A Super-Earth Transiting a Naked-Eye Star
Author(s)
Winn, Joshua Nathan
Matthews, Jaymie M.
Dawson, Rebekah I.
Fabrycky, Daniel C.
Holman, Matthew J.
Kallinger, Thomas
Kuschnig, Rainer
Sasselov, Dimitar
Dragomir, Diana
Guenther, David B.
Date Issued
July 2011
Journal
Astrophysical Journal. Letters
Publisher
IOP Publishing
Citation
Winn, Joshua N. et al. “A SUPER-EARTH TRANSITING A NAKED-EYE STAR.” The Astrophysical Journal 737.1 (2011): L18.
Version
Author's final manuscript
Abstract
We have detected transits of the innermost planet "e" orbiting 55 Cnc (V = 6.0), based on two weeks of nearly continuous photometric monitoring with the MOST space telescope. The transits occur with the period (0.74 days) and phase that had been predicted by Dawson & Fabrycky, and with the expected duration and depth for the crossing of a Sun-like star by a hot super-Earth. Assuming the star's mass and radius to be 0.963+0.051 – 0.029 M ☉ and 0.943 ± 0.010 R ☉, the planet's mass, radius, and mean density are 8.63 ± 0.35 M ⊕, 2.00 ± 0.14 R ⊕, and 5.9(superscript +1.5) – 1.1 g cm(superscript –3), respectively. The mean density is comparable to that of Earth, despite the greater mass and consequently greater compression of the interior of 55 Cnc e. This suggests a rock-iron composition supplemented by a significant mass of water, gas, or other light elements. Outside of transits, we detected a sinusoidal signal resembling the expected signal due to the changing illuminated phase of the planet, but with a full range (168 ± 70 ppm) too large to be reflected light or thermal emission. This signal has no straightforward interpretation and should be checked with further observations. The host star of 55 Cnc e is brighter than that of any other known transiting planet, which will facilitate future investigations.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
Terms of Use
Creative Commons Attribution-Noncommercial-Share Alike 3.0
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1088/2041-8205/737/1/l18
