The evolution of solar-like activity of low-mass stars

Katsova, M. M.; Livshits, M. A.

doi:10.1134/s1063772911120055

Cited by 20 publications

(31 citation statements)

References 21 publications

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“…Katsova & Livshits (2011) find that the ideas about the gyrochronology (Mamajek & Hillenbrand 2008) is valid for the stars that are hotter than the Sun (with T eff > T eff ), but for the late-type dwarfs stars (with T eff < T eff ), whose convection zones are thicker than the solar ones, the activity evolves in time apparently according to the other law. Studing those stars that are both hotter and cooler than the Sun, can clarify the understanding of the features and causes of activity of the FGK dwarfs, as well as the real relation between the enhancement of Li and activity.…”

Section: Introductionmentioning

confidence: 97%

“…Moreover, a close value of log R HK ∼ −4.80 was declared in the study by Jenkins et al (2011) and Katsova & Livshits (2011).…”

Section: Levels Of Activity Of the Investigated Starsmentioning

confidence: 99%

“…The chromospheric and coronal activities of late-type stars have been studied more in past decades (Guedel 2004;Guinnan & Enge 2009;Katsova & Livshits 2011). Katsova & Livshits (2011) find that the ideas about the gyrochronology (Mamajek & Hillenbrand 2008) is valid for the stars that are hotter than the Sun (with T eff > T eff ), but for the late-type dwarfs stars (with T eff < T eff ), whose convection zones are thicker than the solar ones, the activity evolves in time apparently according to the other law.…”

Section: Introductionmentioning

confidence: 99%

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Activity and the Li abundances in the FGK dwarfs

Mishenina

Soubiran

Kovtyukh

et al. 2012

A&A

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Aims. The aim of the present study is to determine the Li abundances for a large set of the FGK dwarfs and to analyse the connections between the Li content, stellar parameters, and activity. Methods. The atmospheric parameters, rotational velocities and the Li abundances were determined from a homogeneous collection of the echelle spectra with high resolution and a high signal-to-noise ratio. The rotational velocities v sin i were determined by calibrating the cross-correlation function. The effective temperatures T eff were estimated by the line-depth ratio method. The surface gravities log g were computed by two methods: the iron ionization balance and the parallax. The LTE Li abundances were computed using synthetic spectra method. The behaviour of the Li abundance was examined in correlation with T eff , [Fe/H], as well as with v sin i and the level of activity in three stellar groups of the different temperature range. Results. The stellar parameters and the Li abundances are presented for 150 slow rotating stars of the lower part of the main sequence. The studied stars show a decline in the Li abundance with decreasing temperature T eff and a significant spread, which should be due to the difference of age of stars. The correlations between the Li abundances, rotational velocities v sin i, and the level of the chromospheric activity were discovered for the stars with 6000 > T eff > 5700 K, and it is tighter for the stars with 5700 > T eff > 5200 K. The target stars with T eff < 5200 K do not show any correlation between log A(Li) and v sin i. The relationship between the chromospheric and coronal fluxes in active with detected Li as well as in less active stars gives a hint that there exist different conditions in the action of the dynamo mechanism in those stars. Conclusions. We found that the Li-activity correlation is evident only in a restricted temperature range and the Li abundance spread seems to be present in a group of low chromospheric activity stars that also show a broad spread in the chromospheric vs. coronal activity.

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Section: Introductionmentioning

confidence: 97%

“…Moreover, a close value of log R HK ∼ −4.80 was declared in the study by Jenkins et al (2011) and Katsova & Livshits (2011).…”

Section: Levels Of Activity Of the Investigated Starsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Activity and the Li abundances in the FGK dwarfs

Mishenina

Soubiran

Kovtyukh

et al. 2012

A&A

Self Cite

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“…These problems of the evolution of activity were discussed in more details by Katsova (2012). Note that activity of stars situated below the straight line, that describes single-parametric gyrochronology, can evolve through another path (Katsova and Livshits, 2011).…”

Section: On the Evolution Of Activity Of Late-type Starsmentioning

confidence: 99%

“…One can expect that such kind of activity was formed on a main-sequence G star to the age slightly older than 1 Gyr (see, for example, Katsova and Livshits, 2011;. On young stars of ages from 50 to 500 Myr, the character of the magnetic fields and non-stationary processes differ from the solar ones.…”

Section: Introductionmentioning

confidence: 99%

The Origin of Superflares on G-Type Dwarf Stars of Various Ages

Katsova

Livshits

2015

Sol Phys

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We analyze new observations of superflares on G stars discovered in the optical and near IR-ranges with the Kepler mission. An evolution of solar-type activity is discussed. We give an estimate of the maximal total energy, E tot = 10 34 erg of a flare that can occur on the young Sun at its age of 1 Gyr when the cycle was formed. We believe that the main source of the flare optical continuum is a low-temperature condensation forming in the course of the response of the chromosphere to an impulsive heating. For a superflare on the young Sun, we adopt the accelerated electron flux, F e (E > 20 keV) = 3 × 10 11 erg cm −2 s −1 , that is limited by the return current, and obtain the area of the optical continuum source on a G star, S ≈ 10 19 cm 2 . This value is close to the area of the H α -ribbons in the largest solar flares, while the area of bright patches of a white-light flare on the contemporary Sun is smaller by about two orders of magnitude. At the same electron flux and the hard electron spectrum, the stellar flare of the similar energy should be accompanied by the microwave source of about 2 mJy at frequencies 10-100 GHz at a distance of 100 pc. We discuss the possible detection of the flare-produced lithium in the course of spallation reactions. The detection of the flare microwave source and the emission in the Li resonant line could demonstrate how effective can be particle acceleration on stars in the lower part of the main sequence.

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The Evolution of Cyclic Activity of the Sun in the Context of Physical Processes on Late-Type Stars

Katsova

2012

The Sun: New Challenges

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The evolution of solar-like activity of low-mass stars

Cited by 20 publications

References 21 publications

Activity and the Li abundances in the FGK dwarfs

Activity and the Li abundances in the FGK dwarfs

The Origin of Superflares on G-Type Dwarf Stars of Various Ages

The Evolution of Cyclic Activity of the Sun in the Context of Physical Processes on Late-Type Stars

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