Abstract
Observations of extrasolar planets were not projected to be a substantial part of the Spitzer Space Telescope’s mission when it was conceived and designed. Nevertheless, Spitzer was the first facility to detect thermal emission from a hot Jupiter-sized planet, and the range of its exoplanetary investigations grew to encompass transiting planets, microlensing, brown dwarfs, and direct imaging searches and astrometry. Spitzer used phase curves to measure the longitudinal distribution of heat as well as time-dependent heating on hot Jupiters. Its secondary eclipse observations strongly constrained the dayside thermal emission spectra and corresponding atmospheric compositions of hot Jupiters, and the timings of eclipses were used for studies of orbital dynamics. Spitzer’s sensitivity to carbon-based molecules such as methane and carbon monoxide was key to atmospheric composition studies of transiting exoplanets as well as imaging spectroscopy of brown dwarfs, and complemented Hubble Space Telescope spectroscopy at shorter wavelengths. Its capability for long continuous observing sequences enabled searches for new transiting planets around cool stars and helped to define the architectures of planetary systems such as TRAPPIST-1. Spitzer measured masses for small planets at large orbital distances using microlensing parallax. Spitzer observations of brown dwarfs probed their temperatures, masses and weather patterns. Imaging and astrometry from Spitzer was used to discover new planetary-mass brown dwarfs and to measure distances and space densities of many others.
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References
Mayor, M. & Queloz, D. A Jupiter-mass companion to a solar-type star. Nature 378, 355–359 (1995).
Guillot, T., Burrows, A., Hubbard, W. B., Lunine, J. I. & Saumon, D. Giant planets at small orbital distances. Astrophys. J. Lett 459, L35 (1996).
Seager, S. & Sasselov, D. D. Theoretical transmission spectra during extrasolar giant planet transits. Astrophys. J. 537, 916–921 (2000).
Seager, S., Whitney, B. A. & Sasselov, D. D. Photometric light curves and polarization of close-in extrasolar giant planets. Astrophys. J. 540, 504–520 (2000).
Beichman, C. A. & Deming, D. Observing Exoplanets with the Spitzer Space Telescope 78 (Springer, 2018).
Chen, C., Su, K. & Xu, S. Spitzer’s debris disk legacy from main-sequence stars to white dwarfs. Nat. Astron. 4, 328–338 (2020).
Burrows, A. et al. A nongray theory of extrasolar giant planets and brown dwarfs. Astrophys. J. 491, 856–875 (1997).
Burrows, A. & Sharp, C. M. Chemical equilibrium abundances in brown dwarf and extrasolar giant planet atmospheres. Astrophys. J. 512, 843–863 (1999).
Sudarsky, D., Burrows, A. & Pinto, P. Albedo and reflection spectra of extrasolar giant planets. Astrophys. J. 538, 885–903 (2000).
Charbonneau, D. et al. Detection of thermal emission from an extrasolar planet. Astrophys. J. 626, 523–529 (2005).
Deming, D., Seager, S., Richardson, L. J. & Harrington, J. Infrared radiation from an extrasolar planet. Nature 434, 740–743 (2005).
Barman, T. S., Hauschildt, P. H. & Allard, F. Phase-dependent properties of extrasolar planet atmospheres. Astrophys. J. 632, 1132–1139 (2005).
Burrows, A., Hubeny, I. & Sudarsky, D. A Theoretical interpretation of the measurements of the secondary eclipses of TrES-1 and HD 209458b. Astrophys. J. Lett. 625, L135–L138 (2005).
Seager, S. et al. On the dayside thermal emission of hot Jupiters. Astrophys. J. 632, 1122–1131 (2005).
Deming, D., Harrington, J., Seager, S. & Richardson, L. J. Strong infrared emission from the extrasolar planet HD 189733b. Astrophys. J. 644, 560–564 (2006).
Bouchy, F. et al. ELODIE metallicity-biased search for transiting hot Jupiters. II. A very hot Jupiter transiting the bright K star HD 189733. Astron. Astrophys. 444, L15–L19 (2005).
Charbonneau, D., Brown, T. M., Latham, D. W. & Mayor, M. Detection of planetary transits across a Sun-like star. Astrophys. J. Lett 529, L45–L48 (2000).
Crouzet, N., McCullough, P. R., Deming, D. & Madhusudhan, N. Water vapor in the spectrum of the extrasolar planet HD 189733b. II. The eclipse. Astrophys. J. 795, 166 (2014).
Knutson, H. A. et al. Multiwavelength constraints on the day–night circulation patterns of HD 189733b. Astrophys. J. 690, 822–836 (2009).
Knutson, H. A. et al. 3.6 and 4.5 μm phase curves and evidence for non-equilibrium chemistry in the atmosphere of extrasolar planet HD 189733b. Astrophys. J. 754, 22 (2012).
Kilpatrick, B. M. et al. Evaluating climate variability of the canonical hot Jupiters Hd 189733b & Hd 209458b through multi-epoch eclipse observations. Astron. J. 159, 51 (2020).
Zhang, M., Chachan, Y., Kempton, E. M. R. & Knutson, H. A. Forward modeling and retrievals with PLATON, a fast open-source tool. Publ. Astron. Soc. Pac. 131, 034501 (2019).
Houck, J. R. et al. The Infrared Spectrograph (IRS) on the Spitzer Space Telescope. Astrophys. J. Suppl. 154, 18–24 (2004).
