34 research outputs found
Nova Sagittarii 1998 (V4633 Sgr) - a permanent superhump system or an asynchronous polar?
We report the results of observations of V4633 Sgr (Nova Sagittarii 1998)
during 1998-2000. Two photometric periodicities were present in the light curve
during the three years of observations: a stable one at P=3.014 h, which is
probably the orbital period of the underlying binary system, and a second one
of lower coherence, approximately 2.5 per cent longer than the former. The
latter periodicity may be a permanent superhump, or alternatively, the spin
period of the white dwarf in a nearly synchronous magnetic system. A third
period, at P=5.06 d, corresponding to the beat between the two periods was
probably present in 1999. Our results suggest that a process of mass transfer
took place in the binary system since no later than two and a half months after
the nova eruption. We derive an interstellar reddening of E(B-V)~0.21 from our
spectroscopic measurements and published photometric data, and estimate a
distance of d~9 kpc to this nova.Comment: 13 pages, latex, 7 figures, accepted for publication in MNRA
BMO spaces associated with semigroups of operators
We study BMO spaces associated with semigroup of operators and apply the
results to boundedness of Fourier multipliers. We prove a universal
interpolation theorem for BMO spaces and prove the boundedness of a class of
Fourier multipliers on noncommutative Lp spaces for all 1 < p < \infty, with
optimal constants in p.Comment: Math An