J/AJ/163/67ivo://CDS.VizieR/J/AJ/163/67doi:10.26093/cds/vizier.51630067CDSZhang M.Knutson H.A.Wang L.Dai F.Barragan O.2022-06-13T11:26:42Z2022-05-20T06:31:29ZCDS support team

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

cds-question@unistra.frk-starsexoplanetsspectroscopyultraviolet-astronomyvisible-astronomyinfrared-astronomyx-ray-sourcesWe report helium absorption from the escaping atmosphere of TOI560.01 (HD73583b), an R=2.8R{Earth}, P=6.4day mini-Neptune orbiting a young (~600Myr) K-dwarf. Using Keck/NIRSPEC, we detect a signal with an average depth of 0.68%{+/-}0.08% in the line core. The absorption signal repeats during a partial transit obtained a month later, but is marginally stronger and bluer, perhaps reflecting changes in the stellar wind environment. Ingress occurs on time, and egress occurs within 12 minutes of the white light egress, although absorption rises more gradually than it declines. This suggests that the outflow is slightly asymmetric and confined to regions close to the planet. The absorption signal also exhibits a slight 4km/s redshift rather than the expected blueshift; this might be explained if the planet has a modest orbital eccentricity, although the radial velocity data disfavors such an explanation. We use XMM-Newton observations to reconstruct the high-energy stellar spectrum and model the planet's outflow with 1D and 3D hydrodynamic simulations. We find that our models generally overpredict the measured magnitude of the absorption during transit, the size of the blueshift, or both. Increasing the metallicity to 100x solar suppresses the signal, but the dependence of the predicted signal strength on metallicity is non-monotonic. Decreasing the assumed stellar EUV flux by a factor of three likewise suppresses the signal substantially.2022AJ....163...67Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/163/67CatalogResearchIsServedByTAP VizieR generic servicerelated-toI/196 : Hipparcos Input Catalogue, Version 2 (Turon+ 1993)J/ApJ/687/1264 : Age estimation for solar-type dwarfs (Mamajek+, 2008)J/MNRAS/441/2361 : Stellar magnetism, age and rotation (Vidotto+, 2014)J/A+A/576/A21 : The PLUTO CLOUDY Interface (TPCI) (Salz+, 2015)J/A+A/586/A75 : Simulations of hot gas planets atmospheres (Salz+, 2016)J/ApJ/834/17 : Mass & radius of planets, moons, low mass stars (Chen+, 2017)J/AJ/154/109 : California-Kepler Survey. III. Planet radii (Fulton+, 2017)J/A+A/601/A10 : A grid of MARCS model atmospheres for S stars (Van Eck+, 2017)J/AJ/156/264 : California-Kepler Survey VII Planet radius gap (Fulton+, 2018)J/AJ/155/48 : California-Kepler Survey. V. Masses and radii (Weiss+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/163/67https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/163/67http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/163/67https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/163/67https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/163/67http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/163/67GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapX-rayUVOpticalInfrareddefaultJ/AJ/163/67/fig10Fiducial stellar spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWave[5/54990] Wavelength; Angstroms0.1nmem.wlfloatFlux[0/28.1] Flux at 1AU; erg/s/cm^2^/AngstromscW.m**-2.nm**-1phot.fluxdouble