Yazar "Surgit, Derya" seçeneğine göre listele

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    Öğe
    Absolute parameters of three southern eclipsing binaries: DQ Car, BK Ind, and V4396 Sgr
    (Oxford Univ Press, 2020) Surgit, Derya; Erdem, Ahmet; Engelbrecht, Chris A.; Marang, Fred
    We present combined photometric and spectroscopic analyses of the three southern eclipsing binary stars: DQ Car, BK Ind, and V4396 Sgr. Radial velocity curves of these three systems were obtained at the South African Astronomical Observatory, and their light curves from the available data bases and surveys were used for the analysis. 75 new times of minima for these three eclipsing binaries were derived, and their ephemerides were updated. Only the O-C diagram of DQ Car indicates a cyclical variation, which was interpreted in terms of the light-time effect due to a third body in the system. Our final models describe these three systems as Algol-like binary stars with detached configurations. The masses and radii were found to be M-1 = 1.86(+/- 0.17) M-circle dot, R-1 = 1.63(+/- 0.06) R-circle dot and M-2 = 1.74(+/- 0.17) M-circle dot, R-2 = 1.52(+/- 0.07) R-circle dot for the primary and secondary components of DQ Car; M-1 = 1.16(+/- 0.05) M-circle dot, R-1 = 1.33(+/- 0.03) R-circle dot and M-1 = 0.98(+/- 0.04) M-circle dot, R-2 = 1.00(+/- 0.03) R-circle dot for BK Ind; and M-1 = 3.14(+/- 0.22) M-circle dot, R-1 = 3.00(+/- 0.09) R-circle dot and M-2 = 3.13(+/- 0.24) M-circle dot, R-2 = 2.40(+/- 0.08) R-circle dot for V4396 Sgr, respectively. The distances to DQ Car, BK Ind, and V4396 Sgr were derived to be 701(+/- 50), 285(+/- 20), and 414(+/- 30) pc from the distance modulus formula, taking into account interstellar extinction. The evolutionary status of these three systems was also studied. It has been found that the components of DQ Car arc very young stars at the age of similar to 25 Myr and those of BK Ind and V4396 Sgr are evolved main-sequence stars at the ages of similar to 2.69 Gyr and similar to 204 Myr, respectively.
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    Öğe
    New Spectroscopic Solution of the Eclipsing Binary HX Vel A
    (Astronomical Soc Pacific, 2015) Surgit, Derya; Erdem, Ahmet; Ozkardes, Burcu; Butland, Roger; Budding, Edwin
    We present a preliminary analysis of new spectroscopic observations of the southern binary HX Vel A. High-resolution spectroscopic observations were made at the Mt. John University Observatory in 2014. Radial velocities for HX Vel A were determined from the Gaussian profile-fitting method. The Keplerian radial velocity model gives the close binary mass ratio as 0.57 +/- 0.06. The resulting orbital elements are ai sin i = 0.0086 +/- 0.0003 au, a(2) sin i = 0.0151 +/- 0.0003 au, M-1 sin(3) i = 0.887 +/- 0.046 M-circle dot, and M-2 sin(3) i = 0.504 +/- 0.032 M-circle dot.
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    Öğe
    V410 Puppis: A useful laboratory for early stellar evolution
    (Oxford Univ Press, 2022) Erdem, Ahmet; Surgit, Derya; Ozkardes, Burcu; Hadrava, Petr; Rhodes, Michael D.; Love, Tom; Blackford, Mark G.
    New spectrometric (HERCULES) and ground-based multicolour photometric data on the multiple star V410 Puppis are combined with satellite photometry (HIPPARCOS and TESS), as well as historic astrometric observations. Absolute parameters for V410 Pup Aab are derived: M-Aa = 3.15 +/- 0.10, M-Ab = 1.83 +/- 0.08 (M-circle dot); R-Aa = 2.12 +/- 0.10, R-Ab = 1.52 +/- 0.08 (R-circle dot); a = 6.57 +/- 0.04 R-circle dot; T-Aa = 12500 +/- 1000, T-Ab = 9070 +/- 800(K), and photometric distance 350 +/- 10 (pc). We report the discovery of a low-amplitude SPB variation in the light curve and also indications of an accretion structure around V410 Pup B as well as emission cores in V410 Pup C. We argue that V410 Pup is probably a young formation connected with the Vela 2 OB Association. The combined evidence allows an age in the range 7-25 Myr from comparisons with standard stellar evolution modelling.