DISCUSSION AND CONCLUSIONS

The line profile behavior and the Doppler imaging may suggest a novel scenario for V617 Sgr. The hypothesis of a wind associated with the hot-spot is supported by the spectroscopic observations presented here. Specially, if the mass transfer is driven on a thermal time-scale as discussed in section 3.3. In this case the high mass transfer rate (M_dot > 10⁸ M_solar/yr) may power a bright and optically thick hot-spot. For such mass transfer rates, typical temperatures at the bright spot region may raise above 40000 K, depending on the amount of kinetic energy that is thermalized in the impact region and the effective extension of the spot. Such hot region at a relatively low gravity location in the disk may on its turn lead to the radiative acceleration of a highly ionized wind. The bright spot as a source of EUV/X-ray radiation may be also important in the companion illumination scenario suggested by the trailed spectrograms and HeII Doppler imaging. An alternative scenario may be built around the hypothesis of a wind formed in the inner disk, whose absorption is seen when the brightest part of the disk is in the line of sight. While the exact source of the wind in the system is still uncertain, observational evidences for its presence are found in the behavior of the HeII emission line during eclipse and also from the Balmer line profile variations.

The Doppler imaging and the orbital flux variation in HeII indicate that a significant fraction of this line is formed in the spot region. The presence of an enhanced emissivity extending in the V_y<0 direction from the spot and the occurrence of high velocity emission in the V_y<0 and V_x<0 may suggest the presence of ionized gas flowing over the disk. This gas is not being incorporated into the disk at the bright spot. Instead, it spills over the edge of the disk assuming different kinematics. Such a spillover geometry is consistent with the idea that the disk has an asymmetric high rim, following the hot spot. Such a geometry describes well the observations of supersoft X-ray binaries (Meyer-Hofmeister, Schandl, & Meyer 1997). In this case the rim may be illuminated and ionized by the central source. Such a configuration is supported by the observation of a maximum emission in HeII at phase 0.3-0.4. Long term photometric monitoring of V617 Sgr aiming to the detection of a secular variation in the orbital period is strongly encouraged.

We are grateful to the LNA staff for the observing assistance during the observing runs. D. Cieslinski acknowledges the support from CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo). M. P. Diaz acknowledges support from CNPq under grant #301029 and FAPEMIG under grant #183696.