Abstract
If stars were uniformly bright across their surfaces, then the analysis of transit observations would require only the subtraction of this bright background from the observed data in order to obtain the transit light curve and the absorption spectrum produced by atoms and molecules in the exoplanet’s atmosphere. Even this unrealistically simple observing scenario is a data analysis challenge because the area of a transiting planet may be only 1% or smaller compared to that of the host star, and the area of a terrestrial exoplanet’s atmosphere seen in absorption against the stellar disk emission may be only 0.01% that of the stellar disk area. Thus high signal/noise data are essential to minimize random noise.
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References
Afram, N., Berdyugina, S.V.: Molecules as magnetic probes of starspots. Astron. Astrophys. 576, 34 (2015)
Baliunas, S.L., Donahue, R.A., Soon, W.H., Horne, J.H., Frazer, J., Woodard-Eklund, L., Bradford, M., Rao, L.M., Wilson, O.C., Zhang, Q., et al.: Chromospheric variations in main-sequence stars. Astrophys. J. 438, 269 (1995)
Barnes, J.R., Jeffers, S.V., Jones, H.R.A., Pavlenko, Ya.V., Jenkins, J.S., Haswell, C.A., Lohr, M.E.: Starspot distributions on fully convective M dwarfs: implications for radial velocity planet searches. Astrophys. J. 812, 42 (2015)
Barnes, J.R., Jeffers, S.V., Haswell, C.A., Jones, H.R.A., Shulyak, D., Pavlenko, Ya.V., Jenkins, J.S.: Surprisingly different star-spot distributions on the near equal-mass equal-rotation-rate stars in the M dwarf binary GJ 65 AB. Mon. Not. R. Astron. Soc. 471, 811 (2017)
Basri, G., Walkowicz, L.M., Reiners, A.: Comparison of Kepler photometric variability with the Sun on different timescales. Astrophys. J. 769, 37 (2013)
Berdyugina, S.: Starspots: a key to the stellar dynamo. Living Rev. Sol. Phys. 2, 8 (2005)
Cegla, H.M., Watson, C.A., Shelyag, S., Chaplin, W.J., Davies, G.R., Mathioudakis, M., Palumbo, M.L., III, Saar, S.H., Haywood, R.D.: Stellar surface magneto-convection as a source of astrophysical noise II. Center-to-limb parameterisation of absorption line profiles and comparison to observations. Astrophys. J. 866, 55 (2018)
Dumusque, X.: Radial velocity fitting challenge. I. Simulating the data set including realistic stellar radial-velocity signals. Astron. Astrophys. 593, A5 (2016)
Fang, X.-S., Zhao, G., Zhao, J.-K., Chen, Y.-Q., Bharat Kumar, Y.: Stellar activity with LAMOST. I. Spot configuration in Pleiades. Mon. Not. R. Astron. Soc. 463, 2494 (2016)
Fröhlich, C., Lean, J.: Solar radiative output and its variability: evidence and mechanisms. Astron. Astrophys. Rev. 12, 273 (2004)
Grimm, S.L., Demory, B.-O., Gillon, M., Dorn, C., Agol, E., Burdanov, A., Delrez, L., Sestovic, M., Triaud, A.H.M.J., et al.: The nature of the TRAPPIST-1 exoplanets. Astron. Astrophys. 613, 68 (2018)
Haywood, R.D., Collier Cameron, A., Unruh, Y.C., Lovis, C., Lanza, A.F., Llama, J., Deleuil, M., Fares, R., Gillon, M., Moutou, C., et al.: The Sun as a planet-host star: proxies from SDO images for HARPS radial-velocity variations. Mon. Not. R. Astron. Soc. 457, 3637 (2016)
