The Evolution of Stellar Activity

AbstractStellar activity has a particularly strong influence on planets at small orbital distances, such as close-in exoplanets. For such planets, we present two extreme cases of stellar variability, namely stellar coronal mass ejections and stellar wind, which both result in the planetary environment being variable on a timescale of billions of years. For both cases, direct interaction of the streaming plasma with the planetary atmosphere would entail servere consequences. In certain cases, however, the planetary atmosphere can be effectively shielded by a strong planetary magnetic field. The efficiency of this shielding is determined by the planetary magnetic dipole moment, which is difficult to constrain by either models or observations. We present different factors which influence the strength of the planetary magnetic dipole moment. Implications are discussed, including nonthermal atmospheric loss, atmospheric biomarkers, and planetary habitability.

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ROSAT observations of V471 Tauri, showing that stellar activity is determined by rotation, not age

Monthly Notices of the Royal Astronomical Society ◽

10.1046/j.1365-8711.1998.01607.x ◽

1998 ◽

Vol 297 (4) ◽

pp. 1145-1150 ◽

Cited By ~ 16

Author(s):

P. J. Wheatley

Keyword(s):

Stellar Activity

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Stellar activity, differential rotation, and exoplanets

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311015067 ◽

2010 ◽

Vol 6 (S273) ◽

pp. 89-95 ◽

Cited By ~ 1

Author(s):

A. F. Lanza

Keyword(s):

Time Series ◽

Differential Rotation ◽

Solar Irradiance ◽

Giant Planet ◽

Total Solar Irradiance ◽

Short Term ◽

Stellar Activity ◽

Transiting Planets ◽

Spot Model ◽

Spot Activity

AbstractThe photospheric spot activity of some of the stars with transiting planets discovered by the CoRoT space experiment is reviewed. Their out-of-transit light modulations are fitted by a spot model previously tested with the total solar irradiance variations. This approach allows us to study the longitude distribution of the spotted area and its variations versus time during the five months of a typical CoRoT time series. The migration of the spots in longitude provides a lower limit for the surface differential rotation, while the variation of the total spotted area can be used to search for short-term cycles akin the solar Rieger cycles. The possible impact of a close-in giant planet on stellar activity is also discussed.

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