Lithium enrichment on the single active K1-giant DI Piscium

Abstract

Aims. We investigate the surface spot activity of the rapidly rotating, lithium-rich active single K-giant DI Psc to measure the surface differential rotation and understand the mechanisms behind the Li-enrichment. Methods. Doppler imaging was applied to recover the surface temperature distribution of DI Psc in two subsequent rotational cycles using the individual mapping lines Ca i 6439, Fe i 6430, Fe i 6421, and Li i 6708. Surface differential rotation was derived by crosscorrelation of the subsequent maps. Difference maps are produced to study the uniformity of Li-enrichment on the surface. These maps are compared with the rotational modulation of the Li i 6708 line equivalent width.Results. Doppler images obtained for the Ca and Fe mapping lines agree well and reveal strong polar spottedness, as well as cool features at lower latitudes. Cross-correlating the consecutive maps yields antisolar differential rotation with a shear coefficient α = −0.083 ± 0.021. The difference of the average and the Li maps indicates that the lithium abundance is non-activity related. There is also a significant rotational modulation of the Li equivalent width.

Rotation–differential rotation relationships for late‐type single and binary stars from Doppler imaging

“…In our sample, there are three single K‐giants, namely DP CVn, DI Psc, and V1192 Ori, all three located at the RGB, rotate rapidly, and show enhanced surface Li abundance (Kővári et al ; Kriskovics et al ; Strassmeier et al ). Moreover, these are the only known single giants that perform antisolar‐type surface differential rotation (cf., Table ).…”

“…cB05: Barnes (), BCL05: Barnes et al (), BJC04: Barnes et al (), DC97: Donati & Collier Cameron (), MWC05: Marsden et al (), DCP03: Donati et al (), PDV04 Petit et al (), KSG04: Kővári et al (), KWF09: Kővári et al (), KBH00: Korhonen et al (), PDO04: Petit et al (), VKS07: Vida et al (), HSK16: Harutyunyan et al (), KW04: Kővári & Weber (), KKO14: Kővári et al (), KKS13: Kővári et al (), KBS07: Kővári et al (), KKK12: Kővári et al (), KKV14: Kriskovics et al (), KKK15: Kővári et al (), WSW05: Weber et al (), ÖCK16: Özdarcan et al (), KKS16: Kővári et al (), MBD07: Marsden et al (), SKW03: Strassmeier et al (), KSO17: Kővári et al (), BVW86: Balthasar et al (), BJM16: Boro Saikia et al ().…”

The EBLM project – VII. Spin–orbit alignment for the circumbinary planet host EBLM J0608-59 A/TOI-1338 A

“…The fit improves the Bayesian Information Criterion by 5.5, showing an improvement in the model, although the reduced χ 2 ν = 0.45 suggests we may be overfitting the data. There have only been detections of antisolar differential rotation in three giant stars (Strassmeier, Kratzwald & Weber 2003;Kővári et al 2013;Kriskovics et al 2014), with only a small handful of main-sequence Sun-like candidates (Benomar et al 2018). Ultimately, we are not able to rule out contributions from correlated noise and therefore consider it unlikely that the star is inclined.…”

The first Doppler imaging of the active binary prototype RS Canum Venaticorum

“…Recent Doppler imaging studies have detected the solar-like surface differential rotation on both of single and binary stars (Barnes et al 2000;Dunstone et al 2008;Kriskovics et al 2014;Özdarcan et al 2016), while some close binaries were reported to show the anti-solar differential rotations, which may be attributed to the tidal force (Kővári et al 2015;Harutyunyan et al 2016). Gastine et al (2014); Brun et al (2017) showed that the different direction of the differential rotations are related to the predominance of the Coriolis force over the buoyancy force and vice versa.…”