We studied the evolution of five active regions (ARs) where strong X-class flares occurred in 2011 – 2012 (NOAA ARs 11158, 11166, 11263, 11283 and 11520). Our study focuses on the pre-flare phase of ...these ARs (during a few days before the flare) to reveal features in the microwave radiation and magnetic-field characteristics of the ARs that indicate that a powerful flare is about to take place. One well-developed AR (NOAA AR 11654) that did not produce large flares was also studied. We used daily multiwavelength spectral-polarization solar observations in the range of 1.65 – 6.0 cm made with the RATAN-600 radio telescope and data obtained by the
Solar Dynamics Observatory/Helioseismic and Magnetic Imager
(SDO/HMI). Whenever X-class flares occurred, we found that a new compact microwave source developed that was associated with the neutral line of the photospheric magnetic field (neutral line associated source – NLS) above the place with highest gradient of magnetic field. In some cases this became predominant in radio emission of the AR one to two days before a large flare. No such source was detected in AR without a powerful flare. An analysis of magnetic-field characteristics of sunspots (based on SDO/HMI data) showed that the large X-flares we investigated occurred in ARs with high magnetic flux (∼ 10
22
Mx) and with an increasing magnetic-field gradient. We first identified the positions of the developing microwave source (NLS) with the location of the large flare that was registered in the AR one to two days later. Radio characteristics and dynamics of NLS detected before large flares possibly reflect the place in the corona where the energy for flaring is stored. Thus, an early detection of a rapidly developing microwave source NLS and an increasing magnetic-field gradient can be used as a factor in predicting large flares.
This paper considers latest highlights in simultaneous and follow-up optical observations of high energy astrophysical phenomena by MASTER Global Robotic Net. Such extreme Universe sources includes ...gamma-ray bursts, gravitational wave events, detected by LIGO/Virgo, fast radio bursts, high energy neutrino sources and others. Some of the neutrinos detected by ground-based facilities owe their births to supermassive black holes – blazars, which are in a special anxious state with high statistical reliability. We discovered the effect of a rapid decrease in the brightness of the blazar PKS 0735+17 at the time of the multiple detection of the high-energy neutrino event IceCube-211208A. This decrease in brightness within several hours was detected with a high confidence (SNR 10) in comparison with a multi-day brightening state of the blazar, which was accompanied not only by a maximum increase in the average brightness, but also by an increase in the amplitude of its brightness fluctuations. Additionally, we analyzed all cases of successful observation of blazars around neutrino events and obtained statistically reliable indications of the relationship between neutrino events and optical activity of blazars in the doubled error box at the 4.2
level.
Asymmetry in the form of solar spots Illarionov, E. A.; Tlatov, A. G.
Geomagnetism and Aeronomy,
12/2016, Letnik:
56, Številka:
8
Journal Article
Recenzirano
We have analyzed the geometric characteristics of sunspots. The form of sunspots has been studied by sunspot image normalization to obtain the average profile of spots and the profile relative to the ...position of cores. The deviation of the sunspot form from the axisymmetric configuration has been studied. We have found that the spots of leading and trailing polarities have a drop shape. The cores of leading and trailing sunspots are shifted toward the western and eastern edges of the photosphere–penumbra boundary, respectively. The strength of the magnetic field of the cores of leading spots in the eastern hemisphere exceeds the field strength in the western hemisphere. We considered the tilt of the form of sunspots as a function of size. The form of spots of a large area (
S
> 1000 ppm of solar hemisphere) is elongated along the magnetic axis of the bipole of a group of sunspots.
We present the results of the prompt, early and afterglow optical observations of five gamma-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations ...were made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the Sierra Nevada Observatory and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before the cessation of gamma-ray emission, at 113 and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted in two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. A more detailed analysis of GRB 100901A and GRB 100906A, supplemented by Swift data, provides the following results and indicates different origins for the prompt optical radiation in the two bursts. The light-curve patterns and spectral distributions suggest that there is a common production site for the prompt optical and high-energy emission in GRB 100901A. The results of the spectral fits for GRB 100901A in the range from optical to X-ray favour power-law energy distributions and a consistent value of the optical extinction in the host galaxy. GRB 100906A produced a smoothly peaking optical light curve, suggesting that the prompt optical radiation in this GRB originated in a front shock. This is supported by a spectral analysis. We have found that the Amati and Ghirlanda relations are satisfied for GRB 100906A. We obtain an upper limit on the value of the optical extinction on the host of GRB 100906A. PUBLICATION ABSTRACT
The results of the work of the global observation network are considered, and a comparative analysis of the data of various coronal observatories is performed. The coronal activity index has been ...reconstructed for the period 1939–2016 based on the data of various observatories in Kislovodsk system. For this purpose, the corona daily intensity maps from the Sacramento Peak and Lomnický Štít observatories according to the Solar-Geophysical Data journal have been digitized; they supplement the data of other observatories. The homogeneity and continuity of the corona observations at the Kislovodsk station, including activity cycle 24, is confirmed. Unfortunately, the only observatory at present that continues observation of the spectral corona in Fe XIV 5303 Å and Fe XIV 6374 Å lines is the Kislovodsk astronomical station Mountain Astronomical Station (MAS) of the Central Astronomical Observatory, Russian Academy of Sciences (Pulkovo). The data on the combined corona in 5303 Å line are analyzed. It is shown that there is a high correlation of the intensity index of green corona with solar radiation measurements in the vacuum UV region. Data on the beginning of the new 25th activity cycle in the corona at high latitudes are presented.
