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1.
Six solar flares were detected by the AVS-F apparatus onboard the CORONAS-F satellite in January 2005. We discuss the temporal profiles and energy spectra of the solar flares of January 20, 17, and 15, 2005 (class X7.1, X3.8, and X2.6, respectively) on the AVS-F data. The active region NOAA 10720 was the source of these flares. The spectra of the flares of January 17 and 20, 2005 contain nuclear lines, a positron line, and a line due to neutron capture line, while only the positron and neutron capture lines can be identified in the spectrum of the flare of January 15, 2005. The spectral features corresponding to these lines were observed during the whole duration of the flares. Analysis of the temporal profile of the flare of January 20, 2005 with a 1-ms temporal resolution in the energy range 0.1–20 MeV reveals the presence of a thin structure (at the 99% confidence level) with typical timescales of 7 to 35 ms.  相似文献   

2.
１９９６年１月～１９９８年３月,我们用光电方法测定了丽江高美古在Ｂ、Ｖ两个波段的夜天光亮度。为便于比较,在１９９６年１月还测定了云南天文台凤凰山台址的夜天光亮度。本文给出了观测结果,同时也列出了世界上一些天文台站的数据以供参考。  相似文献   

3.
In this work an analysis of a series of complex cosmic ray events that occurred between 17 January 2005 and 23 January 2005 using solar, interplanetary and ground based cosmic ray data is being performed. The investigated period was characterized both by significant galactic cosmic ray (GCR) and solar cosmic ray (SCR) variations with highlighted cases such as the noticeable series of Forbush effects (FEs) from 17 January 2005 to 20 January 2005, the Forbush decrease (FD) on 21 January 2005 and the ground level enhancement (GLE) of the cosmic ray counter measurements on 20 January 2005. The analysis is focusing on the aforementioned FE cases, with special attention drawn on the 21 January 2005, FD event, which demonstrated several exceptional features testifying its uniqueness. Data from the ACE spacecraft, together with GOES X-ray recordings and LASCO CME coronagraph images were used in conjunction to the ground based recordings of the Worldwide Neutron Monitor Network, the interplanetary data of OMNI database and the geomagnetic activity manifestations denoted by K p and D st indices. More than that, cosmic ray characteristics as density, anisotropy and density gradients were also calculated. The results illustrate the state of the interplanetary space that cosmic rays crossed and their corresponding modulation with respect to the multiple extreme solar events of this period. In addition, the western location of the 21 January 2005 solar source indicates a new cosmic ray feature, which connects the position of the solar source to the cosmic ray anisotropy variations. In the future, this feature could serve as an indicator of the solar source and can prove to be a valuable asset, especially when satellite data are unavailable.  相似文献   

4.
We present a few newly found old sunspot observations from the years AD 1708, 1709, and 1710, which were obtained by Peter Becker from Rostock, Germany. For 1709, Becker gave a detailed drawing: he observed a sunspot group made up of two spots on January 5, 6, and 7, and just one of the two spots was observed on January 8 and 9. We present his drawing and his explanatory text. We can measure the latitude and longitude of these two spots and estimate their sizes for all five days. While the spots and groups in 1708 and the spot on four of the five days in January 1709 were known before from other observers (e.g. Hoyt & Schatten 1998), the location of the spots in early January 1709 were not known before, so that they can now be considered in reconstructed butterfly diagrams. The sunspots detected by Becker on 1709 January 5 and 1710 September 10 were not known before at all, as the only observer known for those two dates, La Hire, did not detect that spot (group). We estimate new group sunspot numbers for the relevant days, months, and years. The time around 1708–1710 is important, because it documents the recovery of solar activity towards the end of the Maunder Grand Minimum. We also show two new spot observations from G. Kirch for 1708 September 13 and 14 as described in his letter to Wurzelbaur (dated Berlin AD 1708 December 19). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

5.
The sunspot drawing by Peter Becker for 1709 January 5–7 and just one of the two spots was left on January 8 (see R. Neuhäuser et al., this issue, p. 623). (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

6.
１９９６年１月～１９９８年３月,我们用光电方法测定了丽江高美古在Ｂ、Ｖ两个波段的大气消光系数。为便于比较,在１９９６年１月还测定了云南天文台凤凰山台址的大气消光系数。本文给出了观测结果,同时也列出了世界上一些天文台站的数据以供参考。  相似文献   