Swain, M. R., Bouwman, J., Akeson, R. L., Lawler, S. & Beichman, C. A. The mid-infrared spectrum of the transiting exoplanet HD 209458b. Astrophys. J. 674, 482–497 (2008).
Grillmair, C. J. et al. A Spitzer spectrum of the exoplanet HD 189733b. Astrophys. J. Lett. 658, L115–L118 (2007).
Richardson, L. J., Deming, D., Horning, K., Seager, S. & Harrington, J. A spectrum of an extrasolar planet. Nature 445, 892–895 (2007).
Brogi, M. & Line, M. R. Retrieving temperatures and abundances of exoplanet atmospheres with high-resolution cross-correlation spectroscopy. Astron. J. 157, 114 (2019).
Line, M. R. et al. No thermal inversion and a solar water abundance for the hot Jupiter HD 209458b from HST/WFC3 spectroscopy. Astron. J. 152, 203 (2016).
Madhusudhan, N. et al. A high C/O ratio and weak thermal inversion in the atmosphere of exoplanet WASP-12b. Nature 469, 64–67 (2011).
Line, M. R., Knutson, H., Wolf, A. S. & Yung, Y. L. A systematic retrieval analysis of secondary eclipse spectra. II. A uniform analysis of nine planets and their C to O ratios. Astrophys. J. 783, 70 (2014).
Madhusudhan, N. & Seager, S. On the inference of thermal inversions in hot Jupiter atmospheres. Astrophys. J. 725, 261–274 (2010).
Burrows, A., Hubeny, I., Budaj, J., Knutson, H. A. & Charbonneau, D. Theoretical spectral models of the planet HD 209458b with a thermal inversion and water emission bands. Astrophys. J. Lett. 668, L171–L174 (2007).
Burrows, A., Ibgui, L. & Hubeny, I. Optical albedo theory of strongly irradiated giant planets: the case of HD 209458b. Astrophys. J. 682, 1277–1282 (2008).
Fortney, J. J., Lodders, K., Marley, M. S. & Freedman, R. S. A unified theory for the atmospheres of the hot and very hot Jupiters: two classes of irradiated atmospheres. Astrophys. J. 678, 1419–1435 (2008).
Spiegel, D. S., Silverio, K. & Burrows, A. Can TiO explain thermal inversions in the upper atmospheres of irradiated giant planets? Astrophys. J. 699, 1487–1500 (2009).
Knutson, H. A., Charbonneau, D., Allen, L. E., Burrows, A. & Megeath, S. T. The 3.6–80 μm broadband emission spectrum of HD 209458b: evidence for an atmospheric temperature inversion. Astrophys. J. 673, 526–531 (2008).
Diamond-Lowe, H., Stevenson, K. B., Bean, J. L., Line, M. R. & Fortney, J. J. New analysis indicates no thermal inversion in the atmosphere of HD 209458b. Astrophys. J. 796, 66 (2014).
Deming, D. et al. Spitzer secondary eclipses of the dense, modestly-irradiated, giant exoplanet HAT-P-20b using pixel-level decorrelation. Astrophys. J. 805, 132 (2015).
Kreidberg, L. et al. Global climate and atmospheric composition of the ultra-hot Jupiter WASP-103b from HST and Spitzer phase curve observations. Astron. J. 156, 17 (2018).
Evans, T. M. et al. An ultrahot gas-giant exoplanet with a stratosphere. Nature 548, 58–61 (2017).
Morley, C. V. et al. Forward and inverse modeling of the emission and transmission spectrum of GJ 436b: investigating metal enrichment, tidal heating, and clouds. Astron. J. 153, 86 (2017).
Stevenson, K. B., Bean, J. L., Madhusudhan, N. & Harrington, J. Deciphering the atmospheric composition of WASP-12b: a comprehensive analysis of its dayside emission. Astrophys. J. 791, 36 (2014).
Fazio, G. G. et al. The Infrared Array Camera (IRAC) for the Spitzer Space Telescope. Astrophys. J. Suppl. 154, 10–17 (2004).
Triaud, A. H. M. J. Colour–magnitude diagrams of transiting exoplanets—I. Systems with parallaxes. Mon. Not. R. Astron. Soc. 439, L61–L64 (2014).
Triaud, A. H. M. J., Lanotte, A. A., Smalley, B. & Gillon, M. Colour–magnitude diagrams of transiting exoplanets—II. A larger sample from photometric distances. Mon. Not. R. Astron. Soc. 444, 711–728 (2014).
Triaud, A. H. M. J. et al. WASP-80b has a dayside within the T-dwarf range. Mon. Not. R. Astron. Soc. 450, 2279–2290 (2015).
Beatty, T. G. et al. Spitzer phase curves of KELT-1b and the signatures of nightside clouds in thermal phase observations. Astron. J. 158, 166 (2019).
Garhart, E. et al. Statistical characterization of hot Jupiter atmospheres using Spitzer’s secondary eclipses. Astron. J. 159, 137 (2020).
Fortney, J. J., Cooper, C. S., Showman, A. P., Marley, M. S. & Freedman, R. S. The influence of atmospheric dynamics on the infrared spectra and light curves of hot Jupiters. Astrophys. J. 652, 746–757 (2006).
Stevenson, K. B. et al. Possible thermochemical disequilibrium in the atmosphere of the exoplanet GJ 436b. Nature 464, 1161–1164 (2010).
Lanotte, A. A. et al. A global analysis of Spitzer and new HARPS data confirms the loneliness and metal-richness of GJ 436 b. Astron. Astrophys. 572, A73 (2014).
