Spectroscopic monitoring of V1357 Cyg = Cyg X-1 in 2002–2004

Karitskaya, E. A.; Bochkarev, N. G.; Bondar, A.; Галазутдинов, Г. А.; Lee, B. C.; Мусаев, Ф. А.; Sapar, A.; Shimanskii, V. V.

doi:10.1134/s106377290805003x

Cited by 4 publications

(5 citation statements)

References 20 publications

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“…The lowest contours of χ 2 ν in Figure 1 indicate that the best fits are found for T eff = 26.5 − 28.5 kK and log g = 2.9 − 3.1. Both of these estimates are lower than found in earlier studies (Canalizo et al 1995;Herrero et al 1995;Karitskaya et al 2008), but they are consistent with recent studies that demonstrate that the inclusion of line blanketing in stellar atmosphere models tends to lower the derived effective temperature (Repolust et al 2004;Martins et al 2005;Lefever 2007;Searle et al 2008).…”

Section: Ultraviolet and Optical Line Spectrumsupporting

confidence: 89%

“…The spectra appear in three plots: the short wavelength range from the lower resolution CF data is shown in the top panel while the bottom two panels illustrate the longer wavelength region from the higher resolution RC spectra (compare with Fig. 1 in Karitskaya et al 2008). In general the agreement between the observed and model spectrum is satisfactory.…”

Section: Ultraviolet and Optical Line Spectrummentioning

confidence: 71%

“…Their results led to mass estimates of 17.8 and 10.1 M for the supergiant and BH, respectively. More recently, Karitskaya et al (2008) Vol. 701 classified HD 226868 as an ON star with a temperature of T eff = 30.4 ± 0.5 kK and gravity of log g = 3.31 ± 0.07 using a semigray model atmosphere that accounts for non-LTE effects in some lines and for X-ray illumination.…”

Section: Introductionmentioning

confidence: 99%

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THE ULTRAVIOLET SPECTRUM AND PHYSICAL PROPERTIES OF THE MASS DONOR STAR IN HD 226868 = Cygnus X-1

Caballero-Nieves

Gies

Bolton

et al. 2009

ApJ

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We present an examination of high-resolution, ultraviolet (UV) spectroscopy from Hubble Space Telescope of the photospheric spectrum of the O-supergiant in the massive X-ray binary HD 226868 = Cyg X-1. We analyzed this and ground-based optical spectra to determine the effective temperature and gravity of the O9.7 Iab supergiant. Using non-LTE, line-blanketed, plane-parallel models from the TLUSTY grid, we obtain T eff = 28.0 ± 2.5 kK and log g 3.00 ± 0.25, both lower than in previous studies. The optical spectrum is best fit with models that have enriched He and N abundances. We fit the model spectral energy distribution for this temperature and gravity to the UV, optical, and infrared (IR) fluxes to determine the angular size and extinction toward the binary. The angular size then yields relations for the stellar radius and luminosity as a function of distance. By assuming that the supergiant rotates synchronously with the orbit, we can use the radius-distance relation to find mass estimates for both the supergiant and black hole (BH) as a function of the distance and the ratio of stellar to Roche radius. Fits of the orbital light curve yield an additional constraint that limits the solutions in the mass plane. Our results indicate masses of 23 +8 −6 M for the supergiant and 11 +5 −3 M for the BH.

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Section: Ultraviolet and Optical Line Spectrumsupporting

confidence: 89%

Section: Ultraviolet and Optical Line Spectrummentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

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THE ULTRAVIOLET SPECTRUM AND PHYSICAL PROPERTIES OF THE MASS DONOR STAR IN HD 226868 = Cygnus X-1

Caballero-Nieves

Gies

Bolton

et al. 2009

ApJ

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“…Cross-correlation analysis revealed lags of X-ray (2-10 keV) long-term variations in respect to the optical ones (7 d in 1996 and 12 d in 1997-1998). It allowed determining accretion time which is much shorter than with the standard accretion model.The results of Cyg X-1 spectral monitoring are presented in Karitskaya et al (2003Karitskaya et al ( , 2005Karitskaya et al ( , 2006Karitskaya et al ( , 2007a, Karitskaya et al (2008). The observations were carried out with the Echelle-spectrographs of the Peak Terskol observatory (altitude 3100 m, North Caucasus) 2 m telescope (spectral resolution R = 13000 or 45000) and BOAO (Korea) 1.8 m telescope (R = 30000) covering most of the optical range.…”

