This paper presents a new approach to analyzing the change of cometary brightness.In our considerations,we assume that astronomical silicates(dust agglomerates)and gas are present in the coma.This assumption is a cons...This paper presents a new approach to analyzing the change of cometary brightness.In our considerations,we assume that astronomical silicates(dust agglomerates)and gas are present in the coma.This assumption is a consequence of the analysis of the result observed during the Rosetta mission to comet67 P/Churyumov-Gerasimenko(abbreviated 67 P/Ch-G).The dimensions of these agglomerates can be up to several centimeters.However,the large ones are few compared to particles with dimensions of several micrometers.This paper presents the results of calculations on the change in hypothetical comet brightness as a result of its outburst.The calculations take into account the percentage of carbonaceous particles and silicates rich in magnesium.展开更多
We investigate the existence of Ion-Acoustic solitary/shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot electrons and cold ...We investigate the existence of Ion-Acoustic solitary/shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot electrons and cold electrons. The KPB equation is derived for the system;its solution is plotted for different kappa values, as well as for the temperature ratios of ions. It is found that the amplitude of solitary structure increases with increasing kappa values and negatively charged oxygen ion densities. As the temperature of the positively charged oxygen ions increases, the amplitude of solitary wave also increases. We have also studied the dependence of coefficients of the KPB equation on physical parameters relevant to comet Halley.展开更多
Stability of the kinetic Alfven wave in a plasma of hydrogen, oxygen and electrons is studied. Each species is modeled by drifting ring distributions in the direction parallel to the magnetic field, while in the perpe...Stability of the kinetic Alfven wave in a plasma of hydrogen, oxygen and electrons is studied. Each species is modeled by drifting ring distributions in the direction parallel to the magnetic field, while in the perpendicular direction the distribution is simulated with a loss cone type distribution obtained through the subtraction of two Maxwellian distributions with different temperatures. It is found that for frequencies ω＊ 〈 ωcH with ω＊ and ωcH the Doppler shifted and hydrogen ion gyro-frequencies, respectively, the growth rate of the kinetic Alfven wave increases with the increase in propagation angles and density of oxygen ions. On the other hand, for frequencies ω＊ 〈 ωco with ωco the oxygen ion gyro-frequency the growth rate is independent of the oxygen ion density.展开更多
Unpredicted apparitions of bright comets appearing on the night sky for a few months movingfast among the stars have intrigued mankind whenever the sky was observed. Records ofcomets are found in the oldest documents ...Unpredicted apparitions of bright comets appearing on the night sky for a few months movingfast among the stars have intrigued mankind whenever the sky was observed. Records ofcomets are found in the oldest documents and can be still useful as demonstrated during the as-sessment of the non-gravitational forces acting on comet Halley(Yeomans and Kiang, 1981).chinese records with relatively precise positions from more than 2000 years ago gave展开更多
An expeditionary study of the area of the alleged impact event that occurred on 3.08.1993 in the area of the Lower Konkuli River(southeast of the Aldan Highlands,Lurikan Range,Russia)was carried out.According to the m...An expeditionary study of the area of the alleged impact event that occurred on 3.08.1993 in the area of the Lower Konkuli River(southeast of the Aldan Highlands,Lurikan Range,Russia)was carried out.According to the materials of remote sensing,the places of collision with the earth of a cosmic body are determined.In the area of the impact of the shock wave on the Earth’s surface,peat samples were selected,the micro probe analysis of which showed the presence of a cosmogenic substance in concentrations 6-8 times higher than the background.Silicate and magnetite micro spheres,native iron,moissanite,and carbon micro tubes coated with a film consisting of pure nickel were found.Of particular interest were the findings of specific Ni film micro structures that allow us to make an assumption about the cometary nature of the Uchur cosmic body.Most researchers associate the observed flights of fireballs with the subsequent fall of meteorites.Researchers are trying to find the massive body of the fallen space body.However,often,even after many years of searching,a massive cosmic body cannot be found.This happened when studying the site of the fall of the Tunguska cosmic body.In this case,it remains to be assumed that the cosmic body contained microscopic dust particles.The structure and composition of such particles can only be studied using microscopic research methods.When studying the Uchur cosmic body,the authors concluded that it could be of a cometary nature due to the findings of specific particles-thin films of pure nickel on the surface of plant remains of terrestrial origin.This hypothesis arose from the recent discovery of atomic nickel vapors in comets.展开更多