Kammer, J. A. et al. Spitzer secondary eclipse observations of five cool gas giant planets and empirical trends in cool planet emission spectra. Astrophys. J. 810, 118 (2015).
Wallack, N. L. et al. Investigating trends in atmospheric compositions of cool gas giant planets using Spitzer secondary eclipses. Astron. J. 158, 217 (2019).
Moses, J. I., Madhusudhan, N., Visscher, C. & Freedman, R. S. Chemical consequences of the C/O ratio on hot Jupiters: examples from WASP-12b, CoRoT-2b, XO-1b, and HD 189733b. Astrophys. J. 763, 25 (2013).
Drummond, B. et al. The carbon-to-oxygen ratio: implications for the spectra of hydrogen-dominated exoplanet atmospheres. Mon. Not. R. Astron. Soc. 486, 1123–1137 (2019).
Kreidberg, L. et al. A precise water abundance measurement for the hot Jupiter WASP-43b. Astrophys. J. Lett. 793, L27 (2014).
Wakeford, H. R. et al. HAT-P-26b: a Neptune-mass exoplanet with a well-constrained heavy element abundance. Science 356, 628–631 (2017).
Spake, J. J. et al. A super-solar metallicity atmosphere for WASP-127b revealed by transmission spectroscopy from HST and Spitzer. Preprint at https://arxiv.org/abs/1911.08859 (2019).
Lodders, K. Solar system abundances and condensation temperatures of the elements. Astrophys. J. 591, 1220–1247 (2003).
Thorngren, D. & Fortney, J. J. Connecting giant planet atmosphere and interior modeling: constraints on atmospheric metal enrichment. Astrophys. J. Lett. 874, L31 (2019).
Fortney, J. J. et al. A framework for characterizing the atmospheres of low-mass low-density transiting planets. Astrophys. J. 775, 80 (2013).
Blumenthal, S. D. et al. A comparison of simulated JWST observations derived from equilibrium and non-equilibrium chemistry models of giant exoplanets. Astrophys. J. 853, 138 (2018).
Bean, J. L. et al. The transiting exoplanet community early release science program for JWST. Publ. Astron. Soc. Pac. 130, 114402 (2018).
Schlawin, E., Greene, T. P., Line, M., Fortney, J. J. & Rieke, M. Clear and cloudy exoplanet forecasts for JWST: maps, retrieved composition, and constraints on formation with MIRI and NIRCam. Astron. J. 156, 40 (2018).
Drummond, B. et al. Observable signatures of wind-driven chemistry with a fully consistent three-dimensional radiative hydrodynamics model of HD 209458b. Astrophys. J. Lett. 855, L31 (2018).
Öberg, K. I. & Bergin, E. A. Excess C/O and C/H in outer protoplanetary disk gas. Astrophys. J. Lett. 831, L19 (2016).
Eistrup, C., Walsh, C. & van Dishoeck, E. F. Molecular abundances and C/O ratios in chemically evolving planet-forming disk midplanes. Astron. Astrophys. 613, A14 (2018).
Mollière, P., van Boekel, R., Dullemond, C., Henning, T. & Mordasini, C. Model atmospheres of irradiated exoplanets: the influence of stellar parameters, metallicity, and the C/O ratio. Astrophys. J. 813, 47 (2015).
Helling, C., Tootill, D., Woitke, P. & Lee, G. Dust in brown dwarfs and extrasolar planets. V. Cloud formation in carbon- and oxygen-rich environments. Astron. Astrophys. 603, A123 (2017).
Hebb, L. et al. WASP-12b: the hottest transiting extrasolar planet yet discovered. Astrophys. J. 693, 1920–1928 (2009).
Kreidberg, L. et al. A detection of water in the transmission spectrum of the hot Jupiter WASP-12b and implications for its atmospheric composition. Astrophys. J. 814, 66 (2015).
Oreshenko, M. et al. Retrieval analysis of the emission spectrum of WASP-12b: sensitivity of outcomes to prior assumptions and implications for formation history. Astrophys. J. Lett. 847, L3 (2017).
Ehrenreich, D. et al. Near-infrared transmission spectrum of the warm-Uranus GJ 3470b with the Wide Field Camera-3 on the Hubble Space Telescope. Astron. Astrophys. 570, A89 (2014).
Stevenson, K. B. et al. Transmission spectroscopy of the hot Jupiter WASP-12b from 0.7 to 5 μm. Astron. J. 147, 161 (2014).
Nikolov, N. et al. HST hot-Jupiter transmission spectral survey: haze in the atmosphere of WASP-6b. Mon. Not. R. Astron. Soc. 447, 463–478 (2015).
Fischer, P. D. et al. HST hot-Jupiter transmission spectral survey: clear skies for cool Saturn WASP-39b. Astrophys. J. 827, 19 (2016).
Alam, M. K. et al. The HST PanCET program: hints of Na I and evidence of a cloudy atmosphere for the inflated hot Jupiter WASP-52b. Astron. J. 156, 298 (2018).
Ducrot, E. et al. The 0.8–45 μm broadband transmission spectra of TRAPPIST-1 planets. Astron. J. 156, 218 (2018).
Benneke, B. et al. A sub-Neptune exoplanet with a low-metallicity methane-depleted atmosphere and Mie-scattering clouds. Nat. Astron. 3, 813–821 (2019).
