Hubble Space Telescope hot Jupiter transmission spectral survey: a detection of Na and strong optical absorption in HAT-P-1b

By N. Nikolov, D. Sing, F. Pont, Adam Burrows, Jon Fortney, Gilda E. Ballester, T. Evans, C. Huitson, H. Wakeford, P. Wilson and 9 more. 2013

137 citations recorded by the source corpus.

We present an optical to near-infrared transmission spectrum of the hot Jupiter HAT-P-1b, based on Hubble Space Telescope observations, covering the spectral regime from 0.29 to 1.027 μm with Space Telescope Imaging Spectrograph (STIS), which is coupled with a recent Wide Field Camera 3 (WFC3) transit (1.087 to 1.687 μm). We derive refined physical parameters of the HAT-P-1 system, including an improved orbital ephemeris. The transmission spectrum shows a strong absorption signature shortward of 0.55 μm, with a strong blueward slope into the near-ultraviolet. We detect atmospheric sodium absorption at a 3.3σ significance level, but find no evidence for the potassium feature. The red data imply a marginally flat spectrum with a tentative absorption enhancement at wavelength longer than ∼0.85 μm. The STIS and WFC3 spectra differ significantly in absolute radius level (4.3 ± 1.6 pressure scaleheights), implying strong optical absorption in the atmosphere of HAT-P-1b. The optical to near-infrared difference cannot be explained by stellar activity, as simultaneous stellar activity monitoring of the G0V HAT-P-1b host star and its identical companion show no significant activity that could explain the result. We compare the complete STIS and WFC3 transmission spectrum with theoretical atmospheric models which include haze, sodium and an extra optical absorber. We find that both an optical absorber and a supersolar sodium to water abundance ratio might be a scenario explaining the HAT-P-1b observations. Our results suggest that strong optical absorbers may be a dominant atmospheric feature in some hot Jupiter exoplanets.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/004c23180a5e5c5834f86a17d17eeb4dfaa09734

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. D. Sing
4. A. Showman
5. D. Deming
6. J. D'esert
7. H. Knutson
8. Suzanne Aigrain

Citations in the corpus

• Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, unknown): “T-P-26b (277), HAT-P-32b (60), HAT-P-41b (266), XO-1b (63) Na HD 189733b (214), HD 209458b (50), WASP-17b (244), WASP-39b (194), WASP-52b (52), WASP-69b (48), WASP-96b (193), WASP-127b (53), HAT-P-1b (195), XO-2b (245) Continued on next page 18 N. Madhusudhan Table 1 { Continued from previous page C”
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering (2014, methodology): “Similar to our previous STIS analysis (Sing et al. 2013; Huitson et al. 2013; Nikolov et al. 2014b), we intended to discard the entire first orbit to minimise the effect of the breathing trend, but found for two of the three HST visits, a few of the exposures taken toward the end of the first orbit…”
• Spectrally resolved detection of sodium in the atmosphere of HD 189733b with the HARPS spectrograph (2015, background): “…exoplanets (Charbonneau et al. 2002; Snellen et al. 2008; Sing et al. 2008a, 2012, 2015; Langland-Shula et al. 2009; Wood et al. 2011; Zhou & Bayliss 2012; Murgas et al. 2014; Nikolov et al. 2014; Burton et al. 2015), we calculated the relative absorption depth across various bins in wavelength.”
• A CONSISTENT RETRIEVAL ANALYSIS OF 10 HOT JUPITERS OBSERVED IN TRANSMISSION (2016, background): “The spectral fits shown here do not provide a good match to these data points, but the IRAC points for WASP-6b are derived from incomplete transits (Nikolov et al. 2014), so may be considered less reliable than the STIS data.”
• DETECTION OF H2O AND EVIDENCE FOR TiO/VO IN AN ULTRA-HOT EXOPLANET ATMOSPHERE (2016, background): “Transmission spectra at optical wavelengths show evidence for Rayleigh scattering by molecular hydrogen and high-altitude aerosols, and absorption by alkali metals (e.g. Charbonneau et al. 2002; Pont et al. 2008; Sing et al. 2013, 2015; Nikolov et al. 2014, 2015).”