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Publisher: Springer-Verlag (Total: 2355 journals)

 Astronomy Letters   [SJR: 0.58]   [H-I: 30]   [21 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1562-6873 - ISSN (Online) 1063-7737    Published by Springer-Verlag  [2355 journals]
• Multiple X-ray bursts and the model of a spreading layer of accreting
matter over the neutron star surface
• Authors: S. A. Grebenev; I. V. Chelovekov
Pages: 583 - 594
Abstract: Abstract We report the detection of series of close type I X-ray bursts consisting of two or three events with a recurrence time much shorter than the characteristic (at the observed mean accretion rate) time of matter accumulation needed for a thermonuclear explosion to be initiated on the neutron star surface during the JEM-X/INTEGRAL observations of several X-ray bursters. We show that such series of bursts are naturally explained in the model of a spreading layer of accreting matter over the neutron star surface in the case of a sufficiently high (Ṁ ≳ 1 × 10−9 M ⊙ yr−1) accretion rate (corresponding to a mean luminosity L tot ≳ 1 × 1037erg s−1). The existence of triple bursts requires some refinement of the model—the importance of a central ring zone is shown. In the standard model of a spreading layer no infall of matter in this zone is believed to occur.
PubDate: 2017-09-01
DOI: 10.1134/s106377371709002x
Issue No: Vol. 43, No. 9 (2017)

• Double Hall instability: A catalyzer of magnetic energy release
• Authors: L. L. Kitchatinov
Pages: 624 - 633
Abstract: Abstract A pictorial explanation for shear-Hall instability is suggested and shows that the shear flow is not necessary for the instability because its role can be played by the Hall effect of an inhomogeneous backgroundmagnetic field. Linear stability analysis for a simplemodel of magnetic field varying periodically in space confirms such a “double Hall” instability. Numerical computations show a considerable increase in Ohmic dissipation rate at the nonlinear stage of instability development. Field dissipation has a spiky character associated with magnetic reconnection in current sheets and X-points. Double Hall instability can be significant for magnetic field dissipation in neutron star crusts and, possibly, in the solar corona.
PubDate: 2017-09-01
DOI: 10.1134/s1063773717090043
Issue No: Vol. 43, No. 9 (2017)

• Type I X-ray Bursts Detected by the JEM-X Telescope Onboard the INTEGRAL
Observatory in 2003–2015
• Authors: I. V. Chelovekov; S. A. Grebenev; I. A. Mereminskiy; A. V. Prosvetov
Pages: 781 - 795
Abstract: Abstract We present the results of our analysis of the JEM-X/INTEGRAL data obtained from January 2003 to January 2015 aimed at searching for type I X-ray bursts from known and new bursters. Such bursts are caused by thermonuclear explosions on the surface of a neutron star. We have searched for bursts in the records of the count rate of the JEM-X detectors in the 3–20 keV energy band. We have separately reconstructed and analyzed the light curves of 104 X-ray bursters known to date based on the JEM-X data. A similar search for bursts was previously carried out in the 15–25 keV data from the IBIS/ISGRI telescope onboard the INTEGRAL observatory obtained in 2003–2009. We have continued to analyze the data from this telescope up until the observations in January 2015. The joint catalog of bursts detected by the two instruments includes 2201 events; their basic parameters are given. The large size of the sample of bursts makes it one of the most representative of the existing one and allows various statistical studies of bursts to be performed. In particular, we have constructed the dependence of the mean rate of type I bursts from bursters on the luminosity (accretion rate), revealed an appreciable burst rate from sources with a near-Eddington luminosity, and investigated the population of multiple bursts with a recurrence time much shorter than the time it takes for a critical mass of matter required for the initiation of an explosion to be accumulated on the neutron star surface. Almost all of the detected bursts are associated with already known bursters,we have found only one previously unknown burster, IGRJ17380-3749, in the archival data, and one more known, but poorly studied source, AX J1754.2-2754, has been identified as a burster. Several similar sources have previously been identified as bursters directly during the INTEGRAL observations.
PubDate: 2017-12-01
DOI: 10.1134/s1063773717120076
Issue No: Vol. 43, No. 12 (2017)