Sotzen, K. S. et al. Transmission spectroscopy of WASP-79b from 0.6 to 5.0 μm. Astron. J. 159, 5 (2020).
Raymond, S. N., Kokubo, E., Morbidelli, A., Morishima, R. & Walsh, K. J. in Protostars and Planets VI (eds Beuther, H. et al.) 595 (Univ. Arizona Press, 2014).
Demory, B.-O. et al. Detection of thermal emission from a super-Earth. Astrophys. J. Lett. 751, L28 (2012).
Seager, S. & Deming, D. On the method to infer an atmosphere on a tidally locked super Earth exoplanet and upper limits to GJ 876d. Astrophys. J. 703, 1884–1889 (2009).
Demory, B.-O. et al. A map of the large day–night temperature gradient of a super-Earth exoplanet. Nature 532, 207–209 (2016).
Kreidberg, L. et al. Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b. Nature 573, 87–90 (2019).
Demory, B.-O., Gillon, M., Madhusudhan, N. & Queloz, D. Variability in the super-Earth 55 Cnc e. Mon. Not. R. Astron. Soc. 455, 2018–2027 (2016).
Tamburo, P., Mandell, A., Deming, D. & Garhart, E. Confirming variability in the secondary eclipse depth of the super-Earth 55 Cancri e. Astron. J. 155, 221 (2018).
Cowan, N. B. & Agol, E. Inverting phase functions to map exoplanets. Astrophys. J. Lett 678, L129 (2008).
Parmentier, V. & Crossfield, I. J. M. in Handbook of Exoplanets (Deeg, H. & Belmote, J.) 116 (Springer, 2018).
Harrington, J. et al. The phase-dependent infrared brightness of the extrasolar planet υ Andromedae b. Science 314, 623–626 (2006).
Cowan, N. B., Agol, E. & Charbonneau, D. Hot nights on extrasolar planets: mid-infrared phase variations of hot Jupiters. Mon. Not. R. Astron. Soc. 379, 641–646 (2007).
Knutson, H. A. et al. A map of the day-night contrast of the extrasolar planet HD 189733b. Nature 447, 183–186 (2007).
Knutson, H. A. et al. The 8 μm phase variation of the hot Saturn HD 149026b. Astrophys. J. 703, 769–784 (2009).
Cowan, N. B. et al. Thermal phase variations of WASP-12b: defying predictions. Astrophys. J. 747, 82 (2012).
Lewis, N. K. et al. Orbital phase variations of the eccentric giant planet HAT-P-2b. Astrophys. J. 766, 95 (2013).
Maxted, P. F. L. et al. Spitzer 3.6 and 4.5 μm full-orbit light curves of WASP-18. Mon. Not. R. Astron. Soc. 428, 2645–2660 (2013).
Lewis, N. K., Showman, A. P., Fortney, J. J., Knutson, H. A. & Marley, M. S. Atmospheric circulation of eccentric hot Jupiter HAT-P-2b. Astrophys. J. 795, 150 (2014).
Shporer, A. et al. Atmospheric characterization of the hot Jupiter Kepler-13Ab. Astrophys. J. 788, 92 (2014).
Wong, I. et al. Constraints on the atmospheric circulation and variability of the eccentric hot Jupiter XO-3b. Astrophys. J. 794, 134 (2014).
Zellem, R. T. et al. The 4.5 μm full-orbit phase curve of the hot Jupiter HD 209458b. Astrophys. J. 790, 53 (2014).
Wong, I. et al. 3.6 and 4.5 μm phase curves of the highly irradiated eccentric hot Jupiter WASP-14b. Astrophys. J. 811, 122 (2015).
Wong, I. et al. 3.6 and 4.5 μm Spitzer phase curves of the highly irradiated hot Jupiters WASP-19b and HAT-P-7b. Astrophys. J. 823, 122 (2016).
Krick, J. E. et al. Spitzer IRAC sparsely sampled phase curve of the exoplanet WASP-14B. Astrophys. J. 824, 27 (2016).
Stevenson, K. B. et al. Spitzer phase curve constraints for WASP-43b at 3.6 and 4.5 μm. Astron. J. 153, 68 (2017).
Zhang, M. et al. Phase curves of WASP-33b and HD 149026b and a new correlation between phase curve offset and irradiation temperature. Astron. J. 155, 83 (2018).
Dang, L. et al. Detection of a westward hotspot offset in the atmosphere of hot gas giant CoRoT-2b. Nat. Astron. 2, 220–227 (2018).
Mendonça, J. M., Malik, M., Demory, B.-O. & Heng, K. Revisiting the phase curves of WASP-43b: confronting re-analyzed Spitzer data with cloudy atmospheres. Astron. J. 155, 150 (2018).
Rauscher, E., Suri, V. & Cowan, N. B. A More informative map: inverting thermal orbital phase and eclipse light curves of exoplanets. Astron. J. 156, 235 (2018).
Steinrueck, M. E., Parmentier, V., Showman, A. P., Lothringer, J. D. & Lupu, R. E. The effect of 3D transport-induced disequilibrium carbon chemistry on the atmospheric structure, phase curves, and emission spectra of hot Jupiter HD 189733b. Astrophys. J. 880, 14 (2019).
Heng, K. & Showman, A. P. Atmospheric dynamics of hot exoplanets. Annu. Rev. Earth Planet. Sci. 43, 509–540 (2015).
Showman, A. P., Cooper, C. S., Fortney, J. J. & Marley, M. S. Atmospheric circulation of hot Jupiters: three-dimensional circulation models of HD 209458b and HD 189733b with simplified forcing. Astrophys. J. 682, 559–576 (2008).
