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1.
The large solar vacuum telescope (LSVT) was designed to study solar phenomenas with high spatial and spectral resolution.
Due to the large size of the telescope, its real spatial resolution may be as high as ≈0.4 arcsec, which makes it possible
to observe fine-structure solar phenomenas like Ellerman bombs and pores. At present, the main subjects of investigation are
solar flares. The LSVT research methods—spectral, spectropolarimetric, and filter—provide valuable information on the physical
parameters in the phenomenas under study. Spectra and images of the Sun are recorded through an birefringent filter by two
CCD cameras. 相似文献
2.
N. M. Firstova 《Solar physics》1984,90(2):269-279
Using the Baranger-Mozer method, we explore the possibility of diagnosing the flare plasma of forbidden Hei lines, that permits the determination of the plasma oscillation frequency and noise level. Examination of the Hei lines observed in solar flare has led us to conclude that:
- the appearance of satellites of forbidden components in the flares spectrum, due to turbulent electric fields, is the most probable for Hei 3819.606 Å lines;
- the Baranger-Mozer method is more sensitive to the high-frequency component of turbulent fields than to the low-frequency ones;
- the upper limit of the turbulent oscillation level in flares is evaluated.
3.
The performance of the optics of the Large Solar Vacuum Telescope (LSVT) and examples of the spectrograms taken with the spectrograph are presented. A new pneumo-mechanical support system for the siderostat mirror and monitoring system of the telescope optics is described. 相似文献
4.
On 2002 July23,a 2B/X4.8 flare was observed in the Hα line spec-tropolarimetrically by the Large Solar Vacuum Telescope of Baikal Astrophysical Observatory.Linear polarization of 3%-10% was detected in the Hα line,particu-larly where the line showed central reversal.The linear polarization is mainly radial on the solar disk and appears at the impulsive phase of the hard X-ray and γ-ray bursts.It is limited to some relatively small regions of the flare.The polarization in a limited small region(～4″-5″）changed its direction within a short period of time(～10s). 相似文献
5.
6.
Astronomy Letters - During our spectropolarimetric observations of the 2B/4.8X flare on July 23, 2002, with the Large Solar Vacuum Telescope (LSVT), we detected impact linear polarization in the... 相似文献
7.
N. M. Firstova V. I. Polyakov V. I. Skomorovsky V. M. Grigoriev 《Geomagnetism and Aeronomy》2009,49(7):927-934
Impact linear polarization in solar flares is studied with the Large Solar Vacuum Telescope (LSVT) using the spectral polarimetric
method. This method makes it possible to minimize the effect of instrumental polarization with an error of up to 10−2 owing to the normalization of the spectral line intensity to the continuum spectrum intensity with negligible linear polarization.
As a result, the Hα line intensity in two orthogonally polarized spectral stripes coincides in the absence of solar polarization.
However, in the presence of linear polarization in a flare, the spectral polarimetric method does not rule out that the error
can be present in determining the Stokes parameters Q and U because of their possible relative “leakage.” Linear instrumental polarization of LSVT has been performed using polaroid
rotation before the major mirror. Twelve elements of a telescope matrix, characterizing linear polarization, have been determined.
The usage of a matrix makes it possible to specify the observed Q and U values accurate to 10−3 of their magnitude. 相似文献
8.
We present the results of studying the impact linear polarization of 32 solar flares of X-ray classes C, M, and X (two flares) observed with the Large Solar Vacuum Telescope. It has turned out that there is evidence for impact polarization only in 13 of them. The newly obtained data have confirmed that the linear Stokes parameters are predominantly 2–7%, while the spatial sizes of flaring points with nonzero Stokes parameters are small (1″-2″). Two features of the manifestation of impact polarization in flares revealed by these studies are of greatest interest: (1) at the two foot points of a single flare loop or an arcade of loops, both the Hα intensity profiles and the Stokes profiles differ in behavior; (2) based on the Hα line, we have found for the first time that the sign of the Stokes parameters changes not only across the flare ribbon but also with depth of the chromosphere. 相似文献
9.
The shapes of the Ca ii H and K lines in sunspot umbral spectra vary from single asymmetric peaks near the centre of the disk to almost symmetric double peaks at the limb. In addition, there are other differences in the behaviour of both H and K lines in sunspots compared to the quiet Sun. The whole complex of the phenomena observed can not be explained by large scale chromosphere motions. Instead, a satisfactory model reproducing in detail peculiarities of the umbral emission reversals contains a cloud of emitting and absorbing gas located above the chromosphere, which flows into the sunspot. The radiation field parameters in such a cloud are consistent with the concept of weak quiescent prominences above the umbra. 相似文献
10.
Skomorovsky V.I. Firstova N.M. Kashapova L.K. Kushtal G.I. Boulatov A.V. 《Solar physics》2001,199(1):37-45
A new two-bandpass birefringent filter has been produced at ISTP, Irkutsk for the investigation of the fine structure of the chromosphere. One filter passband is centered on the Hei 10830 Å line, the second one is centered on H. The FWHM of the Hei 10830 Å passband is 0.46 Å and of the H passband is 0.3 Å. A large number of filtergrams were obtained with the filter at the Sayan observatory. At the same time, spectral observations with high spatial and spectral resolution were carried out by the large solar vacuum telescope at the Baikal Observatory. We selected 29 `dark point' spectra with sizes from 2 to 13, as well as `dark points' on the filtergrams. Comparison of spectrograms and filtergrams has shown a good agreement of their size and intensity in relation with the surrounding chromosphere as well as the absence of primary line-of-sight velocities in both observation types. From spectral observations, the depth of 10830 Å is over 30% for some `dark points', and the FWHM is more than 1 Å. Hei 10830 Å line profiles in `dark points' are more deep and wide than in quiet regions. The optical depth of the chromosphere in `dark points' is estimated. Comparison with the unperturbed chromosphere showed that `dark points' in Hei 10830 Å are more optically thin than the nearby chromosphere. 相似文献