Search results for "Rossby number"

showing 3 items of 3 documents

Supersaturation and activity-rotation relation in PMS stars: the young Cluster h Per

2016

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…

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 AstrophysicsDynamo
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Subphotospheric convection and magnetic activity dependence on metallicity and age: Models and tests

2001

We present an extensive study on the dependence of the convective turnover time (conv) on the stellar metallicity and age for main-sequence stars of masses 0.6{1.6 M. To this aim we have used and compared predictions by stellar models based on the classical Mixing Length Theory and models incorporating a Full Spectrum of Turbulence treatment of subphotospheric convection. We show that the metallicity eect is relevant for dG stars but negligible for dK stars, while stellar age is important when computing the turnover times for red dwarfs younger than logt 8:5 yr. A scatter by up to a factor 3 could be spuriously introduced in the activity vs. Rossby number relationships if such eects are neg…

Rotation periodPhysicsMetallicityStellar collisionAstronomyAstronomy and AstrophysicsAstrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicsRossby numberStarsSpace and Planetary ScienceMixing length modelAstrophysics::Solar and Stellar AstrophysicsPleiadesAstrophysics::Galaxy AstrophysicsOpen clusterAstronomy & Astrophysics
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Activity, Rotation And Convection in Orion: Are the Data Inconsistent with the MS Activity-Rossby Number Relation?

2004

A relation between activity and rotation in young ~ 1Myr PMS in often not observed, suggesting that the mechanism responsible for the X-ray emission may differ from the α - ω dynamo. We re-investigate the matter utilizing recent X-ray and rotational data on the Orion Nebula Cluster (ONC).

PhysicsConvectionRossby numberClassical mechanics010504 meteorology & atmospheric sciencesRelation (database)0103 physical sciencesAstrophysicsRotation010303 astronomy & astrophysics01 natural sciences0105 earth and related environmental sciences
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