12 research outputs found
Radial Velocity Studies of Close Binary Stars.VIII
Radial-velocity measurements and sine-curve fits to the orbital velocity
variations are presented for the seventh set of ten close binary systems: V410
Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HX UMa, HD
93917, NSV 223. All systems, but three (V523 Cas, HD 93917, NSV 223), were
discovered photometrically by the Hipparcos mission. All systems are
double-lined (SB2) binaries and all, but the detached, very close system V1130
Tau, are contact binaries. The broadening-function permitted improvement of the
orbital elements for V523 Cas, which was the only system observed before for
radial velocity variations. Spectroscopic/visual companions were detected for
V410 Aur and HX UMa.Comment: AASTeX5, 4 figures, 3 tables, to appear AJ, June 200
High Speed Photometry of SDSS J013701.06-091234.9
We present high speed photometry of the Sloan Digital Sky Survey cataclysmic
variable SDSS J013701.06-091234.9 in quiescence and during its 2003 December
superoutburst. The orbital modulation at 79.71\pm0.01 min is double humped; the
superhump period is 81.702\pm0.007 min. Towards the end of the outburst late
superhumps with a period of 81.29\pm0.01 min were observed. We argue that this
is a system of very low mass transfer rate, and that it probably has a long
outburst interval.Comment: 5 pages, 8 figures. Accepted for publication in MNRA
Radial Velocity Studies of Close Binary Stars. IX
Radial-velocity measurements and sine-curve fits to the orbital velocity
variations are presented for the eighth set of ten close binary systems: AB
And, V402 Aur, V445 Cep, V2082 Cyg, BX Dra, V918 Her, V502 Oph, V1363 Ori, KP
Peg, V335 Peg. Half of the systems (V445 Cep, V2082 Cyg, V918 Her, V1363 Ori,
V335 Peg) were discovered photometrically by the Hipparcos mission and all
systems are double-lined (SB2) contact binaries. The broadening function method
permitted improvement of the orbital elements for AB And and V502 Oph. The
other systems have been observed for radial velocity variations for the first
time; in this group are five bright (V<7.5) binaries: V445 Cep, V2082 Cyg, V918
Her, KP Peg and V335 Peg. Several of the studied systems are prime candidates
for combined light and radial-velocity synthesis solutions.Comment: 17+ pages, 2 tables, 4 figure
Dwarf novae in the Hamburg quasar survey : rarer than expected
Aims. We report the discovery of five new dwarf novae that were spectroscopically identified in the Hamburg Quasar Survey (HQS),and discuss the properties of the sample of new dwarf novae from the HQS.
Methods. Follow-up time-resolved spectroscopy and photometry have been obtained to characterise the new systems.
Results. The orbital periods determined from analyses of the radial velocity variations and/or orbital photometric variability are Porb 105.1min or Porb 109.9min for HS 0417+7445, Porb = 114.3 ± 2.7min for HS 1016+3412, Porb = 92.66 ± 0.17 min for HS 1340+1524, Porb = 272.317 ± 0.001 min for HS 1857+7127, and Porb = 258.02 ± 0.56 min for HS 2214+2845. HS 1857+7127 is found to be partially eclipsing. In HS 2214+2845 the secondary star of spectral type M3 ± 1 is clearly detected, and we estimate the distance to the system to be d = 390 ± 40 pc. We recorded one superoutburst of HS 0417+7445, identifying the system as a SUUMatype
dwarf nova. HS 1016+3412 and HS 1340+1524 have rare outbursts, and their subtype is yet undetermined. HS 1857+7127 frequently varies in brightness and may be a ZCam-type dwarf nova. HS 2214+2845 is a UGem-type dwarf nova with a most likely cycle length of 71 d.
Conclusions. To date, 14 new dwarf novae have been identified in the HQS. The ratio of short-period (3 h)systems of this sample is 1.3, much smaller compared to the ratio of 2.7 found for all known dwarf novae. The HQS dwarf novae display typically infrequent or low-amplitude outburst activity, underlining the strength of spectroscopic selection in identifying new
CVs independently of their variability. The spectroscopic properties of short-period CVs in the HQS, newly identified and previously known, suggest that most, or possibly all of them are still evolving towards the minimum period. Their total number agrees with the predictions of population models within an order of magnitude. However, the bulk of all CVs is predicted to have evolved past the minimum period, and those systems remain unidentified. This suggests that those post-bounce systems have markedly weaker HÎČ emission lines compared to the average known short-period CVs, and undergo no or extremely rare outbursts
A model of the dwarf nova WXÂ Cet
We analyse time-resolved spectroscopy of
WXÂ Cet, a dwarf nova of the WZÂ Sge class, by means of a dynamical model
based on the measured K1 and using the superhump period excess Ï”
to constrain the mass ratio q of this CB. From time resolved spectroscopy
of Thorstensen et al. we determine orbital amplitude K1 and separation
of the disk emission lines as well as the S-wave amplitude
As and relative phase α of the hot spot. Our dynamical
analysis, following Smak's inclination independent solution for WZÂ Sge, yields
rather high q, hardly compatible with the superhump resonance condition within
the accretion disc. Rejecting K1 as affected by tidal and/or stream effects,
we follow Patterson and determine from relation based on
superhump dynamics. In this way we obtain likely masses of the components
and . From
this result we argue that despite similarities to WZÂ Sge, WXÂ Cet
with its relatively massive secondary represents an earlier stage of mass
transfer in a cataclysmic binary than WZÂ Sge
Erratum: Radial velocity studies of close binary stars. IX (The Astronomical Journal (2004) 127 (1712))
Radial Velocity Studies of Close Binary Stars
ABSTRACT Radial velocity measurements and sine-curve fits to orbital velocity variations are presented for the ninth set of 10 close binary systems: V395 And, HS Aqr, V449 Aur, FP Boo, SW Lac, KS Peg, IW Per, V592 Per, TU UMi, and FO Vir. The first three are very close, possibly detached, early-type binaries, and all three require further investigation. Particularly interesting is V395 And, whose spectral type is as early as B7/8 for a 0.685 day orbit binary. KS Peg and IW Per are single-line binaries, with the former probably hosting a very low mass star. We have detected a low-mass secondary in an important semidetached system, FO Vir, at q Œ 0:125 AE 0:005. The contact binary FP Boo is also a very small mass ratio system, q Œ 0:106 AE 0:005. The other contact binaries in this group are V592 Per, TU UMi, and the wellknown SW Lac. V592 Per and TU UMi have bright tertiary companions; for these binaries, and for V395 And, we used a novel technique of arranging the broadening functions into a two-dimensional image in phase. The case of TU UMi turned out to be intractable even using this approach, and we have not been able to derive a firm radial velocity orbit for this binary. Three systems of this group were observed spectroscopically before: HS Aqr, SW Lac, and KS Peg