Optical Observations of the CBS HZ Her=Her X-1
aa r X i v : . [ a s t r o - ph . S R ] D ec Optical Observations of the CBS HZ Her=Her X-1 c (cid:13) Introduction
The high accuracy and long time span of photoelectric observations allow them tobe used for multifactor analyses and refining some of the ”fine” photometric effectsin the light curves of close binary systems. The results obtained can be subsequentlyinterpreted in terms of the model of mass flow from the optical component of theclose binary systems onto the accretion disk of the neutron star, which can explainsatisfactorily the irregularities of the gaseous flow, the “hot spot”, and the presenceof splashes moving in individual Keplerian trajectories about the outer parts of theaccretion disk of the neutron star Her X-1.
Photometric peculiarities of the accretion formation of the neutron star Her X-1 andits geometry in 1986-1990
When analyzing the photometric data in during the 1986 season (fig01(a-d)), onemust bear in mind that the scatter of individual measurements in the B, and espe-cially, in the W filter at times exceeds, on the average, the corresponding standarderrors (up to 0 m . m . he system exhibits certain light variations at various precession phases,which can be linked to the observed x-ray variations of the Her X-1 source andwhich appear to depend on the spatial orientation of the tilted and geometricallywarped disk of the neutron star (NS) precessing with a period of P ∼ = 34 d . P ∼ = 34 d . he accretor of the CBS with ever increasing velocities due to the gravitational accel-eration caused by the primary component and which we can interpret as a complexstructure — a shock — interacting with the ambient matter — i.e., with the accre-tion disk of the compact object. As a result, if a star, like HZ Her, fills completelyits inner critical Roche lobe (ICRL), most of the mass flows through the L point,falls onto the NS, and feeds the AD.However, gas may partly scatter beyond the ICRL of the 7-type star and thepulsar, mostly in the vicinity of the orbital plane of the CBS and at small heightsin the ± z plane [7], [8], [13], [14]; it can also escape from the system via the L point, crossing the neighboring ballistic trajectories of the particles of the gaseousflow emerging from the optical component of the system at small distances from theinner Lagrange point L , i.e., before the jet encounters the outer edge of the AD ofthe neutron star.The location of the region where trajectories intersect depends significantlyon the initial velocities of flow particles. With increasing absolute value of initialvelocities of flow particles the crossing region shifts downstream so that the jet mat-ter should collide with the accretion disk of the neutron star before the trajectoriesintersect with each other.The intersection of ballistic trajectories of flow particles in HZ Her= Her X-1may explain, among other factors, the formation of irregularities in the gaseous jetof the CBS, which result in the flicker of the ”hot line” in the HZ Her= Her X-1CBS, which appears in the region where the gaseous jet collides with the disk-likeenvelope as observed at optical wavelengths.We thus conclude that:- The 1986 observations exhibit a certain increase of the accretion rate onto theneutron star (fig02(a-d));- During the 1987 season optical outbursts were observed in the 0.15-0.25 and0.75-0.85 orbital phase intervals. Short flux outbursts in the phase interval near0.015 were recorded in the R,V,B, and W filters with the amplitudes of 0 m . m .
15, 0 m .
25, and 0 m .
35, respectively; During the 1988 observing season the system behaved somewhat chaoticallynear Min , especially at UV wavelengths, and this behavior should be interpretedas a spatial manifestation of an optically thick warped accretion disk;- The WBVR light curves of 1989 reflect the dynamics of the behavior of thesystem. Most of the observations were made during the ”off” phase, however, someobservations were made during the high state. The accretion formation exhibits asomewhat asymmetric behavior with the sign reversed compared to the previousseason. A ”sharp” minimum, like in the 1987 season, appeared once near Min. NearMin II the light curve has a ”classic” flat form.- During the same observing season the light curve exhibited a photometricpeculiarity in the orbital phase interval ϕ = 0 . − .
875 resembling a coolinggaseous condensation or a ”blob” (a blob of high-temperarture plasma circulatingat the outer edge of the AD of the neutron star) [15], [16].- The WBRI light curves of the 1990 season are indicative of a certain decreaseand equalization of the luminosities of both halves of the accretion formations, andof a certain change of the asymmetry of the light curve (especially in the B and Vfilters). The size of the emitting region of the accretion formation appears to haveremained unchanged compared to its appearance during the 1988-1989 seasons.
