Examinando por Autor "Rosales, J. A."

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    Fundamental Parameters of the Eclipsing Binary DD CMa and Evidence for Mass Exchange
    (American Astronomical Society (Aas), 2021) Rosales, J. A.; Mennickent, R. E.; Djurašević, G.; González, J. F.; Araya, I.; Cabezas, M.; Schleicher, D. R. G.; Curé M.
    We present a detailed photometric and spectroscopic analysis of DD CMa, based on published survey photometry and new spectroscopic data. We find an improved orbital period of Po = 2.0084530(6) days. Our spectra reveal Hβ and Hα absorptions with weak emission shoulders, and we also find a color excess in the Wide-field Infrared Survey Explorer multiband photometry, interpreted as signatures of circumstellar matter. We model the V-band orbital light curve derived from the ASAS and ASAS-SN surveys, assuming a semidetached configuration and using the mass ratio and temperature of the hotter star derived from our spectroscopic analysis. Our model indicates that the system consists of a B2.5 dwarf and a B9 giant of radii 3.2 and 3.7 R⊙, respectively, orbiting in a circular orbit of radius 6.75 R⊙. We also found Mc = 1.7 ± 0.1 M⊙, Tc = 11,350 ± 100 K, and Mh = 6.4 ± 0.1 M⊙, Th = 20,000 ± 500 K, for the cooler and hotter star, respectively. We find broad single emission peaks in Hα and Hβ after subtracting the synthetic stellar spectra. Our results are consistent with mass exchange between the stars and suggest the existence of a stream of gas being accreted onto the early B-type star.
  • Miniatura
    Ítem
    Stellar and Accretion Disk Parameters of the Close Binary HD 50526
    (American Astronomical Society (Aas), 2021) Rosales, J. A.; Mennickent, R. E.; Djurašević, G.; Schleicher, D. R. G.; Zharikov, S.; Araya, I.; Celedón, L.; Curé, M.
    We present a photometric and spectroscopic study of HD 50526, an ellipsoidal binary member of the group Double Periodic Variable stars. Performing data mining in photometric surveys and conducting new spectroscopic observations with several spectrographs during 2008–2015, we obtained orbital and stellar parameters of the system. The radial velocities were analyzed with the genetic PIKAIA algorithm, whereas Doppler tomography maps for the Hα and Hβ lines were constructed with the Total Variation Minimization code. An optimized simplex algorithm was used to solve the inverse problem adjusting the light curve with the best stellar parameters for the system. We find an orbital period of 6fd701 ± 0fd001 and a long photometric cycle of 191 ± 2 days. We detected the spectral features of the coldest star and modeled it with a $\mathrm{log}g=2.79\pm 0.02\,\mathrm{dex}$ giant of mass 1.13 ± 0.02 M⊙ and effective temperature 10500 ± 125 K. In addition, we determine a mass ratio q = 0.206 ± 0.033 and that the hot star is a B-type dwarf of mass 5.48 ± 0.02 M⊙. The V-band orbital light curve can be modeled including the presence of an accretion disk around the hotter star. This fills the Roche lobe of the hotter star and has a radius 14.74 ± 0.02 R⊙ and the temperature at the outer edge is 9400 K. Two bright spots located in the disk account for the global morphology of the light curve. The Doppler tomography maps of Hα and Hβ reveal complex structures of mass fluxes in the system.