Identifying solar-like magnetic cycles with Zeeman-Doppler-Imaging

Lehmann, L. T.; Hussain, G. A. J.; Vidotto, A. A.; Jardine, M.; Mackay, D. H.

doi:10.1093/mnras/staa3284

Cited by 16 publications

(12 citation statements)

References 48 publications

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“…7. According to Lehmann et al (2021) periodicities are not easily detectable in the magnetic energy fractions of ZDI magnetic maps. Instead, the authors identified the axisymmetric fraction as a good tracer of the magnetic cycles.…”

Section: Magnetic Morphologymentioning

confidence: 94%

Time evolution of magnetic activity cycles in young suns: The curious case of κ Ceti

Saikia

Lüftinger

Antonova

et al. 2022

A&A

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Context. A detailed investigation of the magnetic properties of young Sun-like stars can provide valuable information on our Sun's magnetic past and its impact on the early Earth. Aims. We determine the properties of the moderately rotating young Sun-like star κ Ceti's magnetic and activity cycles using 50 years of chromospheric activity data and six epochs of spectropolarimetric observations. Methods. The chromospheric activity was determined by measuring the flux in the Ca ii H and K lines. A generalised Lomb-Scargle periodogram and a wavelet decomposition were used on the chromospheric activity data to establish the associated periodicities. The vector magnetic field of the star was reconstructed using the technique of Zeeman Doppler imaging on the spectropolarimetric observations. Results. Our period analysis algorithms detect a 3.1 year chromospheric cycle in addition to the star's well-known ∼ 6 year cycle period. Although the two cycle periods have an approximate 1:2 ratio, they exhibit an unusual temporal evolution. Additionally, the spectropolarimetric data analysis shows polarity reversals of the star's large-scale magnetic field, suggesting a ∼10 year magnetic or Hale cycle. Conclusions. The unusual evolution of the star's chromospheric cycles and their lack of a direct correlation with the magnetic cycle establishes κ Ceti as a curious young Sun. Such complex evolution of magnetic activity could be synonymous with moderately active young Suns, which is an evolutionary path that our own Sun could have taken.

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Section: Magnetic Morphologymentioning

confidence: 94%

Time evolution of magnetic activity cycles in young suns: The curious case of κ Ceti

Saikia

Lüftinger

Antonova

et al. 2022

A&A

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“…We note that a contemporary spectropolarimetric monitoring of AU Mic using both optical (e.g., HARPS-Pol, ESPaDOnS, Neo-NARVAL) and nIR (e.g., SPIRou, CRIRES+) should be able to confirm or infirm this assumption. Moreover, the magnetic properties derived from time series of circularly-polarized Zeeman signatures with Zeeman-Doppler imaging have been shown to be excellent proxies of solar-like magnetic cycles (Lehmann et al 2021). Monitoring the long-term evolution of the large-scale field at the surface of AU Mic will allow us to (i) unveil the origin of the discrepancies in spot coverage and latitudinal DR between HARPS and SPIRou observations and (ii) help investigate the nature of the putative 5-yr activity cycle reported in Ibañez Bustos et al (2019).…”

Section: Stellar Activity and Differential Rotationmentioning

confidence: 99%

One year of AU Mic with HARPS – II. Stellar activity and star–planet interaction

Klein

Zicher

Kavanagh

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present a spectroscopic analysis of a 1-year intensive monitoring campaign of the 22-Myr old planet-hosting M dwarf AU Mic using the HARPS spectrograph. In a companion paper, we reported detections of the planet radial velocity (RV) signatures of the two close-in transiting planets of the system, with respective semi-amplitudes of 5.8 ± 2.5 m s−1 and 8.5 ± 2.5 m s−1 for AU Mic b and AU Mic c. Here, we perform an independent measurement of the RV semi-amplitude of AU Mic c using Doppler imaging to simultaneously model the activity-induced distortions and the planet-induced shifts in the line profiles. The resulting semi-amplitude of 13.3 ± 4.1 m s−1 for AU Mic c reinforces the idea that the planet features a surprisingly large inner density, in tension with current standard models of core accretion. Our brightness maps feature significantly higher spot coverage and lower level of differential rotation than the brightness maps obtained in late 2019 with the SPIRou spectropolarimeter, suggesting that the stellar magnetic activity has evolved dramatically over a ∼1-yr time span. Additionally, we report a 3-σ detection of a modulation at 8.33 ± 0.04 d of the He I D3 (5875.62 Å) emission flux, close to the 8.46-d orbital period of AU Mic b. The power of this emission (a few 1017 W) is consistent with 3D magnetohydrodynamical simulations of the interaction between stellar wind and the close-in planet if the latter hosts a magnetic field of ∼10 G. Spectropolarimetric observations of the star are needed to firmly elucidate the origin of the observed chromospheric variability.

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“…Activity amplitudes (symbol size) and the poloidal fraction of the large-scale magnetic field (symbol colour) are also shown in Figure 8 for a selection of stars with published ZDI maps. We show the Sun with the usual symbol, which is scaled for its activity variability during cycle 23 (Lehmann et al 2021). The fractional poloidal field of the Sun we show here is the minimum value measured by Lehmann et al (2021); note that since the Sun's magnetic field has been observed in much higher cadence compared to the other stars, its large-scale toroidal component has been better recovered.…”

Section: Chromospheric Activity and Magnetic Field Geometry Versus Ef...mentioning

confidence: 79%

Linking chromospheric activity and magnetic field properties for late-type dwarf stars

Brown,

Jeffers,

Marsden

et al. 2022

Preprint

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Spectropolarimetric data allow for simultaneous monitoring of stellar chromospheric log 𝑅HK activity and the surface-averaged longitudinal magnetic field, 𝐵 𝑙 , giving the opportunity to probe the relationship between large-scale stellar magnetic fields and chromospheric manifestations of magnetism. We present log 𝑅 HK and/or 𝐵 𝑙 measurements for 954 mid-F to mid-M stars derived from spectropolarimetric observations contained within the PolarBase database. Our magnetically active sample complements previous stellar activity surveys that focus on inactive planet-search targets. We find a positive correlation between mean log 𝑅 HK and mean log |𝐵 𝑙 |, but for G stars the relationship may undergo a change between log 𝑅 HK ∼ −4.4 and −4.8. The mean log 𝑅 HKshows a similar change with respect to the log 𝑅 HK variability amplitude for intermediately-active G stars. We also combine our results with archival chromospheric activity data and published observations of large-scale magnetic field geometries derived using Zeeman Doppler Imaging. The chromospheric activity data indicate a slight under-density of late-F to early-K stars with −4.75 ≤ log 𝑅 HK ≤ −4.5. This is not as prominent as the original Vaughan-Preston gap, and we do not detect similar underpopulated regions in the distributions of the mean |𝐵 𝑙 |, or the 𝐵 𝑙 and log 𝑅 HK variability amplitudes. Chromospheric activity, activity variability and toroidal field strength decrease on the main sequence as rotation slows. For G stars, the disappearance of dominant toroidal fields occurs at a similar chromospheric activity level as the change in the relationships between chromospheric activity, activity variability and mean field strength.

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Identifying solar-like magnetic cycles with Zeeman-Doppler-Imaging

Cited by 16 publications

References 48 publications

Time evolution of magnetic activity cycles in young suns: The curious case of κ Ceti

Time evolution of magnetic activity cycles in young suns: The curious case of κ Ceti

One year of AU Mic with HARPS – II. Stellar activity and star–planet interaction

Linking chromospheric activity and magnetic field properties for late-type dwarf stars

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