Rauscher, E. & Menou, K. A General circulation model for gaseous exoplanets with double-gray radiative transfer. Astrophys. J. 750, 96 (2012).
Dobbs-Dixon, I. & Agol, E. Three-dimensional radiative-hydrodynamical simulations of the highly irradiated short-period exoplanet HD 189733b. Mon. Not. R. Astron. Soc. 435, 3159–3168 (2013).
Komacek, T. D. & Showman, A. P. Atmospheric circulation of hot Jupiters: dayside–nightside temperature differences. Astrophys. J. 821, 16 (2016).
Komacek, T. D., Showman, A. P. & Tan, X. Atmospheric circulation of hot Jupiters: dayside–nightside temperature differences. II. Comparison with observations. Astrophys. J. 835, 198 (2017).
Tan, X. & Komacek, T. D. The atmospheric circulation of ultra-hot Jupiters. Astrophys. J. 886, 26 (2019).
Cowan, N. B. & Agol, E. A Model for thermal phase variations of circular and eccentric exoplanets. Astrophys. J. 726, 82 (2011).
Perez-Becker, D. & Showman, A. P. Atmospheric heat redistribution on hot Jupiters. Astrophys. J. 776, 134 (2013).
Keating, D., Cowan, N. B. & Dang, L. Uniformly hot nightside temperatures on short-period gas giants. Nat. Astron. 3, 1092–1098 (2019).
Parmentier, V. et al. From thermal dissociation to condensation in the atmospheres of ultra hot Jupiters: WASP-121b in context. Astron. Astrophys. 617, A110 (2018).
Arcangeli, J. et al. H− opacity and water dissociation in the dayside atmosphere of the very hot gas giant WASP-18b. Astrophys. J. Lett. 855, L30 (2018).
Lothringer, J. D., Barman, T. & Koskinen, T. Extremely irradiated hot Jupiters: non-oxide inversions, H− opacity, and thermal dissociation of molecules. Astrophys. J. 866, 27 (2018).
Sheppard, K. B. et al. Evidence for a dayside thermal inversion and high metallicity for the hot Jupiter WASP-18b. Astrophys. J. Lett. 850, L32 (2017).
Mansfield, M. et al. An HST/WFC3 thermal emission spectrum of the hot Jupiter HAT-P-7b. Astron. J. 156, 10 (2018).
Bell, T. J. et al. Mass loss from the exoplanet WASP-12b inferred from Spitzer phase curves. Mon. Not. R. Astron. Soc. 489, 1995–2013 (2019).
Fossey, S. J., Waldmann, I. P. & Kipping, D. M. Detection of a transit by the planetary companion of HD 80606. Mon. Not. R. Astron. Soc. 396, L16–L20 (2009).
Laughlin, G. et al. Rapid heating of the atmosphere of an extrasolar planet. Nature 457, 562–564 (2009).
deWit, J. et al. Direct measure of radiative and dynamical properties of an exoplanet atmosphere. Astrophys. J. Lett. 820, L33 (2016).
Cowan, N. B. & Agol, E. The statistics of albedo and heat recirculation on hot exoplanets. Astrophys. J. 729, 54 (2011).
Schwartz, J. C. & Cowan, N. B. Balancing the energy budget of short-period giant planets: evidence for reflective clouds and optical absorbers. Mon. Not. R. Astron. Soc. 449, 4192–4203 (2015).
Schwartz, J. C., Kashner, Z., Jovmir, D. & Cowan, N. B. Phase offsets and the energy budgets of hot Jupiters. Astrophys. J. 850, 154 (2017).
Williams, P. K. G., Charbonneau, D., Cooper, C. S., Showman, A. P. & Fortney, J. J. Resolving the surfaces of extrasolar planets with secondary eclipse light curves. Astrophys. J. 649, 1020–1027 (2006).
Agol, E. et al. The climate of HD 189733b from fourteen transits and eclipses measured by Spitzer. Astrophys. J. 721, 1861–1877 (2010).
de Wit, J., Gillon, M., Demory, B. O. & Seager, S. Towards consistent mapping of distant worlds: secondary-eclipse scanning of the exoplanet HD 189733b. Astron. Astrophys. 548, A128 (2012).
Majeau, C., Agol, E. & Cowan, N. B. A Two-dimensional infrared map of the extrasolar planet HD 189733b. Astrophys. J. Lett. 747, L20 (2012).
Komacek, T. D. & Showman, A. P. Temporal variability in hot Jupiter atmospheres. Astrophys. J. 888, 2 (2020).
Dawson, R. I. & Johnson, J. A. Origins of hot Jupiters. Annu. Rev. Astron. Astrophys. 56, 175–221 (2018).
Deming, D. et al. Spitzer transit and secondary eclipse photometry of GJ 436b. Astrophys. J. Lett. 667, L199––L202 (2007).
Blecic, J. et al. Thermal emission of WASP-14b revealed with three Spitzer eclipses. Astrophys. J. 779, 5 (2013).
Knutson, H. A. et al. Friends of hot Jupiters. I. A radial velocity search for massive, long-period companions to close-in gas giant planets. Astrophys. J. 785, 126 (2014).
Knutson, H. A., Charbonneau, D., Burrows, A., O’Donovan, F. T. & Mandushev, G. Detection of a temperature inversion in the broadband infrared emission spectrum of TrES-4. Astrophys. J. 691, 866–874 (2009).
