A quest for activity cycles in low‐mass stars

Vida, K.; Kriskovics, L.; Oláh, K.

doi:10.1002/asna.201211973

Cited by 22 publications

(34 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…005 amplitude) corresponding to P = 0.445518 days in the Fourier spectrum is seen. If we accept this as a signal that also stems from the rotation, this would yield a differential rotation shear of |α| = |∆P/P| 0.0004, which is very close to a rigid-body rotation, in agreement with the findings of Vida et al (2013), of Morin et al (2008a) (α = 0.0004), and of Donati et al (2006) (α = 0.0014). On GJ 1243, another M4 star with a fast rotation of 0.59 days, Davenport et al (2015) found a similar differential rotation (|α| = 0.0011) to our estimate on V374 Peg.…”

Section: Fourier Analysissupporting

confidence: 76%

Investigating magnetic activity in very stable stellar magnetic fields

Vida

Kriskovics

Oláh

et al. 2016

A&A

Self Cite

111

113

View full text Add to dashboard Cite

The ultrafast-rotating (P rot ≈ 0.44 d) fully convective single M4 dwarf V374 Peg is a well-known laboratory for studying intense stellar activity in a stable magnetic topology. As an observable proxy for the stellar magnetic field, we study the stability of the light curve, hence the spot configuration. We also measure the occurrence rate of flares and coronal mass ejections (CMEs). We have analysed spectroscopic observations, BV(RI) C photometry covering 5 yrs, and additional R C photometry that expands the temporal base over 16 yr. The light curve suggests an almost rigid-body rotation and a spot configuration that is stable over about 16 yrs, confirming the previous indications of a very stable magnetic field. We observed small changes on a nightly timescale and frequent flaring, including a possible sympathetic flare. The strongest flares seem to be more concentrated around the phase where the light curve indicates a smaller active region. Spectral data suggest a complex CME with falling-back and re-ejected material with a maximal projected velocity of ∼675 km s −1 . We observed a CME rate that is much lower than expected from extrapolations of the solar flare-CME relation to active stars.

show abstract

Section: Fourier Analysissupporting

confidence: 76%

Investigating magnetic activity in very stable stellar magnetic fields

Vida

Kriskovics

Oláh

et al. 2016

A&A

Self Cite

111

113

View full text Add to dashboard Cite

show abstract

“…For this, we carefully selected 47 single, inactive M dwarfs with previous published P cycle and P rot (Savanov 2012;Robertson et al 2013;Suárez Mascareño et al 2016, 2018Wargelin et al 2017;Küker et al 2019) and the stars of our sample for which we have found P cycle and P rot (see Table 2). In our sample of field M dwarfs we did not include fast-rotating, probably very young M dwarfs tabulated by Vida et al (2013Vida et al ( , 2014 and Distefano et al (2016Distefano et al ( , 2017. Figure 8 shows the plot P cycle /P rot vs. 1/P rot in log-log scale.…”

Section: Long-period Cyclesmentioning

confidence: 99%

CARMENES input catalogue of M dwarfs

Alonso

Caballero

Montes

et al. 2019

A&A

101

View full text Add to dashboard Cite

Aims. The main goal of this work is to measure rotation periods of the M-type dwarf stars being observed by the CARMENES exoplanet survey to help distinguish radial-velocity signals produced by magnetic activity from those produced by exoplanets. Rotation periods are also fundamental for a detailed study of the relation between activity and rotation in late-type stars. Methods. We look for significant periodic signals in 622 photometric time series of 337 bright, nearby M dwarfs obtained by long-time baseline, automated surveys (MEarth, ASAS, SuperWASP, NSVS, Catalina, ASAS-SN, K2, and HATNet) and for 20 stars which we obtained with four 0.2–0.8 m telescopes at high geographical latitudes. Results. We present 142 rotation periods (73 new) from 0.12 d to 133 d and ten long-term activity cycles (six new) from 3.0 a to 11.5 a. We compare our determinations with those in the existing literature; we investigate the distribution of Prot in the CARMENES input catalogue, the amplitude of photometric variability, and their relation to v sini and pEW(Hα); and we identify three very active stars with new rotation periods between 0.34 d and 23.6 d.

show abstract

“…8, we plot the cycle period (in years) vs. the stellar rotation period (in days) for the sample stars. We use the stellar sample discussed in detail by Brandenburg et al (1998) and Böhm-Vitense (2007) (blue and green triangles), the stars with confirmed X-ray cycles discussed in the introduction section (magenta circles) and individual fast rotators with activity cycles as discussed by Bernhard & Frank (2006), Taš (2011), andVida et al (2013) (red circles); the data point for AB Dor A is also shown, using its 0.52 day rotation period and 17 year activity-cycle period. Brandenburg et al (1998) showed that active and inactive stars follow different branches in a P cyc − P rot -diagram.…”

Section: Comparison Of Ab Dor A's Activity Cycle With That Of Other Smentioning

confidence: 99%

X-ray activity cycle on the active ultra-fast rotator AB Doradus A?

Lalitha

Schmitt

2013

A&A

View full text Add to dashboard Cite

Context. Although chromospheric activity cycles have been studied in a larger number of late-type stars for quite some time, very little is known about coronal activity-cycles in other stars and their similarities or dissimilarities with the solar activity cycle. Aims. While it is usually assumed that cyclic activity is present only in stars of low to moderate activity, we investigate whether the ultra-fast rotator AB Dor, a K dwarf exhibiting signs of substantial magnetic activity in essentially all wavelength bands, exhibits an X-ray activity cycle in analogy to its photospheric activity cycle of about 17 years and possible correlations between these bands. Methods. We analysed the combined optical photometric data of AB Dor A, which span ∼35 years. Additionally, we used ROSAT and XMM-Newton X-ray observations of AB Dor A to study the long-term evolution of magnetic activity in this active K dwarf over nearly three decades and searched for X-ray activity cycles and related photometric brightness changes. Results. AB Dor A exhibits photometric brightness variations ranging between 6.75 < V mag ≤ 7.15 while the X-ray luminosities range between 29.8 < log L X [erg/s] ≤ 30.2 in the 0.3-2.5 keV. As a very active star, AB Dor A shows frequent X-ray flaring, but in the long XMM-Newton observations a kind of basal state is attained very often. This basal state probably varies with the photospheric activity-cycle of AB Dor A, which has a period of ∼17 years, but the X-ray variability amounts at most to a factor of ∼2, which is, much lower than the typical cycle amplitudes found on the Sun.

show abstract

A quest for activity cycles in low‐mass stars

Cited by 22 publications

References 24 publications

Investigating magnetic activity in very stable stellar magnetic fields

Investigating magnetic activity in very stable stellar magnetic fields

CARMENES input catalogue of M dwarfs

X-ray activity cycle on the active ultra-fast rotator AB Doradus A?

Contact Info

Product

Resources

About