6533b7d2fe1ef96bd125f74a
RESEARCH PRODUCT
Supersaturation and activity-rotation relation in PMS stars: the young Cluster h Per
Jerome BouvierSalvatore SciortinoM. CaramazzaEttore FlaccomioEstelle MorauxCostanza ArgiroffiCostanza ArgiroffiGiuseppina Micelasubject
Stars: activityRotation periodFOS: Physical sciencesAstrophysicsAstrophysics::Cosmology and Extragalactic Astrophysics01 natural sciencesRossby numberSettore FIS/05 - Astronomia E Astrofisica0103 physical sciencesRadiative transferAstrophysics::Solar and Stellar AstrophysicsStars: coronaeX-rays: star010303 astronomy & astrophysicsSolar and Stellar Astrophysics (astro-ph.SR)Astrophysics::Galaxy AstrophysicsPhysics010308 nuclear & particles physicsStars: rotationAstronomy and AstrophysicsAstronomy and AstrophysicEffective temperatureAccretion (astrophysics)Magnetic fieldStarsAstrophysics - Solar and Stellar AstrophysicsSpace and Planetary ScienceStars: pre-main sequenceAstrophysics::Earth and Planetary AstrophysicsDynamodescription
The magnetic activity of late-type MS stars is characterized by different regimes, and their activity levels are well described by Ro, the ratio between P_rot and the convective turnover time. Very young PMS stars show, similarly to MS stars, intense magnetic activity. However they do not show clear activity-rotation trends, and it still debated which stellar parameters determine their magnetic activity levels. To bridge the gap between MS and PMS stars, we studied the activity-rotation relation in the young cluster h Per, a ~13 Myr old cluster, that contains both fast and slow rotators, whose members have ended their accretion phase and have already developed a radiative core. It offers us the opportunity to study the activity level of intermediate-age PMS stars with different rotational velocities, excluding any interactions with the circumstellar environment. We constrained the magnetic activity levels of h Per members measuring their X-ray emission from a Chandra observation, while P_rot were obtained by Moraux et al. (2013). We collected a final catalog of 414 h Per members with known P_rot, T_eff, M_star, with 169 of them having also detected X-ray emission. We found that h Per members, with 1.0 M_sun < M_star < 1.4 M_sun, display different activity regimes: fast rotators show supersaturation, while slower rotators have activity levels compatible to the non-saturated regime. At 13 Myr h Per is therefore the youngest cluster showing activity-rotation regimes analogous to that of MS stars, indicating that, at this age, magnetic field production is likely regulated by the alpha-Omega type dynamo. Moreover we observed that supersaturation is better described by P_rot than Ro, and that the observed patterns are compatible with the hypothesis of centrifugal stripping. In this scenario we inferred that coronae can produce structures as large as ~2 R_star above the stellar surface.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2016-02-11 |