000002142 001__ 2142
000002142 005__ 20160706150123.0
000002142 0247_ $$2DOI$$a10.1051/0004-6361/201423976
000002142 037__ $$aASTROimport-299
000002142 100__ $$aSódor, Á.
000002142 245__ $$aMOST light-curve analysis of the γ Doradus pulsator HR 8799, showing resonances and amplitude variations
000002142 260__ $$c2014
000002142 520__ $$aContext. The central star of the HR 8799 system is a γ Doradus-type pulsator. The system harbours four planetary-mass companions detected by direct imaging, and is a good solar system analogue. The masses of the companions are not accurately known because the estimation depends greatly on the age of the system, which is also not known with sufficient accuracy. Asteroseismic studies of the star might help to better constrain the age of HR 8799. We organized an extensive photometric and multi-site spectroscopic observing campaign to study the pulsations of the central star.  Aims: The aim of the present study is to investigate the pulsation properties of HR 8799 in detail via the ultra-precise 47 d nearly continuous photometry obtained with the Microvariability and Oscillations in STars (MOST) space telescope, and to find as many independent pulsation modes as possible, which is the prerequisite for an asteroseismic age determination.  Methods: We carried out Fourier analysis of the wide-band photometric time series.  Results: We find that resonance and sudden amplitude changes characterize the pulsation of HR 8799. The dominant frequency is always at f1 = 1.978 d-1.Many multiples of one-ninth of the dominant frequency appear in the Fourier spectrum of the MOST data: n/9 f1, where n = {1,2,3,4,5,6,7,8,9,10,13,14,17,18}. Our analysis also reveals that many of these peaks show strong amplitude decrease and phase variations even on the 47 d time scale. The dependencies between the pulsation frequencies of HR 8799 make the planned subsequent asteroseismic analysis rather difficult. We point out some resemblance between the light curve of HR 8799 and the modulated pulsation light curves of Blazhko RR Lyrae stars. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna.
000002142 700__ $$aChené, A.-N.
000002142 700__ $$aDe Cat, P.
000002142 700__ $$aBognár, Z.
000002142 700__ $$aWright, D. J.
000002142 700__ $$aMarois, C.
000002142 700__ $$aWalker, G. A. H.
000002142 700__ $$aMatthews, J. M.
000002142 700__ $$aKallinger, T.
000002142 700__ $$aRowe, J. F.
000002142 700__ $$aKuschnig, R.
000002142 700__ $$aGuenther, D. B.
000002142 700__ $$aMoffat, A. F. J.
000002142 700__ $$aRucinski, S. M.
000002142 700__ $$aSasselov, D.
000002142 700__ $$aWeiss, W. W.
000002142 773__ $$cA106$$pAstronomy and Astrophysics$$v568$$y2014
000002142 85642 $$ahttp://esoads.eso.org/abs/2014A%26A...568A.106S
000002142 905__ $$apublished in
000002142 980__ $$aREFERD