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Title: A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e

Abstract

We present the analysis of high-resolution optical spectra of four transits of 55Cnc e, a low-density super-Earth that orbits a nearby Sun-like star in under 18 hr. The inferred bulk density of the planet implies a substantial envelope, which, according to mass–radius relationships, could be either a low-mass extended or a high-mass compact atmosphere. Our observations investigate the latter scenario, with water as the dominant species. We take advantage of the Doppler cross-correlation technique, high-spectral resolution, and the large wavelength coverage of our observations to search for the signature of thousands of optical water absorption lines. Using our observations with HDS on the Subaru telescope and ESPaDOnS on the Canada–France–Hawaii Telescope, we are able to place a 3 σ lower limit of 10 g mol{sup −1} on the mean-molecular weight of 55Cnc e’s water-rich (volume mixing ratio >10%), optically thin atmosphere, which corresponds to an atmospheric scale-height of ∼80 km. Our study marks the first high-spectral resolution search for water in a super-Earth atmosphere, and demonstrates that it is possible to recover known water-vapor absorption signals in a nearby super-Earth atmosphere, using high-resolution transit spectroscopy with current ground-based instruments.

Authors:
 [1]; ;  [2];  [3];  [4]
  1. Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada)
  2. Astrophysics Research Centre, School of Mathematics and Physics, Queens University, Belfast (United Kingdom)
  3. Physics and Astronomy, York University, Toronto, Ontario L3T 3R1 (Canada)
  4. Leiden Observatory, Leiden University, Postbus 9513, 2300 RA, Leiden (Netherlands)
Publication Date:
OSTI Identifier:
22663545
Resource Type:
Journal Article
Journal Name:
Astronomical Journal (Online)
Additional Journal Information:
Journal Volume: 153; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1538-3881
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; BULK DENSITY; CANADA; CORRELATIONS; HAWAII; MASS; MIXING RATIO; ORBITS; PLANETS; SATELLITE ATMOSPHERES; SATELLITES; SCALE HEIGHT; SPECTROSCOPY; SUN; TELESCOPES; WATER; WATER VAPOR; WAVELENGTHS

Citation Formats

Esteves, Lisa J., De Mooij, Ernst J. W., Watson, Chris, Jayawardhana, Ray, and De Kok, Remco, E-mail: esteves@astro.utoronto.ca, E-mail: ernst.demooij@dcu.ie, E-mail: c.a.watson@qub.ac.uk, E-mail: rayjay@yorku.ca, E-mail: r.j.de.kok@sron.nl. A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e. United States: N. p., 2017. Web. doi:10.3847/1538-3881/AA7133.
Esteves, Lisa J., De Mooij, Ernst J. W., Watson, Chris, Jayawardhana, Ray, & De Kok, Remco, E-mail: esteves@astro.utoronto.ca, E-mail: ernst.demooij@dcu.ie, E-mail: c.a.watson@qub.ac.uk, E-mail: rayjay@yorku.ca, E-mail: r.j.de.kok@sron.nl. A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e. United States. doi:10.3847/1538-3881/AA7133.
Esteves, Lisa J., De Mooij, Ernst J. W., Watson, Chris, Jayawardhana, Ray, and De Kok, Remco, E-mail: esteves@astro.utoronto.ca, E-mail: ernst.demooij@dcu.ie, E-mail: c.a.watson@qub.ac.uk, E-mail: rayjay@yorku.ca, E-mail: r.j.de.kok@sron.nl. Thu . "A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e". United States. doi:10.3847/1538-3881/AA7133.
@article{osti_22663545,
title = {A Search for Water in a Super-Earth Atmosphere: High-resolution Optical Spectroscopy of 55Cancri e},
author = {Esteves, Lisa J. and De Mooij, Ernst J. W. and Watson, Chris and Jayawardhana, Ray and De Kok, Remco, E-mail: esteves@astro.utoronto.ca, E-mail: ernst.demooij@dcu.ie, E-mail: c.a.watson@qub.ac.uk, E-mail: rayjay@yorku.ca, E-mail: r.j.de.kok@sron.nl},
abstractNote = {We present the analysis of high-resolution optical spectra of four transits of 55Cnc e, a low-density super-Earth that orbits a nearby Sun-like star in under 18 hr. The inferred bulk density of the planet implies a substantial envelope, which, according to mass–radius relationships, could be either a low-mass extended or a high-mass compact atmosphere. Our observations investigate the latter scenario, with water as the dominant species. We take advantage of the Doppler cross-correlation technique, high-spectral resolution, and the large wavelength coverage of our observations to search for the signature of thousands of optical water absorption lines. Using our observations with HDS on the Subaru telescope and ESPaDOnS on the Canada–France–Hawaii Telescope, we are able to place a 3 σ lower limit of 10 g mol{sup −1} on the mean-molecular weight of 55Cnc e’s water-rich (volume mixing ratio >10%), optically thin atmosphere, which corresponds to an atmospheric scale-height of ∼80 km. Our study marks the first high-spectral resolution search for water in a super-Earth atmosphere, and demonstrates that it is possible to recover known water-vapor absorption signals in a nearby super-Earth atmosphere, using high-resolution transit spectroscopy with current ground-based instruments.},
doi = {10.3847/1538-3881/AA7133},
journal = {Astronomical Journal (Online)},
issn = {1538-3881},
number = 6,
volume = 153,
place = {United States},
year = {2017},
month = {6}
}