Doppler imaging of stellar surface structure

Free access article

Issue		A&A Volume 373, Number 3, July III 2001


Page(s)		974 - 986
Section		Stellar atmospheres
DOI		http://dx.doi.org/10.1051/0004-6361:20010580

A&A 373, 974-986 (2001)
DOI: 10.1051/0004-6361:20010580

XV. A possible detection of differential rotation and local meridional flows on the rapidly-rotating giant HD 218153 = KU Pegasi

M. Weber and K. G. Strassmeier

Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: kstrassmeier@aip.de

(Received 21 February 2001 / Accepted 11 April 2001)

Abstract
Time-resolved Doppler images of the rapidly rotating, but long-period (25 days), giant KU Pegasi show several cool low-to-medium latitude spots as well as an asymmetric polar feature. The average spot temperature is about 700 K below the photospheric temperature of 4700 K. KU Peg is one of the most massive, and currently the most evolved, late-type star with a Doppler image. We obtained two independent images from two consecutive stellar rotations covering 50 nights with a total of 43 spectra. From a cross-correlation analysis of the two maps, we detect systematic longitudinal and latitudinal shifts that we tentatively interpret as latitude-dependent differential rotation and local meridional flows, respectively. The differential-rotation pattern is more complex than on the Sun, but on average in the sense that the poles rotate slower than the stellar equator, i.e. in the same direction and also of the same order than on the Sun. The latitudinal shifts are of the order of 0.4°day^-1 towards the stellar pole and occur at longitudes of around 40° and 330°. The residual H $\alpha$ profiles show a stationary emission component at rest wavelength and a blue-shifted absorption. The latter suggests an outward pointed velocity field with a flow velocity of approximately 35 km s^-1.

Key words: stars: activity -- stars: atmospheres -- stars: imaging -- stars: individual: HD 218153 -- stars: late-type

Offprint request: M. Weber, mweber@aip.de

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.