For a complete list of publications, here is the link to my ADS library records.

First author publication

  1. Aerosols impact on optical satellite transmission (Gressier and Kaillault Aerotecnica Missili & Spazio, Associazione italiana di aeronautica e astronautica, 2019, 98 (3), pp.207-219.)

  2. Near-Infrared transmission spectrum of TRAPPIST-1 h using Hubble WFC3 G141 (Gressier et al. 2022 Astronomy & Astrophysics Volume 658, id.A133, 25 pp). This paper presents the first Hubble WFC3 G141 transmission spectrum of a cold, rocky planet, TRAPPIST-1 h. I extracted and corrected the three raw transit observations using the pipeline iraclis. I give the first atmospheric constraint using a Bayesian atmospheric retrieval code. This planet is unlikely to bear a H/He clear dominated atmosphere, but a cloudy/hazy light atmosphere can not be ruled out. The planet might have lost its atmosphere or possesses a secondary N2 or CO2-rich atmosphere.

  3. The Hubble PanCET Program: The near-UV transmission spectrum of WASP-79b (Gressier et al. 2023a Astronomy & Astrophysics). This paper presents a method to decorrelate the systematics noise from the transit signal and fit light curves of near-UV Hubble STIS E230M observations. I apply the technique to WASP-121 b’s observations and confirm the photo-evaporation of its atmosphere previously detected by Sing et al. 2019. Besides, I analysed two unprecedented transit observations of WASP-79 b and observed an increase in the planet-to-star radius ratio at short wavelengths. The difference between the radius ratios at 2400Å and 3000Å reaches 0.0191±0.0042 (4.5 sigma). Although the NUV transmission spectrum does not show evidence of hydrodynamical escape, the strong atmospheric features are likely due to species at very high altitudes. The comparison of WASP-79 b’s transmission spectrum with three other warmer Hot-Jupiters shows a similar absorption level to WASP-178 b and WASP-121 b.

  4. Population study: Exploring the transition from Super-Earth to Sub-Neptune with a Hubble transmission survey (Gressier et al. 2023b submitted to A&A). In this work I present the first large-scale consistent Hubble WFC3 G141 transmission survey of Super-Earth and Sub-Neptunes. I collected 26 transmission spectra of planets smaller than 6REarth . All transmission spectra are obtained using the same pipeline, iraclis and consistently analysed using a Bayesian atmospheric retrieval code, Tau-REx. I present a model comparison method to quantify atmospheric and molecular detections. I confirmed, the detection of an atmosphere for 13 planets with a radius larger than 1.7REarth and detected water vapour with high confidence for nine planets. The most striking result is the absence of methane detection in Sub-Neptune atmospheres. I evaluate the impact of KCl and Na2S clouds on the water feature amplitude around 1.4microns using self-consistent simulations with Exo-REM. I built a grid of model spanning the metallicity, temperature and cloud coverage. We confirmed the retrieval results and refined the nature of clouds in Sub-Neptune atmospheres. We concluded that we could not fit flat spectra with radiative clouds only and that photochemical hazes are probably responsible for low water amplitudes in the atmosphere of Sub-Neptunes between 500 and 800 K. For smaller planets, although the HST data cannot be used to distinguish a light atmosphere with clouds from a high mean molecular weight atmosphere, I have shown by performing telescope simulations for the James Webb Space Telescope and the future ESA-Ariel space mission that the extended wavelength range and increasing spectral resolution will allow to distinguish those scenarios.

Second author publication

  1. ARES IV: Probing the atmospheres of two warm Neptune planets HD 106315 c and HD 3167 c with HST/WFC3 camera (Guilluy et al. 2021, The Astronomical Journal, Volume 161, Issue 1, id.19, 22pp.) I prepared this paper in collaboration with Gloria Guilluy. We present the transmission spectrum of two warm Neptune-like planets. I extracted, corrected and fitted the raw light curves of HD 106315 c and led the atmospheric retrieval analysis on both planets. We found a robust hydrogen-dominated atmospheric signal (over 5 sigma) linked to a strong water feature around 1.4 microns in both spectra. Carbon dioxide is also detected in HD 3167 c’s atmosphere. The atmospheric detection of these two planets is promising for intermediate-sized planets atmospheric characterisation.

Major co-author publication

These papers are part of the work done during the ARIEL Retrieval of Exoplanets School (ARES Summer School)

  1. ARES I: WASP-76 b a tale of two HST spectra (Edwards et al. 2020, The Astronomical Journal, Volume 160, Issue 1, id.8, 14pp.)

  2. ARES II: Characterising the Hot Jupiters WASP-127 b, WASP-79 b and WASP-62 b with HST (Skaf et al. 2020, The Astronomical Journal, Volume 160, Issue 3, id.109)

  3. ARES III: Unveiling the two faces of KELT-7 b with HST/WFC3 (Pluriel et al. 2020, The Astronomical Journal, Volume 160, Issue 3, id.112)

  4. ARES V: No evidence for molecular absorption in the HST/WFC3 spectrum of GJ 1132 b (Mugnai et al. 2021, The Astronomical Journal, Volume 161, Issue 6, id.284, 13pp)