On chromospheric variations modeling for main-sequence stars of G and K spectral classes

E A Bruevich

doi:10.4236/ns.2011.38087

Abstract

We present a method of 13 late-type main-sequence stars chromospheric flux observation data calculations. These Sun-like stars have well-determined cyclic flux variations similar to the 11-year solar activity cycle. Our flux prediction is based on chromospheric HK emission time series measurements from the Mount Wilson Observatory and comparable solar data. We show that solar three - component modeling explains well the stellar observations. We find that the 10 - 20% of K - stars disc’s surfaces are occupied by bright active regions.

Highlights

This paper continues the study of variability among Sun-like stars
We find that the 10 − 20% of K - stars disc surfaces are occupied by bright active regions
We can note that the maximum amplitude of photospheric flux variability in 11 yr solar cycle may be as much as 1 − 3% of the average photospheric flux level but the maximum amplitude of CaII chromospheric flux may be as much as 20% of the average level

Summary

INTRODUCTION

This paper continues the study of variability among Sun-like stars. Here the purpose is to obtain the possibility of modeling the behavior of the star’s chromospheric emission in future or for periods of time without measurements. The Vernazza’s calculations take into account the influence of 6 main different components on the solar surface and their contributions to the total emission in this spectral interval These components are: the dark areas inside the chromospheric network cells, the centers of networks, the areas of quiet Sun, the average level of network emission region, the bright areas of network, the most bright areas of network. Lean’s three-component model (that’s made for 40 − 140 nm spectral interval) based on NIMBUS 7 observations (Lean et al, 1983) assumed that the full flux from chromosphere is determined by three main components These components are: (1) - the constant component with uniform distributed sources on solar surface, (2) - the ”active” network component (uniformly distributed too and connected with destroyed parts of previous AR and so is proportional to total AR areas), (3) - the AR component. The value Pmim - that is equal to BASAL emission for different stars which we can determine from Baliunas’s data (Fig 1.)

Object Sun

Findings

SUMMARY AND CONCLUSIONS