• Fine Structure of the Core of the Blazar OJ 287-I
• Authors: L. I. Matveyenko; S. S. Sivakon’
Pages: 796 - 811
Abstract: Abstract The fine structure of the active region, the bulge, of the blazar OJ 287 has been investigated with a resolution of 20 μas (0.1 pc) at a wavelength of 7 mm, the epochs of 2007–2017. The structure and kinematics correspond to a vortex nature. The surrounding matter, the plasma, is transferred to the center along two arms from opposite directions. The emerging excess angular momentum is carried away along the rotation axis by bipolar outflows, rotating coaxial tubes, in a direction X ≈ −120◦ in the plane of the sky as it is accumulated. The central high-velocity bipolar outflow has a helical shape. The diameters of the low-velocity flows are ø1 ≈ 0.3 and ø2 ≈ 0.65 mas, or 1.4 and 3 pc, respectively. Ring currents whose tangential directions are observed as parallel chains of components are excited in the flow walls. The peak brightness temperature of the nozzle reaches Tb ≈ 1012−1013 K. A “disk” with a diameter ø ≈ 0.5 mas (≈2.2 pc) is observed by the absorption of synchrotron radiation. The disk is inclined to the plane of the sky at an angle of 60◦ in the jet direction. The fragments are seen from a distance of ∼0.2 mas outside the absorption zone. The jet sizes exceed considerably the counterjet ones. An enhanced supply of plasma from the northern arm gives rise to an independent vortex 0.2 mas away from the central one in the NW direction. As in the first case, the helical central bipolar outflow is surrounded by a low-velocity component ø ≈ 0.28 mas in diameter with built-in ring currents. The jet is ejected in the direction X = −50◦ in the plane of the sky. The jet orientation changes, X = −130◦ at a distance of 1 mas. A high activity of the central and two side nozzles spaced 0.22 mas apart in the direction X = −40◦ is occasionally observed simultaneously. The active region of the blazar is observed through an ionized medium, a screen, whose influence is significant even at a wavelength of 7 mm. The absorption and refraction of the transmitted emission in the screen affect the apparent brightness relative to the positions of the fragments.
PubDate: 2017-12-01
DOI: 10.1134/s1063773717120027
Issue No: Vol. 43, No. 12 (2017)

• SDSS J170745+302056: A low-surface-brightness galaxy in a group
• Authors: V. P. Reshetnikov; S. S. Savchenko; A. V. Moiseev; O. V. Egorov
Pages: 812 - 819
Abstract: Abstract Based on SDSS data and spectroscopic observations with the 6-m BTA telescope at SAO RAS, we have studied the galaxy SDSS J170745+302056. By the set of its characteristics— an exponential brightness distribution, a central stellar disk surface brightness μ0(B) = 23m. 25/—, blue colors, a low metallicity, and a moderate star formation rate—this galaxy belongs to typical low-surfacebrightness spiral galaxies. The exponential scale length of the galaxy’s disk is ≈3 kpc, while its optical diameter exceeds 20 kpc. SDSS J170745+302056 is a member of a group of five galaxies and possibly interacts with the galaxy UGC 10716. The existence of a large low-surface-brightness galaxy in such a dense environment is very unusual.
PubDate: 2017-12-01
DOI: 10.1134/s1063773717120064
Issue No: Vol. 43, No. 12 (2017)

• Heating of the polar caps of old radio pulsars
• Authors: A. I. Tsygan
Pages: 820 - 830
Abstract: Abstract The X-ray luminosity and temperature of the polar cap heated by the back flux of positrons from a radio pulsar with a period P ∼ 1 s and a magnetic field B ~ 1012 G have been estimated. An additional source of X-ray emission—a thin, hotter semiring on the polar-cap periphery—is shown to also exist. It is heated by the back flux of electrons from the light cylinder. Furthermore, the electric field near the hot semiring accelerates the ions of the surface layer that leave the neutron-star magnetosphere. The semiring area is smaller than the polar-cap area approximately by a factor of 100, i.e., at the same luminosity the temperature is higher by a factor of 3. The observed X-ray emission from old radio pulsars is the emission from thin hot polar-cap semirings. The emission from the polar caps themselves is strongly attenuated by interstellar absorption.
PubDate: 2017-12-01
DOI: 10.1134/s1063773717110056
Issue No: Vol. 43, No. 12 (2017)