mentioning

confidence: 99%

Multi-Technique Study of the X-Ray Binary Cygnus X-1

Karitskaya¹

2011

Proc. IAU

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Abstract. Short review of our 36-year Cyg X-1 study using multi-technique methods and based on our optical photometric, high-resolution spectral and spectropolarimetrical observations. Keywords. Stars: magnetic fields, stars: atmospheres, stars: abundances, accretion disks, techniques: polarimetric, techniques: spectroscopic, techniques: image processing, stars: early-type, stars: individual (Cyg X-1 = HDE 226868=V1357 Cyg), X-rays: binaries Cyg X-1/HDE226868/V1357 Cyg (m V = 9 m ) is an X-ray binary system (the orbital period P = 5.6 d ) whose relativistic component is the first black hole (BH) candidate. The optical component, an O9.7 Iab supergiant, is responsible for about 95% of the system's optical luminosity. The remaining 5% is due to the accretion structure (disc and surrounding gas) near the BH. The intensive investigations of Cyg X-1 are being carried on for 40 years, but a lot of phenomena in the system remain unclear. Here there is a short review of our 36-year Cyg X-1 study using multi-technique methods and based on our optical photometric, high-resolution spectral and spectropolarimetrical observations.The main optical photometric variation (the ellipsoidality effect) was studied in detail with the Roche model. Thirty-six years ago, Bochkarev, Karitskaya & Shakura (1975) used the amplitude A = 0.035 − 0.050 m , the difference in depth minima ∆A < 0.005 m to derive the admissible values of parameters for Cyg X-1: inclination 25 < i < 67; mass ratios 0.2 < q < 0.55; filling factor 0.9 < µ < 1; M o > 17M sun ; 7M sun < M x < 27M sun . It is interesting that very new research (Orosz et al., 2011) has obtained values within our ranges for the parameters. In the frame of the 1994-1998 international campaign "Optical Monitoring of Unique Astrophysical Objects" 2258 UBVR observations of Cyg X-1 were made during 407 nights. The main results are reported by Karitskaya et al. (2000) and Karitskaya et al. (2001). Evidence of irregularities in matter flowing between the components was found. By comparing photoelectric (UBVR) and X-ray ASM/RXTE (3-12 keV) flux variations we found different kinds of variability (orbital variations, various flares, dips, socalled precession period 147/294 days) and a correspondence between optical and Xray variations. Cross-correlation analysis revealed lags of X-ray (2-10 keV) long-term variations in respect to the optical ones (7 d in 1996 and 12 d in 1997-1998). It allowed determining accretion time which is much shorter than with the standard accretion model.The results of Cyg X-1 spectral monitoring are presented in Karitskaya et al. (2003Karitskaya et al. ( , 2005Karitskaya et al. ( , 2006Karitskaya et al. ( , 2007a, Karitskaya et al. (2008). The observations were carried out with the Echelle-spectrographs of the Peak Terskol observatory (altitude 3100 m, North Caucasus) 2 m telescope (spectral resolution R = 13000 or 45000) and BOAO (Korea) 1.8 m telescope (R = 30000) covering most of the optical range. Optical spectral line profile variations were found during the X-ray...

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“…The rather extreme value for the are amplitude might favour speculations whether or not this are is indeed related to a GRB. In fact, the possible relation with stellar ares was among the rst models proposed to explain GRBs (Stecker & Frost (1973), Brecher & Morrison (1974), Karitskaya (1975)). Nearby are stars are isotropic in the sky and have a -3/2 slope in their logN{logS distribution (for a sampling distance smaller than 300 pc) and thus meet one of the statistical GRB criteria.…”

Section: The Relation To Gbs 0008+13mentioning

confidence: 99%

A large amplitude flaring dMe star in the 1978 October 6B γ-ray burst error box

Greinen

Motch

Flares and Flashes

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Spectroscopic observations provide evidence that the optical transient object observed in 1966 on archival plates of Sonneberg Observatory is a B=18.5 dMe star. For an assumed are duration of 40 min. (or longer)the are amplitude was 4m B 5.2 mag. If the recorded event was belonging to the class of 'fast' ares its amplitude could have reached 7-9 mag.. We estimate a lower limit for the optical are energy release of 10 35 (d/100 pc) 2 erg/s. We discuss the positional coincidence of this large amplitude aring star with the error box of the -ray burst 1978 October 6B and conclude that the are star is probably not related to the -ray burst. The fact that no other optical are was found from this object restricts their frequency to be less than 7210 04 h 01 for amplitudes (in B) greater than 4.5 mag. Nevertheless, large amplitude ares constitute a serious background problem for the wide eld search for possible optical counterparts of -ray bursters.

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Spectroscopic monitoring of V1357 Cyg = Cyg X-1 in 2002–2004

Cited by 4 publications

References 20 publications

THE ULTRAVIOLET SPECTRUM AND PHYSICAL PROPERTIES OF THE MASS DONOR STAR IN HD 226868 = Cygnus X-1

THE ULTRAVIOLET SPECTRUM AND PHYSICAL PROPERTIES OF THE MASS DONOR STAR IN HD 226868 = Cygnus X-1

Multi-Technique Study of the X-Ray Binary Cygnus X-1

A large amplitude flaring dMe star in the 1978 October 6B γ-ray burst error box

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