An effective temperature calibration for solar type stars using equivalent width ratios

Asteroseismic Inference for Solar-type Stars

The oscillation spectra of solar-type stars may in the not-too-distant future be used to constrain certain properties of the stars. The CD diagram of large versus small frequency separations is one of the powerful tools available to infer the properties – including perhaps masses and ages – of stars which display a detectable spectrum of oscillation. Also, the border of a convective region in a...

Beryllium anomalies in solar-type field stars

We present a study of beryllium (Be) abundances in a large sample of field solar-type dwarfs and sub-giants spanning a large range of effective temperatures. The Be abundances, computed using a very uniform set of stellar parameters and near-UV spectra obtained with 3 different instruments, are used to study the depletion of this light element. The analysis shows that Be is severely depleted fo...

Low-Mass Companions to Solar-Type Stars

We present preliminary results from a coronagraphic survey of young nearby Sun-like stars using the Palomar and Keck adaptive optics systems. We have targeted 251 solar analogs (F5–K5) at 20–160 pc from the Sun, spanning the 3–3000 Myr age range. The youngest (<500 Myr) ≈100 of these have been imaged with deeper exposures to search for sub-stellar companions. The deep survey is sensitive to bro...

Convective Envelopes in Solar - Type Stars :

Convection in Oblate Solar-Type Stars

We present the first global 3D simulations of thermal convection in the oblate envelopes of rapidly-rotating solar-type stars. This has been achieved by exploiting the capabilities of the new Compressible High-ORder Unstructured Spectral difference (CHORUS) code. We consider rotation rates up to 85% of the critical (breakup) rotation rate, which yields an equatorial radius that is up to 17% lar...