J/AN/332/616 V444 Cyg BV differential light curves (Eris+, 2011)
A 2007 photometric study and UV spectral analysis of the Wolf-Rayet binary
V444 Cyg.
Eris F.Z., Ekmekci F.
<Astron. Nachrichten, 332, 616-625 (2011)>
=2011AN....332..616E 2011AN....332..616E
ADC_Keywords: Binaries, eclipsing ; Photometry, UBV
Keywords: binaries: eclipsing - binaries: spectroscopic - circumstellar matter -
stars: individual (V444 Cyg) - stars: Wolf-Rayet - ultraviolet: stars
Abstract:
Photometric and spectroscopic characteristics of the WN5+O6 binary
system, V444 Cyg, were studied. The Wilson-Devinney (WD) analysis,
using new BV observations carried out at the Ankara University
Observatory, revealed the masses, radii, and temperatures of the
components of the system as MWR=10.64M☉, MO=24.68M☉,
RWR=7.19R☉, RO=6.85R☉, TWR=31000K, and TO=40000K,
respectively. It was found that both components had a full spherical
geometry, whereas the circumstellar envelope of the WR component had
an asymmetric structure. The O-C analysis of the system revealed a
period lengthening of 0.139±0.018s/yr, implying a mass loss
rate of (6.76±0.39)x10-6M_☉/yr for the WR component.
Moreover, 106 IUE-NEWSIPS spectra were obtained from NASA's IUE
archive for line identification and determination of line profile
variability with phase, wind velocities and variability in continuum
fluxes. The integrated continuum flux level (between 1200-2000Å)
showed a mild and regular increase from orbital phase 0.00 up to 0.50
and then a decrease in the same way back to phase 0.00. This is
evaluated as the O component making a constant and regular
contribution to the system's UV light as the dominant source. The CIV
line, originating in the circumstellar envelope, had the highest
velocity while N IV line, originating in deeper layers of the
envelope, had the lowest velocity. The average radial velocity
calculated by using the CIV line (wind velocity) was found as
2326km/s.
Objects:
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RA (2000) DE Designation(s)
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20 19 32.42 +38 43 54.0 V444 Cyg = V* V444 Cyg
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 19 1814 Observational data for V444 Cyg
table3.dat 42 106 The log of IUE observations of V444 Cygni
fig4.ps 289 4045 Low resolution short wavelength IUE spectra obtained
at 0.001, 0.289, 0.503 and 0.727 orbital phases
fig8.ps 240 5351 SiII line seen successively as P-Cygni and
reverse P-Cygni profiles in a narrow phase angle
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.4 d HJD Heliocentric Julian date (HJD-2450000)
11- 14 F4.2 mag DBmag ?=- Differential B magnitude
16- 19 F4.2 mag DVmag ?=- Differential V magnitude
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Image Image designation in IUE Archive (VI/110)
11- 20 A10 "date" Date Observation date
22- 26 F5.3 --- Phase [0/1] Phase
28- 37 F10.4 s ExpTime Exposure time
39- 42 A4 --- Disp [High Low] Dispersion
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Acknowledgements:
Fehmi Ekmekc, Fehmi.Ekmekci(at)science.ankara.edu.tr
(End) Patricia Vannier [CDS] 13-Apr-2015