J/AJ/165/5ivo://CDS.VizieR/J/AJ/165/5doi:10.26093/cds/vizier.51650005CDSGardner-Watkins C.N.Kobulnicky H.A.Jang-Condell H.Kasper D.H.,Parker B.A.Bucci T.Cook E.M.Doublestein K.A.Freels C.,Galloway D.G.T.Helck S.Komlodi C.Lindman M.J.Lyon M.,Piccone A.N.,Wilkerson S.2023-07-03T13:23:52Z2023-05-12T11:52:39ZCDS support team

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

cds-question@unistra.frexoplanetsk-starsvisible-astronomysloan-photometryinfrared-photometrybroad-band-photometryTransmission spectroscopy offers an invaluable opportunity to characterize the atmospheres of exoplanets. We present new ground-based optical transmission spectra of the hot Jupiter HD189733b, derived from nine transits observed over a six year time span (2016-2021) using near-simultaneous u' g' r' i' broadband observations. We achieve an average (best) precision of 435(280)ppm by implementing an optical diffuser on the prime focus spectrograph from the 2.3m Wyoming Infrared Observatory telescope. The data provide new measurements of the apparent planetary radius with respect to the stellar radius, the spectral index of atmospheric opacity, and the time variability of the two quantities. Our results indicate an enhanced spectral slope in the optical regime ~2.4 times steeper than would be expected from canonical Rayleigh scattering and that is consistent with earlier measurements of a super-Rayleigh slope (SRS). While the effect of stellar activity on the transmission spectrum complicates the measurement of the spectral slope, our multiepoch data set over six years can measure and average over stellar variations, yielding a mean spectral index of -9.9{+/-}4.4. The 1200K equilibrium temperature of HD189733b places it in a sweet spot for the formation of SRSs and is consistent with vigorously mixing hazes in the atmosphere. Additionally, we find variations in the depth of the lightcurve during two of the transits, explainable as an increase in occulted star spots during June 2021. Although the star is active, the mean level of stellar activity does not seem to vary dramatically over our six years of observations, leading us to conclude that the variability in stellar activity is modest at most.2023AJ....165....5Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/165/5CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/396/1023 : Transiting planetary system WASP-5 (Southworth+, 2009)J/other/A+ARV/17.251 : Stars observed with Doppler imaging (Strassmeier, 2009)J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)J/ApJ/770/36 : APOSTLE transits of XO-2 system (Kundurthy+, 2013)J/MNRAS/436/2 : Transits of WASP-19b (Mancini+, 2013)J/ApJ/791/55 : HD 189733b in transit light curve (McCullough+, 2014)J/ApJ/819/27 : OAO/MuSCAT light curves of HAT-P-14b (Fukui+, 2016)J/A+A/587/A67 : WASP-49b FORS2 multi-epoch spectra (Lendl+, 2016)J/MNRAS/472/1618 : Kepler study of starspot lifetimes (Giles+, 2017)J/AJ/153/136 : Planets and their host stars with Gaia plxs (Stassun+, 2017)J/A+A/628/A115 : WASP-12, CoRoT-1 and TrES-3 light curves (von Essen+, 2019)J/MNRAS/497/5182 : WASP-21b light curves (Alderson+, 2020)J/A+A/642/A50 : WASP-74 griz_s_ light curves (Luque+, 2020)J/MNRAS/500/5420 : Transit light curves of WASP-104b (Chen+, 2021)J/MNRAS/510/4857 : WASP-94A light curves (Ahrer+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/165/5https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/165/5http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/165/5https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/165/5https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/165/5http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/165/5GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/AJ/165/5/table2Extracted photometry from astroImage JrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJD[2457602/2459440] Julian Date at mid-exposuredtime.epochdoubleBJD[2457602/2459440] Barycentric Julian Dates in Barycentric Dynamical Timedtime.epochdoubleFiltFilter; u, g, r or Iinstr.filtercharFlux[0.97/1.1] Normalized flux ratio in Filterphot.flux;arith.ratiodoublee_Flux[7e-05/0.0006] Normalized flux errorstat.error;phot.fluxdoubleAirmass[1.05/1.98] Airmass of the target coordinates at mid-exposureobs.airMassfloatX[805/2662] X-location in FITS coordinates of the center of aperturepixphys.angSize;instr.det;meta.fitsfloatY[1583/2119] Y-location in FITS coordinates of the center of aperturepixphys.angSize;instr.det;meta.fitsfloatTexp[11/320] Exposure timestime.duration;obs.exposureintSumSum of net integrated counts in all comparison apertures (1)ctphot.countdoubleCountNet integrated counts within aperturectphot.countdoubleSky/Pix[148/5867] Sky Background flux / pixelphot.flux;instr.skyLevelfloat