TRANSMISSION SPECTROSCOPY OF THE HOT JUPITER WASP-12b FROM 0.7 TO 5 μm

Stevenson, Kevin B.; Bean, Jacob L.; Seifahrt, Andreas; Désert, Jean-Michel; Madhusudhan, Nikku; Bergmann, Marcel; Kreidberg, Laura; Homeier, D.

doi:10.1088/0004-6256/147/6/161

Cited by 195 publications

(233 citation statements)

References 40 publications

(80 reference statements)

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“…These results are similar to the values reached with GEMINI-N/GMOS in comparable spectrophotometric studies (G13; Stevenson et al 2014). The properties of the chromatic light curves are summarized in Table A.1.…”

Section: Creation Of Light Curvessupporting

confidence: 88%

Transmission spectroscopy of HAT-P-32b with the LBT: confirmation of clouds/hazes in the planetary atmosphere

Mallonn

Strassmeier

2016

A&A

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Aims. Spectroscopic observations of a transit event of an extrasolar planet offer the opportunity to study the composition of the planetary atmosphere. This can be done with comparably little telescope time using a low-resolution multi-object spectrograph at a large aperture telescope. We observed a transit of the inflated hot Jupiter HAT-P-32b with the Multi-Object Double Spectrograph at the Large Binocular Telescope to characterize its atmosphere from 3300 to 10 000 Å. Methods. A time series of target and reference star spectra was binned in two broad-band wavelength channels, from which differential transit light curves were constructed. These broad-band light curves were used to confirm previous transit parameter determinations. To derive the planetary transmission spectrum with a resolution of R ∼ 60, we created a chromatic set of 62 narrow-band light curves. The spectrum was corrected for the third light of a nearby M star. Additionally, we undertook a photometric monitoring campaign of the host star to correct for the influence of starspots. Results. The transmission spectrum of HAT-P-32b shows no pressure-broadened absorption features from Na and K, which is interpreted by the presence of clouds or hazes in the planetary atmosphere. This result is in agreement with previous studies on the same planet. The presence of TiO in gas phase could be ruled out. We find a 2.8σ indication of increased absorption in the line core of potassium (K I 7699 Å). No narrow absorption features of Na and Hα were detected. Furthermore, tentative indications were found for a slope of increasing opacity toward blue wavelengths from the near-IR to the near-UV with an amplitude of two scale heights. If confirmed by follow-up observations, it can be explained by aerosols either causing Mie scattering or causing Rayleigh scattering with an aerosol -gas scale height ratio below unity. The host star was found to be photometrically stable within the measurement precision.

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Section: Creation Of Light Curvessupporting

confidence: 88%

Transmission spectroscopy of HAT-P-32b with the LBT: confirmation of clouds/hazes in the planetary atmosphere

Mallonn

Strassmeier

2016

A&A

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“…More recent observations of the day-side emission spectrum of HD 209458b, call the existence of the inversion layer into question (Zellem et al 2014;Diamond-Lowe et al 2014). Interestingly, Stevenson et al (2014) observed molecular absorption features in the near-infrared dayside spectrum of Wasp-12b, possibly attributable to TiO. This contrasts with the optical transmission spectra of the same planet, as put forth by Sing et al (2013).…”

Section: Introductionmentioning

confidence: 87%

A search for TiO in the optical high-resolution transmission spectrum of HD 209458b: Hindrance due to inaccuracies in the line database

