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Observational evidence of anti-solar differential rotation of K-type giant stars is presented. Time-series Doppler imaging based on 70 nights of spectroscopic data was used to derive the spot evolution of the stellar surfaces. The relative differential rotation parameters (α) of the binary stars IMPeg, HD208472, and HKLac were obtained using two techniques, cross-correlation analysis and the sheared-image method. Additionally, two previously published single giant stars are revisited and qualitatively compared to recent theoretical models. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We present a simultaneous photometric and spectroscopic imaging analysis of the long-period RS CVn binary σ Gem, covering 3.6 consecutive rotation cycles with high time resolution. From six overlapping but consecutive Doppler maps we trace the evolution of individual spots throughout the time range covered. All spots group either along a band at approximately +45°latitude and a width of 30°, or appear centered at the equator. No polar spot is detected. We did not find a conclusive migration pattern from the cross-correlation maps from one rotation to the next and attribute this to a masking effect of short-term spot changes.

This paper presents a time-series spectrum analysis of the two chromospherically active binary stars, UX Fornacis and AG Doradus. To investigate the rotational behaviour, in combination with activity in the H line, we obtained almost 40 high-resolution, high-S=N spectra for each system. Both binaries, UX For and AG Dor, show H of the primary star in absorption but lled in by chromospheric emission while the H line of the secondaries appear in pure emission. Line variations are seen and are approximately 5- detections but are not linked to the orbital nor the rotational periods and seem to be erratic. We obtained new orbital elements for both systems and used them in combination with Hipparcos parallaxes and our H-spectrum synthesis to determine absolute parameters. We present the rst Doppler image of the AG Dor primary using line-prole variations of the Fe i 6546 line. The image reveals a cool polar feature and three equatorial spots with an average surface temperature dierence, photosphere minus spots, of up to 1500 K for the polar spot and800 K for the equatorial spots. Since AG Dor is one of the slowest rotators (v sini =1 8 km s 1 ) that has ever been Doppler imaged, we

We present the results from a spectroscopic Ca II HK 23% with strong emission, 36% with moderate emission, and 41% with weak emission. These spectra are used to determine absolute H&K emission-line fluxes, radial velocities, and equivalent widths of the luminosity-sensitive Sr II line at 4077 ˚ A. Red-wavelength spectroscopic and Stromgren y photometric follow-up obser- vations of the 371 stars with H&K emission are used to ad- ditionally determine the absolute H-core flux, the lithium abundance from the Li I 6708 ˚ A equivalent width, the rotational velocity v sin i, the radial velocity, and the light variations and its periodicity. The latter is interpreted as the stellar rotation period due to an inhomogeneous surface brightness distribu- tion. 156 stars were found with photometric periods between 0.29 and 64 days, 11 additional systems showed quasi-periodic variations possibly in excess of 50 days. Further 54 stars had variations but no unique period was found, and four stars were essentially constant. Altogether, 170 new variable stars were discovered. Additionally, we found 17 new SB1 (plus 16 new candidates) and 19 new SB2 systems, as well as one definite and two possible new SB3 systems. Finally, we present a list of 21 stars that we think are most suitable candidates for a detailed study with the Doppler-imaging technique.

Orbital elements have been determined for 10 chromospherically active binaries from a combination of new velocities and velocities in the literature. First orbits for three binaries, HD 33363, HD 152178, and HD 208472, are presented, as well as updated orbits for seven other bi- naries. Two of the latter systems, LN Peg and HD 106225 were discovered to be triple, and both short- and long- period orbits have been computed for each. Fundamental properties have been determined for the chromopherically active primary in each system.

We present time-series Doppler images of the rapidly-rotating active binary star EI Eri from spectroscopic observations collected during the MUSICOS multi-site campaign in 1998, since the critical rotation period of 1.947 days makes it impossible to obtain time-resolved images from a single site. From the surface reconstructions a weak solar-type differential rotation, as well as a tiny poleward meridional flow are measured., 4 pages, 3 figures, 1 table, proceedings of Cool Stars 15, St Andrews, July 2008, to be published in the Conference Proceedings Series of the AIP

Extended CCD monitoring of RR Gem revealed that it is a Blazhko type RRab star with the shortest Blazhko period (7.23d) and smallest modulation amplitude (Delta Mmax, 10 pages, 12 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics

This volume of AN contains the proceedings of the 1st Potsdam Thinkshop on Sunspots & Starspots held in Potsdam from May 6 to 10, 2002. The aim of this meeting was to bring together the solar and stellar community on a particular topic and discuss various inter-disciplinary results related to magnetic field. All contributions are fully refereed.

Our data-reduction pipeline is based on the NOAO Image Reduction and Analysis Facility (IRAF). It consists of a number of IRAF-CL scripts which are invoked by a master script (see Ritter & Washuettl 2002 for more details). The subtasks access a parameter file where all relevant IRAF parameters are stored. If a particular parameter is not found in the parameter file (or the parameter file itself is not present or accessible), standard parameters, which are stored in the subtasks, are used. Four reference files are needed for cleaning the images of bad pixels, for defining the position of the Echelle orders on the CCD, for identifying Th-Ar emission lines for the wavelength calibration and for the radial-velocity measurement (which is not implemented yet in the pipeline because of missing reference star spectra for the individual types of stars).