http://www.researchonline.mq.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:23311 We present results of a long-baseline interferometry campaign using the PAVO beam combiner at the CHARA Array to measure the angular sizes of five main-sequence stars, one subgiant and four red giant stars for which solar-like oscillations have been detected by either Kepler or CoRoT. By combining interferometric angular diameters, Hipparcos parallaxes, asteroseismic densities, bolometric fluxes, and high-resolution spectroscopy, we derive a full set of near-model-independent fundamental properties for the sample. We first use these properties to test asteroseismic scaling relations for the frequency of maximum power (ν max) and the large frequency separation (Δν). We find excellent agreement within the observational uncertainties, and empirically show that simple estimates of asteroseismic radii for main-sequence stars are accurate to ≲ 4%. We furthermore find good agreement of our measured effective temperatures with spectroscopic and photometric estimates with mean deviations for stars between T eff = 4600-6200 K of -22 ± 32 K (with a scatter of 97K) and -58 ± 31 K (with a scatter of 93K), respectively. Finally, we present a first comparison with evolutionary models, and find differences between observed and theoretical properties for the metal-rich main-sequence star HD173701. We conclude that the constraints presented in this study will have strong potential for testing stellar model physics, in particular when combined with detailed modeling of individual oscillation frequencies. 2013-06-17T06:17:14.345Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:15101 We present preliminary asteroseismic results from Kepler on three G-type stars. The observations, made at one-minute cadence during the first 33.5days 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 separations to provide first results on the radii, masses, and ages of the stars, and comment in the light of these results on prospects for inference on other solar-type stars that Kepler will observe. 2011-09-29T06:52:07.263Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:15065 We report on the ground-based follow-up program of spectroscopic and photometric observations of solar-like asteroseismic targets for the Kepler space mission. These stars constitute a large group of more than a thousand objects which are the subject of an intensive study by the Kepler Asteroseismic Science Consortium Working Group 1 (KASC WG-1). In the current work we will discuss the methods we use to determine the fundamental stellar atmospheric parameters using high-quality stellar spectra. These provide essential constraints for the asteroseismic modelling and make it possible to verify the parameters in the Kepler Input Catalogue (KIC). 2011-09-27T06:10:49.554Z ]]> http://www.researchonline.mq.edu.au/vital/access/manager/Repository/mq:14936 The triple system HD 158926 (λ Sco) has been observed interferometrically with the Sydney University Stellar Interferometer, and the elements of the wide orbit have been determined. These are significantly more accurate than the previous elements found spectroscopically. The inclination of the wide orbit is consistent with the inclination previously found for the orbit of the close companion. The wide orbit al so has low eccentricity, suggesting that the three stars were formed at the same time. The brightness ratio between the two B stars was also measured at λ = 442 and 700 nm. The brightness ratio and colour index are consistent with the previous classification of A. Sco A as B1.5 and λ Sco B as B2. Evolutionary models show that the two stars lie on the main sequence. Since they have the same age and luminosity class (IV), the mass-luminosity relation can be used to determine the mass ratio of the two stars: MB/MA = 0.76 ±0.04. The spectroscopic data have been reanalyzed using the interferometric values for P, T, e and ω, leading to revised values for ai sin i and the mass function. The individual masses can be found from the mass ratio, the mass function, spectrum synthesis and the requirement that the age of both components must be the same: MA = 10.4 ±1.3 and MB = 8.1 ±1.0 M⊙. The masses, angular semimajor axis and the period of the system can be used to determine the dynamical parallax. We find the distance to λ Sco to be 112 ±5 pc, which is approximately a factor of 2 closer than the Hipparcos value of 216 ± 42 pc. 2011-09-16T07:31:07.308Z ]]>