scholarly journals Statistical studies of flare stars and other flashing objects carried out at the Byurakan Observatory

2021 ◽  
pp. 150-162
Author(s):  
A. A. Akopian
Keyword(s):  
Open Clusters ◽  
Physical Parameters ◽  
Evolutionary Status ◽  
Flare Activity ◽  
Short Term ◽  
T Tauri ◽  
Statistical Studies ◽  
Flare Stars

The review briefly presents the statistical studies of flare stars and related objects carried out at the Byurakan Astrophysical Observatory, in particular: i) determination of the evolutionary status of flare stars, ii) an explanation of the observed difference between flare stars of the galactic field (type UV Cet) and flare stars of systems (open clusters, associations), iii) the connection between flare stars and T Tauri stars, iv) short-term and long-term (evolutionary) variability of flare activity, v) original statistical methods developed for the study of flare stars and their systems, vi) recent advances in research on flashing objects. This review does not present such important areas of research on flare stars as the determination of physical parameters, photometry and colorimetry of stars and their flares, detailed studies of individual stars, theoretical works on possible mechanisms of flares. These areas were well presented in many books and reviews by Ambartsumian and Mirzoyan.

CSF Pulse Pressure and B Waves

2005 ◽  
Vol 103 (4) ◽  
pp. 767-768 ◽  
Author(s):  
Zofia Czosnyka ◽  
Marek Czosnyka ◽  
John D. Pickard
Keyword(s):  
Pulse Pressure ◽  
Pressure Coefficient ◽  
Joint Effect ◽  
Physical Parameters ◽  
Wave Analysis ◽  
Short Term ◽  
Content Type ◽  
Pulse Pressure Method ◽  
Fine Print

Abstract Object. The appearance of numerous B waves during intracranial pressure (ICP) registration in patients with idiopathic adult hydrocephalus syndrome (IAHS) is considered to predict good outcome after shunt surgery. The aim of this study was to describe which physical parameters of the cerebrospinal fluid (CSF) system B-waves reflect and to find a method that could replace long-term B-wave analysis. Methods. Ten patients with IAHS were subjected to long-term registration of ICP and a lumbar constant-pressure infusion test. The B-wave presence, CSF outflow resistance (Rout), and relative pulse pressure coefficient (RPPC) were assessed using computerized analysis. The RPPC was introduced as a parameter reflecting the joint effect of elastance and pulsatory volume changes on ICP and was determined by relating ICP pulse amplitudes to mean ICP. Conclusions. The B-wave presence on ICP registration correlates strongly with RPPC (r = 0.91, p < 0.001, 10 patients) but not with CSF Rout. This correlation indicates that B waves—like RPPC—primarily reflect the ability of the CSF system to reallocate and store liquid rather than absorb it. The RPPC-assessing lumbar short-term CSF pulse pressure method could replace the intracranial long-term B-wave analysis.

scholarly journals Flare-Like Events on the T-Tauri Star RU LUP1

1989 ◽  
Vol 104 (2) ◽  
pp. 139-142 ◽  
Author(s):  
F. Giovannelli ◽  
D. Castaldo ◽  
E. Covino ◽  
A.A. Vittone ◽  
C. Rossi
Keyword(s):  
Tauri Star ◽  
Quiescent State ◽  
Complete Coverage ◽  
Patchy Distribution ◽  
Active Star ◽  
X Ray ◽  
T Tauri ◽  
Observed Behaviour ◽  
Flare Stars

AbstractA long term multifrequency campaign on the T Tauri star RU Lupi has been carried out in the X-Ray, UV optical and IR spectral regions with ASTRON and IUE satellites and ESO 1.5 m+IDS, 1.4 m CAT, 0.5 m UBVRI and 1 m IR telescopes, respectively.We present two flare-like events occurred on April 17, 1984 and June 30, 1986. The first one was detected only in the UV, clue to lack the of simultaneous observations in other spectral regions. The second one was observed in UV, optical and IR regions showing a maximum roughly in the U band A comparison of the whole energy distribution of this event with that of a quiescent state observed on June 27 shows a flux enhancement of (89 ± 2)%. A detailed analysis of UV continuum and lines, namely N V, C I, CII, CIV, Si II and Si IV, shows that ihe surfaces fluxes of RU Lupi are always larger than those observed on typical flare stars and on the Sun by a factor of roughly 2 and 3 orders of magnitude, respectively. This fact allows us to conclude that RU Lupi activity cannot be explained even invoking a complete coverage by solar-like plages. On the contrary a patchy distribution of the emitting regions could explain the observed behaviour of this active star.

