Flares of H2O maser radio line in the sources GDD 25 and Sgr B2

Astrophysics ◽  
1989 ◽  
Vol 30 (1) ◽  
pp. 71-75
Author(s):  
I. V. Gosachinskii ◽  
R. A. Kandalyan ◽  
F. S. Nazaretyan ◽  
N. A. Yudaeva
Keyword(s):  
Radio Line ◽  
Maser Radio

scholarly journals History of the Light Curves and Molecular Maser Emission of the Miras U Ori and R Leo

1993 ◽  
Vol 155 ◽  
pp. 323-323
Author(s):  
I. L. Andronov ◽  
L. S. Kudashkina ◽  
G. M. Rudnitskij
Keyword(s):  
Radio Emission ◽  
Molecular Species ◽  
Light Curves ◽  
Evolutionary Status ◽  
Maser Emission ◽  
Radio Line ◽  
History Of ◽  
Maser Radio

We have collected all the available data on light curves, OH, H2O and SiO maser observations for a sample of Mira-type variables. We consider in detail the data on two stars, U Ori and R Leo. There is a net correlation between optical and radio line variations for all the three molecular species in these stars. More pronounced maser flares seem to follow brighter-than-average visual maxima of the stars. We discuss also the drastic changes in the type of the OH maser radio emission which happened in these stars some years ago. Implications for the mechanisms of maser pumping and the evolutionary status of these stars (probably undergoing the helium flash) are discussed.

scholarly journals On the nature of protostellar H2O masers

1987 ◽  
Vol 122 ◽  
pp. 141-142
Author(s):  
G. M. Rudnitskij
Keyword(s):  
Active Phase ◽  
Young Star ◽  
Line Profiles ◽  
Free Electrons ◽  
Heavy Particles ◽  
Vlbi Observations ◽  
Generation Region ◽  
Star Formation Regions ◽  
Maser Radio ◽  
Two Temperature

Most sources of B2O maser radio emission at 1.35 cm, associated with star formation regions, show strong variability with, sometimes, rapid bursts of emission (see, e.g., Liljeström 1984, Rowland and Cohen 1986, and references therein). A preliminary conclusion on the possible cyclicity of H2O maser variability can be drawn (Lekht et al. 1982, 1983), with a quasiperiod of several years. The “quiet” state of a maser source, with moderate, slowly varying values of the line flux density, turns to the “active” phase with H2O line bursts (Lekht et al. 1983). The H2O maser generation region is probably located in a rotating gas-and-dust disc (torus) around a protostar (or young star). This is pointed to by VLBI observations showing in some sources maser features arranged in an ellipsoidal structure around a common centre (presumably, the protostellar object - see Downes et al. 1979), as well as by symmetrical character of E2O line profiles of many masers (Lekht et al. 1982). As an excitation mechanism for H2O, collisional pumping in two-temperature medium behind a shock front (with hot heavy particles and cold free electrons or vice versa) is widely accepted (Bolgova et al. 1982, Kylafis and Norman 1986).

Methodology for assessing the range of reception by modern telemetric means when launching products from cosmodromes

2020 ◽  
pp. 3-12
Author(s):  
Э.М. Аббасов
Keyword(s):  
Point Of View ◽  
Energy Reserve ◽  
Angular Orientation ◽  
Radio Lines ◽  
Measuring Point ◽  
Radio Line ◽  
Full Volume

Проведен анализ места размещения измерительного пункта с точки зрения получения полного объема телеметрической информации при пусках изделий с заданного космодрома. Методика оценки дальности приема основана на расчёте зон радиовидимости стационарных измерительных пунктов по трассе выведения с учетом угловой ориентации изделия в ходе полета, расчёте энергетического запаса радиолиний для существующих и перебазируемых средств приёма телеметрической информации, оценке потерь уровня сигнала в радиолинии, проверке отсутствия экранирования радиолинии факелом двигателя. The analysis of the location of the measuring point from the point of view of obtaining the full volume of telemetric information when launching products from a given cosmodrome is carried out. The method for assessing the reception range is based on calculating the radio visibility zones of stationary measuring points along the injection route, taking into account the angular orientation of the product during flight, calculating the energy reserve of radio lines for existing and relocatable means of receiving telemetry information, assessing the signal level loss in the radio line, checking the absence of shielding of the radio line by the engine torch.

