Search Publications
Solar Analogs: Spectral Energy Distributions and Physical Parameters of Their Atmospheres
Shenavrin, V. I.; Glushneva, I. N.; Roshchina, I. A.
The angular diameters, radii, and effective temperatures of 16 G0-G5 main-sequence stars with color excesses 0.60≤ B-V≤0.68 and parallaxes derived from Hipparcos data have been determined using their infrared fluxes, obtained from JHKLM photometric observations. For all the stars except BS 483, these effective temperatures differ from the spectros…
Short-Period Variations in the Proper Motions of Sunspots from SOHO (MDI) Observations
Didkovskiĭ, L. V.
Short-period (1 60 min) variations in the coordinates of the centers of gravity of isolated sunspots are analyzed. The sunspot coordinated were determined using two sets of observational data—magnetograms and intensities—obtained by SOHO (MDI) on December 6, 1998, from 01:00 to 21:57 UT with temporal resolution 60 s and spatial resolution 0.6″/pix…
Parameters of the Galactic rotation curve and spiral pattern from Cepheid kinematics
Mishurov, Yu. N.; Zenina, I. A.
A method is developed for analyzing stellar velocity fields in our Galaxy, with allowance for spiral-density-wave perturbations. The parameters of the Galactic rotation curve, spiral pattern, and mean solar motion are inferred using new Cepheid radial velocities and proper motions measured by the HIPPARCOS space telescope. The Sun is very close to…
Zero points of the magnetic field in the solar atmosphere
Filippov, B. P.
Examples of saddle structures observed in images of the Sun in Hα, soft X-ray (YOHKOH SXT), and ultraviolet (SOHO EIT) emission are presented. Since the plasma distribution is controlled by the magnetic field, the saddles testify to the presence of hyperbolic singularities in the magnetic field. Such singularities play an important role in the the…
Structure and dynamics of the nuclear region of the spiral galaxy NGC 7217
Sil'chenko, O. K.; Zasov, A. V.
The gas velocities and brightness distribution in the inner region of NGC 7217 are analyzed. This galaxy has a regular axially symmetric shape with flocullent spiral arms that have a system of three distinct rings (outer, inner, and nuclear) - a structure that is rarely observed in the absence of a bar. Observations on the 6-m telescope of the Spe…
Young nuclei in elliptical galaxies
Sil'chenko, O. K.
Chemically distinct nuclei have been found in the three elliptical galaxies NGC 4564, NGC 4621, and NGC 5576. These nuclei are appreciably younger than the surrounding regions: in the nuclei of NGC 4564 and NGC 4621, the mean age of the stellar population is 8 billion years, and in NGC 5576, it is 3 billion years. Studies of the rotation of the st…