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83 - K. von Braun 2011
The bright star 55 Cancri is known to host five planets, including a transiting super-Earth. We use the CHARA Array to directly determine the following of 55 Cncs stellar astrophysical parameters: $R=0.943 pm 0.010 R_{odot}$, $T_{rm EFF} = 5196 pm 24 $ K. Planet 55 Cnc f ($M sin i = 0.155 M_{Jupiter}$) spends the majority of the duration of its elliptical orbit in the circumstellar habitable zone (0.67--1.32 AU) where, with moderate greenhouse heating, it could harbor liquid water. Our determination of 55 Cancris stellar radius allows for a model-independent calculation of the physical diameter of the transiting super-Earth 55 Cnc e ($simeq 2.1 R_{earth}$), which, depending on the assumed literature value of planetary mass, implies a bulk density of 0.76 $rho_{earth}$ or 1.07 $rho_{earth}$.
We present new results from a radial velocity study of six bright OB stars with little or no prior measurements. One of these, HD 45314, may be a long-period binary, but the velocity variations of this Be star may be related to changes in its circums tellar disk. Significant velocity variations were also found for HD 60848 (possibly related to nonradial pulsations) and HD 61827 (related to wind variations). The other three targets, HD 46150, HD 54879, and HD 206183, are constant velocity objects, but we note that HD 54879 has H$alpha$ emission that may originate from a binary companion. We illustrate the average red spectrum of each target.
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