Long-term variations in sunspot magnetic field-area relation
| Autor: | Alexei A. Pevtsov, A. A. Osipova, Yury A. Nagovitsyn |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Physics
Sunspot 010504 meteorology & atmospheric sciences Field (physics) Phase (waves) Astronomy and Astrophysics Field strength Astrophysics 01 natural sciences Term (time) Magnetic field Solar cycle Space and Planetary Science Observatory 0103 physical sciences 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | Astronomische Nachrichten. 338:26-34 |
| ISSN: | 0004-6337 |
| Popis: | Using observations of sunspot magnetic field strengths (H) from the Crimean Astrophysical Observatory (CrAO) and area (S) of sunspots from the Kislovodsk Mountain Astronomical Station of Pulkovo Observatory, we investigate the changes in the relation between H and S over the period of about two solar cycles (1994-2013). The data were fitted by H = A + B log S, where A = (778+/-46) and B = (778+/-25). We show that the correlation between H and S varies with the phase of solar cycle, and $A$ coefficient decreases significantly after year 2001, while B coefficient does not change significantly. Furthermore, our data confirm the presence of two distinct populations in distribution of sunspots (small sunspots with weaker field strength and large sunspots with stronger field). We show that relative contribution of each component to the distribution of sunspots by their area changes with the phase of solar cycle and on longer-then-cycle periods. We interpret these changes as a signature of a long-term (centennial) variations in properties of sunspots. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Plný text