LS I +61 303 and LS 5039 are two of only a handful of known high mass X-ray binaries (HMXBs) that exhibit very high energy emission in the MeV-TeV range, and these "γ-ray binaries" are of renewed interest due to the recent launch of the Fermi Gamma-ray Space Telescope.Here we present new radial velocities of both systems based on recent red and blue optical spectra. Both systems have somewhat discrepant orbital solutions available in the literature, and our new measurements result in improved orbital elements and resolve the disagreements. The improved geometry of each orbit will aid in studies of the high energy emission region near each source.
We present the first K 0 -band, long-baseline interferometric observations of the northern Be stars Cas, Per, Tau, and Dra. The measurements were made with multiple telescope pairs of the CHARA Array interferometer and in every case the observations indicate that the circumstellar disks of the targets are resolved. We fit the interferometric visibilities with predictions from a simple disk model that assumes an isothermal gas in Keplerian rotation. We derive fits of the four model parameters (disk base density, radial density exponent, disk normal inclination, and position angle) for each of the targets. The resulting densities are in broad agreement with prior studies of the IR excess flux, and the resulting orientations generally agree with those from interferometric H and continuum polarimetric observations. We find that the angular size of the K 0 disk emission is smaller than that determined for the H emission, and we argue that the difference is the result of a larger H opacity and the relatively larger neutral hydrogen fraction with increasing disk radius. All the targets are known binaries with faint companions, and we find that companions appear to influence the interferometric visibilities in the cases of Per and Dra. We also present contemporaneous observations of the H, H, and Br emission lines. Synthetic model profiles of these lines that are based on the same disk inclination and radial density exponent as derived from the CHARA Array observations match the observed emission line strength if the disk base density is reduced by %1.7 dex.
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