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Paper: Orbital Effects in VLT–UVES Spectra of AADor and NYVir
Volume: 392, Hot Subdwarf Stars and Related Objects
Page: 199
Authors: Vuckovic, M.; Østensen, R.; Bloemen, S.; Decoster, I.; Aerts, C.
Abstract: We analyse VLT/UVES spectra of two eclipsing subdwarf binary systems NY Vir, a rapidly pulsating subdwarf B primary with an M5 companion and AA Dor, an sdOB primary with a degenerate dwarf companion. We report the detection of the Rossiter-McLaughlin effect in the radial velocity curve of NY Vir, as previously seen in AA Dor. Reexamining the AA Dor spectra and simulating the amplitude of the Rossiter-McLaughlin effect, we find it to be in the accordance with the amplitude seen in the radial velocity residuals. In addition to the Rossiter-McLaughlin effect we observe clear radial velocity deviations in the Balmer lines at phases where the contribution from the secondary is greatest in both AA Dor and NY Vir. After careful subtraction of the contribution from the AA Dor primary we clearly detect both emission and absorption features originating from the superheated surface of the secondary. This allows us for the first time to estimate K2 and the masses of the primary and secondary star in the AA Dor system.
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