Detection of a transit of the super-Earth 55 Cnc e with Warm Spitzer

TL;DR

This paper reports the first detection of a transit of super-Earth 55 Cnc e using warm Spitzer, providing key measurements of its size, mass, and density, and highlighting its suitability for detailed characterization.

Contribution

It presents the first transit detection of 55 Cnc e with warm Spitzer and provides precise measurements of its physical properties, enhancing understanding of super-Earths.

Findings

Transit depth of 410 ± 63 ppm measured

Planetary radius of 2.08 ± 0.16 R_Earth

Planetary density of 4.8 ± 1.3 g/cm^3

Abstract

We report on the detection of a transit of the super-Earth 55 Cnc e with warm Spitzer in IRAC's 4.5-micron band. Our MCMC analysis includes an extensive modeling of the systematic effects affecting warm Spitzer photometry, and yields a transit depth of 410 +- 63 ppm, which translates to a planetary radius of 2.08 +- 0.16 R_Earth as measured in IRAC 4.5-micron channel. A planetary mass of 7.81 +- 0.58 M_Earth is derived from an extensive set of radial-velocity data, yielding a mean planetary density of 4.8 +- 1.3 g cm-3. Thanks to the brightness of its host star (V = 6, K = 4), 55 Cnc e is a unique target for the thorough characterization of a super-Earth orbiting around a solar-type star.