8 documents found, page 1 of 1
A more realistic representation of overshoot at the base of the solar convectiv...
Christensen Dalsgaard, J; Monteiro, MJPFG; Rempel, M; Thompson, MJThe stratification near the base of the Sun's convective envelope is governed by processes of convective overshooting and element diffusion, and the region is widely believed to play a key role in the solar dynamo. The stratification in that region gives rise to a characteristic signal in the frequencies of solar p modes, which has been used to determine the depth of the solar convection zone and to investigate...
Ensemble Asteroseismology of Solar-Type Stars with the NASA Kepler Mission
Chaplin, WJ; Kjeldsen, H; Christensen Dalsgaard, J; Basu, S; Miglio, A; Appourchaux, T; Bedding, TR; Elsworth, Y; Garcia, RA; Gilliland, RL; Girardi, LIn addition to its search for extrasolar planets, the NASA Kepler mission provides exquisite data on stellar oscillations. We report the detections of oscillations in 500 solar-type stars in the Kepler field of view, an ensemble that is large enough to allow statistical studies of intrinsic stellar properties (such as mass, radius, and age) and to test theories of stellar evolution. We find that the distributio...
A PRECISE ASTEROSEISMIC AGE AND RADIUS FOR THE EVOLVED SUN-LIKE STAR KIC 11026764
Metcalfe, TS; Monteiro, MJPFG; Thompson, MJ; Molenda Zakowicz, J; Appourchaux, T; Chaplin, WJ; Dogan, G; Eggenberger, P; Bedding, TR; Bruntt, HThe primary science goal of the Kepler Mission is to provide a census of exoplanets in the solar neighborhood, including the identification and characterization of habitable Earth-like planets. The asteroseismic capabilities of the mission are being used to determine precise radii and ages for the target stars from their solar-like oscillations. Chaplin et al. published observations of three bright G-type stars...
THE ASTEROSEISMIC POTENTIAL OF KEPLER: FIRST RESULTS FOR SOLAR-TYPE STARS
Chaplin, WJ; Appourchaux, T; Elsworth, Y; Garcia, RA; Houdek, G; Karoff, C; Metcalfe, TS; Molenda Zakowicz, J; Monteiro, MJPFG; Thompson, MJ; Brown, TMWe present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5 days of science operations, reveal high signal-to-noise solar-like oscillation spectra in all three stars: about 20 modes of oscillation may be clearly distinguished in each star. We discuss the appearance of the oscillation spectra, use the frequencies and frequency...
Asteroseismology and interferometry
Cunha, MS; Aerts, C; Christensen Dalsgaard, J; Baglin, A; Bigot, L; Brown, TM; Catala, C; Creevey, OL; Domiciano D de Souza; Eggenberger, P; Garcia, PJVAsteroseismology provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Recent developments, including the first systematic studies of solar-like pulsators, have boosted the impact of this field of research within astrophysics and have led to a significant increase in the size of the research community. In the present paper we start by reviewing the basic observat...
Seismic study of stellar convective regions: the base of the convective envelop...
Monteiro, MJPFG; Christensen Dalsgaard, J; Thompson, MJThe possibility of observing solar-type oscillations on other stars is of great relevance to investigating the uncertain aspects of the internal structure of stars. One of these aspects is the convective overshoot that takes place at the borders of the envelopes of stars of mass similar to, or lower than, the Sun. It affects the temperature stratification, mixing, rotation and magnetic-field generation. Asteros...
The seismic structure of the sun
Gough, DO; Kosovichev, AG; Toomre, J; Anderson, E; Antia, HM; Basu, S; Chaboyer, B; Chitre, SM; ChristensenDalsgaard, J; Dziembowski, WA; EffDarwich, AGlobal Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps ...
Seismic properties of the Sun's superadiabatic layer .1. Theoretical modelling ...
Monteiro, MJPFG; ChristensenDalsgaard, J; Thompson, MJSome alternatives to the traditional mixing-length theory (MLT) have recently been proposed for modelling convective heat transport inside stars. The ideal formulation is one that does not involve any free parameters. However, in our present state of ignorance we still need at least one free parameter in order to build solar models with the correct radius. Having adjusted this parameter (e.g. the mixing-length ...