scholarly journals Young and Old Subsystems of Flare Stars

1995 ◽  
Vol 151 ◽  
pp. 63-64
Author(s):  
L.V. Mirzoyan ◽  
V.V. Hambarian
Keyword(s):  
Evolutionary Status ◽  
Wide Field ◽  
Flare Activity ◽  
Multiple Systems ◽  
Star Evolution ◽  
Orion Association ◽  
Evolutionary Connection ◽  
Long Time ◽  
Flare Stars ◽  
T Tau

Photographic observations with wide-field telescopes of flare stars in the Orion association and the Pleiades cluster have been carried out since 40 years. About 500 flare stars were found in each of these systems. The ages of these stellar systems differ by one or two orders of magnitude (Mirzoyan 1991). This fact allows us to compare them, in order to show that they fit into the concept, suggested first by Haro (1957), that the evolutionary status of flare stars is a stage of red dwarf star evolution which follows that of the T Tau stars (Haro 1976, Ambartsumian & Mirzoyan 1970).The basic difference between the Orion and Pleiades subsystems of flare stars has been known for a long time: the coexistence of flare stars and T Tau stars in the Orion association, and the absence of the latter group in the Pleiades. Some of the T Tau stars show flare activity (Haro 1964). This fact and the existence of multiple systems of trapezium type, which are dynamically unstable, in the Orion association, are arguments in favour of an evolutionary connection between these two types of stars.

scholarly journals Flare Stars Database

1994 ◽  
Vol 161 ◽  
pp. 380-382
Author(s):  
M. Tsvetkov ◽  
M. Chukova ◽  
K. Tsvetkova
Keyword(s):  
Wide Field ◽  
Flare Activity ◽  
The Galaxy ◽  
Statistical Regularities ◽  
Ceti Type ◽  
Formation And Evolution ◽  
Flare Stars ◽  
Machine Readable

The important role of flare stars (UV Ceti type variables) in astrophysics is due to the fact that the flare activity is not only typical for red stars with small masses but is a necessary stage during their evolution. The flare star search in stellar aggregates has led to the accumulation of rich observational material allowing us to look for statistical regularities in star formation and evolution. At present, there are more than 1500 known flare stars in the Galaxy; these were discovered mainly during the last 30 years. Most results of the long term monitoring with wide-field telescopes are listed in existing catalogues of flare stars in stellar aggregates and in the solar neighbourhood. These catalogues and their machine-readable versions were the basis for the present database of flare stars in the Galaxy.

The Shift towards Smart, Green and Integrated Raw Materials Efficiency

2014 ◽  
Vol 718 ◽  
pp. 105-109
Author(s):  
Eva Oravcová ◽  
Miroslav Zelko
Keyword(s):  
Decision Support ◽  
Raw Materials ◽  
Decision Makers ◽  
Short Term ◽  
Supervision System ◽  
Requirements Development ◽  
And Control ◽  
Term Data

Comprehensive environmental observation, eco-innovation and smartization are essential to ensure the delivery of the long-term data and information required to address the shift towards smart, green and integrated raw materials efficiency. For this reason we need the mine-wide digitalization and informatization base model, an advanced mine-wide decision support system and a smart supervision system to supervise and control the production, back to predefined short-term production targets with most likelihood and optimal approaches. There are three main steps to be taken: analysis, evaluation and determination of the shift requirements, development of the models as well as modeling of the scenarios and connection to the smart platform for the support of the decision makers. The paper aims to consider what would be required for a raw materials area to operate as a modern smart technology-supported business. It attempts to provide a vision of some future smart architectures scenarios.

scholarly journals Determination of heavy metal deposition in the county of Obrenovac (Serbia) using mosses as bioindicators, IV: Manganese (Mn), Molybdenum (Mo), and Nickel (Ni)

