Multi-instrumental view of magnetic fields and activity of $\epsilon$ Eridani with SPIRou, NARVAL, and TESS

Abstract

We report on observations of the active K2 dwarf $\epsilon$ Eridani based on contemporaneous SPIRou, NARVAL, and TESS data obtained over two months in late 2018, when the activity of the star was reported to be in a non-cyclic phase. We first recover the fundamental parameters of the target from both visible and nIR spectral fitting. The large-scale magnetic field is investigated from polarimetric data. From unpolarized spectra, we estimate the total magnetic flux through Zeeman broadening of magnetically sensitive nIR lines and the chromospheric emission using the CaII H & K lines. The TESS photometric monitoring is modeled with pseudo-periodic Gaussian Process Regression. Fundamental parameters of $\epsilon$ Eridani derived from visible and near-infrared wavelengths provide us with consistent results, also in agreement with published values. We report a progressive increase of macroturbulence towards larger nIR wavelengths. Zeeman broadening of individual lines highlights an unsigned surface magnetic field $B_{\mathrm{mono}}=1.90\pm 0.13$ kG, with a filling factor $f=12.5\pm 1.7$% (unsigned magnetic flux $Bf=237\pm 36$ G). The large-scale magnetic field geometry, chromospheric emission, and broadband photometry display clear signs of non-rotational evolution over the course of data collection. Characteristic decay times deduced from the light curve and longitudinal field measurements fall in the range 30-40 d, while the characteristic timescale of surface differential rotation, as derived through the evolution of the magnetic geometry, is equal to $57\pm 5$ d. The large-scale magnetic field exhibits a combination of properties not observed previously for $\epsilon$ Eridani, with a surface field among the weakest previously reported, but also mostly axisymmetric, and dominated by a toroidal component.

arXiv commentA&A, in press, abridged abstract

References in corpus (40)

• Gaia Data Release 2. Summary of the contents and survey properties
• The Transiting Exoplanet Survey Satellite
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• The surprising magnetic topology of tauSco: fossil remnant or dynamo output?
• Large-scale magnetic topologies of mid-M dwarfs
• The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPS
• Least squares deconvolution of the stellar intensity and polarization spectra
• The Palomar/MSU Nearby Star Spectroscopic Survey III: Chromospheric Activity, M-dwarf Ages and the Local Star Formation History
• Gaia FGK Benchmark Stars - Metallicity
• Gaia FGK Benchmark Stars: Effective temperatures and surface gravities
• Evidence for a Long-period Planet Orbiting Epsilon Eridani
• Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles
• A Bcool magnetic snapshot survey of solar-type stars
• The evolution of surface magnetic fields in young solar-type stars I: the first 250 Myr
• PolarBase: a data base of high resolution spectropolarimetric stellar observations
• SPIRou: nIR velocimetry & spectropolarimetry at the CFHT
• Structure in the Epislon Eridani dusty disk caused by mean motion resonances with a 0.3 eccentricity planet at periastron
• The evolution of surface magnetic fields in young solar-type stars II: The early main sequence (250-650 Myr)
• Spectropolarimetric observations of the transiting planetary system of the K dwarf HD 189733
• Magnetic Activity Cycles in the Exoplanet Host Star epsilon Eridani
• Magnetic fields in M dwarfs from the CARMENES survey
• A hot Jupiter around the very active weak-line T Tauri star TAP 26
• Estimating magnetic filling factors from Zeeman-Doppler magnetograms
• Magnetic field and wind of Kappa Ceti: towards the planetary habitability of the young Sun when life arose on Earth
• The energy budget of stellar magnetic fields
• A near-infrared interferometric survey of debris disk stars. I. Probing the hot dust content around epsilon Eridani and tau Ceti with CHARA/FLUOR
• Testing the Reality of Strong Magnetic Fields on T Tauri Stars: The Naked T Tauri Star Hubble 4
• The Northern Arc of $\epsilon$ Eridani's Debris Ring as Seen by ALMA
• An X-ray activity cycle on the young solar-like star $\epsilon \mathrm{Eridani}$
• Telluric-line subtraction in high-accuracy velocimetry: a PCA-based approach
• Characterising the surface magnetic fields of T Tauri stars with high-resolution near-infrared spectroscopy
• Characterisation of the HD 219134 multi-planet system I. Observations of stellar magnetism, wind, and high-energy flux
• The relation between stellar magnetic field geometry and chromospheric activity cycles I: The highly variable field of Epsilon Eridani at activity minimum
• A combined spectroscopic and photometric stellar activity study of Epsilon Eridani
• Magnetic fields of intermediate mass T Tauri stars
• Magnetic field measurements of $\epsilon$ Eridani from Zeeman broadening
• Detection of 2$-$4 GHz Continuum Emission from $\epsilon$ Eridani
• Pollux: A weak dynamo-driven dipolar magnetic field and implications for its probable planet

Cited by in corpus (21)

• TOI-1759 b: a transiting sub-Neptune around a low mass star characterized with SPIRou and TESS
• The SPIRou Legacy Survey Rotation period of quiet M dwarfs from circular polarization in near-infrared spectral lines: I. The SPIRou APERO analysis
• Monitoring the large-scale magnetic field of AD~Leo with SPIRou, ESPaDOnS and Narval. Toward a magnetic polarity reversal?
• Estimating the atmospheric properties of 44 M dwarfs from SPIRou spectra
• Estimating fundamental parameters of nearby M dwarfs from SPIRou spectra
• The crucial role of surface magnetic fields for stellar dynamos: Epsilon Eridani, 61 Cygni A, and the Sun
• The space weather around the exoplanet GJ 436b
• Coronal mass ejections and type II radio emission variability during a magnetic cycle on the solar-type star $\epsilon$ Eridani
• Asteroseismology and Spectropolarimetry of the Exoplanet Host Star $\lambda$ Serpentis
• Determination of small-scale magnetic fields on Sun-like stars in the near-infrared using CRIRES${}^{+}$
• Time evolution of magnetic activity cycles in young suns: The curious case of kappa Ceti
• A BCool survey of stellar magnetic cycles
• Stellar dating using chemical clocks and Bayesian inference
• Short-term variations of surface magnetism and prominences of the young Sun-like star V530 Per
• First Millimeter Flares Detected from Epsilon Eridani with ALMA
• A multi-wavelength view of the multiple activity cycles of $\epsilon$~Eridani
• Testing the Rossby Paradigm: Weakened Magnetic Braking in early K-type Stars
• Ultraviolet Spectropolarimetry: Investigating stellar magnetic field diagnostics
• Modeling the Mg I from the NUV to MIR. II. Testing stellar models
• Using Doppler Imaging to model stellar activity and search for planets around Sun-like stars
• Simulating starspot activity jitter for spectral types F--M: realistic estimates for a representative sample of known exoplanet hosts