99 research outputs found
The confirmation and revision on the orbital period change of the possible type Ia supernova progenitor V617 Sagittarii
This work reports new photometric results of eclipsing cataclysmic variable
V617 Sagittarii (V617 Sgr). We analyzed the orbital period change of V617 Sgr,
by employing three new CCD eclipse timings since 2010 along with all the
available data from the literature. It was found that the orbital period of
V617 Sgr undergoes an obvious long-term increase, which confirms the result
revealed by Steiner et al. (2006). The rate of orbital period increase was
calculated to be = +2.14(0.05) 10 day/year. This
suggests the lifetime of the secondary star will attain to the end in a
timescale of 0.97 10 years faster than that predicted previously.
In particular, a cyclic variation with a period of 4.5 year and an amplitude of
2.3 minutes may present in the O-C diagram. Dominated by the wind-accretion
mechanism, high mass transfer from the low mass secondary to the white dwarf is
expected to sustain in the V Sge-type star V617 Sgr during its long-term
evolution. The mass transfer rate was estimated to be in the
range of about 2.2 10 to 5.2 10 M
yr. Accordingly, the already massive ( 1.2 M) white
dwarf primary will process stable nuclear burning, accrete a fraction of mass
from its companion to reach the standard Chandrasekhar mass limit (
1.38 M), and ultimately produce a type Ia supernova (SN Ia) within
about 4 8 10 years or earlier.Comment: 5 pages, 2 figures, Accepted by PASJ on 20 August 201
The Photometric Investigation of V921 Her using the Lunar-based Ultraviolet Telescope of Chang'e-3 mission
The light curve of V921 Her in ultraviolet band observed by the Lunar-based
Ultraviolet Telescope (LUT) is analyzed by the Wilson-Devinney code. Our
solutions conclude that V921 Her is an early type marginal contact binary
system with an additional close-in component. The binary system is under poor
thermal contact with a temperature difference of nearly between the two
components. The close-in component contributes about of the total
luminosity in the triple system. Combining the radial velocity study together
with our photometric solutions, the mass of the primary star and secondary one
are calculated to be , . The evolutionary scenario of V921 Her is discussed.
All times of light minimum of V921 Her available in the bibliography are taken
into account and the curve is analyzed for the first time. The most
probable fitting results are discussed in the paper, which also confirm the
existence of a third component ( year) around the binary system. The
period of V921 Her is also undergoing a continuously rapid increase at a rate
of , which may due to mass
transfer from the less massive component to the more massive one
Confirmation and revision on the orbital period change of the possible type Ia supernova progenitor V617 Sagittarii
This work reports new photometric results of eclipsing cataclysmic variable V617 Sagittarii (V617 Sgr). We analyzed the orbital period change of V617 Sgr by employing three new (since 2010) CCD eclipse timings along with all the available data from the literature. It was found that the orbital period of V617 Sgr undergoes an obvious long-term increase, which confirms the result revealed by Steiner et al. (2006). The rate of orbital period increase was calculated to be P = +2.14(0.05) × 10-7 d yr-1. This suggests the lifetime of the secondary star will end in a timescale of 0.97 × 106 yr faster than that predicted previously. In particular, a cyclic variation with a period of 4.5 yr and an amplitude of 2.3 min may appear in the O - C diagram. Dominated by the wind-accretion mechanism, high mass transfer from the low mass secondary to the white dwarf is expected to continue in the V Sge-type star V617 Sgr during its long-term evolution. The mass transfer rate |Mtr| was estimated to be in the range of about 2.2 × 10-7 to 5.2 × 10-7 M⊙ yr-1. Accordingly, the already massive (≥ 1.2 M⊙) white dwarf primary will process stable nuclear burning, accrete a fraction of the mass from its companion to reach the standard Chandrasekhar mass limit (≃ 1.38 M⊙), and ultimately produce a type Ia supernova (SN Ia) within about 4-8 × 105 yr or earlier.Facultad de Ciencias Astronómicas y GeofÃsicasInstituto de AstrofÃsica de La Plat
First R and I Lights and Their Photometric Analyses of GSC 02393-00680
We obtained complete and light curves of GSC 02393-00680 in 2008 and
analyzed them with the 2003 version of the W-D code. It is shown that GSC
02393-00680 is a W-type shallow contact binary system with a high mass ratio
and a degree of contact factor . It will be a good
example to check up on the TRO theory. A period investigation based on all
available data suggests that the system has a small-amplitude period
oscillation (; years). This may indicate it has a
moderate mass close third body, which is similar to XY Leo
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