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Basic parameters and properties of the rapidly rotating magnetic helium-strong B star HR 7355
Štefl, S.; Baade, D.; Kochukhov, O. +4 more
The spectral and magnetic properties and variability of the B2Vnp emission-line magnetosphere star HR 7355 were analysed. The object rotates at almost 90 per cent of the critical value, meaning it is a magnetic star for which oblateness and gravity darkening effects cannot be ignored any longer. A detailed modelling of the photospheric parameters …
Optical interferometry of early-type stars with PAVO@CHARA - I. Fundamental stellar properties
White, T. R.; Tuthill, P. G.; Huber, D. +8 more
We present interferometric observations of seven main-sequence and three giant stars with spectral types from B2 to F6 using the Precision Astronomical Visible Observations beam combiner at the Center for High Angular Resolution Astronomy array. We have directly determined the angular diameters for these objects with an average precision of 2.3 pe…
Two rings but no fellowship: LoTr 1 and its relation to planetary nebulae possessing barium central stars
Boumis, P.; Pollacco, D.; Santander-García, M. +8 more
LoTr 1 is a planetary nebula thought to contain an intermediate-period binary central star system (that is, a system with an orbital period, P, between 100 and, say, 1500 d). The system shows the signature of a K type, rapidly rotating giant and most likely constitutes an accretion-induced post-mass-transfer system similar to other PNe, such as Lo…
The use and calibration of read-out streaks to increase the dynamic range of the Swift Ultraviolet/Optical Telescope
Carter, M.; Page, M. J.; Symeonidis, M. +12 more
The dynamic range of photon counting micro-channel-plate (MCP) intensified charged-coupled device (CCD) instruments such as the Swift Ultraviolet/Optical Telescope (UVOT) and the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded by the CCD. …
Radiative transfer modelling of dust in IRAS 18333-2357: the only planetary nebula in the metal-poor globular cluster M22
Parthasarathy, M.; Ita, Y.; Muthumariappan, C.
We report results from our 1D radiative transfer modelling of dust in the hydrogen-deficient planetary nebula IRAS 18333-2357 located in the globular cluster M22. A spectral energy distribution was constructed from archival UV, optical and IR data including Akari photometry at its 18, 65, 90, 140 and 160 µm bands. An archival Spitzer spectru…
The low-mass companion of HIP 45314 (HR 3672)
Neuhäuser, R.; Schmidt, T. O. B.; Mugrauer, M. +2 more
We report the discovery of a very low mass companion to HIP 45314 (HR 3672) located about 2.7 arcsec north-west of HR 3672 A. With four years of epoch difference between the two observations obtained with the Very Large Telescope we can reject by more than 4σ that B would be a non-moving background object unrelated to A. HR 3672 A is a B 7-8 main-…