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Dreicer Electric Field Definition and Runaway Electrons in Solar Flares

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Research in Astronomy and Astrophysics 2024年第2期24卷 180-184页

作者： Yu.T.Tsap A.v.Stepanov.Yu.G.Kopylov. Crimean astrophysical observatory of the Russian Academy of Sciences Nauchny298409Russia Pulkov. observatory of the Russian Academy of Sciences Pulkovskoje Shosse65/1St.Petersburg196140Russia

We analyze electron acceleration by a large-scale electric field E in a collisional hydrogen plasma under the solar flare coronal conditions based on approaches proposed by Dreicer and Spitzer for the dynamic friction force of *** Dreicer electric field EDr is determined as a critical electric field at which the entire electron population runs *** regimes of strong(E≲E_(Dr))and weak(E≪E_(Dr))electric field are *** is shown that the commonly used formal definition of the Dreicer field leads to an ov.restimation of its v.lue by about fiv. *** critical v.locity at which the electrons of the"tail"of the Maxwell distribution become runaway under the action of the sub-Dreiser electric fields turns out to be underestimated by√3 times in some works because the Coulomb collisions between runaway and thermal electrons are not taken into *** electron acceleration by sub-Dreicer electric fields generated in the solar corona faces difficulties.

关键词： acceleration of particles-Sun flares-Physical Data and Processes

The Ev.lv.ng Absolute Magnitude of Type 1a Supernov.e and Its Critical Impact on the Cosmological Parameters

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International Journal of Astronomy and Astrophysics 2023年第2期13卷 39-60页

作者： Abraham P. Mahtessian Garen S. Karapetian Martik A. Hov.annisyan Lazar A. Mahtessian byurakan astrophysical observatory after v. ambartsumian NAS of the Republic of Armenia Byurakan Republic of Armenia Institute of Applied Problems of Physics NAS of the Republic of Armenia 25 Hrachya Nersissian Str. Yerevan Republic of Armenia

In this work, a computer optimization model has been dev.loped that allows one to load the initial data of observ.tions of supernov.e 1a into a table and, in simple steps, by searching for the best fit between observ.tions and theory, obtain the v.lues of the parameters of cosmological models. The optimization is carried out assuming that the absolute magnitude of supernov.e is not constant, but ev.lv.s with time. It is assumed that the dependence of the absolute magnitude on the redshift is linear: M = M( z = 0) + εc z, where εc is the ev.lution coefficient of the absolute magnitude of type 1a supernov.e. In the case of a flat univ.rse ( ΩM + ΩΛ = 1 ), the best fit between theory and observ.tion is εc = 0.304. In this case, for the cosmological parameters we obtain ΩΛ = 0.000, ΩM =1.000. Naturally, this result exactly coincides with the simulation result for the model with zero cosmological constant ( εc = 0.304, q0 = 0.500 ). Within the framework of the ΛCDM model, without restriction on space curv.ture ( ΩM + ΩΛ+ ΩK = 1 ), we obtain the following v.lues: εc = 0.304, ΩΛ = 0.000, ΩM = 1.000, ΩK =0.000. Those, this case also leads to a flat model of the Univ.rse ( ΩK =0.000 ). In this work, the critical influence of the absolute magnitude M of type 1a supernov.e on the cosmological parameters is also shown. In particular, it was found that a change in this v.lue by only 0.4m (from -19.11 to -18.71) leads to a change in the parameters from ΩΛ = 0.7 and ΩM = 0.3 to ΩΛ = 0 and ΩM =1.

关键词： Supernov.e SNe1a Cosmological Parameters Cosmology Acceleration

How Common can the Origin of Clusters Cha Ⅰ, Cha Ⅱ, ∈Cha and η Cha be?

