2016A&A...596A..53K


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.12CEST09:49:51

2016A&A...596A..53K - Astronomy and Astrophysics, volume 596A, 53-53 (2016/12-1)

Time-series Doppler images and surface differential rotation of the effectively single, rapidly rotating K-giant KU Pegasi.

KOVARI Z., KUNSTLER A., STRASSMEIER K.G., CARROLL T.A., WEBER M., KRISKOVICS L., OLAH K., VIDA K. and GRANZER T.

Abstract (from CDS):

Context. According to most stellar dynamo theories, differential rotation (DR) plays a crucial role in the generation of toroidal magnetic fields. Numerical models predict surface differential rotation to be anti-solar for rapidly rotating giant stars, i.e. their surface angular velocity could increase with stellar latitude. However, surface differential rotation has been derived only for a handful of individual giant stars to date.
Aims. The spotted surface of the K-giant KU Pegasi is investigated in order to detect its time evolution and to quantify the surface differential rotation.
Methods. We present 11 Doppler images from spectroscopic data collected with the robotic telescope STELLA between 2006 and 2011. All maps are obtained with the surface reconstruction code iMap. Differential rotation is extracted from these images by detecting systematic (latitude-dependent) spot displacements. We apply a cross-correlation technique to find the best differential rotation law.
Results. The surface of KU Peg shows cool spots at all latitudes and one persistent warm spot at high latitude. A small cool polar spot exists for most but not all of the epochs. Re-identification of spots in at least two consecutive maps is mostly possible only at middle and high latitudes and thus restricts the differential-rotation determination mainly to these latitudes. Our cross-correlation analysis reveals solar-like differential rotation with a surface shear of α=+0.040±0.006, i.e., approximately five times weaker than on the Sun. We also derive a more accurate and consistent set of stellar parameters for KU Peg including a small Li abundance of ten times less than solar.

Abstract Copyright: © ESO, 2016

Journal keyword(s): stars: activity - stars: imaging - stars: late-type - starspots - stars: individual: KU Pegasi

Simbad objects: 13

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Number of rows : 13

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* XX Tri RS* 02 03 47.1138016857 +35 35 28.669244792   9.52 8.42     K0III 117 0
2 V* V1192 Ori RS* 05 00 08.2195451291 +03 17 12.021405034   8.75 7.503   6.223 K1/2III 78 0
3 HD 33798 Ro* 05 15 15.45749 +47 10 14.6314       7.55   G5III 71 0
4 HD 233517 * 08 22 46.7144627395 +53 04 49.232441095   10.85 9.71     K2 80 0
5 V* IL Hya RS* 09 24 49.0137313673 -23 49 34.713618005   8.38 7.37     K2IV/Vp 161 0
6 V* DP CVn Ro* 12 36 16.9716641813 +51 30 52.287118123   9.59 8.58     K1III 19 0
7 V* FK Com Ro* 13 30 46.7993742986 +24 13 57.786184235   9.04 8.245   7.204 G4III 346 1
8 V* UZ Lib SB* 15 32 23.2091329303 -08 32 00.933695382   10.12 9.115   7.904 K0III 110 1
9 V* IM Peg RS* 22 53 02.2658951462 +16 50 28.291474642   7.024 5.890     K2III 318 1
10 V* DI Psc LP? 22 59 59.3874154903 +05 09 34.474494065   8.32 7.16     K0III/IV 25 0
11 V* KU Peg RS* 23 05 29.2736614948 +26 00 33.469093033   8.79 7.66     G9IV(e) 56 0
12 HD 218610 * 23 09 09.6594174365 +26 54 46.715234200   8.99 7.62     K2III 9 0
13 HD 219050 * 23 12 42.8155337448 +25 34 25.251140131   8.92 8.53     F5 2 0

    Equat.    Gal    SGal    Ecl

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2020.07.12-09:49:51

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