Vol 42, No 2 (2016)

Based on data from the SWIFT, INTEGRAL, MAXI/ISS orbital observatories, and the ground-based RTT-150 telescope, we have investigated the broadband (from the optical to the hard X-ray bands) spectrum of the X-ray nova MAXI J1828-249 and its evolution during the outburst of the source in 2013–2014. The optical and infrared emissions from the nova are shown to be largely determined by the extension of the power-law component responsible for the hard X-ray emission. The contribution from the outer cold regions of the accretion disk, even if the X-ray heating of its surface is taken into account, turns out to be moderate during the source’s “high” state (when a soft blackbody emission component is observed in the X-ray spectrum) and is virtually absent during its “low” (“hard”) state. This result suggests that much of the optical and infrared emissions from such systems originates in the same region of main energy release where their hard X-ray emission is formed. This can be the Compton or synchro-Compton radiation from a high-temperature plasma in the central accretion disk region puffed up by instabilities, the synchrotron radiation from a hot corona above the disk, or the synchrotron radiation from its relativistic jets.

We consider stars with radial velocities, proper motions, and distance estimates from the RAVE4 catalogue. Based on a sample of more than 145 000 stars at distances r < 0.5 kpc, we have found the following kinematic parameters: \({\left( {U,{\kern 1pt} V,{\kern 1pt} W} \right)_ \odot }\) = (9.12, 20.80, 7.66) ± (0.10, 0.10, 0.08) km s⁻¹, Ω₀ = 28.71 ± 0.63 km s⁻¹ kpc⁻¹, and Ω₀^’ = −4.28 ± 0.11 km s⁻¹ kpc⁻². This gives the linear rotation velocity V₀ = 230 ± 12 km s⁻¹ (for the adopted R₀ = 8.0 ± 0.4 kpc) and the Oort constants A = 17.12 ± 0.45 km s⁻¹ kpc⁻¹ and B = −11.60 ± 0.77 km s⁻¹ kpc⁻¹. The 2D velocity distributions in the UV, UW, and VW planes have been constructed using a local sample, r < 0.25 kpc, consisting of ~47 000 stars. A difference of the UV velocity distribution from the previously known ones constructed from a smaller amount of data has been revealed. It lies in the fact that our distribution has an extremely enhanced branch near the Wolf 630 peak. A previously unknown peak at (U, V) = (−96, −10) km s⁻¹ and a separate new feature in the Wolf 630 stream, with the coordinates of its center being (U, V) = (30, −40) km s⁻¹, have been detected.

The chaotic orbital dynamics of the planet in the wide visual binary star system 16 Cyg is considered. The only planet in this system has a significant orbital eccentricity, e = 0.69. Previously, Holman et al. suggested the possibility of chaos in the orbital dynamics of the planet due to the proximity of 16 Cyg to the separatrix of the Lidov–Kozai resonance. We have calculated the Lyapunov characteristic exponents on the set of possible orbital parameters for the planet. In all cases, the dynamics of 16 Cyg is regular with a Lyapunov time of more than 30 000 yr. The dynamics is considered in detail for several possible models of the planetary orbit; the dependences of Lyapunov exponents on the time of their calculation and the time dependences of osculating orbital elements have been constructed. Phase space sections for the system dynamics near the Lidov–Kozai resonance have been constructed for all models. A chaotic behavior in the orbital motion of the planet in 16 Cyg is shown to be unlikely, because 16 Cyg in phase space is far from the separatrix of the Lidov–Kozai resonance at admissible orbital parameters, with the chaotic layer near the separatrix being very narrow.