Hoeijmakers

Kok

Snellen

et al. 2015

A&A

111

120

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Context. The spectral signature of an exoplanet can be separated from the spectrum of its host star using high-resolution spectroscopy. During these observations, the radial component of the planet's orbital velocity changes, resulting in a significant Doppler shift that allows its spectral features to be extracted. Aims. In this work, we aim to detect TiO in the optical transmission spectrum of HD 209458b. Gaseous TiO has been suggested as the cause of the thermal inversion layer invoked to explain the dayside spectrum of this planet. Methods. We used archival data from the 8.2 m Subaru telescope taken with the High Dispersion Spectrograph of a transit of HD 209458b in 2002. We created model transmission spectra that include absorption by TiO, and cross-correlated them with the residual spectral data after removal of the dominating stellar absorption features. We subsequently co-added the correlation signal in time, taking the change in Doppler shift due to the orbit of the planet into account. Results. We detect no significant cross-correlation signal due to TiO, though artificial injection of our template spectra into the data indicates a sensitivity down to a volume-mixing ratio of ∼10 −10 . However, cross-correlating the template spectra with a HARPS spectrum of Barnard's star yields only a weak wavelength-dependent correlation, even though Barnard's star is an M4V dwarf that exhibits clear TiO absorption. We infer that the TiO line list poorly matches the real positions of TiO lines at spectral resolutions of ∼100 000. Similar line lists are also used in the PHOENIX and Kurucz stellar atmosphere suites and we show that their synthetic M-dwarf spectra also correlate poorly with the HARPS spectra of Barnard's star and five other M dwarfs. We conclude that the lack of an accurate TiO line list is currently critically hampering this high-resolution retrieval technique.

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“…While the host star is fairly faint (V = 12), WASP-12b's close semimajor axis and large radius (a = 0.0234 au, R R 1.90 Collins et al 2017) make it an excellent target for detailed study. Transit observations of WASP-12b range from 0.3 to 4.5μm, and eclipse observations range from 0.9 to 8.0μm (e.g., Hebb et al 2009;López-Morales et al 2010;Campo et al 2011;Madhusudhan et al 2011;Cowan et al 2012;Crossfield et al 2012;Copperwheat et al 2013;Föhring et al 2013;Sing et al 2013;Swain et al 2013;Stevenson et al 2014aStevenson et al , 2014bCroll et al 2015;Sing et al 2016). This work presents the first optical eclipse measurement of WASP-12b.…”

Section: Introductionmentioning

confidence: 92%

The Very Low Albedo of WASP-12b from Spectral Eclipse Observations with Hubble

Bell

Nikolov

Cowan

et al. 2017

ApJL

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We present an optical eclipse observation of the hot Jupiter WASP-12b using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. These spectra allow us to place an upper limit of A 0.064 g < (97.5% confidence level) on the planet's white light geometric albedo across 290-570 nm. Using six wavelength bins across the same wavelength range also produces stringent limits on the geometric albedo for all bins. However, our uncertainties in eclipse depth are ∼40% greater than the Poisson limit and may be limited by the intrinsic variability of the Sun-like host star-the solar luminosity is known to vary at the 10 −4 level on a timescale of minutes. We use our eclipse depth limits to test two previously suggested atmospheric models for this planet: Mie scattering from an aluminum-oxide haze or cloud-free Rayleigh scattering. Our stringent nondetection rules out both models and is consistent with thermal emission plus weak Rayleigh scattering from atomic hydrogen and helium. Our results are in stark contrast with those for the much cooler HD 189733b, the only other hot Jupiter with spectrally resolved reflected light observations; those data showed an increase in albedo with decreasing wavelength. The fact that the first two exoplanets with optical albedo spectra exhibit significant differences demonstrates the importance of spectrally resolved reflected light observations and highlights the great diversity among hot Jupiters.

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TRANSMISSION SPECTROSCOPY OF THE HOT JUPITER WASP-12b FROM 0.7 TO 5 μm

Cited by 195 publications

References 40 publications

Transmission spectroscopy of HAT-P-32b with the LBT: confirmation of clouds/hazes in the planetary atmosphere

Transmission spectroscopy of HAT-P-32b with the LBT: confirmation of clouds/hazes in the planetary atmosphere

A search for TiO in the optical high-resolution transmission spectrum of HD 209458b: Hindrance due to inaccuracies in the line database

The Very Low Albedo of WASP-12b from Spectral Eclipse Observations with Hubble

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