• A search for photometric and spectroscopic evolutionary changes in the
young planetary nebula Vy 2-2
• Authors: V. P. Arkhipova; M. A. Burlak; V. F. Esipov; N. P. Ikonnikova; G. V. Komissarova
Pages: 831 - 843
Abstract: Abstract The results of long-term photometric and spectroscopic observations of the young compact planetary nebula Vy 2-2 (PNG 045.4-02.7) are presented. The UBV photometry in 1990–2016 has revealed a slight brightness trend in the yearly averaged data, most pronounced in the V band. We have measured the relative fluxes of optical emission lines on the spectrograms taken with the 1.25-m telescope at the Southern Station of the SAI MSU in 1999–2016, estimated the absolute flux in the Hβ line to be F(Hβ) = (2.1 ± 0.4) × 10−12 erg cm−2 s−1, and determined the interstellar extinction constant c(Hβ) = 1.8. The electron temperature and density in the nebula have been estimated from diagnostic line ratios: Te = (10−12) × 103 K and Ne ≥ 105 cm−3. To detect any possible evolutionary changes, we have compared the new observations with the archival data obtained over the entire history of spectroscopic observations of Vy 2-2. No significant changes in the relative intensities of the strongest emission lines and the integrated flux in the Hβ line exceeding the observational errors have been found. We have revealed a tendency for the intensity ratio F(λ4363)/F(λ4959) to decrease with time, which may be related to a decrease in the electron density in the nebula. Based on our photometric and spectroscopic data, we have estimated the luminosity of the central star of Vy 2-2, which corresponds to the evolutionary tracks for the most massive post-AGB stars of the O-rich sequence.
PubDate: 2017-12-01
DOI: 10.1134/s1063773717110019
Issue No: Vol. 43, No. 12 (2017)

• On searching for observational manifestations of Alfvén waves in
solar faculae
• Authors: N. I. Kobanov; S. A. Chupin; A. A. Chelpanov
Pages: 844 - 853
Abstract: Abstract In an effort to detect torsional oscillations, we have studied the periodic half-width variations for several spectral lines in solar faculae. The duration of the series being analyzed was from 40 to 150 min. We have determined the dominant frequencies and amplitudes of the half-width oscillations and considered their phase relations to the intensity and line-of-sight velocity oscillations. Five-minute profile halfwidth oscillations with a peak-to-peak amplitude of ∼10 m ˚A are recorded with confidence in the upperphotospheric Si I 10 827 ˚A line in faculae. The chromospheric He I 10 830 A˚ and Hα line profiles shows ∼40–60 m ˚A variations in two frequency bands, 2.5–4 and 1–1.9 mHz. No center-to-limb dependence that, according to the theory, must accompany the torsional oscillations has been revealed in the behavior of the oscillation amplitudes. According to present views, these variations cannot be caused by periodic temperature and magnetic field changes. Our observations do not allow us to explain these variations by the sausage mode action either, which should manifest itself at the double frequency.
PubDate: 2017-12-01
DOI: 10.1134/s1063773717110044
Issue No: Vol. 43, No. 12 (2017)

• A beam of particles in ultrahigh-energy cosmic rays'
• Authors: G. F. Krymsky; M. I. Pravdin; I. E. Sleptsov
Pages: 703 - 705
Abstract: Abstract Three particles with energies of 36, 35, and 58 EeV arrived from one sky region were recorded by two EAS arrays during a day. The events are assumed to have been produced by the beam of particles that resulted from the interaction of cosmic rays with a relativistic shock front.
PubDate: 2017-11-01
DOI: 10.1134/s1063773717100048
Issue No: Vol. 43, No. 11 (2017)

• Radius of the neutron star magnetosphere during disk accretion
• Authors: E. V. Filippova; I. A. Mereminskiy; A. A. Lutovinov; S. V. Molkov; S. S. Tsygankov
Pages: 706 - 729
Abstract: Abstract The dependence of the spin frequency derivative $$\dot \nu$$ of accreting neutron stars with a strongmagnetic field (X-ray pulsars) on the mass accretion rate (bolometric luminosity, L bol) has been investigated for eight transient pulsars in binary systems with Be stars. Using data from the Fermi/GBM and Swift/BAT telescopes, we have shown that for seven of the eight systems the dependence $$\dot \nu$$ (L bol) can be fitted by the model of angular momentum transfer through an accretion disk, which predicts the relation $$\dot \nu$$ ∼ L 6/7 bol. Hysteresis in the dependence $$\dot \nu$$ (L bol) has been confirmed in the system V 0332+53 and has been detected for the first time in the systems KS 1947+300, GRO J1008-57, and 1A 0535+26. Estimates for the radius of the neutron star magnetosphere in all of the investigated systems have been obtained. We show that this quantity varies from pulsar to pulsar and depends strongly on the analytical model and the estimates for the neutron star and binary system parameters.
PubDate: 2017-11-01
DOI: 10.1134/s1063773717110020
Issue No: Vol. 43, No. 11 (2017)