The discovery of a giant comet (C/2014 UN271) at a distance of 29 AU in October 2014 and the later discovery in September 2021 of a dramatic brightening episode offers an ideal opportunity for verifying the prediction...The discovery of a giant comet (C/2014 UN271) at a distance of 29 AU in October 2014 and the later discovery in September 2021 of a dramatic brightening episode offers an ideal opportunity for verifying the predictions of a “biological” comet. The eruptions of the comet at a heliocentric distance of 20 AU are plausibly explained as due to high pressure venting of the products of microbial metabolism in radioactively heated subsurface lakes. The standard non-biological model of comets is woefully inadequate to account for eruptions at such large distances from the sun where surface temperatures are as low as 60 K.展开更多
The sun-grazing comet C/2011 W3(Lovejoy)showed a distorted,unconventional tail morphology near its perihelion(1.2Rs).Based on the“Solar Corona and Inner Heliosphere”modeling result of the magnetic field and plasma d...The sun-grazing comet C/2011 W3(Lovejoy)showed a distorted,unconventional tail morphology near its perihelion(1.2Rs).Based on the“Solar Corona and Inner Heliosphere”modeling result of the magnetic field and plasma dynamics in the solar corona,we use the Runge-Kutta method to simulate the moving trajectory of charged dust and ion particles released at different positions from the C/2011 W3 orbit.We find that the dust particles near the sun,which are subject to a strong magnetic Lorentz force,travel differently from their counterparts distant from the sun,where the latter are mainly affected by the solar gravitational force and radiation pressure.According to the simulation results,we propose that the magnetic mirror effect can rebound the charged dust particles back away from the sun and be regarded as one crucial cause of the dust-free zone formation.We find that ions mainly move along magnetic field lines at an acute angle to the comet's direction of motion.The cometary ions'movement direction was determined by the comet's velocity and the coronal magnetic field,which are responsible for the C/2011 W3’s unique comet tail shape near perihelion.Additionally,the ion particles also experience perpendicular drift motion,mainly dominated by the electric field drift,which is similar to and can be used to approximate the solar wind's transverse velocity at its source region.展开更多
Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have ...Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have little effect on the tenuous dust plasma in low-frequency perturbation. For a dense dust plasma, the maximum damping rate of the perturbed wave due to dust charge fluctuations will reach the order of dusty charging frequency. It will affect the existence of the K-H instability in the long wave length perturbation.展开更多
An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continual...An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continually. In addition, a shell structure with at most 5 layers often appeared. It is found that these layers were equal-spaced with a distance of about 2×10 4 km and were moving outward with a speed of about 35 m/s. It is suggested that this phenomenon was possibly a kind of wave created by charged attogram dust grains erupted from the nucleus, which collided with either the solar wind or material of the coma. The propagation period of the wave was about 6 days but the spin of the Comet Hale-Bopp could be very slow and the period was about 3 yr. This spin movement had the opposite direction as its orbital motion.展开更多
The CCD photometric observation of secular periodic comet C/1995 O1 (Hale-Bopp) was carried out at the Sheshan Station of Shanghai Observatory of China. We obtained 23 CCD images on 1996 March 11, April 22 and May 22....The CCD photometric observation of secular periodic comet C/1995 O1 (Hale-Bopp) was carried out at the Sheshan Station of Shanghai Observatory of China. We obtained 23 CCD images on 1996 March 11, April 22 and May 22. We derived the magnitude of the cometary nucleus in V, R bands, and estimated the lower limits of cometary mass and size. The results show that the diameter of nucleus ≈ 5 ～ 10km, which corresponds to a mass of 2 × 10 12～ 3 × 10 13 kg for different parameters when the bulk density is assumed to 1000 kg·m -3.展开更多
In this paper, we adopted a reasonable particle distribution function and used a simplified judgement to analyze the possibility of the ion-pickup caused by two-stream instibility in cometary tail. On calculation, we ...In this paper, we adopted a reasonable particle distribution function and used a simplified judgement to analyze the possibility of the ion-pickup caused by two-stream instibility in cometary tail. On calculation, we get an energy limitation(ΔE 1, ΔE 2) between the solar wind particles and the cometary particles .When the energy diffference is between ΔE 1 and ΔE 2, the pickup of ions in the cometary tail is more effective.展开更多
