The <Emphasis Type="Italic">Wind</Emphasis>/EPACT Proton Event Catalog (1996 – 2016)     

Rositsa Miteva  Susan W. Samwel  Marcus V. Costa-Duarte 《Solar physics》2018,293(2):27

We present the finalized catalog of solar energetic proton events detected by the Wind/EPACT instrument over the period 1996?–?2016. Onset times, peak times, peak proton intensity and onset-to-peak proton fluence are evaluated for the two available energy channels, at about 25 and 50 MeV. We describe the procedure utilized to identify the proton events and to relate them to their solar origin (in terms of flares and coronal mass ejections). The statistical relationships between the energetic protons and their origin (linear and partial correlation analysis) are reported and discussed in view of earlier findings. Finally, the different trends found in the first 8 years of Solar Cycles 23 and 24 are discussed.  相似文献   

Numerical Study of Statistical Properties of the Galactic Center Distance Estimate from the Geometry of Spiral Arm Segments     

I. I. Nikiforov  A. V. Veselova 《Astronomy Letters》2018,44(11):699-719

The influence of various factors on the statistical properties of the Galactic center distance (R₀) estimate obtained by solving the general problem of determining the geometric parameters of a Galactic spiral arm from its segment with the inclusion of the distance to the spiral pole, i.e., R₀, in the set of parameters has been studied by the Monte Carlo method. Our numerical simulations have been performed for the model segments representing the Perseus and Scutum arms based on masers in high-mass star forming regions. We show that the uncertainty in the present-day parallax measurements for these objects systematically decreases (!) with increasing heliocentric distance, while the relative uncertainty in the parallaxes is, on average, approximately constant. This lucky circumstance increases significantly (by a factor of 1.4–1.7) the accuracy of estimating R₀ from the arm segment traced by masers. Our numerical experiments provide evidence for the consistency of the R₀ estimate from the spiral-segment geometry. The significant biases of the estimate detected only for the Scutum arm are caused mainly by the random parallax errors, the small angular extent of the segment, and the small number of objects representing it. The dispersion of the R₀ estimate depends most strongly on the angular extent of the segment and the parallax uncertainty if the latter, on average, does not depend on the distance. The remaining parameters, except for the pitch angle, exert an equally significant, but weaker influence on the statistical accuracy of the estimate. When the data on 3–8 segments are processed simultaneously, the predicted standard error of the final estimate is σR₀ ? 0.5?0.3 kpc, respectively. The accuracy can be improved by increasing the extent of the identified segments and the number of objects belonging to them. The method of determining R₀ from spiral segments has turned out to be operable for a wide set of possible parameters even when using an L-estimator (median). This makes the development of a more complex method based on an M-estimator, which allows one to properly take into account the measuring and natural dispersions of objects relative to the arm center line and, thus, to avoid the biases of the parameter estimates, meaningful.  相似文献   

Fine-resolution analysis of exoplanetary distributions by wavelets: hints of an overshooting iceline accumulation     

Roman V. Baluev  Vakhit S. Shaidulin 《Astrophysics and Space Science》2018,363(9):192

We investigate 1D exoplanetary distributions using a novel analysis algorithm based on the continuous wavelet transform. The analysis pipeline includes an estimation of the wavelet transform of the probability density function (p.d.f.) without pre-binning, use of optimized wavelets, a rigorous significance testing of the patterns revealed in the p.d.f., and an optimized minimum-noise reconstruction of the p.d.f. via matching pursuit iterations.In the distribution of orbital periods, \(P\), our analysis revealed a narrow subfamily of exoplanets within the broad family of “warm Jupiters”, or massive giants with \(P\gtrsim 300~\mbox{d}\), which are often deemed to be related with the iceline accumulation in a protoplanetary disk. We detected a p.d.f. pattern that represents an upturn followed by an overshooting peak spanning \(P\sim 300\mbox{--}600~\mbox{d}\), right beyond the “period valley”. It is separated from the other planets by p.d.f. concavities from both sides. It has at least 2-sigma significance.In the distribution of planet radii, \(R\), and using the California Kepler Survey sample properly cleaned, we confirm the hints of a bimodality with two peaks about \(R=1.3R_{\oplus }\) and \(R=2.4R_{ \oplus }\), and the “evaporation valley” between them. However, we obtain just a modest significance for this pattern, 2-sigma only at the best. Besides, our follow-up application of the Hartigan and Hartigan dip test for unimodality returns 3 per cent false alarm probability (merely 2.2-sigma significance), contrary to 0.14 per cent (or 3.2-sigma), as claimed by Fulton et al. (2017).  相似文献   

