The Secular influence of the change in the heliocentric gravitational constant on the evolution of orbits of Meteor Streams is examined by using the method of celestial mechanics with variable mass and variable gravitational constant. The change in the heliocentric gravitational constant includes the combined changes in the sun’s mass and gravitational constant obtained from the modern observation of planets and spacecraft. The perturbation equations are solved by expanding series with mean anomaly. The solutions of the secular and periodic variation of orbital elements are derived. The theoretical results for the secular variables of the semi-major axes, solar distances at perihelion and orbital periods are given for three Meteor Streams: Dracorids, Quadrantids, and Ursids. The numerical results are shown in Table 2. The discussion and conclusion are drawn. 相似文献
Using 141 CME-interplanetary shock (CME-IPS) events and foF2 from eight ionosonde stations from January 2000 to September 2005, from the statistical results we find that there is a “same side?–?opposite side effect” in ionospheric negative storms, i.e., a large portion of ionospheric negative disturbances are induced by the same-side events (referring to the CMEs whose source located on the same side of the heliospheric current sheet (HCS) as the Earth), while only a small portion is associated with the opposite-side events (the CMEs source located on the opposite side of the HCS as the Earth); the ratio is 128 vs. 46, and it reaches 41 vs. 14 for the intense ionospheric negative storms. In addition, the ionospheric negative storms associated with the same-side events are often more intense. A comparison of the same-side event (4 April 2000) and the opposite-side event (2 April 2001) shows that the intensity of the ionospheric negative storm caused by the same-side event is higher than that by the opposite-side event, although their initial conditions are quite similar. Our preliminary results show that the HCS has an “impeding” effect to CME-IPS, which results in a shortage of energy injection in the auroral zone and restraining the development of ionospheric negative perturbations. 相似文献
We revisit the vertical structure of neutrino-dominated accretion flows (NDAFs) in spherical coordinates with a new boundary
condition based on the mechanical equilibrium. The solutions show that NDAF is significantly thick. The Bernoulli parameter
and neutrino trapping are determined by the mass accretion rate and the viscosity parameter. According to the distribution
of the Bernoulli parameter, the possible outflow may appear in the outer region of the disk. The neutrino trapping can essentially
affect the neutrino radiation luminosity. The vertical structure of NDAF is like a “sandwich”, and the multilayer accretion
may account for the flares in gamma-ray bursts. 相似文献
The DArk Matter Particle Explorer(DAMPE),also known as Wukong in China,which was launched on 2015 December 17,is a new high energy cosmic ray and γ-ray satellite-borne observatory.One of the main scientific goals of DAMPE is to observe Ge V-Te V high energy γ-rays with accurate energy,angular and time resolution,to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays,it is challenging to identify γ-rays with sufficiently high efficiency,minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations,using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at~10 Ge V amounts to less than 1% of the selected sample.Finally,we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar. 相似文献
Fast radio bursts(FRBs) are bright radio pulses from the sky with millisecond durations and Jansky-level flux densities. Their origins are still largely uncertain. Here we suggest a new model for FRBs. We argue that the collision of a white dwarf with a black hole can generate a transient accretion disk, from which powerful episodic magnetic blobs will be launched. The collision between two consecutive magnetic blobs can result in a catastrophic magnetic reconnection, which releases a large amount of free magnetic energy and forms a forward shock. The shock propagates through the cold magnetized plasma within the blob in the collision region, radiating through the synchrotron maser mechanism,which is responsible for a non-repeating FRB signal. Our calculations show that the theoretical energetics, radiation frequency, duration timescale and event rate can be very consistent with the observational characteristics of FRBs. 相似文献