Multicomponent Activity Cycles Using Hilbert-Huang Analysis

E. N. Velloso

doi:10.3847/2041-8213/acb8b4

Multicomponent Activity Cycles Using Hilbert-Huang Analysis

2023-03-03

4

OA

AI

DOI：10.3847/2041-8213/acb8b4

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The temporal analysis of stellar activity evolution is usually dominated by a complex trade-off between model complexity and interpretability, often by neglecting the nonstationary nature of the process. Recent studies appear to indicate that the presence of multiple coexisting cycles in a single star is more common than previously thought. The correct identification of physically meaningful cyclic components in spectroscopic time series is therefore a crucial task, which cannot overlook local behaviors. Here we propose a decomposition technique that adaptively recovers amplitude- and frequency-varying components. We present our results for the solar activity as measured both by the sunspot number and the K-line emission index, and we consistently recover the Schwabe and Gleissberg cycles as well as the Gnevyshev-Ohl pattern probably related to the Hale cycle. We also recover the known 8 yr cycle for 61 Cygni A, in addition to evidence of a three-cycles-long pattern reminiscent of the Gnevyshev-Ohl rule. This is particularly interesting as we cannot discard the possibility of a relationship between the measured field polarity reversals and this Hale-like periodicity.

Keyword:

EMPIRICAL MODE DECOMPOSITION

LOCAL MEAN DECOMPOSITION

MAGNETIC-FIELD GEOMETRY

SUN-LIKE STARS

CA-II H

CHROMOSPHERIC VARIATIONS

SURVEY. I.

K-DWARF

VARIABILITY

EVOLUTION

Multicomponent Activity Cycles Using Hilbert-Huang Analysis

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