Spectral disentangling applied on triple systems: RV Crt

H. Hensberge, L.P. R. Vaz & K.B. Torres

RV Crt is a hierarchical triple consisting of an eclipsing close binary
with an orbital period of 28 hours and a F-type tertiary. The spectrum
is dominated by the sharp lines of the tertiary. The secondary is much
fainter than the other components. Hence, radial velocities are not easy
to measure, even not when using a late-type correlation mask. Using the
spectral disentangling technique as implemented by Hadrava (1995, A&AS 114,
393), the radial velocities of the three components and the mass ratio of
the close binary are measured accurately, and the spectra of the components
are separated. The nature of the triple is discussed, especially whether the
components are still in the PMS evolutionary phase.

I will first describe the basics of the spectral disentangling techniques
and outline possibilities and limitations. Then, extensions of the available
code (korel), to take into account the analysis of the light curve, are
discussed. Finally, the photometric and high-resolution spectroscopic data
on RV Crt are presented and their analysis is discussed.