系外行星研究组知识库

We present the first Doppler images of the prototypical active binary star RS Callum Venaticorum, derived from high-resolution spectra observed in 2004, 2016 and 2017, using three different telescopes and observing sites. We apply the least-squares deconvolution technique to all observed spectra to obtain high signal-to-noise line profiles, which arc used to derive the surface images of the active K-type component. Our images show a complex spot pattern on the K star, distributed widely in longitude. All star-spots revealed by our Doppler images are located below a latitude of about 70 degrees. In accordance with previous light-curve modelling studies, we find no indication of a polar spot on the K star. Using Doppler images derived from two consecutive rotational cycles, we estimate a surface differential rotation rate of Delta Omega = -0.039 +/- 0.003 rad d(-1) and alpha = Delta Omega/Omega(eq) = -0,030 +/- 0.002 for the K star. Given the limited phase coverage during those two rotations, the uncertainty of our differential rotation estimate is presumably higher.