The velocity shear instability in a magnetized, three-component dusty plasma is investigated for both positively and negatively charged dust particles. The critical shears as a function of the relative charge of dust ...The velocity shear instability in a magnetized, three-component dusty plasma is investigated for both positively and negatively charged dust particles. The critical shears as a function of the relative charge of dust grains for both positively and negatively charged dust grains are in the same form. The instability excitation is easier in colder proton’s environment for positively charged dust, and so also in colder electron’s environment for negatively charged dust. For a certain flow pattern, the instability excites in different direction for different sign of charged dust grains. This conclusion may be helpful in interpreting the helical structures and streamer splitted phenomena in a cometary tail.展开更多
基金the support the author received from the Centre for Innovation and Transfer of Natural Sciences and Engineering Knowledge,University of Rzeszow,Poland。
文摘This paper presents a new approach to analyzing the change of cometary brightness.In our considerations,we assume that astronomical silicates(dust agglomerates)and gas are present in the coma.This assumption is a consequence of the analysis of the result observed during the Rosetta mission to comet67 P/Churyumov-Gerasimenko(abbreviated 67 P/Ch-G).The dimensions of these agglomerates can be up to several centimeters.However,the large ones are few compared to particles with dimensions of several micrometers.This paper presents the results of calculations on the change in hypothetical comet brightness as a result of its outburst.The calculations take into account the percentage of carbonaceous particles and silicates rich in magnesium.
文摘We investigate the existence of Ion-Acoustic solitary/shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot electrons and cold electrons. The KPB equation is derived for the system;its solution is plotted for different kappa values, as well as for the temperature ratios of ions. It is found that the amplitude of solitary structure increases with increasing kappa values and negatively charged oxygen ion densities. As the temperature of the positively charged oxygen ions increases, the amplitude of solitary wave also increases. We have also studied the dependence of coefficients of the KPB equation on physical parameters relevant to comet Halley.
基金the University Grants Commission under its Special Assistance Programme is gratefully acknowledged
文摘Stability of the kinetic Alfven wave in a plasma of hydrogen, oxygen and electrons is studied. Each species is modeled by drifting ring distributions in the direction parallel to the magnetic field, while in the perpendicular direction the distribution is simulated with a loss cone type distribution obtained through the subtraction of two Maxwellian distributions with different temperatures. It is found that for frequencies ω＊ 〈 ωcH with ω＊ and ωcH the Doppler shifted and hydrogen ion gyro-frequencies, respectively, the growth rate of the kinetic Alfven wave increases with the increase in propagation angles and density of oxygen ions. On the other hand, for frequencies ω＊ 〈 ωco with ωco the oxygen ion gyro-frequency the growth rate is independent of the oxygen ion density.
文摘Unpredicted apparitions of bright comets appearing on the night sky for a few months movingfast among the stars have intrigued mankind whenever the sky was observed. Records ofcomets are found in the oldest documents and can be still useful as demonstrated during the as-sessment of the non-gravitational forces acting on comet Halley(Yeomans and Kiang, 1981).chinese records with relatively precise positions from more than 2000 years ago gave
基金The work was carried out within the framework of the state tasks of the IPE RAS(project no.FMWU-2022-0026,project no.FMWU-2022-0027)IVMiMG SO RAN(project no.0251-2021-0004).
文摘An expeditionary study of the area of the alleged impact event that occurred on 3.08.1993 in the area of the Lower Konkuli River(southeast of the Aldan Highlands,Lurikan Range,Russia)was carried out.According to the materials of remote sensing,the places of collision with the earth of a cosmic body are determined.In the area of the impact of the shock wave on the Earth’s surface,peat samples were selected,the micro probe analysis of which showed the presence of a cosmogenic substance in concentrations 6-8 times higher than the background.Silicate and magnetite micro spheres,native iron,moissanite,and carbon micro tubes coated with a film consisting of pure nickel were found.Of particular interest were the findings of specific Ni film micro structures that allow us to make an assumption about the cometary nature of the Uchur cosmic body.Most researchers associate the observed flights of fireballs with the subsequent fall of meteorites.Researchers are trying to find the massive body of the fallen space body.However,often,even after many years of searching,a massive cosmic body cannot be found.This happened when studying the site of the fall of the Tunguska cosmic body.In this case,it remains to be assumed that the cosmic body contained microscopic dust particles.The structure and composition of such particles can only be studied using microscopic research methods.When studying the Uchur cosmic body,the authors concluded that it could be of a cometary nature due to the findings of specific particles-thin films of pure nickel on the surface of plant remains of terrestrial origin.This hypothesis arose from the recent discovery of atomic nickel vapors in comets.
