Surface imaging with atomic and molecular features

I. A new inversion technique and first numerical tests

Astrophysical Institute Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany e-mail: [isavanov;kstrassmeier]@aip.de

Received: 25 April 2005
Accepted: 11 August 2005

Abstract

We present a new Doppler-imaging inversion code that uses quasi-optimal filtering of the object's principal components of a Fisher information matrix. The new code allows one to perform the reconstruction of stellar surface temperature maps using molecular features like TiO, CO, OH, CN etc. which are numerous in spectra of late-type dwarfs. It is possible to use atomic and molecular features simultaneously in the restoration. Our tests verify the robustness of OPC but also emphasize its dependency on the various atomic and molecular line lists. Without inclusion of molecules, Doppler imaging of stars with photospheric temperatures below ≈4250 K (K7-M0) remains unreliable.