7.
Solar circumstances have been evaluated for January 28, 1967, the date of an observed ground level enhancement of cosmic rays which was not preceded by observation of a suitably great Hα flare. On the visible solar hemisphere, a bright subflare at S23° E19° occurred in appropriate time association with the cosmic ray event, and was accompanied by weak X-ray enhancement and radio frequency emission. If this flare, alone, or in combination with other minor flares observed on the visible hemisphere on January 28 was the source of the energetic cosmic rays recorded on that date, then current thinking regarding the characteristics of cosmic ray flares must be modified. An initial study of probable circumstances on the invisible hemisphere did not lead to the immediate recognition of amajor center of activity as the probable source of a cosmic ray flare. Further evaluation of all centers of activity on the invisible hemisphere identified one region, McMath Plage No. 8687, 64° beyond the west limb, as the most plausible, possible site for the cosmic ray flare on January 28, 1967. The location of this region is in accord with the source-position deduced in Lockwood's analysis (1968) of the cosmic ray event. This center of activity could not have been more than 5 days old on January 28, 1967. The interval of major activity in the region was confined primarily to the invisible hemisphere. The occurrence of an ‘isolated’ major flare in the region on February 13, 1967 is discussed. The present study exemplifies the partial nature of solar observations which are limited to the visible hemisphere. The possible role of exceptional geomagnetic calm, 1963–1967, in permitting atypical cosmic ray enhancements, as on January 28, 1967, is mentioned.  相似文献   

8.
The results of photometric observations of the optical component of the known variable radio source Z0524+03 are reported. The light variations amounted to 1.5 m during the period from January 21, 1998 to January 28, 2001 and occurred synchronously in the BVRI bands on time scales ranging from several years to 0.05 days. The spectral index of the object (S ～ ν α) varied from ?2.4 to ?1.3 from minimum to maximum light.Polarimetric observations made on January 22/23, 1999 showed that the linear polarization of the radiation of the object did not exceed 1% at the time of observation.Three local-standard candidates have been selected in the field of the object.  相似文献   

9.
High-resolution, time-resolved spectroscopic observations of Z CMa carried out on 1997 January 14–17 are presented. Large night-to-night and hour-to-hour variations in Hα, Hβ and Na i D P Cygni absorptions, as well as an Hβ emission peak, were observed. Variations in the red wings of the hydrogen emission lines were also detected. The high-velocity wide-emission component on the blue side of Hα appeared on January 17. The observations are discussed in the framework of current wind models.  相似文献   

10.
We report on multi-epoch X-ray observations of the Type IIn (narrow emission line) Supernova (SN) 1995N with the ROSAT and ASCA satellites. The 1998 January ASCA X-ray spectrum is well fitted by a thermal bremsstrahlung         or power-law         model. The X-ray light curve shows evidence for significant flux evolution between 1996 August and 1998 January: the count rate from the source decreased by 30 per cent between our 1996 August and 1997 August ROSAT observations, and the X-ray luminosity most likely increased by a factor of ∼2 between our 1997 August ROSAT and 1998 January ASCA observations, although evolution of the spectral shape over this interval is not ruled out. The high X-ray luminosity,     places SN 1995N in a small group of Type IIn supernovae with strong circumstellar interaction, and the evolving X-ray luminosity suggests that the circumstellar medium is distributed inhomogeneously.  相似文献   

11.
David Morrison 《Icarus》1975,26(1):111-123
Visual estimates of total coma brightness define the light curve of Comet Kohoutek between November 24, 1973 and February 6, 1974. These data are well fitted by straight lines on the M-log r diagram. The preperihelion value of n is 2.2, and the post perihelion value is 3.8 up to January 16. A standstill in the decline is suspected between January 16 and 19. If the standstill is ignored the postperihelion data can be fitted less precisely by a single line with n = 3.3. From photoelectric measures on four nights between January 5 and 13 after perihelion, n is found to be 4.1.The average B-V with a 32.4 arc sec diaphragm for those four nights is 0.79 ± 0.04; no clear systematic variation with time is noted.  相似文献   

12.
Distribution, over the lunar age, of the frequency of occurrence of the afternoon counter-electrojet events at Trivandrum during the period 1959–1978 is examined in each of the calendar months. A strong lunar modulation on the occurrence frequency is seen in January; this may be related to the global enhancement of the lunar tide during January. The modulation is also prominent in April, although 62% of the events in that month occur irrespective of the lunar age. The occurrence frequency at Trivandrum appears to be least influenced by the Moon in the northern summer months.  相似文献   

13.
A noise storm center clearly associated to an active center has been followed from January 2 to January 8, 1969. The study of the mean distribution of continuum and of type 1 bursts has shown a global and systematic displacement interpreted in terms of the coronal magnetic structure. This structure is formed by field lines connecting the active center to a stable region of inverse polarity, characterized by the existence of a coronal condensation. These results show the possibility of using this method for the systematic study of coronal magnetic structures, the knowledge of which is vital as far as the problems of particle propagation in the corona and in the interplanetary medium are concerned.  相似文献   

