New M-Type Variables in Galactic Dark Clouds

The results of the spectral classification of newly discovered M-type variables obtained as part of an H-alpha survey of Galactic dark cloud regions are presented. The survey was carried out with the 40 Schmidt camera of Byurakan Observatory, and the spectra of the variable stars for the classification were obtained with the Observatory's 2.6-m telescope. The observational material allowed register of late M-type variables as well as their brightness variations. Among the 97 newly discovered M-type stars, 22 show brightness variations. The results of the spectral classification of these new variables show that 21 out of 22 are red giants, and in all probability they are Mira Ceti type long period variables.     

The Solar Flare of November 4, 2001, and Its Manifestations in Energetic Particles from Coronas-F Data

Based on X-ray, gamma-ray, and charged-particle measurements with several instruments onboard the Coronas-F satellite and on ACE and GOES experimental data presented on the Internet, we investigate the parameters of the solar flare of November 4, 2001, and the energetic-particle fluxes produced by it in circumterrestrial space. The increase in relativistic-electron fluxes for about 1.5 days points to a moving source (shock front). The structure of the energetic-particles fluxes in the second half of November 5, 2001, can be explained by the passage of the coronal mass ejection that was ejected on November 1, 2001, and that interacted with the shock wave from the flare of November 4, 2001.     

Photospheric and chromospheric oscillations in the base of coronal holes

In this paper we carry out an analysis of the spatial–temporal line-of-sight velocity variations measured in the chromospheric (H, H) and photospheric (Fei 6569 Å, Fei 4864 Å, Nii 4857 Å) lines at the base of 17 coronal holes. Time series of a duration from 43 to 120 min were recorded with the CCD line-array and the CCD matrix. Rather frequently we observed quasi-stationary upward flows with a measured velocity of up to 1 km s^–1 in the photosphere and up to 4–5 km s^–1 in the chromosphere (equivalent radial velocity of up to 3 km s^–1 and up to 12–15 km s^–1 accordingly) near dark points on the chromospheric network boundary inside polar CH. Line-of-sight velocity fluctuation spectra contain meaningful maxima in the low-frequency region clustering around the values 0.4, 0.75, and 1 mHz. Usually, the spatial localization of these maxima mutually coincides and, in our opinion, coincides with the chromospheric network boundary. Acoustic 3- and 5-min oscillations are enhanced in the coronal hole region and reach 1 km s^–1 in the photosphere and 3–4 km s^–1 in the chromosphere. These oscillations are not localized spatially and are distinguished throughout the entire region observed.     

Common Proper Motion Search for Faint Companions Around Early-Type Field Stars – Progress Report

The multiplicity of early-type stars is still not well established. The derived binary fraction is different for individual star forming regions, suggesting a connection with the age and the environment conditions. The few studies that have investigated this connection do not provide conclusive results. To fill in this gap, we started the first detailed adaptive-optic-assisted imaging survey of early-type field stars to derive their multiplicity in a homogeneous way. The sample has been extracted from the Hipparcos Catalog and consists of 341 BA-type stars within ∼300 pc from the Sun. We report the current status of the survey and describe a Monte-Carlo simulation that estimates the completeness of our companion detection.     

Phasing segmented mirrors using defocused images at visible wavelengths

Plans for future optical telescopes of diameter more than 10 m are based on segmented mirrors, made up of hundreds or even thousands of segments. A challenge for these telescopes is the alignment in piston (cophasing) where phase differences between individual segments have to be reduced to a small fraction of the observing wavelength in order to avoid degradation of image quality.
Based on the phase discontinuity sensing method used at the Keck telescopes to measure small piston errors using infrared wavelengths, we develop a new method that allows fast high-precision measurements of large piston errors even at visible wavelengths.     

Imaging coronal emission lines under high sky-background conditions

We have obtained images in solar coronal emission lines under high sky-background conditions by making precise differential measurements between the coronal emission line and the near-by continuum, which is primarily due to scattered light from the solar disk. Chopping between the two wavelengths was performed at 100 kHz to avoid artifacts from fast-flying dust particles and other aerosols, and also from seeing effects. The differential signal was detected with a novel CCD camera that demodulates signals up to 100 kHz. These preliminary observations show coronal emission at the 0.2% level of the scattered-light background and pave the way to efficient and precise imaging of coronal emission features under less than ideal coronal-sky conditions.Operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.