A Near-Infrared Chemical Inventory of the Atmosphere of 55 Cancri e

Abstract

We present high-resolution near-infrared spectra taken during eight transits of 55 Cancri e, a nearby low-density super-Earth with a short orbital period (< 18 hours). While this exoplanet's bulk density indicates a possible atmosphere, one has not been detected definitively. Our analysis relies on the Doppler cross-correlation technique, which takes advantage of the high spectral resolution and broad wavelength coverage of our data, to search for the thousands of absorption features from hydrogen-, carbon-, and nitrogen-rich molecular species in the planetary atmosphere. Although we are unable to detect an atmosphere around 55 Cancri e, we do place strong constraints on the levels of HCN, NH${}_3$, and C${}_2$H${}_2$ that may be present. In particular, at a mean molecular weight of 5 amu we can rule out the presence of HCN in the atmosphere down to a volume mixing ratio (VMR) of 0.02%, NH${}_3$ down to a VMR of 0.08%, and C${}_2$H${}_2$ down to a VMR of 1.0%. If the mean molecular weight is relaxed to 2 amu, we can rule out the presence of HCN, NH${}_3$, and C${}_2$H${}_2$ down to VMRs of 0.001%, 0.0025%, and 0.08% respectively. Our results reduce the parameter space of possible atmospheres consistent with the analysis of HST/WFC3 observations by Tsiaras et al. (2016), and indicate that if 55 Cancri e harbors an atmosphere, it must have a high mean molecular weight and/or clouds.

arXiv comment32 pages, 34 figures. Accepted for publication in AJ

References in corpus (50)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Analytic Lightcurves for Planetary Transit Searches
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• The orbital motion, absolute mass, and high-altitude winds of exoplanet HD209458b
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• Radial Velocities for 889 Late-type Stars
• Correcting systematic effects in a large set of photometric lightcurves
• Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra
• Detection of a NEPTUNE-mass planet in the ${\rho }^1$ Cancri system using the Hobby-Eberly Telescope
• Exoplanetary Atmospheres: Key Insights, Challenges and Prospects
• Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• A map of the large day-night temperature gradient of a super-Earth exoplanet
• A Super-Earth Transiting a Naked-Eye Star
• 55 Cancri (Copernicus): A Multi-Planet System with a Hot Super-Earth and a Jupiter Analogue
• Spectrally resolved helium absorption from the extended atmosphere of a warm Neptune-mass exoplanet
• Detection of an atmosphere around the super-Earth 55 Cancri e
• Chemistry of Silicate Atmospheres of Evaporating Super-Earths
• Exoplanetary Atmospheres - Chemistry, Formation Conditions, and Habitability
• Detection of a transit of the super-Earth 55 Cnc e with Warm Spitzer
• Photochemistry in Terrestrial Exoplanet Atmospheres III: Photochemistry and Thermochemistry in Thick Atmospheres on Super Earths and Mini Neptunes
• Hint of a transiting extended atmosphere on 55 Cancri b
• Detection of He I $\lambda 10830$ Å absorption on HD 189733 b with CARMENES high-resolution transmission spectroscopy
• Variability in the super-Earth 55 Cnc e
• SPIRou: the near-infrared spectropolarimeter/high-precision velocimeter for the Canada-France-Hawaii telescope
• The 55 Cnc system reassessed
• 55 Cancri: Stellar Astrophysical Parameters, a Planet in the Habitable Zone, and Implications for the Radius of a Transiting Super-Earth
• A search for TiO in the optical high-resolution transmission spectrum of HD 209458b: Hindrance due to inaccuracies in the line database
• Compositions of Hot Super-Earth Atmospheres: exploring Kepler Candidates
• Improved precision on the radius of the nearby super-Earth 55 Cnc e
• Detection of neutral atomic species in the ultra-hot jupiter WASP-121b
• Search for water vapor in the high-resolution transmission spectrum of HD189733b in the visible
• Linking the Climate and Thermal Phase Curve of 55 Cancri e
• Multiple water band detections in the CARMENES near-infrared transmission spectrum of HD 189733 b
• Search for water in a super-Earth atmosphere: High-resolution optical spectroscopy of 55 Cancri e
• A Case for an Atmosphere on Super-Earth 55 Cancri e
• Water vapor detection in the transmission spectra of HD 209458 b with the CARMENES NIR channel
• Arid or Cloudy: Characterizing the Atmosphere of the super-Earth 55 Cancri e using High-Resolution Spectroscopy
• Cloud formation in metal-rich atmospheres of hot super-Earths like 55 Cnc e and CoRot7b
• Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS) V. Detection of sodium on the bloated super-Neptune WASP-166b
• Atmospheric compositions and observability of nitrogen dominated ultra-short period super-Earths
• Telluric correction in the near-infrared: Standard star or synthetic transmission?
• High-Resolution Transit Spectroscopy of Warm Saturns
• A weak spectral signature of water vapour in the atmosphere of HD 179949 b at high spectral resolution in the L-band
• Observability of molecular species in a nitrogen dominated atmosphere for 55 Cancri e
• Mass, radius, and composition of the transiting planet 55 Cnc e : using interferometry and correlations --- A quick update
• The hidden depths of planetary atmospheres

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