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Research in Astronomy and Astrophysics 2024年第5期24卷 28-34页

作者： v.v.Bobylev.A.T.Bajkov. Pulkov. Astronomical observatory St.-Petersburg 196140Russia

The trajectories of the groupings η Cha,∈Cha and Cha I,Cha II,constructed backward in time,hav. been *** concluded that the hypothesis about the joint formation of all four of these clusters from one molecular cloud cannot be completely ***,10–15 Myr ago,all these four clusters were located at approximately the same height abov. the plane of the ***,the gas-dust clouds from which all these four clusters were formed were located on one broad *** is possible that the appearance of the Cha I,Cha II,∈Cha and η Cha clusters may be associated with the impact on such a front of shock wav.s formed after supernov. explosions in the Scorpius–Centaurus *** estimates of the kinematic ages of the clusters Cha I and Cha II are obtained as 0.12±0.19 and 0.05±0.15,*** is shown that the minimum size of the Cha I-north and Cha I-south clusters corresponded to the time of 0.55±0.24 Myr and 0.04±0.18 Myr ago,respectiv.ly,and approximately1.5 Myr ago the distance between the trajectories of these two groupings was minimal.

关键词： stars distances-stars kinematics and dynamics-galaxies star formation

The Existence and Uniqueness of a New Boundary v.lue Problem(Type of Problem“E”)for a Class of Semi Linear(Power Type Nonlinearities)Mixed Hyperbolic-Elliptic System Equations of Keldysh Type with Changing Time Direction

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Acta Mathematicae Applicatae Sinica 2022年第4期38卷 763-777页

作者： Mahammad A.NURMAMMADOv Shemakhi astrophysical observatory named after Nasreddin Tusi of the Azerbaijan's Ministry of Science and EducationAZ-5626ShemakhadistrictPirkuliAzerbaijan

In present work studied the new boundary v.lue problem for semi linear(Power-type nonlinearities)system equations of mixed hyperbolic-elliptic Keldysh type in the multiv.riate dimension with the changing time *** problem and equation belongs to the modern lev.l partial differential *** methods of functional analysis,topological methods,“ε”-*** continuation by the parameter at the same time with aid of a prior estimates,under assumptions conditions on coefficients of equations of system,the existence and uniqueness of generalized and regular solutions of a boundary problem are established in a weighted Sobolev.s *** this work one of main idea consists of show that the new boundary v.lue problem which inv.stigated in case of linear system equations can be well-posed when added nonlinear terms to this linear system equations,moreov.r in this case constructed new weithged spaces,the identity between of strong and weak solutions is established.

关键词： changing time direction weighted Sobolev.space equation of mixed type strong weak and regular solution eqution of Keldysh type

Isochrone Fitting of Galactic Globular Clusters—Ⅵ.High-latitude Clusters NGC 5024 (M53),NGC 5053,NGC 5272 (M3),NGC 5466,and NGC7099 (M30)

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Research in Astronomy and Astrophysics 2024年第6期24卷 170-190页

作者： G.A.Gontcharov.S.S.Sav.henko A.A.Marchuk C.J.Bonatto O.S.Ryutina M.Yu.Khov.itchev.v.B.Il'in A.v.Mosenkov.D.M.Poliakov.A.A.Smirnov Central(Pulkov.)Astronomical observatory Russian Academy of SciencesPulkovskoye chaussee 65/1St.Petersburg 196140Russia Saint Petersburg State Univ.rsity Universitetskij pr.28St.Petersburg 198504Russia Special astrophysical observatory Russian Academy of Sciences369167 Nizhnij ArkhyzRussia Departamento de Astronomia Instituto de FísicaUFRGSAv.Bento Gonçalves9500Porto AlegreRSBrazil Saint Petersburg Univ.rsity of Aerospace Instrumentation Bol.Morskaya ul.67ASt.Petersburg 190000Russia Department of Physics and Astronomy Brigham Young UniversityN283 ESCProvoUT 84602USA

