Warm ice giant GJ 3470b - II. Revised planetary and stellar parameters from optical to near-infrared transit photometry

Biddle, Lauren I.; Pearson, Kyle A.; Crossfield, Ian J. M.; Fulton, Benjamin J.; Ciceri, S.; Eastman, Jason D.; Barman, Travis; Mann, Andrew W.; Henry, Gregory W.; Howard, Andrew W.; Williamson, Michael H.; Sinukoff, Evan; Dragomir, Diana; Vican, Laura; Mancini, L.; Southworth, J.; Greenberg, Adam; Turner, Jake D.; Thompson, Robert M.; Taylor, B.; Levine, S. E.; Webber, Matthew

doi:10.1093/mnras/stu1199

Cited by 81 publications

(31 citation statements)

References 90 publications

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“…Also, day-side spectral features may be absent due to an isothermal pressuretemperature profile (Fortney et al 2006). These planets are consistent with other transiting exoplanet observations with flat spectra in optical wavelengths on TrES-3b , GJ 3470b (a hot Uranus; Biddle et al 2014), GJ 1214b (Bean et al 2011;Kreidberg et al 2014), WASP-29b (Gibson et al 2013a), and HAT-P-32b (Gibson et al 2013b).…”

Section: Wavelength Dependence On the Planetary Radiussupporting

confidence: 89%

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

Turner

Pearson

Biddle

et al. 2016

Mon. Not. R. Astron. Soc.

109

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Transits of exoplanets observed in the near-UV have been used to study the scattering properties of their atmospheres and possible star-planet interactions. We observed the primary transits of 15 exoplanets (CoRoT-1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-16b, HAT-P-22b, TrES2b, in the near-UV and several optical photometric bands to update their planetary parameters, ephemerides, search for a wavelength dependence in their transit depths to constrain their atmospheres, and determine if asymmetries are visible in their light curves. Here, we present the first ground-based near-UV light curves for 12 of the targets (CoRoT1b, GJ436b, HAT-P-1b, HAT-P-13b, HAT-P-22b, TrES-2b, TrES-4b, WASP-1b, WASP-33b, WASP-36b, WASP-48b, and WASP-77Ab). We find that none of the near-UV transits exhibit any non-spherical asymmetries, this result is consistent with recent theoretical predictions by Ben-Jaffel et al. and Turner et al. The multiwavelength photometry indicates a constant transit depth from near-UV to optical wavelengths in 10 targets (suggestive of clouds), and a varying transit depth with wavelength in 5 targets (hinting at Rayleigh or aerosol scattering in their atmospheres). We also present the first detection of a smaller near-UV transit depth than that measured in the optical in WASP-1b and a possible opacity source that can cause such radius variations is currently unknown. WASP-36b also exhibits a smaller near-UV transit depth at

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Section: Wavelength Dependence On the Planetary Radiussupporting

confidence: 89%

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

Turner

Pearson

Biddle

et al. 2016

Mon. Not. R. Astron. Soc.

109

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“…The data were compiled using exoplanets.org (Wright et al 2011) and the following publications: HAT-P-2: Bakos et al (2007), van Leeuwen (2007), Pál et al (2010), P rot from v sin i, T eq varies due to eccentricity ( (Salz et al 2015b); HAT-P-20: Bakos et al (2011), P rot from (Salz et al 2015b); WASP-8: Queloz et al (2010), Cubillos et al (2012), P rot from (Salz et al 2015b); WASP-80: Triaud et al (2013), P rot from v sin i; WASP-43: Hellier et al (2011);WASP-18: Hellier et al (2009), Pillitteri et al (2014, P rot from v sin i; HD 209458: Charbonneau et al (2000), Henry et al (2000), Torres et al (2008), Silva-Valio (2008), dayside brightness temperature from Spitzer observation (Crossfield et al 2012);HD 189733: Bouchy et al (2005), Henry & Winn (2008), Southworth (2010), dayside brightness temperature from Spitzer observation (Knutson et al 2007);GJ 1214), Berta et al (2011), Narita et al (2013; GJ 3470: Bonfils et al (2012), Biddle et al (2014);GJ 436: Butler et al (2004), Knutson et al (2011);55 Cnc: Butler et al (1997), McArthur et al (2004, Gray et al (2003), Fischer et al (2008); HAT-P-11: Bakos et al (2010);HD 149026: Sato et al (2005), P rot from v sin i, dayside brightness temperature from Spitzer observation (Knutson et al 2009);HD 97658: Howard et al (2011…”