• Properties of the Tycho-2 catalogue from Gaia data release
• Authors: V. V. Vityazev; A. S. Tsvetkov; S. D. Petrov; D. A. Trofimov; V. I. Kiyaev
Pages: 730 - 750
Abstract: Abstract Based on the measurements performed in the first 14 months of Gaia operation, we have solved the problem of obtaining the systematic differences between the stellar positions and proper motions of the TGAS (Tycho–Gaia Astrometric Solution) and Tycho-2 catalogues. By dividing the common stars from the TGAS and Tycho-2 catalogues into three G-magnitude groups for mean values of $$10\underset{\raise0.3em\hbox{\(\smash{\scriptscriptstyle\cdot}$$}}{m} 5,11\underset{\raise0.3em\hbox{$$\smash{\scriptscriptstyle\cdot}$$}}{m} 5,and13\underset{\raise0.3em\hbox{$$\smash{\scriptscriptstyle\cdot}$$}}{m} 0,\) we have obtained the systematic differences between the stellar equatorial coordinates and proper motions of both catalogues in the form of a decomposition into vector spherical harmonics by taking into account the magnitude equation. The systematic components have been extracted from the individual differences with a probability of 0.977–0.999. The constructed model of systematic differences allows any position measurements performed using Tycho-2 as a reference catalogue to be transformed to the TGAS frame. An important fact is the existence of a magnitude equation in the systematic differences: when passing from bright (G = 10 m ) to faint (G = 13 m ) stars, the systematic position differences change within the range from approximately −40 to 15 mas, while the systematic proper motion differences change from −3 to 3 mas yr−1. The orientation and mutual rotation parameters of the Tycho-2 and TGAS frames have also been found to be different for stars of different magnitudes: when passing from bright to faint stars, the rotation angle of the Tycho-2 frame relative to TGAS changes from 3.51 to 5.63 mas, while the angular velocity of rotation changes from 0.35 to 1.22 mas yr−1. Based on the developed method that allows the extent to which the systematic errors in the equatorial propermotions of stars affect the results of a kinematic analysis of the Galactic proper motions to be estimated within the Ogorodnikov–Milne model, we have shown that the slope of the Galactic rotation curve and the Oort parameter C are most sensitive to the transition from the Tycho-2 frame to the TGAS one. Their relative changes after the transformation to the TGAS frame reach 56 and 100%, respectively. At the same time, the changes in the estimates of the Oort parameters A and B as well as the linear velocity of the Sun relative to the Galactic center, the Galactic rotation period, the ratio of the epicyclic frequency to the angular velocity of Galactic rotation, and the mass of the Galaxy within the Galactocentric distance of the Sun are not so large, being 2−10%.
PubDate: 2017-11-01
DOI: 10.1134/s106377371711007x
Issue No: Vol. 43, No. 11 (2017)

• Spectroscopic studies of the unique yellow supergiant α Aqr in the
Cepheid instability strip
• Authors: I. A. Usenko; A. S. Miroshnichenko; S. Danford
Pages: 751 - 767
Abstract: Abstract Based on 21 spectra with resolutions from 12 000 to 42 000 taken in 1997–2016 for the yellow supergiant α Aqr (which is believed to be nonvariable in the Cepheid instability strip), we have determined its effective temperature T eff and radial velocities from metal and hydrogen absorption lines. Blue and red components that account for 20–25% of the total number of lines used have been detected in the profiles of these lines. The effective temperature and radial velocities estimated from metal lines and their components do not show any noticeable variations, while the radial velocities determined from hydrogen lines show variations that are largest for the Hα line, with an amplitude of more than 10 km s−1. These variations resemble periodic (∼100 days) and sporadic ones. The presence of variable red components in the hydrogen line cores confirms that there is a circumstellar envelope around the supergiant. The radial velocities of these components exhibit a behavior similar to that of the hydrogen lines but with larger amplitudes (it is twice that for the R component of the Hα line). Such an unusual variability as well as the presence of blue components in metal lines and the star’s position at the red edge of the Cepheid instability strip can be explained by a possible residual pulsational activity in the upper atmospheric layers of the star, which “swings” the envelope with a larger amplitude when passing into a less dense medium. The multicomponent structure of the Na I D doublet lines and their variations over long time intervals may be indicative of a chromospheric activity and a change in the stellar wind intensity. These processes can affect the sporadic variations of the radial velocities in the upper atmospheric layers of the star and its envelope. We raise the question about a revision of the classification of α Aqr as a yellow nonvariable supergiant.
PubDate: 2017-11-01
DOI: 10.1134/s1063773717110068
Issue No: Vol. 43, No. 11 (2017)