Todorov, K. et al. Spitzer IRAC secondary eclipse photometry of the transiting extrasolar planet HAT-P-1b. Astrophys. J. 708, 498–504 (2010).
Deming, D. et al. Warm Spitzer photometry of the transiting exoplanets CoRoT-1 and CoRoT-2 at secondary eclipse. Astrophys. J. 726, 95 (2011).
Winn, J. N. in Exoplanets (ed. Seager, S.) 55–77 (Univ. Arizona Press, 2010).
Batygin, K., Bodenheimer, P. & Laughlin, G. Determination of the interior structure of transiting planets in multiple-planet systems. Astrophys. J. Lett. 704, L49––L53 (2009).
Buhler, P. B. et al. Dynamical constraints on the core mass of hot Jupiter HAT-P-13b. Astrophys. J. 821, 26 (2016).
Hardy, R. A. et al. Secondary eclipses of HAT-P-13b. Astrophys. J. 836, 143 (2017).
Patra, K. C. et al. The apparently decaying orbit of WASP-12b. Astron. J. 154, 4 (2017).
Yee, S. W. et al. The orbit of WASP-12b is decaying. Astrophys. J. Lett. 888, L5 (2020).
Goldreich, P. & Soter, S. Q in the Solar System. Icarus 5, 375–389 (1966).
Charbonneau, D. et al. A super-Earth transiting a nearby low-mass star. Nature 462, 891–894 (2009).
Fraine, J. D. et al. Spitzer transits of the super-Earth GJ1214b and implications for its atmosphere. Astrophys. J. 765, 127 (2013).
Gillon, M. et al. Search for a habitable terrestrial planet transiting the nearby red dwarf GJ 1214. Astron. Astrophys. 563, A21 (2014).
Gillon, M. et al. Temperate Earth-sized planets transiting a nearby ultracool dwarf star. Nature 533, 221–224 (2016).
Gillon, M. et al. Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1. Nature 542, 456–460 (2017).
de Wit, J. et al. Atmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1. Nat. Astron. 2, 214–219 (2018).
Ducrot, E. et al. The 0.8–45 μm broadband transmission spectra of TRAPPIST-1 planets. Astron. J. 156, 218 (2018).
Lincowski, A. P. et al. Evolved climates and observational discriminants for the TRAPPIST-1 planetary system. Astrophys. J. 867, 76 (2018).
Hu, R., Peterson, L. & Wolf, E. T. O2- and CO-rich atmospheres for potentially habitable environments on TRAPPIST-1 planets. Astrophys. J. 888, 122 (2020).
Dobos, V., Barr, A. C. & Kiss, L. L. Tidal heating and the habitability of the TRAPPIST-1 exoplanets. Astron. Astrophys. 624, A2 (2019).
Kislyakova, K. G. et al. Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction heating. Nat. Astron. 1, 878–885 (2017).
Morley, C. V., Kreidberg, L., Rustamkulov, Z., Robinson, T. & Fortney, J. J. Observing the atmospheres of known temperate Earth-sized planets with JWST. Astrophys. J. 850, 121 (2017).
Lustig-Yaeger, J., Meadows, V. S. & Lincowski, A. P. The detectability and characterization of the TRAPPIST-1 exoplanet atmospheres with JWST. Astron. J. 158, 27 (2019).
Holman, M. J. & Murray, N. W. The use of transit timing to detect terrestrial-mass extrasolar planets. Science 307, 1288–1291 (2005).
Agol, E. & Fabrycky, D. C.in Handbook of Exoplanets (eds Deeg, H. J. & Belmonte, J.A.) 797–816 (Springer, 2018).
Luger, R., Lustig-Yaeger, J. & Agol, E. Planet–planet occultations in TRAPPIST-1 and other exoplanet systems. Astrophys. J. 851, 94 (2017).
Delrez, L. et al. Early 2017 observations of TRAPPIST-1 with Spitzer. Mon. Not. R. Astron. Soc. 475, 3577–3597 (2018).
Grimm, S. L. et al. The nature of the TRAPPIST-1 exoplanets. Astron. Astrophys. 613, A68 (2018).
Dorn, C., Mosegaard, K., Grimm, S. L. & Alibert, Y. Interior characterization in multiplanetary systems: TRAPPIST-1. Astrophys. J. 865, 20 (2018).
Richardson, L. J., Harrington, J., Seager, S. & Deming, D. A Spitzer infrared radius for the transiting extrasolar planet HD 209458b. Astrophys. J. 649, 1043–1047 (2006).
Nutzman, P. et al. A precise estimate of the radius of the exoplanet HD 149026b from Spitzer photometry. Astrophys. J. 692, 229–235 (2009).
Gillon, M. et al. Improved precision on the radius of the nearby super-Earth 55 Cnc e. Astron. Astrophys. 539, A28 (2012).
Demory, B. O. et al. Detection of a transit of the super-Earth 55 Cancri e with warm Spitzer. Astron. Astrophys. 533, A114 (2011).
Ballard, S. et al. Kepler-93b: a terrestrial world measured to within 120 km, and a test case for a new Spitzer observing mode. Astrophys. J. 790, 12 (2014).
Chen, G. et al. An improved transit measurement for a 2.4 R ⊕ planet orbiting a bright mid-M dwarf K2–28. Astron. J. 155, 223 (2018).
