SciNews archive

The sample of the Local Volume galaxies (distance smaller than 10 Mpc) gives a unique opportunity to study the properties of galaxies including the weakest objects: the absolute magnitude M_B≈-10 and the virial mass M_vir≈10⁹M☼. More...

Based on the magnetic field measurements of the chemically peculiar star HD965, conducted in 2000-2015 with the SAO RAS 6-m telescope, we have found that this object is an ultra slow magnetic rotator with a rotation period of about 20 years. The obtained result is strong evidence in favor of the so-called fossil theory of large-scale field formation in these objects. More...

The Galactic low-mass X-ray binary GS 2023+338 was discovered during the burst on May 22, 1989 with the Japanise satellite Ginga (aka Galaxy). The flux reached 17 crabs (this unit of flux measurement is an bright X-ray source, Crab Nebula) at 10-35 keV. More...

Variability of emission at scales from fractions of a second to tens of years is one of characteristic properties of different celestial objects. Transient events are also the emission variability though not regularly observed. Such events are difficult to detect for that reason. During the analysis of the surveys carried out on RATAN-600, it was found that almost one fifth of the detected sources shows significant radio flux variations. We discovered three radio transients in our search. More...

Currently, there is very little information on comets which are active beyond the orbit of Jupiter. Dust tails and comas of such comets are observed at large distances from the Sun (greater than 5 au), where water ice sublimation is inconsiderable. More...

Two new LBV stars have been discovered in the Andromeda Galaxy. Since the middle of the last century, only four such objects had been known in this galaxy, they were discovered by American scientists Edwin Hubble and Allan Sandage with colleagues. Astronomers from SAO added two more stars to this list in 2015. More...

The March 20 total solar eclipse was visible over the North Atlantic and Arctic Oceans. The partial phases were observed in Europe, the western regions of Russia, Central Asia, the Middle East and partially in the North Africa. In the Special Astrophysical Observatory it was also partial with the Moon coverage of the Sun of less than 40%. More...

In January 2015 using the Mini-MegaTORTORA multichannel optical sky-monitoring system with subsecond temporal resolution, the observations of comet C/2014 Q2 (Lovejoy) and asteroid 357439 2004 BL86 were carried out. More...

Our recent observations with the Hubble Space Telescope (August 29, 2014) led to revealing a highly isolated dwarf spheroidal galaxy KKs 3 situated at a distance of 2.12±0.07 Mpc from the Milky Way. The dSph galaxy locates on the southern sky (RA=02^h24^m44.4^s, Dec.=-73°30'51", J2000.0) and has a stellar mass about 1/10000 of the Milky Way mass. More...

SS433 is a close binary system, one star is a supergiant, a second one is a black hole. The supergiant's matter overflows to the neighbouring black hole and floods the hole with a powerful mass flux: 6 millions of billions tons per second (that is one Earth mass for 11 days). Even a black hole cannot accept such an enormous mass flux, a supercritical accretion disk appears More...

The variability of the spectrum of the optical component of the IR-source IRAS01005+7910 was discovered for the first time in the BTA spectra [1]. Long-term monitoring of the object was carried out during 2002-2013 with a high spectral resolution (R=60000). More...

Astronomers of the SAO together with an international group of scientists have proposed an explanation to the long-standing mystery of why magnetic fields are more common amongst cool white dwarf stars than amongst young and hotter ones. More...

According to the most popular cosmological paradigm, the greater part of the galaxy mass is accumulated in the dark matter halo. The mass value can be measured in terms of various model assumptions, analyzing the available observational data, for example, the distribution of the rotation velocity at large distances from the center (the rotation curve). It is much more difficult to make an estimate of the shape of the dark halo in a particular galaxy, i.e. to understand whether it is spherical, flattened or triaxial. More...

SAO researchers have discovered that supercritical accretion disks eject hot gas with a velocity of a few thousand kilometers per second. The supercritical regime of accretion onto black holes is very important for astrophysics. In the first half-billion years just after our Universe was born, supermassive black holes (quasars) began to appear and grow in centers of young galaxies. More...

A unique set of linear polarization measurements in the spectrum of the Seyfert galaxy Mkn 6 was obtained with the 6-meter telescope. It was shown for the first time that the analysis of the polarization angle dependence on the velocity across the hydrogen line profiles due to the gas emission in the broad-line formation region near the massive AGN allows to determine directly from observations the type of motion in the broad-line formation region, which in the case of Mkn 6 turned out to be Keplerian at distances less than 0.02 pc from the nucleus. The lower mass limit determined for the supermassive black hole in the center of the Mkn 6 galaxy is equal to 150 million solar masses. More...

High spectral resolution echelle spectroscopy of supergiants at the post-ABG stage resulted in the formation of a sample of these objects possessing a high infrared excess, an emission at 21 μm, and also large overabundances of carbon and heavy metals, synthesized by the s-process at the preceding AGB stage. More...

Among the newly observed objects, we discovered the galaxies UGC 2172 and NGC 3239 in the stage of a vigorous burst of star formation. More...

