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501.
502.
Rodolfo Gustavo Cionco Rosa Hilda Compagnucci 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The planetary hypothesis of the solar cycle is an old idea in which the gravitational influence of the planets has a non-negligible effect on the causes of the solar magnetic cycle. The advance of this hypothesis is based on phenomenological correlations between dynamical parameters of the Sun’s movement around the barycentre of the Solar System and sunspots time series; and more especially, identifying relationships linking solar barycentric dynamics with prolonged minima (especially Grand Minima events). However, at present there is no clear physical mechanism relating these phenomena. The possible celestial influence on solar cycle modulation is of great importance not only in solar physics but also in Earth sciences, because prolonged solar minima have associated important climatic and telluric variations, in particular, during the Maunder and Dalton Minimum. In this work we looked for a possible causal link in relation with solar barycentric dynamics and prolonged minima events. We searched for particular changes in the Sun’s acceleration and concentrated on long-term variations of the solar cycle. We show how the orbital angular momentum of the Sun evolves and how the inclination of the solar barycentric orbit varies during the epochs of orbital retrogressions. In particular, at these moments, the radial component of the Sun’s acceleration (i.e., in the barycentre-Sun direction) had an exceptional magnitude. These radial impulses occurred at the very beginning of the Maunder Minimum, during the Dalton Minimum and also at the maximum of cycle 22 before the present extended minimum. We also found a strong correlation between the planetary torque and the observed sunspots international number around that maximum. We apply our results in a novel theory of Sun–planets interaction that it is sensitive to Sun barycentric dynamics and found a very important effect on the Sun’s capability of storing hypothetical reservoirs of potential energy that could be released by internal flows and might be related to the solar cycle. This process begins about 40 years before the solar angular momentum inversions, i.e., before Maunder Minimum, Dalton Minimum, and before the present extended minimum. Our conclusions suggest a dynamical characterization of peculiar prolonged solar minima. We discuss the possible implications of these results for the solar cycle including the present extended minimum. 相似文献
503.
M.V. Sunil Krishna Vir Singh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
A comprehensive model is developed to study the atomic oxygen OI 8446 Å dayglow emission. The emission rate profiles and intensities are obtained using the recently developed Solar2000 EUV (Extreme Ultra Violet) flux model. These emission profiles are used to construct the morphology of the 8446 Å emission between equator and 45°N in the northern hemisphere. The longitudinal variation of 8446 Å dayglow emission is found about 5% and is not included in the presentation of morphology. A span of five years is chosen to study the effect of varying solar activity on the morphology of the OI 8446 Å dayglow emission. The morphology is studied on April 3 which lies under the equinox conditions. In year 2001 the solar F10.7 index on the chosen date was as high as 223.1 which is the case of solar maximum. From the present calculations it is found that the intensity does not vary linearly with the F10.7 solar index. The morphology shows that the region of maximum emission rate expands towards the higher latitudes as F10.7 solar index increases. The similar effects have also been found in the morphology of 7320 Å dayglow emission (Sunil Krishna and Singh, 2009). The similarities in the morphology of 7320 Å and 8446 Å dayglow emissions further suggest that the photoelectron flux has strong bearing on the production of these emissions. 相似文献
504.
Bernardo Vargas Cárdenas José F. Valdés-Galicia 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
We performed a search for ground level solar cosmic ray enhancements on the full five minute database of the Mexico City neutron monitor using wavelet filters and two different statistical tests. We present a detailed analysis of the time series of November 2, 1992, where we found a previously unreported increment matching the onset time of the impulsive phase of GLE 54, thus providing evidence of an effective detection of high energy solar cosmic rays. 相似文献
505.
G. Facskó J.G. Trotignon I. Dandouras E.A. Lucek P.W. Daly 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
Hot flow anomalies (HFAs) were first discovered in the early 1980s at the bow shock of the Earth. In the 1990s these features were studied, observed and simulated very intensively and many new missions (Cluster, THEMIS, Cassini and Venus Express) focused the attention to this phenomenon again. Many basic features and the HFA formation mechanism were clarified observationally and using hybrid simulation techniques. We described previous observational, theoretical and simulation results in the research field of HFAs. We introduced HFA observations performed at the Earth, Mars, Venus and Saturn in this paper. We share different observation results of space mission to give an overview to the reader. 相似文献
506.