文摘The discovery of a giant comet (C/2014 UN271) at a distance of 29 AU in October 2014 and the later discovery in September 2021 of a dramatic brightening episode offers an ideal opportunity for verifying the predictions of a “biological” comet. The eruptions of the comet at a heliocentric distance of 20 AU are plausibly explained as due to high pressure venting of the products of microbial metabolism in radioactively heated subsurface lakes. The standard non-biological model of comets is woefully inadequate to account for eruptions at such large distances from the sun where surface temperatures are as low as 60 K.
基金supported by NSFC under contracts No.41874200 and 41421003supported by CNSA under contracts No.D020301 and D020302.
文摘The sun-grazing comet C/2011 W3(Lovejoy)showed a distorted,unconventional tail morphology near its perihelion(1.2Rs).Based on the“Solar Corona and Inner Heliosphere”modeling result of the magnetic field and plasma dynamics in the solar corona,we use the Runge-Kutta method to simulate the moving trajectory of charged dust and ion particles released at different positions from the C/2011 W3 orbit.We find that the dust particles near the sun,which are subject to a strong magnetic Lorentz force,travel differently from their counterparts distant from the sun,where the latter are mainly affected by the solar gravitational force and radiation pressure.According to the simulation results,we propose that the magnetic mirror effect can rebound the charged dust particles back away from the sun and be regarded as one crucial cause of the dust-free zone formation.We find that ions mainly move along magnetic field lines at an acute angle to the comet's direction of motion.The cometary ions'movement direction was determined by the comet's velocity and the coronal magnetic field,which are responsible for the C/2011 W3’s unique comet tail shape near perihelion.Additionally,the ion particles also experience perpendicular drift motion,mainly dominated by the electric field drift,which is similar to and can be used to approximate the solar wind's transverse velocity at its source region.
文摘Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have little effect on the tenuous dust plasma in low-frequency perturbation. For a dense dust plasma, the maximum damping rate of the perturbed wave due to dust charge fluctuations will reach the order of dusty charging frequency. It will affect the existence of the K-H instability in the long wave length perturbation.
文摘An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continually. In addition, a shell structure with at most 5 layers often appeared. It is found that these layers were equal-spaced with a distance of about 2×10 4 km and were moving outward with a speed of about 35 m/s. It is suggested that this phenomenon was possibly a kind of wave created by charged attogram dust grains erupted from the nucleus, which collided with either the solar wind or material of the coma. The propagation period of the wave was about 6 days but the spin of the Comet Hale-Bopp could be very slow and the period was about 3 yr. This spin movement had the opposite direction as its orbital motion.
文摘The CCD photometric observation of secular periodic comet C/1995 O1 (Hale-Bopp) was carried out at the Sheshan Station of Shanghai Observatory of China. We obtained 23 CCD images on 1996 March 11, April 22 and May 22. We derived the magnitude of the cometary nucleus in V, R bands, and estimated the lower limits of cometary mass and size. The results show that the diameter of nucleus ≈ 5 ～ 10km, which corresponds to a mass of 2 × 10 12～ 3 × 10 13 kg for different parameters when the bulk density is assumed to 1000 kg·m -3.
基金theNationalNaturalScienceFoundationofChinaUnderGrant (No .199730 18& 196 5 30 0 1)
文摘In this paper, we adopted a reasonable particle distribution function and used a simplified judgement to analyze the possibility of the ion-pickup caused by two-stream instibility in cometary tail. On calculation, we get an energy limitation(ΔE 1, ΔE 2) between the solar wind particles and the cometary particles .When the energy diffference is between ΔE 1 and ΔE 2, the pickup of ions in the cometary tail is more effective.
文摘The velocity shear instability in a magnetized, three-component dusty plasma is investigated for both positively and negatively charged dust particles. The critical shears as a function of the relative charge of dust grains for both positively and negatively charged dust grains are in the same form. The instability excitation is easier in colder proton’s environment for positively charged dust, and so also in colder electron’s environment for negatively charged dust. For a certain flow pattern, the instability excites in different direction for different sign of charged dust grains. This conclusion may be helpful in interpreting the helical structures and streamer splitted phenomena in a cometary tail.