The spatially resolved structure near the hydrogen emission Hα line was found in the spectrum taken with the BTA/SCORPIO in June, 2013. It extendeds by 6.5 arcsec along the frame vertical, and by 2600 km/s (radial velocity) along the centre line of the frame. The structure has been formed by an empty spherical shell that has erupted during the outburst 13.5 years ago, and is now expanding with the velocity of 1300 km/s. The expansion velocity of 0.24 arcsec/yr corresponds to the distance to the nova of 1.2±0.2 kpc. More...

An estimate the rotation period of cometary nuclei is important for understanding and describing the physical processes of the cometary activity. Unfortunately, the measurements of the rotation periods of the comet nucleus depend on the model assumptions and it is one of the main reasons for the scatter of the estimates given in various articles for a given comet. More...

Ultraluminous X-ray sources (ULXs) are located in external galaxies, their X-ray luminosities are thousand times greater than those of brightest black holes in the Galaxy. It has been found in the VLT and BTA observations of extragalactic stellar clusters related to the ULXs, that these objects are stellar-mass black holes with supercritical accretion disks. More...

Recent studies indicate that stars are most likely forming within the binary and multiple systems. In our Galaxy, according to various estimates, at least 50 percent of stars have companions. Therefore, the study of binary and multiple stars is important for understanding the mechanisms of star formation in general. More...

The HH flow associated with young stellar object HL Tau has an exciting history and even until now the origin of some its features is not clear yet. Flow starts as the relatively faint and narrow jet from HL Tau but at distance of about 20" from the star it abruptly changes direction by about 14 deg and becomes much brighter and appears complex knotty morphology. More...

Galaxies with polar rings (PRGs) are a unique class of extragalactic objects, consisting of a ring or disk of gas, stars and dust orbiting in a plane nearly perpendicular to the disk of a central galaxy. More...

The results of long-term monitoring of Gigahertz-Peaked Spectrum sources were found the statistically significant differences (0.05 significance level) in the high-frequency spectral index distribution between subgroups of galaxies and quasars. More...

According to modern views on the evolution and origin of stars, most of the stars are members of binary systems. If both components are massive enough, they eventually go supernova one by one, whereas their cores collapse, turning into black holes or neutron stars. More...

The history of star formation was successfully analyzed for the first time based on the spectra of the stellar population of dwarf galaxies of low surface brightness outside the Local Group. We have investigated the stellar population of two dwarf spheroidal galaxies KDG61 and KDG64 in the central part of a close group of galaxies M81. More...

Solar flare activity is produced by the processes of accumulation and release of energy in an active region. A complex magnetic structure is formed over the spots, the reconnection of which leads to the generation of a flare. The information about the magnetic field can be retrieved from is polarized microwave radiation, the spectrum of which is correlated with the flare activity. More...

As a result of BTA observations of 23 chemically peculiar stars with strong magnetic fields, it was found that in 22 of them the longitudinal magnetic field, measured from the hydrogen line cores are considerably lower (by about 1/3) than the value measured from metal lines in the same spectra. More...

According to the current estimates, a few percent of Main Sequence B5-F5 stars reveal strong surface magnetic fields reaching the values of tens of kilogauss, which is an order of magnitude greater than the maximal magnetic field in sunspots. More...

The close X-ray binary with relativisic jest, contained probably a black hole, Cygnus X-3 has been detected in first time in Gamma-rays at enegries higher 100 ÌeV (AGILE, Tavani et al., Nature, 2009) during the intense radio flares, monitored with RATAN-600 radio telecope. More...

By means of deep optical images obtained at the Special Astrophysical Observatory 6-m telescope it was discovered that some Seyfert galaxies that were earlier considered to be non-interacting objects displayed signatures of elongated tidal envelopes belonging to satellite debris. More...

CH Cyg is one of the most fascinating as well as the brightest and closest symbiotic stars. It's composed of an M7 giant and a hot companion, most likely an accreting white dwarf. More...

A bright extended nebulosity around a lenticular galaxy NGC 4460 was discovered by Igor Karachentsev and Serafim Kaisin (2008, A&A, 479, 603) during the recent H

survey of nearby galaxies on the SAO RAS 6-m telescope. More...

In the spectral observations of stars with infrared circular nebulae, found in the Spitzer survey (24 microns), a new LBV star was discovered in the Galaxy. More...

The brightest of all GRBs known to date, GRB080319B, the "Naked-Eye Burst", has been observed by our colleagues who acquired its detailed optical light curve during the stage of gamma emission. More...

Dwarf galaxy DDO 68 is the closest to us galaxy (D=10Mpc) with the lowest metal content known to date. In this galaxy, using the 6 m BTA telescope, a new massive blue variable star with high luminosity (>=10⁵ Sun's luminocities in visible light) was found. More...

New observations of the RC J0311+0507 radio source using the MERLIN radio interferometer (UK) and the 6-m optical telescope, have added new strokes to the "portrait" of this unusual object, - one of the most powerful and distant radio galaxies (z=4.51), and raised new questions about the origin of the first galaxies in the early Universe. More...