A tilt-correction adaptive optical system installed on the 430 mm Solar Telescope of Nanjing University has been put in operation. It consists of a tip-tilt mirror, a correlation tracker and an imaging CCD camera. An ...A tilt-correction adaptive optical system installed on the 430 mm Solar Telescope of Nanjing University has been put in operation. It consists of a tip-tilt mirror, a correlation tracker and an imaging CCD camera. An absolute difference algorithm is used for detecting image motion in the correlation tracker. The sampling frequency of the system is 419 Hz. We give a description of the system's configuration, an analysis of its performance and a report of our observational results. A residual jitter of 0.14 arcsec has been achieved. The error rejection bandwidth of the system can be adjusted in the range 5-28 Hz according to the beacon size and the strength of atmospheric turbulence.展开更多
We analyze oscillation behaviours in chromospheric internetwork regions using spectral observations of the C<SUB>II</SUB> 1334 ? line obtained with the Solar Ultraviolet Measurements of Emitted Radiation s...We analyze oscillation behaviours in chromospheric internetwork regions using spectral observations of the C<SUB>II</SUB> 1334 ? line obtained with the Solar Ultraviolet Measurements of Emitted Radiation spectrograph (SUMER) aboard Solar and Heliospheric Observatory (SOHO). Three areas, 26×120arcsec<SUP>2</SUP> each, at the various latitudes from the disk center to the north polar coronal hole, were rastered with a cadence of about 40–60 s in the solar minimum year. We obtained the time evolution of two-dimensional (2D) line intensity, continuum and line core shift. The continuum and the line shift show ~3 min chromospheric oscillations in the internetwork regions underlying the coronal hole as well as at the disk center. We find that the C<SUB>II</SUB> 1334 ? line shift oscillates with an average speed of ~1.7km<SUP>-1</SUP>, independent of the latitude, while its coherent scale decreases with latitude. On the other hand, the oscillation amplitude of the continuum around the 1334 ? and the phase delay between the Doppler shift and continuum slightly increase with latitude.展开更多
基金Supported by the National Natural Science Foundation of China
文摘A tilt-correction adaptive optical system installed on the 430 mm Solar Telescope of Nanjing University has been put in operation. It consists of a tip-tilt mirror, a correlation tracker and an imaging CCD camera. An absolute difference algorithm is used for detecting image motion in the correlation tracker. The sampling frequency of the system is 419 Hz. We give a description of the system's configuration, an analysis of its performance and a report of our observational results. A residual jitter of 0.14 arcsec has been achieved. The error rejection bandwidth of the system can be adjusted in the range 5-28 Hz according to the beacon size and the strength of atmospheric turbulence.
基金Supported by the National Natural Science Foundation of China.
文摘We analyze oscillation behaviours in chromospheric internetwork regions using spectral observations of the C<SUB>II</SUB> 1334 ? line obtained with the Solar Ultraviolet Measurements of Emitted Radiation spectrograph (SUMER) aboard Solar and Heliospheric Observatory (SOHO). Three areas, 26×120arcsec<SUP>2</SUP> each, at the various latitudes from the disk center to the north polar coronal hole, were rastered with a cadence of about 40–60 s in the solar minimum year. We obtained the time evolution of two-dimensional (2D) line intensity, continuum and line core shift. The continuum and the line shift show ~3 min chromospheric oscillations in the internetwork regions underlying the coronal hole as well as at the disk center. We find that the C<SUB>II</SUB> 1334 ? line shift oscillates with an average speed of ~1.7km<SUP>-1</SUP>, independent of the latitude, while its coherent scale decreases with latitude. On the other hand, the oscillation amplitude of the continuum around the 1334 ? and the phase delay between the Doppler shift and continuum slightly increase with latitude.
