A Profile Analysis of Raman-scattered O VI Bands at 6825 Å and 7082 Å in Sanduleak’s Star

Abstract

We present a detailed modeling of the two broad bands observed at 6825 and 7082 Å in Sanduleak?s star, a controversial object in the Large Magellanic Cloud. These bands are known to originate from Raman scattering of O vi λ λ 1032 and 1038 photons with atomic hydrogen and are only observed in bona fide symbiotic stars. Our high-resolution spectrum obtained with the Magellan Inamori Kyocera Echelle spectrograph at the Magellan-Clay Telescope reveals, quite surprisingly, that the profiles of the two bands look very different: while the Raman 6825 Å band shows a single broad profile with a redward extended bump, the Raman 7082 Å band exhibits a distinct triple-peak profile. Our model suggests that the O vi emission nebula can be decomposed into a red, blue, and central emission region from an accretion disk, a bipolar outflow, and a further compact, optically thick region. We also perform Monte Carlo simulations with the aim of fitting the observed flux ratio F(6825)/F(7082) ~ 4.5, which indicates that the neutral region in Sanduleak?s star is characterized by the column density N H i ~ 1 × 1023 cm^(-2).