Convective blueshift strengths of 810 F to M solar-type stars

Convective Envelopes in Solar - Type Stars :

Asteroseismology of solar - type stars : signatures of convective and / or helium cores

Aims. Several frequency combinations are widely used in the analysis of stellar oscillations for comparisons between models and observations. In particular, the " small separations " can help constraining the stellar cores. We showed in a previous paper that they can change sign, in contradiction with the " asymptotic theory " , and that this behaviour could correspond to signatures of convecti...

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...

M–type Vega–like Stars

We carried out a search for M–type Vega–like stars by correlating the IRAS Faint Source Catalog with Hipparcos selected M–type stars. Three stars with apparent IRAS 25 μm excess emission are shown instead to be non–IR–excess stars from ground–based 11.7 and 17.9 μm photometry. Two stars previously suggested to have Vega–like mid–IR excess are also shown to be non–excess stars. These results imp...

Convective Wavelength Shifts in the Spectra of Late-type Stars

We present ultra-high resolution spectra for a set of nearby F-G-K stars on, or close to, the main sequence. The wavelength shifts of stellar lines relative to their laboratory wavelengths are measured for more than a thousand Fe i lines per star, finding a clear correlation with line depth. The observed patterns are interpreted as convective blue-shifts that become more prominent for weaker li...