High-resolution spectropolarimetry of κ Cet: A proxy for the young Sun

Nascimento, J.-D. do; Petit, P.; Castro, M.; Mello, G. F. Porto de; Jeffers, S. V.; Marsden, S. C.; Ribas, I.; Guinan, E. F.

doi:10.1017/s1743921314001902

Cited by 2 publications

(5 citation statements)

References 5 publications

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“…Similarly to previous studies of other proxies of magnetic activity (e.g. Wright et al 2011), the open flux, mass loss-rates and angular momentum-loss rates all show less scatter when plotted against Rossby number rather than rotation period. In the unsaturated regime (Ro 0.1), each of these parameters increase with decreasing Rossby number.…”

Section: Discussionsupporting

confidence: 77%

“…However, the scatter is reduced when plotting against the Rossby number. A similar reduction in the scatter of other magnetic activity proxies is seen when they are plotted against Rossby number rather than rotation period, most notably X-ray emission (Noyes et al 1984;Pizzolato et al 2003;Wright et al 2011). On the other hand, it should be noted that Reiners et al (2014) argues that the rotation period is a more fundamental parameter than Rossby number in the context of dynamo action.…”

Section: Angular Momentum-loss Ratessupporting

confidence: 56%

“…The Rossby number is given by the rotation period divided by the convective turnover time, Ro = P rot /τ c . In this work, we will use the empirical prescription of Wright et al (2011) (their equation (11)) to estimate the convective turnover times for our sample. The reference for the original publication of each ZDI map is also listed in table 1.…”

Section: Sample and Wind Modelmentioning

confidence: 99%

“…It is important to note that the form of this fit, as well as other fits presented in the rest of this work, will depend on the adopted convective turnover times. We have chosen to use the empirically determined prescription of Wright et al (2011) but different prescriptions may produce slightly different fits. Vidotto et al (2014b) determined fits for the surface flux and unsigned average magnetic field strength as a function of Rossby number for a sample of stars similar to the one used in this work.…”

Section: Coronal Magnetic Fieldmentioning

confidence: 99%

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Studying stellar spin-down with Zeeman–Doppler magnetograms

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Jardine

Vidotto

et al. 2016

Mon. Not. R. Astron. Soc.

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Magnetic activity and rotation are known to be intimately linked for low-mass stars. Understanding rotation evolution over the stellar lifetime is therefore an important goal within stellar astrophysics. In recent years, there has been increased focus on how the complexity of the stellar magnetic field affects the rate of angular momentum-loss from a star. This is a topic that Zeeman-Doppler imaging (ZDI), a technique that is capable of reconstructing the large-scale magnetic field topology of a star, can uniquely address.Using a potential field source surface model, we estimate the open flux, mass loss-rate and angular momentum-loss rates for a sample of 66 stars that have been mapped with ZDI. We show that the open flux of a star is predominantly determined by the dipolar component of its magnetic field for our choice of source surface radius. We also show that, on the main sequence, the open flux, mass-and angular momentum-loss rates increase with decreasing Rossby number. The exception to this rule is stars less massive than 0.3 M . Previous work suggests that low mass M dwarfs may possess either strong, ordered and dipolar fields or weak and complex fields. This range of field strengths results in a large spread of angular momentum-loss rates for these stars and has important consequences for their spin down behaviour. Additionally, our models do not predict a transition in the mass-loss rates at the so called wind dividing line noted from Lyα studies.

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Section: Discussionsupporting

confidence: 77%

Section: Angular Momentum-loss Ratessupporting

confidence: 56%

Section: Sample and Wind Modelmentioning

confidence: 99%

Section: Coronal Magnetic Fieldmentioning

confidence: 99%

See 2 more Smart Citations

Studying stellar spin-down with Zeeman–Doppler magnetograms

See

Jardine

Vidotto

et al. 2016

Mon. Not. R. Astron. Soc.

Self Cite

View full text Add to dashboard Cite

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“…Thus, the mean magnetic fields of young G stars exceed the fields of present solar maxima by at least an order of magnitude. Note that our estimate is confirmed by |B l | estimates for stars whose parameters are closest to those of the young Sun: 8.5 G for V 2292 Oph and 7.7 G for κ 1 Cet (according to different data, the field of this star is |B l | = 7.0 G [29]). This agrees with our general conclusion above.…”

Section: Discussion Magnetic Fields On G Starssupporting

confidence: 78%

Solar-type activity: Epochs of cycle formation

2015

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The diagram of indices of coronal and chromospheric activity allowed us to reveal stars where solar-type activity appears and regular cycles are forming. Using new consideration of a relation between coronal activity and the rotation rate, together with new data on the ages of open clusters, we estimate the age of the young Sun corresponding to the epoch of formation of its cycle. The properties of the activity of this young Sun, with an age slightly older than one billion years, are briefly discussed. An analysis of available data on the long-term regular variability of late-type stars leads to the conclusion that duration of a cycle associated with solar-type activity increases with the deceleration of the stellar rotation; i.e., with age. New data on the magnetic fields of comparatively young G stars and changes in the role of the large-scale and the local magnetic fields in the formation of the activity of the young Sun are discussed. Studies in this area aim to provide observational tests aimed at identifying the conditions for the formation of cyclic activity on stars in the lower part of the main sequence, and test some results of dynamo theory.

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High-resolution spectropolarimetry of κ Cet: A proxy for the young Sun

Cited by 2 publications

References 5 publications

Studying stellar spin-down with Zeeman–Doppler magnetograms

Studying stellar spin-down with Zeeman–Doppler magnetograms

Solar-type activity: Epochs of cycle formation

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