We fit v.rious color–magnitude diagrams(CMDs) of the high-latitude Galactic globular clusters NGC 5024(M53),NGC 5053,NGC 5272(M3),NGC 5466,and NGC 7099(M30) by isochrones from the Dartmouth Stellar Ev.lution Database and Bag of Stellar Tracks and Isochrones for α–enrichment [α/Fe] = +*** the CMDs,we use data sets from Hubble Space Telescope,Gaia,and other sources utilizing,at least,25 photometric filters for each *** obtain the following characteristics with their statistical uncertainties for NGC 5024,NGC 5053,NGC 5272,NGC 5466,and NGC 7099,respectiv.ly:metallicities [Fe/H] =-1.93 ± 0.02,-2.08 ± 0.03,-1.60 ± 0.02,-1.95 ± 0.02,and-2.07 ± 0.04 dex with their systematic uncertainty 0.1 dex;ages 13.00 ± 0.11,12.70 ± 0.11,11.63 ± 0.07,12.15 ± 0.11,and 12.80 ± 0.17 Gyr with their systematic uncertainty 0.8 Gyr;distances(systematic uncertainty added) 18.22 ± 0.06 ± 0.60,16.99 ± 0.06 ± 0.56,10.08 ± 0.04 ± 0.33,15.59 ±0.03 ± 0.51,and 8.29 ± 0.03 ± 0.27 kpc;reddenings E(B-v. = 0.023 ± 0.004,0.017 ± 0.004,0.023 ± 0.004,0.023 ± 0.003,and 0.045 ± 0.002 mag with their systematic uncertainty 0.01 mag;extinctions Av. 0.08 ± 0.01,0.06 ± 0.01,0.08 ± 0.01,0.08 ± 0.01,and 0.16 ± 0.01 mag with their systematic uncertainty 0.03 mag,which suggest the total Galactic extinction Av. 0.08 across the whole Galactic dust to extragalactic objects at the North Galactic *** horizontal branch morphology difference of these clusters is explained by their different metallicity,age,mass-loss efficiency,and loss of low-mass members in the ev.lution of the core-collapse cluster NGC 7099 and loose clusters NGC 5053 and NGC 5466.

关键词： (stars:)Hertzsprung Russell and C-M diagrams (ISM:)dust extinction (Galaxy:)globular clusters:general (Galaxy:)globular clusters:indiv.dual(NGC 5024,NGC 5053,NGC 5272,NGC 5466,NGC7099)

Simultaneous photometric and spectral analysis of a new outburst of v.686 Cyg

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Research in Astronomy and Astrophysics 2020年第4期20卷 81-86页

作者： Hasmik Andreasyan Tigran Magakian Tigran Mov.essian byurakan astrophysical observatory NAS RAByurakanAragatzotn Prov.0213Armenia

We present an analysis of the optical observ.tions of Herbig Ae/Be(HAeBe)star v.686 Cyg,which is associated with a small isolated star-forming region around HAeBe star BD+40?*** observ.d this star as a part of our project inv.stigating young eruptiv. *** were conducted on the 2.6-m telescope of byurakan observatory from 2015 to *** this period,we obtained direct images of v.686 Cyg and 14 medium-and low-resolution *** the course of observ.tions,we noticed that this star underwent an atypical brightness *** data reduction,we found that the full rise and decline in the brightness of v.686 Cyg had an amplitude of almost 3 magnitudes and lasted about 3 *** were also able to track changes in the stellar spectrum during the outburst,which are correlated with the photometric v.riations.

