J/A+A/643/A146ivo://CDS.VizieR/J/A+A/643/A146doi:10.26093/cds/vizier.36430146CDSGonzalez Hernandez J.I.Rebolo R.Pasquini L.Lo Curto G.Molaro P.,Caffau E.Ludwig H.-G.Steffen M.Esposito M.Suarez Mascarenno A.,Toledo-Padron B.Probst R.A.Hansch T.W.Holzwarth R.Manescau A.,Steinmetz T.Udem T.Wilken T.2021-05-03T11:34:59Z2020-11-17T05:59:02ZCDS support team

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

cds-question@unistra.frsolar-systemthe-sunline-intensitiesspectroscopyThe General Theory of Relativity predicts the redshift of spectral lines in the solar photosphere, as a consequence of the gravitational potential of the Sun. This effect can be measured from a solar disk-integrated flux spectrum of the Sun's reflected light on solar system bodies. The laser frequency comb (LFC) calibration system attached to the HARPS spectrograph offers the possibility to perform an accurate measurement of the solar gravitational redshift (GRS) by observing the Moon or other solar system bodies. We have analysed the line shift observed in Fe absorption lines from five high-quality HARPS-LFC spectra of the Moon. We select an initial sample of 326 photospheric Fe lines in the spectral range 476-585nm and measure their line positions and equivalent widths (EWs). Accurate line shifts are derived from the wavelength position of the core of the lines compared with the laboratory wavelengths of Fe lines. We also use a CO^5^BOLD 3D hydrodynamical model atmosphere of the Sun to compute 3D synthetic line profiles of a subsample of about 200 spectral Fe lines centred at their laboratory wavelengths. We fit the observed relatively weak spectral Fe lines (with EW<180m{AA}) with the 3D synthetic profiles. Convective motions in the solar photosphere do not affect the line cores of Fe lines stronger than about 150m{AA}. In our sample, only 15 FeI lines have EWs in the range 150<EW(m{AA})<550, providing a measurement of the solar GRS at 639+/-14m/s, consistent with the expected theoretical value on Earth of 633.1m/s. A final sample of about 98 weak Fe lines with EW<180m{AA} allows us to derive a mean global line shift of 638+/-6m/s in agreement with the theoretical solar GRS. These are the most accurate measurements of the solar GRS so far. Ultrastable spectrographs calibrated with the LFC over a larger spectral range, such as HARPS or ESPRESSO, together with a further improvement on the laboratory wavelengths, could provide a more robust measurement of the solar GRS and further tests for the 3D hydrodynamical models.2020A&A...643A.146Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/643/A146CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJS/94/221 : New multiplet table for FeI (Nave+, 1994)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/643/A146https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/643/A146http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/643/A146https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/643/A146https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/643/A146http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/643/A146GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/643/A146/tablea1Line data and line shifts of 188 FeI-II linesExPotExcitation potential (3)eVphys.atmol.excitationfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda-labOriginal wavelengths (1)0.1nmem.wldoublelambda-nistRecalibrated wavelengths (2)0.1nmem.wldoublee_lambda-nistUncertainty in lambda_nist (2)0.1pmstat.errorfloatlambda-ritzRecalibrated Ritz wavelengths (2)0.1nmem.wldoublee_lambda-ritzUncertainty in lambda_ritz (2)0.1pmstat.errorfloatElChemical elementphys.atmol.elementcharIonElement Ionphys.atmol.ionStageintloggfOscillator strength (3)phys.atmol.oscStrengthfloatEWEquivalent widths0.1pmspect.line.eqWidthfloate_EWUncertainty in EW0.1pmstat.error;spect.line.eqWidthfloatv-core-obsLine core shift (4)m/sspect.line.widthfloate_v-core-obsUncertainty in v_core_obsm/sstat.errorfloatJ/A+A/643/A146/tablea2Line data and line shifts of 97 FeI-II linesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda-labOriginal wavelengths (1)0.1nmem.wldoublelambda-nistRecalibrated wavelengths (2)0.1nmem.wldoubleElChemical elementphys.atmol.elementcharIonElement Ionphys.atmol.ionStageintExPotExcitation potential (3)eVphys.atmol.excitationfloatloggfOscillator strength (3)phys.atmol.oscStrengthfloatEWEquivalent width0.1pmspect.line.eqWidthfloate_EWUncertainty in EW0.1pmstat.error;spect.line.eqWidthfloatv-core-obs-nLine core shift (4)m/sspect.line.widthfloate_v-core-obs-nUncertainty in v_core_obsm/sstat.errorfloatv-core-3DLine core shift; 3D line profile (5)m/sspect.line.widthfloatv-fit-3D-nGlobal line shift; 3D profile fit (6)m/sspect.line.widthfloate_v-fit-3D-nUncertainty in v_fit_3D_nm/sstat.errorfloat