Yazar "Blackford, M. G." seçeneğine göre listele

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    Absolute parameters of young stars: HX Velorum
    (Oxford Univ Press, 2019) Blackford, M. G.; Erdem, A.; Surgit, D.; Ozkardes, B.; Budding, E.; Butland, R.; Demircan, O.
    We present combined photometric and spectroscopic analyses of the southern multiple star HX Vel. High-resolution spectra of this system were taken at the University of Canterbury Mt. John Observatory in the years 2009-2015. Absolute parameters for HX Vel tend to confirm its young and near-main-sequence nature. We specify the main adopted parameters of the (non-eclipsing) close binary as follows: M-1 = 8.5 +/- 1.7, M-2 = 5.4 +/- 1.2, R-1 = 5.0 +/- 0.3, R-2 = 3.1 +/- 0.2, (circle dot); T-1 25 000 +/- 1300, T-2 20 000 +/- 2500 (K); systemic M-V -4.2 +/- 0.2. These parameters are sensitive to the low inclination, where we find a small disparity between the photometrically optimal 28 +/- 2 degrees and an adopted value of 26 degrees that gives better consistency with main-sequence stellar modelling. The relationship of HX Vel to the galactic cluster IC 2395 and OB association Vela OB1C is also considered, in the context of photometric parallaxes found for HX Vel and other cluster members.
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    Öğe
    Absolute parameters of young stars: V454 Carinae
    (Oxford Univ Press, 2019) Butland, R. J.; Erdem, A.; Ozkardes, B.; Blackford, M. G.; Surgit, D.; Budding, E.; Demircan, O.
    We present combined photometric and spectroscopic analyses of the multiple star V454 Carinae. High-resolution spectra of the system were taken at the University of Canterbury Mt. John Observatory during the years 2008-18. These have been processed using generic and purpose-built software. New digital single lens reflex photometry of the system has also been collected and similarly analysed. Absolute parameters for the three main stars confirm V454 Car's young and near-Main-Sequence nature. We find: M-1 = 4.6 +/- 0.4, M-2 = 4.4 +/- 0.4, M-3 = 4.5 +/- 0.5, R-1 = 2.83 +/- 0.18, R-2 = 2.74 +/- 0.16, R-3 = 2.78 +/- 0.16 (circle dot); T-1 similar to 17 500, T-2 similar to 15 500, T-3 similar to 15 000 (K), age similar to 30 Myr, photometric distance similar to 500 (pc). The major component V454 Car A is the close binary identified by the HIPPARCOS satellite. This binary and component B appear to be in eccentric orbits about a common centre of gravity with a period of similar to 1900 d. Analysis of the radial velocity curves suggests that the mass of component B is greater than that of its visible member. Measured radial velocities of this visible star show irregularities with a time-scale of about a week. The galactic location, proper motions, and age of V454 Car support the runaway nature proposed by others, and the combined results are consistent with a dynamical ejection scenario from the Vela region of Gould's Belt relatively soon after the stars' formation.