Section: Target Selectionmentioning

confidence: 99%

Simulating the escaping atmospheres of hot gas planets in the solar neighborhood

Salz

Czesla

Schneider

et al. 2016

A&A

177

326

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Absorption of high-energy radiation in planetary thermospheres is generally believed to lead to the formation of planetary winds. The resulting mass-loss rates can affect the evolution, particularly of small gas planets. We present 1D, spherically symmetric hydrodynamic simulations of the escaping atmospheres of 18 hot gas planets in the solar neighborhood. Our sample only includes strongly irradiated planets, whose expanded atmospheres may be detectable via transit spectroscopy using current instrumentation. The simulations were performed with the PLUTO-CLOUDY interface, which couples a detailed photoionization and plasma simulation code with a general MHD code. We study the thermospheric escape and derive improved estimates for the planetary mass-loss rates. Our simulations reproduce the temperature-pressure profile measured via sodium D absorption in HD 189733 b, but show still unexplained differences in the case of HD 209458 b. In contrast to general assumptions, we find that the gravitationally more tightly bound thermospheres of massive and compact planets, such as HAT-P-2 b are hydrodynamically stable. Compact planets dispose of the radiative energy input through hydrogen Lyα and free-free emission. Radiative cooling is also important in HD 189733 b, but it decreases toward smaller planets like GJ 436 b. Computing the planetary Lyα absorption and emission signals from the simulations, we find that the strong and cool winds of smaller planets mainly cause strong Lyα absorption but little emission. Compact and massive planets with hot, stable thermospheres cause small absorption signals but are strong Lyα emitters, possibly detectable with the current instrumentation. The absorption and emission signals provide a possible distinction between these two classes of thermospheres in hot gas planets. According to our results, WASP-80 and GJ 3470 are currently the most promising targets for observational follow-up aimed at detecting atmospheric Lyα absorption signals.

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“…However, it is worth noting that an increase in planetary radius towards UV wavelengths has been detected for a number of planets, for instance, GJ3470b (Nascimbeni et al 2013;Biddle et al 2014), WASP-6b (Nikolov et al 2015), and WASP-31b . Interestingly, the host stars of all these planets and that of HD 189733b are active stars.…”

Section: Other Interpretations Of the Slopementioning

confidence: 99%

Using the chromatic Rossiter-McLaughlin effect to probe the broadband signature in the optical transmission spectrum of HD 189733b

Gloria

Snellen

Albrecht

2015

A&A

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Context. Transmission spectroscopy is a powerful technique for probing exoplanetary atmospheres. A successful ground-based observational method uses a differential technique that uses high-dispersion spectroscopy, but it only preserves narrow features in transmission spectra. Broadband features, such as the remarkable Rayleigh-scattering slope from possible hazes in the atmosphere of HD 189733b as observed by the Hubble Space Telescope, cannot be probed in this way. Aims. Here we use the chromatic Rossiter-McLaughlin (RM) effect to measure the Rayleigh-scattering slope in the transmission spectrum of HD 189733b with the aim to show that it can be effectively used to measure broadband transmission features. The amplitude of the RM effects depends on the effective size of the planet, and in the case of an atmospheric contribution therefore depends on the observed wavelength. Methods. We analysed archival HARPS data of three transits of HD 189733b, covering a wavelength range of 400 to 700 nm. The radial velocity (RV) time-series were determined for white light and for six wavelength bins each 50 nm wide, using the crosscorrelation profiles as provided by the HARPS data reduction pipeline. The RM effect was first fitted to the white-light RV time series using the publicly available code AROME. The residuals to this best fit were subsequently subtracted from the RV time series of each wavelength bin, after which they were also fitted using the same code, leaving only the effective planet radius to vary. Results. We measured the slope in the transmission spectrum of HD 189733b at a 2.5σ significance. Assuming it is due to Rayleigh scattering and not caused by stellar activity, it would correspond to an atmospheric temperature, as set by the scale height, of T = 2300 ± 900 K, well in line with previously obtained results. Conclusions. Ground-based high-dispersion spectral observations can be used to probe broad-band features in the transmission spectra of extrasolar planets, such as the optical Rayleigh-scattering slope of HD 189733b, by using the chromatic Rossiter-McLaughlin effect. The precision achieved with HARPS per transit is about an order of magnitude lower than that with STIS on the Hubble Space Telescope. This method will be particularly interesting in conjunction with the new echelle spectrograph ESPRESSO, which currently is under construction for ESO's Very Large Telescope, which will provide a gain in signal-to-noise ratio of about a factor 4 compared to HARPS. This will be of great value because of the limited and uncertain future of the Hubble Space Telescope and because the future James Webb Space Telescope will not cover this wavelength regime.

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Warm ice giant GJ 3470b - II. Revised planetary and stellar parameters from optical to near-infrared transit photometry

Cited by 81 publications

References 90 publications

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

Ground-based near-UV observations of 15 transiting exoplanets: constraints on their atmospheres and no evidence for asymmetrical transits

Simulating the escaping atmospheres of hot gas planets in the solar neighborhood

Using the chromatic Rossiter-McLaughlin effect to probe the broadband signature in the optical transmission spectrum of HD 189733b

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