Hébrard, E.M., Donati, J.-F., Delfosse, X., Morin, J., Moutou, C., Boisse, I.: Modelling the RV jitter of early-M dwarfs using tomographic imaging. Mon. Not. R. Astron. Soc. 461, 1465 (2016)
Kopp, G., Lawrence, G., Rottman, G.: The Total Irradiance Monitor (TIM): science results. Solar Phys. 230, 129 (2005)
Kreidberg, L., Line, M.R., Thorngren, D., Morley, C.V., Stevenson, K.B.: Water, high-altitude condensates, and possible methane depletion in the atmosphere of the warm super-Neptune WASP-107b. Astrophys. J. 858, 6 (2018)
Lanza, A.F., Pagano, I., Leto, G., Messina, S., Aigrain, S., Alonso, R., Auvergne, M., Baglin, A., Barge, P., Bonomo, A.S., et al.: Magnetic activity in the photosphere of CoRoT-Exo-2a. Active longitudes and short-term spot cycle in a young Sun-like star. Astron. Astrophys. 493, 193 (2009)
Linsky, J.L., Ayres, T.R.: Stellar model chromospheres. VI - empirical estimates of the chromospheric radiative losses of late-type stars. Astrophys. J. 220, 619 (1978)
Llama, J., Shkolnik, E.L.: Transiting the Sun: the impact of stellar activity on X-Ray and ultraviolet transits. Astrophys. J. 802, 41 (2015)
Llama, J., Shkolnik, E.L.: Transiting the Sun II. The impact of stellar activity on Lyα transits. Astrophys. J. 817, 81 (2016)
Lockwood, G.W., Skiff, B.A., Henry, G.W., Henry, S., Radick, R.R., Baliunas, S.L., Donahue, R.A., Soon, W.: Patterns of photometric and chromospheric variation among Sun-like stars: a 20 year perspective. Astrophys. J. 171, 260 (2007)
Maehara, H., Notsu, Y., Notsu, S., Namekata, K., Honda, S. Ishii, T.T., Nogami, Daisaku, N., Shibata, K.: Starspot activity and superflares on solar-type stars. Publ. Astron. Soc. Jpn. 69, 41 (2017)
Mamajek, E.E., Hillenbrand, L.A.: Improved age estimation for Solar-type dwarfs using activity-rotation diagnostics. Astrophys. J. 687, 1264 (2008)
McCullough, P.R., Crouzet, N., Deming, D., Madhusudhan, N.: Water vapor in the spectrum of the extrasolar planet HD 189733b. I. The transit. Astrophys. J. 791, 55 (2014)
Mittag, M., Schmitt, J.H.M.M., Schröder, K.-P.: Ca II H+ K fluxes from S-indices of large samples: a reliable and consistent conversion based on PHOENIX model atmospheres. Astron. Astrophys. 549, A117 (2013)
Morris, B.M., Agol, E., Davenport, J.R.A., Hawley, S.L.: Possible bright starspots on TRAPPIST-1. Astrophys. J. 857, 39 (2018)
Newton, E.R., Irwin, J., Charbonneau, D., Berlind, P., Calkins, M.L., Mink, J.: The Hα emission of nearby M dwarfs and its relation to stellar rotation. Astrophys. J. 835, 85 (2017)
Noyes, R.W., Hartmann, L.W., Baliunas, S.L., Duncan, D.K., Vaughan, A.H.: Rotation, convection, and magnetic activity in lower main-sequence stars. Astrophys. J. 279, 763 (1984)
Oshagh, M., Santos, N.C., Figueira, P., Barros, S.C.C., Donati, J.-F., Adibekyan, V., Faria, J.P., Watson, C.A., Cegla, H.M., Dumusque, X., et al.: Understanding stellar activity-induced radial velocity jitter using simultaneous K2 photometry and HARPS RV measurements. Astron. Astrophys. 606, A107 (2017)
Pont, F., Sing, D.K., Gibson, N.P., Aigrain, S., Henry, G., Husnoo, N.: The prevalence of dust on the exoplanet HD 189733b from Hubble and Spitzer observations. Mon. Not. R. Astron. Soc. 432, 291 (2013)
