Now showing items 1-4 of 4

    • Masses and Other Parameters of the PostCommon Envelope Binary BE Ursae Majoris 

      Ferguson, D.H.; Liebert, J.; Haas, S.; Napiwotzki, R.; James, T.A. (1999)
      The binary star BE Ursae Majoris is recently emerged from the common envelope phase; indeed, the hot sdO/DAO component is the central star of the associated planetary nebula. As such, BE UMa represents an important test ...
    • NLTE Spectral Analysis of Iron Group Elements in the Hot Subluminous O-star BD+28 4211 

      Ramspeck, M.; Haas, S.; Napiwotzki, R.; Heber, U.; Deetjen, J.; Dreizler, S. (Astronomical Society of the Pacific, 2003)
      An analysis of UV spectra of BD+28circ4211 obtained with the STIS spectrograph onboard the HST is presented. The spectral analysis is based on NLTE model calculation, which deal with the lineblanketing of iron group elements ...
    • The planetary nebulae of PG 1159 stars - clues to their evolutionary history 

      Napiwotzki, R.; Haas, S.; Schonberner, D. (Astronomical Society of the Pacific, 1996)
      It is shown that many planetary nebulae (PN) surrounding PG 1159 stars display a bipolar morphology. The frequency of these nebulae is higher than observed in other PN samples. Implications for the evolutionary history of ...
    • Topological order following a quantum quench 

      Tsomokos, D.I.; Hamma, A.; Zhang, W.; Haas, S.; Fazio, R. (2009)
      We determine the conditions under which topological order survives a rapid quantum quench. Specifically, we consider the case where a quantum spin system is prepared in the ground state of the toric code model and, after ...