, and molecular species via individual absorption lines and cross-correlation techniques. These results are compared to literature studies on UHJs characterised to date. With CORALIE and EulerCam observations, we updated the mass of MASCARA-4 b (1.675+/-0.241 Jupiter masses) as well as other system and planet parameters. In the transmission spectrum derived from ESPRESSO observations, we resolve excess absorption by H{alpha}, H{beta}, NaI D1&D2, CaII H&K, and a few strong individual lines of MgI, FeI and FeII. We also present the cross-correlation detection of MgI, CaI, CrI, FeI and FeII. The absorption strength of FeIi significantly exceeds the prediction from a hydrostatic atmospheric model, which is also commonly observed in other UHJs. We attribute this to the presence of FeII in the exosphere as a consequence of hydrodynamic outflows. This is further supported by the positive correlation of absorption strengths of FeII with the H{alpha} line, which is expected to probe the extended upper atmospheres and the mass loss process. Comparing transmission signatures of various species in the UHJ population allows us to disentangle the hydrostatic regime (as traced via the absorption by MgI and FeI) from the exospheres (as probed by H{alpha} and FeII) of the strongly irradiated atmospheres.2022A&A...666A..47Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/666/A47CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/666/A47https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/666/A47http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/666/A47https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/666/A47https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/666/A47http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/666/A47GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/666/A47/photMASCARA-4 transit photometry with EulerCamrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date in the Barycentric Dynamical Time (BJD-2450000)dtime.epochdoubleFluxNormalized Fluxphot.flux;arith.ratiodoublee_FluxNormalized Flux errorstat.error;phot.fluxdoubleJ/A+A/666/A47/rvMASCARA-4 radial velocities measured with CORALIErecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date ((BJD-2400000)dtime.epochdoubleRVBarycentric Radial Velocitykm/sphys.veloc;pos.barycenterdoublee_RVRadial Velocity errorkm/sstat.errordouble