Direct detection of the secondary spectrum of the interacting eclipsing binary TX UMa

Abstract

Eclipsing binary TX UMa was observed with the D.A.O. high-dispersion spectrographs in 1969–1970, with emphasis on the detailed coverage of the primary minimum. One spectrum was taken exclusively within totality, thus exhibiting an uncontaminated spectrum of the secondary component. This leads to spectral reclassification of the secondary (F6 IV). The narrowing of the line profile of the Hγ-line in totality is interpreted in terms of synchronous rotation of the secondary (v sini∼80 km s⁻¹) while the primary rotates faster (v sini∼130 km s⁻¹) than synchronously (v sini∼50 km s⁻¹). Although the secondary does not fill in its Roche lobe fully, the system exhibits pronounced indications of rather strong physical interaction. This is now supported also by the profound changes of the line profiles of the Hγ-line with phase.