Variations in Surface Activity of the Sun and Solar Type Stars
Abstract
Twenty-five-year records of relative CaII H and K emission fluxes of lower Main-Sequence stars have been measured at Mount Wilson Observatory and reveal surface activity in most of the older G- and K-type dwarf stars that is similar to the aperiodical activity cycle of the contemporary Sun (i.e., the cyclic and the occasional episode of reduced activity in the past few centuries). We find an inverse relationship between the amplitude of the activity cycle and the length of the cycle for the ensemble of those solar-type stars. We also find a similar relationship using the 250-year sunspot record (Cycles 1 to 21). The similarity between the two inverse relationships for the solar-type stars observed for 25 years and the Sun for a longer interval of time may suggest one common underlying physical mechanism that is responsible for the variations in surface activity ranging from decades to centuries.
- Publication:
-
Solar Physics
- Pub Date:
- October 1994
- DOI:
- 10.1007/BF00681107
- Bibcode:
- 1994SoPh..154..385S
- Keywords:
-
- Dwarf Stars;
- G Stars;
- K Stars;
- Periodic Variations;
- Stellar Activity;
- Stellar Spectra;
- Sun;
- Sunspot Cycle;
- Calcium;
- Emission Spectra;
- Hydrogen;
- Potassium;
- Solar Physics;
- Inverse Relationship;
- Surface Activity;
- Physical Mechanism;
- Similar Relationship;
- Activity Cycle