First Analysis of Ground-Level Enhancement (GLE) 72 on 10 September 2017: Spectral and Anisotropy Characteristics     

A. Mishev  I. Usoskin  O. Raukunen  M. Paassilta  E. Valtonen  L. Kocharov  R. Vainio 《Solar physics》2018,293(10):136

Using data obtained with neutron monitors and space-borne instruments, we analyzed the second ground-level enhancement (GLE) of Solar Cycle 24, namely the event of 10 September 2017 (GLE 72), and derived the spectral and angular characteristics of associated GLE particles. We employed a new neutron-monitor yield function and a recently proposed model based on an optimization procedure. The method consists of simulating particle propagation in a model magnetosphere in order to derive the cutoff rigidity and neutron-monitor asymptotic directions. Subsequently, the rigidity spectrum and anisotropy of GLE particles are obtained in their dynamical evolution during the event on the basis of an inverse-problem solution. The derived angular distribution and spectra are discussed briefly.  相似文献   

Phytocenoses of the Ob Estuary and Kara Sea Shelf in the Late Spring Season     

Sukhanova  I. N.  Flint  M. V.  Sakharova  E. G.  Fedorov  A. V.  Makkaveev  P. N.  Nedospasov  A. A. 《Oceanology》2018,58(6):802-816

Oceanology - Based on the material obtained in the spring–summer season of 2016, the composition and quantitative distribution of phytoplankton in the Ob estuary and over the Kara Sea shelf...  相似文献   

Probing Twisted Magnetic Field Using Microwave Observations in an M Class Solar Flare on 11 February, 2014     

I. N. Sharykin  A. A. Kuznetsov  I. I. Myshyakov 《Solar physics》2018,293(2):34

This work demonstrates the possibility of magnetic-field topology investigations using microwave polarimetric observations. We study a solar flare of GOES M1.7 class that occurred on 11 February, 2014. This flare revealed a clear signature of spatial inversion of the radio-emission polarization sign. We show that the observed polarization pattern can be explained by nonthermal gyrosynchrotron emission from the twisted magnetic structure. Using observations of the Reuven Ramaty High Energy Solar Spectroscopic Imager, Nobeyama Radio Observatory, Radio Solar Telescope Network, and Solar Dynamics Observatory, we have determined the parameters of nonthermal electrons and thermal plasma and identified the magnetic structure where the flare energy release occurred. To reconstruct the coronal magnetic field, we use nonlinear force-free field (NLFFF) and potential magnetic-field approaches. Radio emission of nonthermal electrons is simulated by the GX Simulator code using the extrapolated magnetic field and the parameters of nonthermal electrons and thermal plasma inferred from the observations; the model radio maps and spectra are compared with observations. We have found that the potential-magnetic-field approach fails to explain the observed circular polarization pattern; on the other hand, the Stokes-\(V\) map is successfully explained by assuming nonthermal electrons to be distributed along the twisted magnetic structure determined by the NLFFF extrapolation approach. Thus, we show that the radio-polarization maps can be used for diagnosing the topology of the flare magnetic structures where nonthermal electrons are injected.  相似文献   

Powerful Solar Flares in September 2017. Comparison with the Largest Flares in Cycle 24     

E. A. Bruevich  V. V. Bruevich 《Astrophysics》2018,61(2):241-253

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Implementation of the Concept for Creating a Spacecraft Double-Launch System as a Part of the Upper Stages of the Fregat Family     

Ishin  S. V.  Vikulenkov  V. P.  Fedoskin  D. I.  Poreshnev  A. Yu.  Jumahanov  N. B.  Yakovlev  B. D. 《Solar System Research》2020,54(7):690-698

Solar System Research - Abstract—Results of the implementation of a single concept for the development of the double launch system (SDZ) are presented, in particular the SDZ-La5 for the...  相似文献   

Study of the Galactic Rotation Based on Masers and Radio Stars with VLBI Measurements of Their Parallaxes     

Bobylev  V. V.  Krisanova  O. I.  Bajkova  A. T. 《Astronomy Letters》2020,46(7):439-448

Astronomy Letters - Based on published data, we have produced a sample of 256 radio sources whose trigonometric parallaxes and proper motions were measured by VLBI. This sample contains Galactic...  相似文献   

Opto-Acoustic Effects by Laser Breakdown of Seawater in an Ultrasonic Field     

Bulanov  A. V.  Sosedko  E. V. 《Doklady Earth Sciences》2020,491(1):183-186

Doklady Earth Sciences - Studies of the opto-acoustic effects accompanying laser breakdown in water generated by focused laser and ultrasonic radiation are performed. For the first time, the...  相似文献