Supersaturation in X-ray emission of clusters stars
نویسنده
چکیده
A population of cool dwarfs with extreme rotational velocities (vsin i ∼ > 100 km/sec) is present in young open clusters. ROSAT observations have shown that these very fast rotators exhibit a level of X-ray activity a factor of 3–5 below the saturated level which is usually observed (both in X-rays and other magnetic activity indicators) for ‘normally’ fast rotators. This phenomenon has been denominated “Supersaturation”. W UMa contact binaries seem to be supersaturated as well, while the scatter in the rotation-activity relation for RS CVn and BY Dra binaries does not allow us to clearly discern whether they exhibit supersaturation or not. Supersaturation is not seen in Hα for α Per supersaturated stars. Two alternative lines of interpretation are discussed.
منابع مشابه
The chromospheric emission of solar - type stars in the young open clusters IC 2391 and IC 2602
In this paper we present chromospheric emission levels of the solar-type stars in the young open clusters IC 2391 and IC 2602. High resolution spectroscopic data were obtained for over 50 F, G, and K stars from these clusters over several observing campaigns using the University College London Echelle Spectrograph on the 3.9-m Anglo-Australian Telescope. Unlike older clusters, the majority (28/...
متن کاملEvolution of X-ray emission from young massive star clusters
The evolution of X-ray emission from young massive star clusters is modeled, taking into account the emission from the stars as well as from the cluster wind. It is shown that the level and character of the soft (0.2-10 keV) X-ray emission change drastically with cluster age and are tightly linked with stellar evolution. Using the modern X-ray observations of massive stars we show that the corr...
متن کاملForty Years of X-Ray Binaries
In 2012 it was forty years ago that the discovery of the first X-ray binary Centaurus X-3 became known. That same year it was discovered that apart from the High-Mass X-ray Binaries (HMXBs) there are also Low-Mass X-ray Binaries (LMXBs), and that Cygnus X-1 is most probably a black hole. By 1975 also the new class of Be/X-ray binaries was discovered. After this it took 28 years before ESAs INTE...
متن کاملA connection between the morphology of the X-ray emission and rotation for solar-type stars in open clusters
It is suggested that the three-segmented morphology of the soft X-ray emission from cluster and field stars may be understood in terms of the recent classification of rotating stars into three kinds: those lying on the convective sequence, on the interface sequence, or in the gap between them. Subject headings: open clusters and associations: general — stars: activity — stars: chromospheres — s...
متن کاملA Search for Hard X-Ray Emission from Globular Clusters - Constraints from BATSE
We have monitored a sample of 27 nearby globular clusters in the hard X-ray band (20 − 120 keV) for ∼1400 days using the BATSE instrument on board the Compton Gamma-Ray Observatory. Globular clusters may contain a large number of compact objects (e.g., pulsars or X-ray binaries containing neutron stars) which can produce hard Xray emission. Our search provides a sensitive (∼50 mCrab) monitor fo...
متن کامل