55 Cancri: Stellar Astrophysical Parameters, a Planet in the Habitable Zone, and Implications for the Radius of a Transiting Super-Earth

October 2011 • 2011ApJ...740...49V

Authors • von Braun, Kaspar • Boyajian, Tabetha S. • ten Brummelaar, Theo A. • Kane, Stephen R. • van Belle, Gerard T. • Ciardi, David R. • Raymond, Sean N. • López-Morales, Mercedes • McAlister, Harold A. • Schaefer, Gail • Ridgway, Stephen T. • Sturmann, Laszlo • Sturmann, Judit • White, Russel • Turner, Nils H. • Farrington, Chris • Goldfinger, P. J.

Abstract • The bright star 55 Cancri is known to host five planets, including a transiting super-Earth. The study presented here yields directly determined values for 55 Cnc's stellar astrophysical parameters based on improved interferometry: R = 0.943 ± 0.010 R _sun, T _EFF = 5196 ± 24 K. We use isochrone fitting to determine 55 Cnc's age to be 10.2 ± 2.5 Gyr, implying a stellar mass of 0.905 ± 0.015 M _sun. Our analysis of the location and extent of the system's habitable zone (HZ; 0.67-1.32 AU) shows that planet f, with period ~260 days and Msin i = 0.155 M _Jupiter, spends the majority of the duration of its elliptical orbit in the circumstellar HZ. Though planet f is too massive to harbor liquid water on any planetary surface, we elaborate on the potential of alternative low-mass objects in planet f's vicinity: a large moon and a low-mass planet on a dynamically stable orbit within the HZ. Finally, our direct value for 55 Cancri's stellar radius allows for a model-independent calculation of the physical diameter of the transiting super-Earth 55 Cnc e (~2.05 ± 0.15 R _⊕), which, depending on the planetary mass assumed, implies a bulk density of 0.76 ρ_⊕ or 1.07 ρ_⊕.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2011ApJ...740...49V
• PDF https://iopscience.iop.org/article/10.1088/0004-637X/740/1/49/pdf
• PDF https://stacks.iop.org/0004-637X/740/49/pdf
• PREPRINT http://arxiv.org/abs/1106.1152
• DATA https://irsa.ipac.caltech.edu/bibdata/2011/V/2011ApJ...740...49V.html
• ELECTR https://doi.org/10.1088%2F0004-637X%2F740%2F1%2F49