A multi-wavelength view of the multiple activity cycles of ~Eridani
arXiv:2303.08487 · doi:10.1051/0004-6361/202245201
Abstract
Eridani is a highly active young K2 star with an activity cycle of about three years established using Ca II H & K line index measurements (S_MWO). This relatively short cycle has been demonstrated to be consistent with X-ray and magnetic flux measurements. Recent work suggested a change in the cyclic behaviour. Here we report new X-ray flux and S_MWO measurements and also include S_MWO measurements from the historical Mount Wilson program. This results in an observational time baseline of over 50 years for the S_MWO data and of over 7 years in X-rays. Moreover, we include Ca II infrared triplet (IRT) index measurements (S_IRT) from 2013-2022 in our study. With the extended X-ray data set, we can now detect the short cycle for the first time using a periodogram analysis. Near-simultaneous S_MWO data and X-ray fluxes, which are offset by 20 days at most, are moderately strongly correlated when only the lowest activity state (concerning short-term variability) is considered in both diagnostics. In the S_MWO data, we find strong evidence for a much longer cycle of about 34 years and an 11-year cycle instead of the formerly proposed -year cycle in addition to the known 3-year cycle. The superposition of the three periods naturally explains the recent drop in S_MWO measurements. The two shorter cycles are also detected in the S_IRT data, although the activity cycles exhibit lower amplitudes in the S_IRT than in the S_MWO data. Finally, the rotation period of Eri can be found more frequently in the S_MWO as well as in the S_IRT data for times near the minimum of the long cycle. This may be explained by a scenario in which the filling factor for magnetically active regions near cycle maximum is too high to allow for notable short-term variations.
arXiv commentaccepted to A&A
References in corpus (26)
- Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
- The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
- The Solar Cycle
- The eROSITA X-ray telescope on SRG
- Ages for illustrative field stars using gyrochronology: viability, limitations and errors
- Chromospheric Activity and Jitter Measurements for 2630 Stars on the California Planet Search
- The evolution of X-ray emission in young stars
- Evidence for a Long-period Planet Orbiting Epsilon Eridani
- Structure in the Epislon Eridani dusty disk caused by mean motion resonances with a 0.3 eccentricity planet at periastron
- Magnetic Activity Cycles in the Exoplanet Host Star epsilon Eridani
- A solar-like magnetic cycle on the mature K-dwarf 61 Cyg A (HD 201091)
- Evolution of coexisting long and short period stellar activity cycles
- The effect of magnetic activity saturation in chromospheric flux-flux relationships
- The Ca II infrared triplet's performance as an activity indicator compared to Ca II H and K
- X-Shooter spectroscopy of young stellar objects III. Photospheric and chromospheric properties of Class III objects
- An X-ray activity cycle on the young solar-like star
- Direct evidence of a full dipole flip during the magnetic cycle of a sun-like star
- Solar activity: intrinsic periodicities beyond 11 years
- Long-term Variability in the Length of the Solar Cycle
- Multi-instrumental view of magnetic fields and activity of Eridani with SPIRou, NARVAL, and TESS
- Multi-wavelength variability of the young solar analog iota Hor. X-ray cycle, star spots, flares, and UV emission
- The differential rotation of epsilon Eri from MOST data
- Magnetic field and prominences of the young, solar-like, ultra-rapid rotator V530 Per
- The crucial role of surface magnetic fields for stellar dynamos: Epsilon Eridani, 61 Cygni A, and the Sun
- Waldmeier Effect in Stellar Cycles
- Shapes of stellar activity cycles