• Structure and physical conditions in the Hα loops of an M7.7 solar
flare
• Authors: N. M. Firstova; V. I. Polyakov
Pages: 768 - 779
Abstract: Abstract The M7.7 solar flare on July 19, 2012, is the most dramatic example of a “Masuda” flare with a well-defined second X-ray above-the-loop-top source. The behavior of the system of loops accompanying this flare has been studied comprehensively by Liu et al. based on Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data. We have performed spectroscopic and filter observations of the Hα loops in this flare with the Large Solar Vacuum Telescope. The basic physical parameters in the loops of this peculiar flare generally coincide with the known data in Hα loops. However, the electron density, 1011 cm−3, and the integrated disk-center continuum intensity, 12%, are quite high, given that the observations were obtained almost 3 h after the flare onset.We have estimated the ascending velocity of the loop arcade (~3.5 km s−1) and the height difference between the Hα and 94 Å loops (~2 × 104 km).
PubDate: 2017-11-01
DOI: 10.1134/s1063773717110032
Issue No: Vol. 43, No. 11 (2017)

• Improvements on a unified dark matter model
• Authors: A. Del Popolo; Xi-Guo Lee
Pages: 635 - 643
Abstract: Abstract We study, by means of a spherical collapse model, the effect of shear, rotation, and baryons on a generalized Chaplygin gas (gCg) dominated universes. We show that shear, rotation, and the baryon presence slow down the collapse with respect to the simple spherical collapse model. The slowing down in the growth of density perturbation is able to solve the instability of the unified dark matter (UDM) models described in previous papers (e.g., Sandvik et al. 2004) at the linear perturbation level, as also shown by a direct comparison of our model with previous results.
PubDate: 2017-10-01
DOI: 10.1134/s1063773717100024
Issue No: Vol. 43, No. 10 (2017)

• A model of the cosmic infrared background produced by distant galaxies
• Authors: S. V. Pilipenko; M. V. Tkachev; A. A. Ermash; T. I. Larchenkova; E. V. Mikheeva; V. N. Lukash
Pages: 644 - 655
Abstract: Abstract The extragalactic background radiation produced by distant galaxies emitting in the far infrared limits the sensitivity of telescopes operating in this range due to confusion. We have constructed a model of the infrared background based on numerical simulations of the large-scale structure of the Universe and the evolution of dark matter halos. The predictions of this model agree well with the existing data on source counts. We have constructed maps of a sky field with an area of 1 deg2 directly from our simulated observations and measured the confusion limit. At wavelengths 100–300 μm the confusion limit for a 10-m telescope has been shown to be at least an order of magnitude lower than that for a 3.5-m one. A spectral analysis of the simulated infrared background maps clearly reveals the large-scale structure of the Universe. The two-dimensional power spectrum of these maps has turned out to be close to that measured by space observatories in the infrared. However, the fluctuations in the number of intensity peaks observed in the simulated field show no clear correlation with superclusters of galaxies; the large-scale structure has virtually no effect on the confusion limit.
PubDate: 2017-10-01
DOI: 10.1134/s1063773717100073
Issue No: Vol. 43, No. 10 (2017)

• IGR J17445-2747—Yet another X-ray burster in the galactic bulge
• Authors: I. A. Mereminskiy; S. A. Grebenev; R. A. Sunyaev
Pages: 656 - 663
Abstract: Abstract The discovery of a type I X-ray burst from the faint unidentified transient source IGR J17445-2747 in the Galactic bulge by the JEM-X telescope onboard the INTEGRAL observatory is reported. Type I bursts are believed to be associated with thermonuclear explosions of accreted matter on the surface of a neutron star with a weak magnetic field in a low-mass X-ray binary. Thus, this observation allows the nature of this source to be established.
PubDate: 2017-10-01
DOI: 10.1134/s106377371710005x
Issue No: Vol. 43, No. 10 (2017)