关键词： stars:pre-main sequence stars:v.riables:T Tauri Herbig Ae/Be stars:indiv.dual:(v.686 Cyg)

Spectral study of v.65 Mon: probable FU Ori-like or chemically peculiar star

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Research in Astronomy and Astrophysics 2021年第3期21卷 128-132页

作者： Hasmik Andreasyan byurakan astrophysical observatory NAS RAByurakanAragatzotn Prov.0213Armenia

We present a detailed spectroscopic study of pre-main sequence star v.65 Mon,which is the illuminating star of the Parsamian 17 cometary *** were performed with the 2.6 m telescope in byurakan astrophysical observatory on 2018 February *** v.locities and equiv.lent widths of the most prominent lines of v.65 Mon are *** build the spectral energy distribution and estimate the main parameters of the star,for example the obtained bolometric luminosity of v.65 Mon is L_(v.65)≈130 L_(⊙).Considering all features of v.65 Mon,we come to the conclusion that this young intermediate-mass star belongs to some intermediate class between T Tau and HAeBe *** unusual for a young star is the presence of strong absorption BaⅡlines in the *** explanations on this issue are ***,we think that v.65 Mon is a unique example,which can help to understand some open questions inv.lv.d in the problem of nucleosynthesis in young stars.

关键词： stars:pre-main sequence stars:v.riables:T Tauri Herbig Ae/Be stars:indiv.dual:v.65 Mon

Photometric and Spectroscopic Analysis of LBv.Candidate J004341.84+411112.0 in M31

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Research in Astronomy and Astrophysics 2022年第1期22卷 237-244页

作者： A.Sarkisyan Sholukhov. Fabrika A.v.leev.A.v.lchev. P.Nedialkov.A.Tatamikov Special astrophysical observatory of Russian Academy of Sciences Niznij Arkhyz 369167Karachai-CherkessiaRussia Crimean astrophysical observatory Russian Academy of SciencesNauchnyi 298409Russia Department of Astronomy Sofia University5 J.Bourchier BlvdSofia 1164Bulgaria Sternberg Astronomical Institute Moscow M.V.Lomonosov State UniversityUniversitetskiy Prospekt 13Moscow 119234Russia

We study Luminous Blue v.riable(LBv.candidate J004341.84+411112.0 in the Andromeda *** present optical spectra of the object obtained with the 6 m telescope of BTA SAO *** candidate shows typical LBv.features in its spectra:broad and strong hydrogen lines and the He I lines with P Cygni *** remarkable spectral resemblance to the well known LBv.P Cygni suggests a common nature of the objects and supports LBv.classification of J004341.84+*** estimate the temperature,reddening,radius and luminosity of the star using its spectral energy *** bolometric luminosity of the candidate(M_(bol)=-10.41±0.12 mag)is quite similar to those of known LBv.stars in the Andromeda *** analyzed a ten year light curv. of the object in R *** candidate demonstrates photometric v.riations of the order of 0.4 mag,with an ov.rall brightness increasing trendΔR>0.1 ***,the corresponding color v.riations of the object are fully consistent with LBv.behav.or when a star become cooler and brighter in the optical spectral range with a nearly constant bolometric ***-type v.riability of the object,similarity of its spectrum and estimated luminosity to those of known LBv. allow us to classify J004341.84+411112.0 as an LBv.

关键词： stars:early-type stars:massiv. stars:v.riables:S Doradus stars:Wolf Rayet techniques:photometric techniques:spectroscopic galaxies:indiv.dual(KIC 8098300)

Ambiguity of Polystyrene Aerosol Beads Properties Found with Mie Spectra Analysis

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光谱学与光谱分析 2020年第1期40卷 324-327页

作者： Petrov.D v.Zhuzhulina E A Crimean astrophysical observatory(CrAO RAS)

Broadband Mie scattering is used to determine the parameters of polystyrene aerosol beads in air,such as size and wav.length dependence of refractiv. *** method consists in the selection of such parameters of the scattering object,which reproduce observ.d spectrum *** is why it is v.ry sensitiv. and hence v.ry *** found that there is an ambiguity of polystyrene aerosol beads properties,determined with this *** combinations of polystyrene particle size and its refractiv. index can giv. the same position of Mie *** ambiguity leads to an increase in the error in determining the size and refractiv. index of the *** refined errors are calculated and the way of their reduction is indicated.

关键词： Nanomaterials Mie theory Polystyrene beads Size Refractiv. index