14.
The brightness temperature of 433 Eros was less than 460°K during the close opposition in January 1975.  相似文献   

15.
We have monitored the X-ray source X-Per (4U 0352+30) on 31 August, 1979 through aU filter for about 1.5 hr using 102-cm telescope of Kavalur observatory. During this period intensity of X-Per fluctuated for some time, on time scales of few minutes but recovered in the end. It was again monitored from 27 December, 1979 to January 1980 through a standardU, B, V photometer attached to a 34-cm telescope. In this paper we present the data on the fast flickerings observed on 31 August, 1979 and on the long term monitoring from December 1979 to January 1980.  相似文献   

16.
The global mean vertical energy flux of the (1,1,1) mode of atmospheric oscillation is evaluated at 80 km altitude by classical tidal theory for mean January, April, July and October conditions using revised profiles of water vapour and ozone heating. Fluxes calculated for January and July are lower than those for April and October due to seasonal changes in water vapour, solar declination and Sun-Earth distance. Flux values obtained are compared with a previously stated requirement for maintaining the residual thermosphere and are adequate unless damping, which is ignored in the present calculations, introduces a factor of more than an order of 10 in magnitude. The relative changes of flux between the above four months are noted to be similar in form to the semi-annual variation of thermospheric air densities.  相似文献   

17.
The orbit of 1970-47B passed very slowly through 14th-order resonance, and the changes in orbital inclination and eccentricity have been analysed over a 4-year period, from January 1977 to January 1981, using 208 U.S. Navy orbits. The analysis has yielded values for three pairs of lumped harmonic coefficients of 14th order, which have accuracies equivalent to 0.4, 1.5 and 2.0 cm in geoid height. Three pairs of values of 28th-order lumped harmonic coefficients were also obtained, and the best of these has a standard deviation (S.D.) corresponding to an accuracy of 0.7 cm in geoid height. The lumped harmonic coefficients have been compared with the corresponding values from the latest geopotential models, and agreement is satisfactory.  相似文献   

18.
The phenomenon of post-flare coronal arches, initially discovered with the Hard X-Ray Imaging Spectrometer (HXIS), was investigated using observations made with the SMM Flat Crystal Spectrometer (FCS) on 20 through 23 January, 1985. Since these observations were made with a different type of instrument from HXIS, they provide independent information on the physical characteristics of the arch phenomenon and extend our knowledge to lower coronal temperatures.Conspicuous arch activity was observed after three flares and after a disturbance which could not be identified. (1) A dynamic flare starting on 20 January at 20: 39 UT was responsible for the formation of the primary arch structure. (2) An arch revival, showing characteristics very similar to those of the arch revivals observed with HXIS, took place after the dynamic flare starting on 21 January at 23: 50 UT. The most conspicious difference relates to the moving thermal disturbance observed very shortly after the onset of the parent flare, in particular to its propagation velocity. This difference in the arch revival is probably related to the different range of plasma temperatures covered by the FCS observations (3 × 106 K through 6 × 106 K) and the HXIS observations (>107 K) and the consequently more important effects of radiative cooling in the FCS arch revival. (3) More arch activity was observed after a (possibly dynamic) flare starting at 03: 40 UT on 21 January and (4) after an unidentified event with estimated time of occurrence near 23: 00 UT on 22 January. Similar to the arch revival, this activity was primarily characterized by the energization of (i.e., input of energy to) a pre-existing arch structure. The activity after the unidentified event suggests the existence of a mode of arch activation which is different from the typical flare-associated revival and is characterized by the absence of significant activity at chromospheric levels.  相似文献   

19.
29 fine time structures (FTS) are found in 103 radio bursts observed with YRSOS of high temporal resolution of 1 ms at 4 frequencies (1.42, 2.00 (or2.13), 2.84 and 4.00 (or 4.26) GHz) from January 1990 to January 1994. The various morphologies of FTSs occurring in different phases of flares and the different FTS in the same event may reflect the transitional property of the low-frequency microwave bursts. Most FTSs are probably consisted with the four characteristics observed previously in literatures. The typical and representative events of FTSs and occurrence frequency of each kind are presented in order to explain the multiplicity, breadth and observational characteristics of FTSs in the range of long centimeter to short decimeter wavelengths. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

20.
The variations of line profiles in the spectrum of FU Ori during several consecutive nights, from January 3 through January 8, 1999, have been traced for the first time in the entire history of studying this star. The variations of the Hα and Na I D line profiles are regular in pattern; at each time, the profiles of these lines were similar to a particular profile observed previously, suggesting that the phenomenon is periodic. We argue that the profile variations result from the axial rotation of the inner accretion-disk and disk-wind regions for which the temperature distribution and the wind-streamline orientation are not axisymmetric. The cause of the asymmetry could be the interaction of circumstellar matter with the stellar magnetic field if the magnetic axis is greatly inclined to the rotation axis. The possible binary nature of FU Ori seems a less likely cause of the asymmetry.  相似文献   

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