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The recent discovery of an Earth-like exoplanet around Proxima Centauri has shined a spot light on slowly rotating fully convective M-stars. When such stars rotate rapidly (period $\lesssim 20$ days), they are known to generate very high…

Solar and Stellar Astrophysics · Physics 2016-12-28 Rakesh K. Yadav , Ulrich R. Christensen , Scott J. Wolk , Katja Poppenhaeger

We used more than $10^5$ Gaia DR3 line broadening vbroad measurements to examine stellar rotation as a function of stellar temperature, mass and age. The large sample clearly displays the Kraft break at $\sim 6{,}500$\,K, or mass of…

Solar and Stellar Astrophysics · Physics 2026-01-29 Amitay Sussholz , Tsevi Mazeh , Simchon Faigler

To understand solar and stellar dynamos combining local and global numerical modelling with long-term observations is a challenging task: even with state of the art computational methods and resources, the stellar parameter regime remains…

Solar and Stellar Astrophysics · Physics 2021-02-08 M. Viviani , A. Prabhu , J. Warnecke , L. Duarte , J. Pekkilä , M. Rheinhardt , M. J. Käpylä

Tidal interaction between an exoplanet and its host star is a possible pathway to transfer angular momentum between the planetary orbit and the stellar spin. In cases where the planetary orbital period is shorter than the stellar rotation…

Solar and Stellar Astrophysics · Physics 2022-04-13 Nikoleta Ilic , Katja Poppenhaeger , S. Marzieh Hosseini

We developed angular momentum evolution models for 0.5 and 0.8 $M_{\odot}$ stars. The parametric models include a new wind braking law based on recent numerical simulations of magnetised stellar winds, specific dynamo and mass-loss rate…

Solar and Stellar Astrophysics · Physics 2015-05-13 Florian Gallet , Jérôme Bouvier

In the solar convection zone, rotation couples with intensely turbulent convection to build global-scale flows of differential rotation and meridional circulation. Our sun must have rotated more rapidly in its past, as is suggested by…

The magnetic activity of planet-hosting stars is an important factor to estimate the atmospheric stability of close-in exoplanets and the age of their host stars. It has long been speculated that close-in exoplanets can influence the…

Solar and Stellar Astrophysics · Physics 2014-05-13 K. Poppenhaeger , S. J. Wolk

I present the results of a multiyear survey of very low mass stars and brown dwarfs, at high spectral resolution. The spectra were gathered with the HIRES echelle at the Keck Observatory. Some of these objects are stellar and others are…

Astrophysics · Physics 2016-08-30 Gibor Basri

The spin rate \Omega of neutron stars at a given temperature T is constrained by the interplay between gravitational-radiation instabilities and viscous damping. Navier-Stokes theory has been used to calculate the viscous damping timescales…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Vahid Rezania , Roy Maartens

The rotational evolution of cool stars is governed by magnetised stellar winds which slow the stellar rotation during their main sequence lifetimes. Magnetic variability is commonly observed in Sun-like stars, and the changing strength and…

Solar and Stellar Astrophysics · Physics 2018-09-19 Adam J. Finley , Sean P. Matt , Victor See

The ever increasing level of precision achieved by present and future radial-velocity instruments is opening the way to discovering very low-mass, long-period planets (e.g. solar-system analogs). These systems will be detectable as…

Earth and Planetary Astrophysics · Physics 2015-05-14 N. C. Santos , J. Gomes da Silva , C. Lovis , C. Melo

In this splinter session, ten speakers presented results on solar and stellar activity and how the two fields are connected. This was followed by a lively discussion and supplemented by short, one-minute highlight talks. The talks presented…

Solar and Stellar Astrophysics · Physics 2014-08-14 H. M. Günther , K. Poppenhaeger , P. Testa , S. Borgniet , S. Brun , H. Cegla , C. Garraffo , A. Kowalski , A. Shapiro , E. Shkolnik , F. Spada , A. Vidotto

We derive the effective temperatures and gravities of 461 OB stars in 19 young clusters by fitting the H-gamma profile in their spectra. We use synthetic model profiles for rotating stars to develop a method to estimate the polar gravity…

Astrophysics · Physics 2008-11-26 W. Huang , D. R. Gies

Chromospheric activity monitoring of a wide range of cool stars can provide valuable information on stellar magnetic activity and its dependence on fundamental stellar parameters such as effective temperature and rotation.We compile a…

Solar and Stellar Astrophysics · Physics 2018-09-07 S. Boro Saikia , C. J. Marvin , S. V. Jeffers , A. Reiners , R. Cameron , S. C. Marsden , P. Petit , J. Warnecke , A. P. Yadav

The rotation-mass-age relationship offers a promising avenue for measuring the ages of field stars, assuming the attendant uncertainties to this technique can be well characterized. We model stellar angular momentum evolution starting with…

Solar and Stellar Astrophysics · Physics 2013-12-31 Courtney R. Epstein , Marc H. Pinsonneault

The polar magnetic field precursor is considered to be the most robust and physics-based method for the prediction of the next solar cycle strength. However, to make a reliable prediction of a cycle, is the polar field at the solar minimum…

Solar and Stellar Astrophysics · Physics 2022-02-09 Pawan Kumar , Bidya Binay Karak , Vindya Vashishth

Here, I review some recent works on magnetism of cool, main-sequence stars, their winds and potential impact on surrounding exoplanets. The winds of these stars are very tenuous and persist during their lifetime. Although carrying just a…

Solar and Stellar Astrophysics · Physics 2016-08-15 A. A. Vidotto

The architecture of many exoplanetary systems is different from the solar system, with exoplanets being in close orbits around their host stars and having orbital periods of only a few days. We can expect interactions between the star and…

Solar and Stellar Astrophysics · Physics 2017-09-20 K. Poppenhaeger

Magnetic activity in Sun-like and low-mass stars causes X-ray coronal emission, which is stronger for more rapidly rotating stars. This relation is often interpreted in terms of the Rossby number, i.e., the ratio of rotation period to…

Solar and Stellar Astrophysics · Physics 2015-06-22 A. Reiners , M. Schuessler , V. M. Passegger

Context. To enable radial velocity (RV) precision on the order of ~0.1 m/s required for the detection of Earth-like exoplanets orbiting solar-type stars, the main obstacle lies in mitigating the impact of stellar activity. Aims. This study…

Solar and Stellar Astrophysics · Physics 2022-08-10 K. Al Moulla , X. Dumusque , M. Cretignier , Y. Zhao , J. A. Valenti