Hébrard, G. et al. Observation of the full 12-hour-long transit of the exoplanet HD 80606b. Warm-Spitzer photometry and SOPHIE spectroscopy. Astron. Astrophys. 516, A95 (2010).
Fraine, J. et al. Water vapour absorption in the clear atmosphere of a Neptune-sized exoplanet. Nature 513, 526–529 (2014).
Morris, B. M., Agol, E., Hebb, L. & Hawley, S. L. Robust transiting exoplanet radii in the presence of starspots from ingress and egress durations. Astron. J. 156, 91 (2018).
Gillon, M. et al. Detection of transits of the nearby hot Neptune GJ 436 b. Astron. Astrophys. 472, L13–L16 (2007).
Beichman, C. et al. Spitzer observations of exoplanets discovered with the Kepler K2 mission. Astrophys. J. 822, 39 (2016).
Benneke, B. et al. Spitzer observations confirm and rescue the habitable-zone super-Earth K2–18b for future characterization. Astrophys. J. 834, 187 (2017).
Berardo, D. et al. Revisiting the HIP 41378 system with K2 and Spitzer. Astron. J. 157, 185 (2019).
Dalba, P. A. & Tamburo, P. Spitzer detection of the transiting Jupiter-analog exoplanet Kepler-167e. Astrophys. J. Lett. 873, L17 (2019).
Livingston, J. H. et al. Spitzer transit follow-up of planet candidates from the K2 mission. Astron. J. 157, 102 (2019).
Janson, M. et al. High-contrast imaging with Spitzer: deep observations of Vega, Fomalhaut, and ε Eridani. Astron. Astrophys. 574, A120 (2015).
Durkan, S., Janson, M. & Carson, J. C. High contrast imaging with Spitzer: constraining the frequency of giant planets out to 1000 au separations. Astrophys. J. 824, 58 (2016).
Leggett, S. K. et al. Properties of the T8.5 dwarf Wolf 940 B. Astrophys. J. 720, 252–258 (2010).
Luhman, K. L., Burgasser, A. J. & Bochanski, J. J. Discovery of a candidate for the coolest known brown dwarf. Astrophys. J. Lett. 730, L9 (2011).
Luhman, K. L. et al. Confirmation of one of the coldest known brown dwarfs. Astrophys. J. 744, 135 (2012).
Gould, A. Microlens parallaxes with SIRTF. Astrophys. J. 514, 869–877 (1999).
Gaudi, B. S. Microlensing surveys for exoplanets. Annu. Rev. Astron. Astrophys. 50, 411–453 (2012).
Street, R. A. et al. Spitzer parallax of OGLE-2015-BLG-0966: a cold Neptune in the Galactic Disk. Astrophys. J. 819, 93 (2016).
Ryu, Y. H. et al. OGLE-2016-BLG-1190Lb: the first Spitzer bulge planet lies near the planet/brown-dwarf boundary. Astron. J. 155, 40 (2018).
Shvartzvald, Y. et al. An Earth-mass planet in a 1 au orbit around an ultracool dwarf. Astrophys. J. Lett. 840, L3 (2017).
Shvartzvald, Y. et al. The first simultaneous microlensing observations by two space telescopes: Spitzer and Swift reveal a brown dwarf in event OGLE-2015-BLG-1319. Astrophys. J. 831, 183 (2016).
Calchi Novati, S. et al. Spitzer microlensing parallax for OGLE-2016-BLG-1067: a sub-Jupiter orbiting an M dwarf in the disk. Astron. J. 157, 121 (2019).
Udalski, A. et al. Spitzer as a microlens parallax satellite: mass measurement for the OGLE-2014-BLG-0124L planet and its host star. Astrophys. J. 799, 237 (2015).
Gould, A. et al. KMT-2018-BLG-0029Lb: A very low mass-ratio Spitzer microlens planet. J. Korean Astron. Soc. 53, 9–26 (2020).
Dang, L., Calchi Novati, S. & Carey, S. Getting better at measuring the galactic distribution of planets with Spitzer. In AAS/Division for Extreme Solar Systems Abstracts Vol. 51, 03 (2019)..
Nielsen, E. L. et al. The Gemini Planet Imager Exoplanet Survey: giant planet and brown dwarf demographics from 10 to 100 au. Astron. J. 158, 13 (2019).
Bowler, B. P., Blunt, S. C. & Nielsen, E. L. Population-level eccentricity distributions of imaged exoplanets and brown dwarf companions: dynamical evidence for distinct formation channels. Astron. J. 159, 63 (2020).
Kratter, K. & Lodato, G. Gravitational instabilities in circumstellar disks. Annu. Rev. Astron. Astrophys. 54, 271–311 (2016).
Kouwenhoven, M. B. N., Li, Y., Stamatellos, D. & Goodwin, S. P. Circumstellar disk fragmentation and the origin of massive planetary companions, brown dwarfs, and very low-mass stars. In IAU Symp. Vol. 345 (eds Elmegreen, B. G. et al.) 239–240 (IAU, 2020).
Kirkpatrick, J. D. et al. Discovery of the Y1 dwarf WISE J064723.23–6232355. Astrophys. J. 776, 128 (2013).
Martin, E. C. et al. Y dwarf trigonometric parallaxes from the Spitzer Space Telescope. Astrophys. J. 867, 109 (2018).
Kirkpatrick, J. D. et al. Preliminary trigonometric parallaxes of 184 late-T and Y dwarfs and an analysis of the field substellar mass function into the ‘planetary’ mass regime. Astrophys. J. Suppl. 240, 19 (2019).
