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The measured properties of stellar oscillations can provide powerful constraints on the internal structure and composition of stars. To begin this process, oscillation frequencies must be extracted from the observational data, typically time series of the star's brightness or radial velocity. In this paper, a probabilistic model is introduced for inferring(More)
Stellar oscillations can provide a wealth of information about a star, which can be extracted from observed time series of the star's brightness or radial velocity. In this paper we address the question of how to extract as much information as possible from such a dataset. We have developed a Markov Chain Monte Carlo (MCMC) code that is able to infer the(More)
We present a source and lens reconstruction for the optical Einstein ring gravitational lens system RXS J1131-1231. We resolve detail in the source, which is the host galaxy of a z = 0.658 quasar, down to a resolution of 0.045 arc seconds (this is the size of the smallest conclusively resolved structures, rather than the pixel scale), using a Bayesian(More)
Asteroseismology is a powerful method for determining fundamental properties of stars. We report the first application to a metal-poor object, namely the subgiant star ν Ind. We measured precise velocities from two sites, allowing us to detect oscillations and infer a large frequency separation of ∆ν = 24.25 ± 0.25µHz. Combining this value with the location(More)
Gravitational lensing can magnify a distant source, revealing structural detail which is normally unresolvable. Recovering this detail through an inversion of the influence of gravitational lensing, however, requires optimisation of not only lens parameters, but also of the surface brightness distribution of the source. This paper outlines a new approach to(More)
We have observed oscillations in the nearby G2 subgiant star β Hyi using high-precision velocity observations obtained over more than a week with the HARPS and UCLES spectrographs. The oscillation frequencies show a regular comb structure, as expected for solar-like oscillations, but with several l = 1 modes being strongly affected by avoided crossings. The(More)
Context. Convection in stars excites resonant acoustic waves which depend on the sound speed inside the star, which in turn depends on properties of the stellar interior. Therefore, asteroseismology is an unrivaled method to probe the internal structure of a star. Aims. We made a seismic study of the metal-poor subgiant star ν Indi with the goal of(More)