Flares of Radio Line Emission H2O in ORI A and W49N

1990 ◽  
pp. 275-278
Author(s):  
I. V. Gosachinskij ◽  
N. A. Yudaeva ◽  
R. A. Kandalian ◽  
F. S. Nazaretian ◽  
V. A. Sanamian
Keyword(s):  
Line Emission ◽  
Radio Line

A METHOD OF PROTECTION OF INFORMATION TRANSMITTED VIA A RADIO LINE

2011 ◽  
Vol 70 (2) ◽  
pp. 129-132
Author(s):  
A. V. Kuznetsov ◽  
M. I. Martyanov ◽  
A. V. Savchenko ◽  
V. A. Serikov ◽  
M. A. Savchenko
Keyword(s):  
Radio Line

scholarly journals Radio Line and Continuum Observations of Quasar-Galaxy Pairs and the Origin of Low Redshift Quasar Absorption Line Systems

1990 ◽  
Vol 124 ◽  
pp. 473-477
Author(s):  
C.L. Carilli ◽  
J.H. van Gorkom ◽  
E.M. Hauxthausen ◽  
J.T. Stocke ◽  
J. Salzer
Keyword(s):  
Absorption Line ◽  
Alternative Hypothesis ◽  
High Redshift ◽  
Gravitational Interaction ◽  
Optical Disk ◽  
Line Of Sight ◽  
Radio Line ◽  
Redshift Galaxy ◽  
Interacting Systems ◽  
Companion Galaxy

There are a number of known quasars for which our line of sight to the high redshift quasar passes within a few Holmberg radii of a low redshift galaxy. In a few of these cases, spectra of the quasar reveal absorption by gas associated with the low redshift galaxy. A number of these pairs imply absorption by gas which lies well outside the optical disk of the associated galaxy, leading to models of galaxies with ‘halos’ or ‘disks’ of gas extending to large radii. We present observations of 4 such pairs. In three of the four cases, we find that the associated galaxy is highly disturbed, typically due to a gravitational interaction with a companion galaxy, while in the fourth case the absorption can be explained by clouds in the optical disk of the associated galaxy. We are led to an alternative hypothesis concerning the origin of the low redshift absorption line systems: the absorption is by gas clouds which have been gravitationally stripped from the associated galaxy. These galaxies are rapidly evolving, and should not be used as examples of absorption by clouds in halos of field spirals. We conclude by considering the role extended gas in interacting systems plays in the origin of higher redshift quasar absorption line systems.

scholarly journals Molecular Masers in Variable Stars

2002 ◽  
Vol 19 (4) ◽  
pp. 499-504 ◽  
Author(s):  
Georgij M. Rudnitskij
Keyword(s):  
Line Emission ◽  
Variable Stars ◽  
Circumstellar Envelope ◽  
Red Giants ◽  
Circumstellar Envelopes ◽  
Emission Data ◽  
Physical Mechanisms ◽  
Stellar Pulsations ◽  
Red Giant ◽  
Maser Radio

AbstractWhen a star with a mass of one to a few solar masses enters the red giant stage of its evolution, the radius of its atmosphere reaches several astronomical units. Pulsational instability is typical for this stage. Most stars become Mira-type or semiregular variables with light cycles of a few hundred days. Red giants lose mass at a rate M = 10−7−10−5M⊙ yr−1. Extensive gas–dust circumstellar envelopes form. These envelopes contain various molecular species. Some of these molecules (OH, H2O, SiO, HCN) manifest themselves in maser radio emission. Data on the H2O maser variability and its connection with the stellar brightness variations are discussed. In the H2O line circumstellar masers can be divided into ‘stable’ (showing persistent emission — R Aql, U Her, S CrB, X Hya) and ‘transient’ (appearing in the H2O line once per 10–15 stellar light cycles — R Leo, R Cas, U Aur). Physical mechanisms of the maser variability are discussed. The most probable process explaining the observed visual–H2O correlation is the influence of shock waves on the masing region. Usually it is assumed that shocks in Mira atmospheres are driven by stellar pulsations. Here an alternative explanation is proposed. If a star during its main sequence life possessed a planetary system, similar to the solar system, the planets will be embedded in a rather dense and hot medium. Effects of a planet revolving around a red giant at a short distance (inside its circumstellar envelope) are discussed. A shock produced by the supersonic motion of a planet can account for the correlated variability of the Hα line emission and H2O maser. If the planetary orbit is highly eccentric, then the connected Hα–H2O flare episodes may be explained by the periastron passage of the planet. New tasks for the upgraded ATCA are discussed.

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