Beichman, C. et al. WISE Y dwarfs as probes of the brown dwarf-exoplanet connection. Astrophys. J. 783, 68 (2014).
Leggett, S. K., Tremblin, P., Esplin, T. L., Luhman, K. L. & Morley, C. V. The Y-type brown dwarfs: estimates of mass and age from new astrometry, homogenized photometry, and near-infrared spectroscopy. Astrophys. J. 842, 118 (2017).
Morley, C. V. et al. Measuring the D/H ratios of exoplanets and brown dwarfs. Astrophys. J. Lett. 882, L29 (2019).
Roellig, T. L. et al. Spitzer Infrared Spectrograph (IRS) observations of M, L, and T dwarfs. Astrophys. J. Suppl. 154, 418–421 (2004).
Cushing, M. C. et al. A Spitzer Infrared Spectrograph spectral sequence of M, L, and T dwarfs. Astrophys. J. 648, 614–628 (2006).
Leggett, S. K. et al. The physical properties of four 600 K T dwarfs. Astrophys. J. 695, 1517–1526 (2009).
Saumon, D. et al. Ammonia as a tracer of chemical equilibrium in the T7.5 dwarf Gliese 570D. Astrophys. J. 647, 552–557 (2006).
Patten, B. M. et al. Spitzer IRAC photometry of M, L, and T dwarfs. Astrophys. J. 651, 502–516 (2006).
Burningham, B. et al. 76 T dwarfs from the UKIDSS LAS: benchmarks, kinematics and an updated space density. Mon. Not. R. Astron. Soc. 433, 457–497 (2013).
Beatty, T. G. et al. Spitzer and z′ secondary eclipse observations of the highly irradiated transiting brown dwarf KELT-1b. Astrophys. J. 783, 112 (2014).
Esplin, T. L. et al. Photometric monitoring of the coldest known brown dwarf with the Spitzer Space Telescope. Astrophys. J. 832, 58 (2016).
Morales-Calderón, M. et al. A sensitive search for variability in late L dwarfs: the quest for weather. Astrophys. J. 653, 1454–1463 (2006).
Artigau, É., Bouchard, S., Doyon, R. & Lafrenière, D. Photometric variability of the T2.5 brown dwarf SIMP J013656.5+093347: evidence for evolving weather patterns. Astrophys. J. 701, 1534–1539 (2009).
Buenzli, E. et al. Vertical atmospheric structure in a variable brown dwarf: pressure-dependent phase shifts in simultaneous Hubble Space Telescope–Spitzer light curves. Astrophys. J. Lett. 760, L31 (2012).
Apai, D. et al. HST spectral mapping of L/T transition brown dwarfs reveals cloud thickness variations. Astrophys. J. 768, 121 (2013).
Yang, H. et al. Extrasolar storms: pressure-dependent changes in light-curve phase in brown dwarfs from simultaneous HST and Spitzer observations. Astrophys. J. 826, 8 (2016).
Leggett, S. K. et al. Observed variability at 1 and 4 μm in the Y0 brown dwarf WISEP J173835.52+273258.9. Astrophys. J. 830, 141 (2016).
Biller, B. A. et al. Simultaneous multiwavelength variability characterization of the free-floating planetary-mass object PSO J318.5–22. Astron. J. 155, 95 (2018).
Vos, J. M., Allers, K. N. & Biller, B. A. The viewing geometry of brown dwarfs influences their observed colors and variability amplitudes. Astrophys. J. 842, 78 (2017).
Apai, D. et al. Zones, spots, and planetary-scale waves beating in brown dwarf atmospheres. Science 357, 683–687 (2017).
Carey, S. J. et al. Improvements to warm IRAC/Spitzer Space Telescope operations. In American Astronomical Soc. Meeting Abstracts Vol. 218, 331.11 (AAS, 2011)..
Ingalls, J. G. et al. Intra-pixel gain variations and high-precision photometry with the Infrared Array Camera (IRAC). Proc. SPIE 8442, 84421Y (2012).
Carey, S., Ingalls, J., Grillmair, C. & Krick, J. Challenges in data analysis of Spitzer exoplanet observations. In Astronomical Data Analysis Software and Systems XXIII (eds Manset, N. & Forshay, P.) 407 (2014).
Grillmair, C. J., Carey, S. J., Stauffer, J. R. & Ingalls, J. G. Improving our understanding of the Spitzer Space Telescope’s pointing drifts. Proc. SPIE 9143, 914359 (2014).
Ingalls, J. G. et al. Spitzer/IRAC precision photometry: a machine learning approach. Proc. SPIE 10698, 106985E (2018).
Ingalls, J. G. et al. Repeatability and accuracy of exoplanet eclipse depths measured with post-cryogenic Spitzer. Astron. J. 152, 44 (2016).
Todorov, K. O., Deming, D., Burrows, A. & Grillmair, C. J. Updated Spitzer emission spectroscopy of bright transiting hot Jupiter HD 189733b. Astrophys. J. 796, 100 (2014).
Acknowledgements
We thank M. Marley for his comments on the brown dwarf section and E. Agol for his comments on the TRAPPIST-1 masses. We thank Y. Chachan, N. Wallack and M. Zhang for making figures.
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Deming, D., Knutson, H.A. Highlights of exoplanetary science from Spitzer. Nat Astron 4, 453–466 (2020). https://doi.org/10.1038/s41550-020-1100-9
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DOI: https://doi.org/10.1038/s41550-020-1100-9