There is a need today to recreate the Havana observational solar station because of the importance of obtaining a regular forecast of solar activity in a wide range of time intervals. The concept of ...the created observation network and the infrastructure of the monitoring station as a network element are described in detail. The functions of this network will provide continuous observational material for the Russian Sun and Space Weather Services and will be independent of space observations, but capable of using them for quality control. The physical foundations of complex observations for a wide range of heliogeophysical phenomena are considered.
We investigate the magnetic fields and total areas of mid- and low-latitude sunspots based on observations at the Greenwich and Kislovodsk (sunspot areas) and Mount Wilson, Crimean, Pulkovo, Ural, ...IMIS, Ussuriysk, IZMIRAN, and Shemakha (magnetic fields) observatories. We show that the coefficients in the linear form of the dependence of the logarithm of the total sunspot area
S
on its maximum magnetic field
H
change with time. Two distinct populations of sunspots are identified using the twodimensional
H
–log
S
occurrence histogram: small and large, separated by the boundaries log
S
= 1.6 (
S
= 40 MSH) and
H
= 2050 G. Analysis of the sunspot magnetic flux also reveals the existence of two lognormally distributed populations with the mean boundary between them Φ = 10
21
Mx. At the same time, the positions of the flux occurrence maxima for the populations change on a secular time scale: by factors of 4.5 and 1.15 for small and large sunspots, respectively. We have confirmed that the sunspots form two physically distinct populations and show that the properties of these populations change noticeably with time. This finding is consistent with the hypothesis about the existence of two magnetic field generation zones on the Sun within the framework of a spatially distributed dynamo.
The parameter
G
, which is determined from the general number of sunspots groups
N
g
according to the daily observations
G
=∑(1/
N
g
)
2
, is offered. This parameter is calculated for the days when ...there is at least one sunspots group. It characterizes the minimum epoch solar activity. Parameter
G
mounts to the maximum during the epoch close to the minimal activity of sunspots. According to the data of the sequence of sunspots group in Greenwich–USAF/NOAA observatory format, observation data of Kislovodsk solar station and also daily Wolf number, the changes of parameter
G
during 100 years were reconstructed. It is demonstrated in the paper that parameter
G
’s amplitude in minimal solar activity
n
is linked with the sunspot cycle’s amplitude
W
n
+1
or one and half cycles. The 24th activity cycle prediction is calculated, which makes
W
24
=135(±12).
The preliminary results of solar filaments distinguished in daily H-alpha observations at Kodaikanal (1912–2002) are presented. To mark the boundaries of solar filaments, methods based on automated ...procedures of marking low-contrast objects on the solar disk, as well as editing of the marked boundaries in a semiautomated manner, were developed. The characteristics of solar filaments were analyzed. Latitudinal diagrams of filaments number in 15–23 activity cycles were constructed. As is shown, one maximum in the filament latitudinal distribution may be clearly distinguished during activity cycles in both hemispheres. This maximum is located slightly higher (θ ~ 25°–30°) than the sunspot distribution maximum (θ ~ 14°–17°). However, there are no other local maxima related to the zonal structure of the large-scale magnetic field (Makarov and Sivaraman, 1989).
•For GRB100906A, GRB110422A, GRB121011A the dimensionless Stokes parameter is obtained.•The polarization of SN 2012bh at the early stage of the envelope expansion was <3%.•Polarization measurements ...for the blazars OC 457, 3C 454.3 are presented.•Polarization degree for the blazars QSOB1215+303, 87GB 165943.2+395846 are presented.•MASTER telescopes can safely register linear polarization in excess of 10%.
We present results of optical polarization observations performed with the MASTER robotic net (Lipunov et al., 2004, 2010; Kornilov et al., 2012) for three types of objects: gamma-ray bursts, supernovae, and blazars. For the gamma-ray bursts GRB100906A, GRB110422A, GRB121011A, polarization observations were obtained Shift during very early stages of optical emission. For GRB100906A it was the first prompt optical polarization observation in the world. Photometry in polarizers is presented for Type Ia Supernova 2012bh during 20days, starting on March 27, 2012. We find that the linear polarization of SN 2012bh at the early stage of the envelope expansion was less than 3%. Polarization measurements for the blazars OC 457, 3C 454.3, QSO B1215+303, 87GB 165943.2+395846 at single nights are presented. We infer the degree of the linear polarization and polarization angle. The blazars OC 457 and 3C 454.3 were observed during their periods of activity. The results show that MASTER is able to measure substantially polarized light; at the same time it is not suitable for determining weak polarization (less than 5%) of dim objects (fainter than 16m). Polarimetric observations of the optical emission from gamma-ray bursts and supernovae are necessary to investigate the nature of these transient objects.
PDF