E.E. Benevolenskaya Yu.D. Ponyavin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The SOHO/MDI data provide the uniform time series of the synoptic magnetic maps which cover the period of the cycle 23 and the beginning of the cycle 24. It is very interesting period because of the long and deep solar minimum between the cycles 23 and 24. Synoptic structure of the solar magnetic field shows variability during solar cycles. It is known that the magnetic activity contributes to the solar irradiance. The axisymmetrical distribution of the magnetic flux (Fig. 3c) is closely associated with the ‘butterfly’ diagram in the EUV emission (Benevolenskaya et al., 2001). And, also, the magnetic field (B∥) shows the non-uniform distributions of the solar activity with longitude, so-called ‘active zones’, and ‘coronal holes’ in the mid-latitude. Polar coronal holes are forming after the solar maxima and they persist during the solar minima. SOHO/EIT data in the emission of Fe XII (195 Å) could be a proxy for the coronal holes tracking. The active longitudinal zones or active longitude exist due to the reappearance of the activity and it is clearly seen in the synoptic structure of the solar cycle. On the descending branch of the solar cycle 23 active zones are less pronounced comparing with previous cycles 20, 21 and 22. Moreover, the weak polar magnetic field precedes the long and deep solar minimum. In this paper we have discussed the development of solar cycles 23 and 24 in details. 相似文献
507.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(7):1843-1851
Accurate measurements of the solar differential rotation parameters are necessary for understanding the solar dynamo mechanism. We use the orthogonalization process to estimate these parameters. The advantage of the orthogonalization of the data in the tracer motion statistical analysis is outlined. The differential rotation is represented in terms of various types of polynomials. We compare the quality of a set of models of the solar differential rotation using the Akaike information criterion and choose the best one. Applying the proposed method, we studied the solar differential rotation and its North-South asymmetry using observations of coronal holes. A statistical analysis of observations from the Atmospheric Imaging Assembly (AIA) on Solar Dynamics Observatory (SDO) reveals the differential rotation pattern of coronal holes and its North-South asymmetry. 相似文献
508.
P. Pappa Kalaivani O. Prakash Li Feng A. Shanmugaraju Liu-Guan Ding Lei Lu Weiqun Gan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3390-3403
We have established a data set of 58 major hybrid SEP events associated with meter-to-decahectometer wavelength (m-to-DH) type II bursts, solar flares, and radio-load CMEs during the period of 1997–2014. The main focus of our study is to address the following two questions: Does the interaction of CMEs play a role in the enhancement of SEP intensity? Is there any difference in the seed population, and parent eruptions in the SEP events with and without CME interactions? Hence, the sample of 58 events is classified into two sets: (i) 35 non-interacting-CME-associated SEP events; (ii) 23 interacting-CME-associated SEP events. All the characteristics of SEPs, their associated CMEs/flares and the relationships between them are statistically analyzed and compared. Some of the basic attributes and relative elemental abundances (Fe/O ratios) of the both the sets are also compared. The results indicate that the seed particles in non-interacting-CME-associated SEP events are mostly from solar wind/coronal materials. But in the case of interacting-CME-associated SEP events, it may be associated with both flare material from preceding flares and coronal materials from solar wind/preceding CMEs. The correlation studies reveal that there are clear correlations between logarithmic peak intensity of SEP events and properties of CMEs (space speed: cc?=?0.56) and solar flares (peak intensity: cc?=?0.40; integrated flux: cc?=?0.52) for non-interacting-CME-associated SEP events. But these correlations are absent for the interacting-CME-associated events. In addition, the results suggest that interaction of primary CMEs with their preceding CMEs plays an important role in the enhancement of peak intensity of SEPs at least for a set of m-to-DH type II bursts associated SEP events. 相似文献
509.
Alessia De Iuliis Francesco Ciampa Leonard Felicetti Matteo Ceriotti 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(9):2795-2811
Literature on solar sailing has thus far mostly considered solar radiation pressure (SRP) as the only contribution to sail force. However, considering a sail in a planetary mission scenario, a new contribution can be added. Since the planet itself emits radiation, this generates a radial planetary radiation pressure (PRP) that is also exerted on the sail. Hence, this work studies the combined effects of both SRP and PRP on a sail for two case studies, i.e. Earth and Venus. In proximity of the Earth, the effect of PRP can be significant under specific conditions. Around Venus, instead, PRP is by far the dominating contribution. These combined effects have been studied for single- and double-sided reflective coating and including eclipse. Results show potential increase in the net acceleration and a change in the optimal attitude to maximise the acceleration in a given direction. Moreover, an increasing semi-major axis manoeuvre is shown with and without PRP, to quantify the difference on a real-case scenario. 相似文献
510.
Xiyao Huang Xiangyuan Zeng Christian Circi Giovanni Vulpetti Dong Qiao 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(9):2613-2627
The deformation of the solar-sail membrane is an important factor for causing inaccuracies in the solar-sail missions. This paper describes the solar sail under deformation by using a new modelling technique based on point cloud and triangular mesh generation. Two types of deformation, stemming from wrinkling and billowing, are modelled. The changes in the solar radiation pressure force and the moment caused by deformation are calculated and compared to the ideal non-deformed case. The heliocentric spiral trajectory and the orbital angular momentum reversal trajectory are taken as examples to quantify the influence of the deformation from an orbit point of view. Additionally, point cloud simplification, based on the normal vector and bounding box, is utilized to simplify the original deformed-sail model. It involves a reasonable reduction and renewal of the points in the model considering the variation of surface curvature. The simplification and its modelling accuracy are numerically investigated as well as computational efficiency. 相似文献