2009 ◽  
Vol 61 (4) ◽  
pp. 835-845 ◽  
Author(s):  
V. Vukojevic ◽  
M. Sabovljevic ◽  
Aneta Sabovljevic ◽  
Nevena Mihajlovic ◽  
Gordana Drazic ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Atmospheric Deposition ◽  
Metal Content ◽  
Tabular Form ◽  
Short Term ◽  
Hypnum Cupressiforme ◽  
Bryum Argenteum ◽  
Heavy Metal Deposition

In this study, the deposition of three heavy metals (Mn, Mo, and Ni) in the county of Obrenovac (Serbia) in four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp., and Hypnum cupressiforme) is presented. The distribution of average heavy metal content in all mosses in the county of Obrenovac is presented on maps, while the long-term atmospheric deposition (in the mosses Bryum argenteum and B. capillare) and short term atmospheric deposition (in the mosses Brachythecium sp. and Hypnum cupressiforme) are discussed and given in tabular form. Areas of the highest contaminations are highlighted.

scholarly journals Determination of heavy metal deposition in the county of Obrenovac (Serbia) using mosses as bioindicators II: Cadmium (CD), cobalt (CO), and chromium (CR)

2006 ◽  
Vol 58 (2) ◽  
pp. 95-104 ◽  
Author(s):  
V. Vukojevic ◽  
M. Sabovljevic ◽  
Aneta Sabovljevic ◽  
Nevena Mihajlovic ◽  
Gordana Drazic ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Atmospheric Deposition ◽  
Metal Content ◽  
Short Term ◽  
Hypnum Cupressiforme ◽  
Bryum Argenteum ◽  
Heavy Metal Deposition

In the present study, the deposition of three heavy metals (Cd, Co and Cr) in the county of Obrenovac (Serbia) is determined using four moss taxa (Bryum argenteum, Bryum capillare, Brachythecium sp. and Hypnum cupressiforme) as bioindicators. Distribution of average heavy metal content in all mosses in the county of Obrenovac is presented in maps, while long term atmospheric deposition (in the mosses Bryum argenteum and B. capillare) and short term atmospheric deposition (in the mosses Brachythecium sp. and Hypnum cupressiforme) are discussed and in tables. Areas of the highest contaminations are highlighted.

scholarly journals Flare Stars in Star Clusters and Associations

1975 ◽  
Vol 67 ◽  
pp. 1-14 ◽  
Author(s):  
V. A. Ambartsumian ◽  
L. V. Mirzoyan
Keyword(s):  
Stellar Evolution ◽  
Star Clusters ◽  
Open Clusters ◽  
Point Of View ◽  
Flare Activity ◽  
Theoretical Point ◽  
Star Clusters And Associations ◽  
Stellar Flare ◽  
Dwarf Stars ◽  
Flare Stars

The study of stellar evolution can be undertaken either from a purely theoretical point of view or from a more observational approach. The present standpoint is the second one. It starts from the concepts of stellar evolution in associations and open clusters and from stellar flare activity. Statistical considerations show that flare activity is a regular stage in the evolution of stars through which all the dwarf stars go.

scholarly journals Radiocarbon and 11-Year Variations of Cosmic Rays

Radiocarbon ◽  
1993 ◽  
Vol 35 (3) ◽  
pp. 347-350 ◽  
Author(s):  
A. A. Burchuladze ◽  
S. V. Pagava ◽  
G. I. Togonidze ◽  
M. V. Avtandilashvili
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
Complex Problem ◽  
Short Term ◽  
The Past ◽  
Terrestrial Origin ◽  
Astrophysical Phenomena

B. P. Konstantinov and G. E. Kocharov (1965, 1967) addressed the complex problem of astrophysical phenomena and radiocarbon. Currently available data show that the determination of cosmogenic 14C in accurately dated samples of terrestrial and atmospheric origin is one of the most reliable and promising methods for studying cosmic-ray variations in the past. 14C dating samples of terrestrial origin has helped solve the problem of long-term (100 yr or more) 14C variations and, accordingly, of cosmic-ray variations in the past. Short-term (ca. 11 yr or less) variations are still under investigation (Alexeyev et al. 1971; Damon, Long and Wallick 1973).

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