Topic: Fundamental Parameters of Cool Stars and Brown Dwarfs
Moving groups (MGs) are kinematically coherent groups of stars that probably share a common origin. Recent years have seen the discovery of several MGs within 100pc of the Sun. Stars in these groups range between millions and tens of million years in age, and their study should tell us about the formation and evolution of sparse stellar associations. Young late-type fast rotating members of MGs offer a unique laboratory for studying stellar dynamos, magnetic structures and coronal heating. The Beta Pictoris moving group (BPMG) is one of the youngest (12Myr) and the closest MGs to the Sun (36pc). We carried out high-resolution spectroscopy and BV(I)C photometric monitoring of the two fastest late-type rotators in BPMG, HD 199143 (F7V) and CD-64º1208 (K7V). The motivation for this work is to investigate the rotation periods and photospheric spot patterns of these very young stars, with a longer term view to probing the evolution of rotation and magnetic activity during the early phases of main-sequence evolution. We also aim to derive information on key physical parameters, such as rotational velocity, rotation period and stellar equatorial radii. We will also present results from Chandra X-ray observations on HD 199143. It has the largest v sini of any known solar-like star accessible to Chandra gratings and represents a unique opportunity to study surface magnetic and coronal structure on a young solar analogue.