Rackham, B., Espinoza, N., Apai, D., López-Morales, M., Jordán, A., Osip, D.J., Lewis, N.K., Rodler, F., Fraine, J.D., Morley, C.V., Fortney, J.J.: ACCESS I: an optical transmission spectrum of GJ 1214b reveals a heterogeneous stellar photosphere. Astrophys. J. 834, 151 (2017)
Rackham, B.V., Apai, D., Giampapa, M.S.: The Transit light source effect: false spectral features and incorrect densities for M-dwarf transiting planets. Astrophys. J. 853, 122 (2018)
Radick, R.R., Mihalas, D., Lockwood, G.W., Thompson, D.T., Warnock, A., III, Hartmann, L.W., Worden, S.P., Henry, G.W., Sherlin, J.M.: The photometric variability of solar-type stars. III. Results from 1981-82, including parallel observations of thirty-six Hyades stars. Publ. Astron. Soc. Pac. 95, 621 (1983)
Radick, R.R., Lockwood, G.W., Skiff, B.A., Baliunas, S.L.: Patterns of variation among Sun-like stars. Astrophys. J. Supl. Ser. 118, 239 (1998)
Radick, R.R., Lockwood, G.W., Henry, G.W., Hall, J.C., Pevtsov, A.A.: Patterns of variation for the Sun and Sun-like stars. Astrophys. J. 855, 75 (2018)
Schrijver, C.J.: Magnetic structure in cool stars. XI - relations between radiative fluxes measuring stellar activity, and evidence for two components in stellar chromospheres. Astron. Astrophys. 172, 111 (1987)
Shapiro, A.I., Solanki, S.K., Krivova, N.A., Schmutz, W.K., Ball, W.T., Knaack, R., Rozanov, E.V., Unruh, Y.C.: Variability of Sun-like stars: reproducing observed photometric trends. Astron. Astrophys. 569, 38 (2014)
Silva-Valio, A., Lanza, A.F., Alonso, R., Barge, P.: Properties of starspots on CoRoT-2. Astron. Astrophys. 510, A25 (2010)
Solanki, S.K., Fligge, M.: A reconstruction of total solar irradiance since 1700. J. Geophys. Res. 26, 2465 (1999)
Topka, K.P., Tarbell, T.D., Title, A.M.: Properties of the smallest solar magnetic elements. II. Observations versus hot wall models of faculae. Astrophys. J. 484, 479 (1997)
Vaughan, A.H., Preston, G.W.: A survey of chromospheric Ca II H and K emission in field stars of the solar neighborhood. Publ. Astron. Soc. Pac. 92, 385 (1980)
Vaughan, A.H., Preston, G.W., Wilson, O.C.: Flux measurements of CA II H and K emission. Publ. Astron. Soc. Pac. 90, 267 (1978)
Walkowicz, L.M., Basri, G., Valenti, J.A.: The information content in analytic spot models of broadband precision light curves. Astrophys. J. Suppl. Ser. 205, 17 (2013)
Wilson, O.C.: Chromospheric variations in main-sequence stars. Astrophys. J. 226, 379 (1978)
Zellem, R.T., Swain, M.R., Roudier, G., Shkolnik, E.L., Creech-Eakman, M.J., Ciardi, D.R., Line, M.R., Iyer, A.R., Bryden, G., Llama, J., Fahy, K.A.: Forecasting the impact of stellar activity on transiting exoplanet spectra. Astrophys. J. 844, 27 (2017)
Zhang, Z., Zhou, Y., Rackham, B., Apai, D.: The near-infrared transmission spectra of TRAPPIST-1 planets b, c, d, e, f, and g and stellar contamination in multi-epoch transit spectra. Astron. J. 156, 178 (2018)
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Linsky, J. (2019). The Effects of Heterogeneous Stellar Surfaces on the Analysis of Exoplanet Transit Light Curves and Spectra. In: Host Stars and their Effects on Exoplanet Atmospheres . Lecture Notes in Physics, vol 955. Springer, Cham. https://doi.org/10.1007/978-3-030-11452-7_13
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