Examinando por Autor "Tappert, C."

Mostrando 1 - 2 de 2
  • Miniatura
    Ítem
    Life after eruption VIII: The orbital periods of novae
    (Royal Astronomical Society, 2021) Fuentes-Morales, I.; Tappert, C.; Zorotovic, M.; Vogt, N.; Puebla, E. C.; Schreiber, M. R.; Ederoclite, A.; Schmidtobreick, L.
    The impact of nova eruptions on the long-term evolution of Cataclysmic Variables (CVs) is one of the least understood and intensively discussed topics in the field. A crucial ingredient to improve with this would be to establish a large sample of post-novae with known properties, starting with the most easily accessible one, the orbital period. Here we report new orbital periods for six faint novae: X Cir (3.71 h), IL Nor (1.62 h), DY Pup (3.35 h), V363 Sgr (3.03 h), V2572 Sgr (3.75 h), and CQ Vel (2.7 h). We furthermore revise the periods for the old novae OY Ara, RS Car, V365 Car, V849 Oph, V728 Sco, WY Sge, XX Tau, and RW UMi. Using these new data and critically reviewing the trustworthiness of reported orbital periods of old novae in the literature, we establish an updated period distribution. We employ a binary-star evolution code to calculate a theoretical period distribution using both an empirical and the classical prescription for consequential angular momentum loss. In comparison with the observational data we find that both models especially fail to reproduce the peak in the 3–4 h range, suggesting that the angular momentum loss for CVs above the period gap is not totally understood.
  • Miniatura
    Ítem
    The White Dwarf Binary Pathways Survey – IV. Three close white dwarf binaries with G-type secondary stars
    (Royal Astronomical Society, 2021) Hernandez, M. S.; Schreiber, M. R.; Parsons , S. G.; Gansicke, B. T.; Lagos, F.; Raddi, R.; Toloza, O.; Tovmassian, G.; Zorotovic, M.; Irawati, P.; Pasten, E.; Rebassa-Mansergas, A.; Ren, J. J.; Rittipruk, P.; Tappert, C.
    Constraints from surveys of post-common envelope binaries (PCEBs) consisting of a white dwarf plus an M-dwarf companion have led to significant progress in our understanding of the formation of close white dwarf binary stars with low-mass companions. The white dwarf binary pathways project aims at extending these previous surveys to larger secondary masses, i.e. secondary stars of spectral-type AFGK. Here, we present the discovery and observational characterization of three PCEBs with G-type secondary stars and orbital periods between 1.2 and 2.5 d. Using our own tools as well as MESA, we estimate the evolutionary history of the binary stars and predict their future. We find a large range of possible evolutionary histories for all three systems and identify no indications for differences in common envelope evolution compared to PCEBs with lower mass secondary stars. Despite their similarities in orbital period and secondary spectral type, we estimate that the future of the three systems is very different: TYC 4962-1205-1 is a progenitor of a cataclysmic variable system with an evolved donor star, TYC 4700-815-1 will run into dynamically unstable mass transfer that will cause the two stars to merge, and TYC 1380-957-1 may appear as supersoft source before becoming a rather typical cataclysmic variable star.