• Spectroscopic study of the optical counterpart to the fast X-ray transient
IGR J17544-2619 based on observations at the 1.5-m RTT-150 telescope
• Authors: I. F. Bikmaev; E. A. Nikolaeva; V. V. Shimansky; A. I. Galeev; R. Ya. Zhuchkov; E. N. Irtuganov; S. S. Melnikov; N. A. Sakhibullin; S. A. Grebenev; L. M. Sharipova
Pages: 664 - 676
Abstract: Abstract We present the results of our long-term photometric and spectroscopic observations at the Russian–Turkish RTT-150 telescope for the optical counterpart to one of the best-known sources, representatives of the class of fast X-ray transients, IGR J17544-2619. Based on our optical data, we have determined for the first time the orbital and physical parameters of the binary system by the methods of Doppler spectroscopy.We have calculated theoretical spectra of the optical counterpart by applying non- LTE corrections for selected lines and obtained the parameters of the stellar atmosphere (T eff = 33 000 K, log g = 3.85, R = 9.5 R ⊙, and M = 23 M ⊙). The latter suggest that the optical star is not a supergiant as has been thought previously.
PubDate: 2017-10-01
DOI: 10.1134/s1063773717100012
Issue No: Vol. 43, No. 10 (2017)

• Modeling of high-frequency variability in X-ray binaries with black holes
• Authors: A. N. Semena; M. G. Revnivtsev; T. I. Larchenkova; A. A. Lutovinov
Pages: 677 - 689
Abstract: Abstract The properties of the aperiodic variability in X-ray binaries with black holes are considered. The power spectra of the luminosity variability for a flat accretion disk that is an emission source with a powerlaw energy spectrum have been modeled. At low frequencies the derived power spectrum has the form of a power law with a slope ϱ ≈ −1 and a cutoff at a frequency corresponding to the characteristic frequency of fluctuations at the inner disk edge; at higher frequencies the power spectrum has a complex form. The high-frequency variability is suppressed due to the arrival time delays of photons emerged in different parts of the disk. The presence of azimuthal accretion rate fluctuations in the disk and the disk surface brightness nonuniformity in the observer’s imaginary plane caused by the relativistic effects give rise to an additional variability component at frequencies ∼ 200 Hz.
PubDate: 2017-10-01
DOI: 10.1134/s1063773717100085
Issue No: Vol. 43, No. 10 (2017)

• Radial pulsations of red giant branch stars
Pages: 690 - 696
Abstract: Abstract We performed hydrodynamic computations of nonlinear stellar pulsations of population I stars at the evolutionary stages of the ascending red giant branch and the following luminosity drop due to the core helium flash. Red giants populating this region of the Hertzsprung–Russel diagram were found to be the fundamental mode pulsators. The pulsation period is the largest at the tip of the red giant branch and for stars with initial masses from 1.1 M ⊙ to 1.9 M ⊙ ranges from ∏ ≈ 254 day to ∏ ≈ 33 day , respectively. The rate of period change during the core helium flash is comparable with rates of secular period change in Mira type variables during the thermal pulse in the helium shell source. The period change rate is largest (∏̇/∏ ≈ −10−2 yr−1) in stars with initial mass M ZAMS = 1.1 M ⊙ and decreases to ∏̇/∏ ∼ −10−3 yr−1 for stars of the evolutionary sequence M ZAMS = 1.9 M ⊙. Theoretical light curves of red giants pulsating with periods ∏ > 200 day show the presence of the secondary maximum similar to that observed in many Miras.
PubDate: 2017-10-01
DOI: 10.1134/s1063773717100036
Issue No: Vol. 43, No. 10 (2017)

• Meridional component of the large-scale magnetic field at minimum and
characteristics of the subsequent solar activity cycle
• Authors: V. N. Obridko; B. D. Shelting
Pages: 697 - 702
Abstract: Abstract The polar magnetic field near the cycle minimum is known to correlate with the height of the next sunspot maximum. There is reason to believe that the hemispheric coupling can play an important role in forming the next cycle. The meridional component of the large-scale magnetic field can be one of the hemispheric coupling indices. For our analysis we have used the reconstructed data on the large-scale magnetic field over 1915–1986. We show that in several cycles not only the height but also the general course of the cycle can be described in this way about 6 years in advance. This coupling has been confirmed by the currently available data from 1976 to 2016, but the ratio of the meridional field to the total absolute value of the field vector has turned out to be a more promising parameter. In this paper it was calculated at a height of ∼70 Mm above the photosphere. The date of the forthcoming minimum is estimated using this parameter to be mid-2018; using the global field as a forecast parameter gives a later date of the minimum, early 2020.
PubDate: 2017-10-01
DOI: 10.1134/s1063773717100061
Issue No: Vol. 43, No. 10 (2017)

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