J/AJ/166/171ivo://CDS.VizieR/J/AJ/166/171doi:10.26093/cds/vizier.51660171CDSPass E.K.Winters J.G.Charbonneau D.Balkanski A.Lewis N.Lally M.,Bean J.L.Cloutier R.Eastman J.D.2024-11-06T20:18:01Z2024-04-22T08:02:43ZCDS support team

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

cds-question@unistra.frexoplanetsmultiple-starshst-photometryPrevious studies of the exoplanet LTT1445Ac concluded that the light curve from the Transiting Exoplanet Survey Satellite (TESS) was consistent with both grazing and nongrazing geometries. As a result, the radius and hence density of the planet remained unknown. To resolve this ambiguity, we observed the LTT1445 system for six spacecraft orbits of the Hubble Space Telescope (HST) using WFC3/UVIS imaging in spatial scan mode, including one partial transit of LTT1445Ac. This imaging produces resolved light curves of each of the three stars in the LTT1445 system. We confirm that the planet transits LTT1445A and that LTT 1445C is the source of the rotational modulation seen in the TESS light curve, and we refine the estimate of the dilution factor for the TESS data. We perform a joint fit to the TESS and HST observations, finding that the transit of LTT1445Ac is not grazing with 97% confidence. We measure a planetary radius of 1.07_-0.07_^+0.10^R{Earth}. Combined with previous radial velocity observations, our analysis yields a planetary mass of 1.37{+/-}0.19M{Earth} and a planetary density of 5.9_-1.5_^+1.8^g/cm^3^. LTT1445Ac is likely an Earth analog with respect to its mass and radius, albeit with a higher instellation, and is therefore an exciting target for future atmospheric studies.2023AJ....166..171Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/166/171CatalogResearchIsServedByTAP VizieR generic servicerelated-toI/337 : Gaia DR1 (Gaia Collaboration, 2016)J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)J/AJ/152/141 : Solar neighborhood. XXXVII. RVs for M dwarfs (Benedict+, 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/AJ/157/143 : Kepler GK dwarf planet candidate samples (Burke+, 2019)J/AJ/161/269 : HST WFC3/UVIS normalized light curve of WASP-43 (Fraine+, 2021)J/A+A/648/A15 : beta Pictoris photometry (Kenworthy+, 2021)J/other/Sci/377.1211 : RV and LC of 8 M dwarf stars with planets (Luque+, 2022)J/AJ/163/168 : Photometry and radial velocity of LTT 1445A (Winters+, 2022)J/A+A/673/A69 : LTT 1445A ESPRESSO observations (Lavie+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/166/171https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/166/171http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/166/171https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/166/171https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/166/171http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/166/171GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/AJ/166/171/table1Raw and systematics-corrected light curves of the LTT 1445 SystemrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJD[2483/2488] TESS Barycentric Julian Datedtime.epochdoubleFluxA[52862829/53097082] Raw flux of LTT 1445Actphot.flux.density;em.optintFluxB[38455361/38581187] Raw flux of LTT 1445Bctphot.flux.density;em.optintFluxC[19841068/20089003] Raw flux of LTT 1445Cctphot.flux.density;em.optintCFluxA[-1.4/0.69] Corrected flux of LTT 1445A; parts per thousand (1)phot.flux.density;em.optfloate_CFluxA[0.2/0.3] Uncertainty on CFluxA; parts per thousandstat.errorfloatCFluxB[-0.47/0.77] Corrected flux of LTT 1445B; parts per thousand (1)phot.flux.density;em.optfloate_CFluxB[0.2/0.3] Uncertainty on CFluxB; parts per thousandstat.errorfloatCFluxC[-0.58/0.76] Corrected flux of LTT 1445C; parts per thousand (1)phot.flux.density;em.optfloate_CFluxC[0.2/0.3] Uncertainty on CFluxC; parts per thousandstat.errorfloat