J/A+A/664/A34ivo://CDS.VizieR/J/A+A/664/A34doi:10.26093/cds/vizier.36640034CDSAl Moulla K.Dumusque X.Cretignier M.Zhao Y.Valenti J.A.2022-11-13T17:32:21Z2022-08-04T08:44:56ZCDS support team

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

cds-question@unistra.frthe-sunspectroscopyvisible-astronomyTo enable radial velocity (RV) precision on the order of ~0.1m/s required for the detection of Earth-like exoplanets orbiting solar-type stars, the main obstacle lies in mitigating the impact of stellar activity. This study investigates the dependence of derived RVs with respect to the formation temperature of spectral line segments. Using spectral synthesis, we compute for each observed wavelength point of unblended spectral lines the stellar temperature below which 50% of the emergent flux originates. We can then construct RV time series for different temperature ranges, using template matching. With HARPS-N solar data and HARPS alpha Cen B measurements, we demonstrate on time intervals of prominent stellar activity that the activity-induced RV signal has different amplitude and periodicity depending on the temperature range considered. We compare the solar measurements with simulated contributions from active surface regions seen in simultaneous images, and find that the suppression of convective motion is the dominant effect. From a carefully selected set of spectral lines, we are able to measure the RV impact of stellar activity at various stellar temperatures ranges. We are able to strongly correlate the effect of convective suppression with spectral line segments formed in hotter temperature ranges. At cooler temperatures, the derived RVs exhibit oppositely directed variations compared to the average RV time series and stronger anti- correlations with chromospheric emission.2022A&A...664A..34Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/664/A34CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/664/A34https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/664/A34http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/664/A34https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/664/A34https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/664/A34http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/664/A34GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapAssociated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/664/A34OpticaldefaultJ/A+A/664/A34/listList of fits spectraTitleTitle of the fits filemeta.title;meta.fitscharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar name (HD128621 or Sun)meta.id;meta.maincharObs.DateObservation datestime.epoch;obsnullableNxNumber of wavelength pointsmeta.number;em.wlintSizeSize of FITS fileMbytephys.size;meta.fitsfloatspShow the spectrummeta.ref.urlcharFileNameName of FITS filemeta.id;meta.fitschar