Dynamics of the Flux Variations in Min I and Min II and Mass Flow from the OpticalComponent
Crosal [15] performed the most detailed analysis of a phenomenological model forthe CBS HZ Her=Her X-1 assuming constant mass flow from the primary star ontothe NS. This model explains the observational manifestations of the system thatwere associated with the physical state of its x-ray flux and that of its accretion disk(AD).A change in the mode of mass flow from the optical component of the CBS tothe accretion disk of the neutron star results in a change of the geometry, degree ofdisk warp and, consequently, of the disk temperature (from 18000 to 25000 [3], [4],), resulting in the variations of different duration (from 30-40 minutes to 2-3 hours) nd amplitude (from 0 m . ± m . m . ± m . m . ϕ orb. = 0 . − . m . − m .
35 over a single observing night ( ∼ − everal hundred km/s [7], [17], namely, more than 210-260 km/s [7] before en-countering the accretor — the fact that was convincingly confirmed in later papers[18]. Here we observe gaseous jets in the CBS, which undoubtedly expand whenreaching the AD of the neutron star, and these processes must depend on the ambientproperties in the vicinity of the CBS (and, in particular, in the vicinity of theaccretion disk of the neutron star) through which the jets move. This medium is farfrom uniform. References [1] Sazonov A.N. // Astron. Tsirk., No. 1518, November 1987.[2] Lyutyi V.M., Voloshina I.B. // Pisma Astron. Zh., V.15.1989, .806.[3] Sazonov A.N. // // Pisma Astron. Zh., 1994. P.20. P.664-683.[5] Bisnovatyi-Kogan G.S and Komberg B.V. // Astron. Zh., 1975. V.52. P.457.[6] Kahabka P. // Der 35-tage Zyklus von Hercules X-1 . Garching: Max-Planck-Inst. Extraterr. Phys. Report 204. 1987.[7] Sazonov A.N.,Shakura N.I. // Soobshch. Spets. Astrofiz. Obs., Vyp. 64,p. 30- 32, 1990.[8] Bisikalo D.V., Boyarchuk A.A, Kuznetsov O.A., Popov Yu.P., ChechetkinV.M. // Astron. Zh. 71,560, 1994.[9] Sheffer E.K. and Lyutyi V.M. // Astron. Zh., 1997, V.74, P.209.
10] Bochkarev N.G., Gnedin Yu.N., and Karitskaya E.A. // Conference Proceed-ings COSPAR.Bulgaria,1987.[11] Bochkarev N.G. // Astron. Zh., 1989. V.66. vyp.6, P.1240.[12] Bochkarev N.G. and Karitskaya E.A. // Astron. Tsirk., No. 1466, P.1,1986.[13] Kilyachkov N.N. and Shevchenko V.S. // Pisma Astron. Zh., 1988. V.14. P.438-444.[14] Lubow S.H. // The Realm of Interacting Binary Stars/ Eds Shade J., Mc-Cluskey J.Jr., Kondo Y. Dordrecht: Kluwer, 1993.P.25[15] Crosa L., Boynton P.E. // Astropys. J., 1980, v.235, p.999.[16] Kippenhann R., Shmidt N., Thomas H.E. // Preprint. MPI-PAE. Max-Plank-Inst. Fur phys. and Astrophys. 1979.[17] Bochkarev N.G. // Doctoral Dissertation in Mathematics and Physics,Moscow: Sternberg Astronomical Institute (Moscow State University), 1988.[18] Bisikalo D.V., Boyarchuk A.A, Kuznetsov O.A., Popov Yu.P., ChechetkinV.M. // Astron. Zh. 1995. 72,190. orb. phase W HZ Her (1986)
Figure 1: The 1986 W-band light curve folded with the period P = 1 d . orb. phase B HZ Her (1986)
Figure 2: The 1986 B-band light curve folded with the period P = 1 d , orb. phase V HZ Her (1986)
Figure 3: The 1986 V-band light curve folded with the period P = 1 d , orb. phase R HZ Her (1986)
Figure 4: The 1986 R-band light curve folded with the period P = 1 d , orb. phase W − B HZ Her (1986)
Figure 5: W-B color of HZ Her as a function of orbital phase ϕ for the 1986 data12 orb. phase B − V HZ Her (1986)
Figure 6: (B-V) color of HZ Her as a function of orbital phase ϕ for the 1986 data13 orb. phase V − R HZ Her (1986)
Figure 7: (V-R) color of HZ Her as a function of orbital phase ϕ for the 1986 data14 orb. phase B − R HZ Her (1986)
Figure 8: (B-R) color of HZ Her as a function of orbital phase ϕ for the 1986 data15 B−V W − B HZ Her (1986)
Figure 9: The 1986 (B-V)-(W-B) two-color diagram of HZ Her16