ACME Stellar Spectra. I. Absolutely Calibrated, Mostly Empirical Flux Densities of 55 Cancri and its Transiting Planet 55 Cancri e

Abstract

The ACME Spectra project provides absolutely calibrated, mostly empirical spectra of exoplanet host stars for use in analysis of the stars and their planets. Spectra are obtained from ground-based telescopes and are tied directly to calibrated ground- and space-based photometry. The spectra remain only "mostly" empirical because of telluric absorption, but interpolation of stellar models over the gaps in wavelength coverage provides continuous stellar spectra. Among other uses, the spectra are suitable for precisely converting observed secondary eclipses (occultations) into absolute flux units with minimal recourse to models. In this letter I introduce ACME's methods and present a calibrated spectrum of the nearby, super-Earth hosting star 55 Cancri that spans the range from 0.81-5.05 micron. This spectrum is well-suited for interpreting near- and thermal-infrared eclipse observations. With this spectrum I show that the brightness temperature of the small, low-mass transiting planet 55 Cnc e is 1950 +260/-190 K at 4.5 micron (cooler than previously reported), which corresponds to a planetary flux of 0.44 +0.12/-0.08 mJy. This result suggests the planet has some combination of a nonzero albedo, a moderately efficient redistribution of absorbed stellar irradiation, and/or an optically thick atmosphere, but more precise eclipse measurements are required to distinguish between these scenarii.

Accepted to A&A. 6 pages, 1 figure, 1 electronic table. See http://irtfweb.ifa.hawaii.edu/~spex/IRTF_Spectral_Library/ for an alternative spectrum

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Cited by in corpus (14)

• The PLATO 2.0 Mission
• A map of the large day-night temperature gradient of a super-Earth exoplanet
• Detection of an atmosphere around the super-Earth 55 Cancri e
• Variability in the super-Earth 55 Cnc e
• A secondary atmosphere on the rocky exoplanet 55 Cancri e
• Linking the Climate and Thermal Phase Curve of 55 Cancri e
• A Case for an Atmosphere on Super-Earth 55 Cancri e
• Warm Ice Giant GJ 3470b. II Revised Planetary and Stellar Parameters from Optical to Near-infrared Transit Photometry
• Confirming Variability in the Secondary Eclipse Depth of the Super-Earth 55 Cancri e
• JWST reveals a rapid and strong day side variability of 55 Cancri e
• Atmospheric compositions and observability of nitrogen dominated ultra-short period super-Earths
• Multi-season optical modulation phased with the orbit of the super-Earth 55 Cnc e
• Characterising the Atmosphere of 55 Cancri e: 1D Forward Model Grid for Current and Future JWST Observations
• Inversion of stellar spectral radiative properties based on multiple star catalogues