1,374 research outputs found

    Periodic points of latitudinal maps of the m-dimensional sphere

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    Let f be a smooth self-map of the m-dimensional sphere Sm. Under the assumption that f preserves latitudinal foliations with the fibres S1, we estimate from below the number of fixed points of the iterates of f. The paper generalizes the results obtained by Pugh and Shub and by Misiurewicz

    The PSU/TCfA Search for Planets around Evolved Stars. Stellar parameters and activity indicators of targets

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    The main objective of the Penn State/Torun Centre for Astronomy Search for Planets around Evolved Stars is the detection of planetary systems around massive, evolved stars. We are also interested in the evolution of these systems on stellar evolution timescales. In this paper we present our approach to determine the basic physical parameters of our targets GK-giants. We also discuss the stellar activity indicators used in our survey: line bisector and curvature, and Halpha variability.Comment: 5 pages, to appear in ,,Exoplanets. Detection, Formation & Dynamics'' IAU Symposium 249, Cambridge University Press, 200

    Precise radial velocities of giant stars IX. HD 59686 Ab: a massive circumstellar planet orbiting a giant star in a ~13.6 au eccentric binary system

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    Context: For over 12 yr, we have carried out a precise radial velocity survey of a sample of 373 G and K giant stars using the Hamilton \'Echelle Spectrograph at Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims: We aim at detecting and characterizing substellar+stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods: We obtained high precision radial velocity (RV) measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. In order to discriminate between RV variations due to non-radial pulsation or stellar spots we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to further characterize the system, we obtain high-resolution images with LMIRCam at the Large Binocular Telescope. Results: We report the likely discovery of a giant planet with a mass of mp sini=6.920.24+0.18 MJupm_{p}~\sin i=6.92_{-0.24}^{+0.18}~M_{Jup} orbiting at ap=1.08600.0007+0.0006a_{p}=1.0860_{-0.0007}^{+0.0006} au from the giant star HD 59686 A. Besides the planetary signal, we discover an eccentric (eB=0.7290.003+0.004e_{B}=0.729_{-0.003}^{+0.004}) binary companion with a mass of mB sini=0.52960.0008+0.0011 MSunm_{B}~\sin i=0.5296_{-0.0008}^{+0.0011}~M_{Sun} orbiting at a semi-major axis of just aB=13.560.14+0.18a_{B}=13.56_{-0.14}^{+0.18} au. Conclusions: The existence of the planet HD 59686 Ab in a tight eccentric binary system severely challenges standard giant planet formation theories and requires substantial improvements to such theories in tight binaries. Otherwise, alternative planet formation scenarios such as second generation planets or dynamical interactions in an early phase of the system's lifetime should be seriously considered in order to better understand the origin of this enigmatic planet.Comment: 14 pages, 11 figures, 2 tables. Accepted for publication in A&A. Updated version to match the published pape
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