scholarly journals On the Short Time Scale Evolutionary History of the Contact Binary VW Cephei

1998 ◽  
Vol 11 (1) ◽  
pp. 396-396
Author(s):  
I. Pustylnik
Keyword(s):  
Evolutionary History ◽  
Light Curves ◽  
Published Data ◽  
Short Time Scale ◽  
Flare Activity ◽  
Considerable Portion ◽  
History Of ◽  
Contact Binary ◽  
Elongation Phase ◽  
Short Time

We study the short-time evolutionary history of the well-known contact binary VW Cep. Our analysis is based partly on the numerous UBV lightcurves obtained at Tartu Observatory, IUE spectra, and samples from the published data. Special attention is given to the effects of asymmetry of the light curves. A higher degree of asymmetry outside the eclipses along with the significant displacements of the brightness maxima in respect to the elongation phase is interpreted as evidence that a considerable portion of the flaring source is concentrated close to the neck connecting the components. We discuss the nature of asymmetry in terms of possible mass exchange and the flare activity and compare the results of our model computations with the record of orbital period variations over the last 60 years.

scholarly journals New CCD Observations of Eclipsing Binary VW Cephei

1998 ◽  
Vol 11 (1) ◽  
pp. 394-394
Author(s):  
Adbdulrahman Ali S. Malawi
Keyword(s):  
Time Scale ◽  
Light Curves ◽  
Short Time Scale ◽  
Eclipsing Binary ◽  
Photometric Elements ◽  
Ccd Observations ◽  
Short Time

New CCD observations of the eclipsing binary VW Cephei were made on the 9th and 10th of October 1996 and on the 11th of Nov. 1996. The light curves and short time-scale variations are discussed. Photometric elements were determined from analyses of the light curves. These new solutions are also discussed.

AI and HCI: Two Fields Divided by a Common Focus

AI Magazine ◽  
2009 ◽  
Vol 30 (4) ◽  
pp. 48 ◽  
Author(s):  
Jonathan Grudin
Keyword(s):  
Time Scale ◽  
Short Time Scale ◽  
Intelligent Behavior ◽  
History Of ◽  
Short Time ◽  
Competition For Resources

Although AI and HCI explore computing and intelligent behavior and the fields have seen some cross-over, until recently there was not very much. This article outlines a history of the fields that identifies some of the forces that kept the fields at arm’s length. AI was generally marked by a very ambitious, long-term vision requiring expensive systems, although the term was rarely envisioned as being as long as it proved to be, whereas HCI focused more on innovation and improvement of widely-used hardware within a short time-scale. These differences led to different priorities, methods, and assessment approaches.  A consequence was competition for resources, with HCI flourishing in AI winters and moving more slowly when AI was in favor. The situation today is much more promising, in part because of platform convergence: AI can be exploited on widely-used systems.

scholarly journals Short time-scale fluctuations in the difference light curves of QSO 0957+561A,B: microlensing or noise?

2001 ◽  
Vol 322 (2) ◽  
pp. 397-410 ◽  
Author(s):  
R. Gil-Merino ◽  
L. J. Goicoechea ◽  
M. Serra-Ricart ◽  
A. Oscoz ◽  
D. Alcalde ◽  
...  
Keyword(s):  
Time Scale ◽  
Light Curves ◽  
Short Time Scale ◽  
The Difference ◽  
Short Time

scholarly journals Detection of small-size planetary candidates with CoRoT data

2010 ◽  
Vol 6 (S276) ◽  
pp. 523-524
Author(s):  
Aldo S. Bonomo ◽  
Pierre-Yves Chabaud ◽  
Magali Deleuil ◽  
Claire Moutou ◽  
Pascal Bordé
Keyword(s):  
Time Scale ◽  
Detection Threshold ◽  
Space Mission ◽  
Light Curves ◽  
Short Time Scale ◽  
Blind Test ◽  
Short Period ◽  
Short Time ◽  
Rocky Planets

AbstractWith the discovery of CoRoT-7b, the first transiting super-Earth, the CoRoT space mission has shown the capability to detect short-period rocky planets around solar-like stars. By performing a blind test with real CoRoT light curves, we want to establish the detection threshold of small-size planets in CoRoT data. We investigate the main obstacles to the detection of transiting super-Earths in CoRoT data, notably the presence of short-time scale variability and hot pixels.

scholarly journals HST spectrophotometric data of the central star of the Planetary Nebula LMC-N66

1997 ◽  
Vol 180 ◽  
pp. 126-127
Author(s):  
M. Peña ◽  
W.-R. Hamann ◽  
L. Koesterke ◽  
J. Maza ◽  
R.H. Méndez ◽  
...  
Keyword(s):  
Planetary Nebula ◽  
Central Star ◽  
Short Time Scale ◽  
Type I ◽  
Ionization Degree ◽  
Filamentary Structure ◽  
High Ionization ◽  
Spectrophotometric Data ◽  
History Of ◽  
Short Time

N66 (WS 35, SMP 83) is a Type I (He-N rich) PN in the LMC with a high ionization degree. It shows a bipolar morphology with a filamentary structure (Dopita et al. 1993). Its central star has shown very impressive changes, in short time scale, that have been investigated. Here we describe the history of these changes:

scholarly journals Evolutionary inheritance of elemental stoichiometry in phytoplankton

2010 ◽  
Vol 278 (1705) ◽  
pp. 526-534 ◽  
Author(s):  
Antonietta Quigg ◽  
Andrew J. Irwin ◽  
Zoe V. Finkel
Keyword(s):  
Elemental Composition ◽  
Environmental Conditions ◽  
Evolutionary History ◽  
Published Data ◽  
Phytoplankton Species ◽  
Genetic Constraints ◽  
Elemental Stoichiometry ◽  
Trace Elemental ◽  
History Of ◽  
Freshwater Environments

The elemental composition of phytoplankton is a fusion of the evolutionary history of the host and plastid, resulting in differences in genetic constraints and selection pressures associated with environmental conditions. The evolutionary inheritance hypothesis predicts similarities in elemental composition within related taxonomic lineages of phytoplankton. To test this hypothesis, we measured the elemental composition (C, N, P, S, K, Mg, Ca, Sr, Fe, Mn, Zn, Cu, Co, Cd and Mo) of 14 phytoplankton species and combined these with published data from 15 more species from both marine and freshwater environments grown under nutrient-replete conditions. The largest differences in the elemental profiles of the species distinguish between the prokaryotic Cyanophyta and primary endosymbiotic events that resulted in the green and red plastid lineages. Smaller differences in trace element stoichiometry within the red and green plastid lineages are consistent with changes in trace elemental stoichiometry owing to the processes associated with secondary endosymbioses and inheritance by descent with modification.

scholarly journals Comparisons of MHD propeller model with observations of cataclysmic variable AE Aqr

2019 ◽  
Vol 487 (2) ◽  
pp. 1754-1763 ◽  
Author(s):  
A A Blinova ◽  
M M Romanova ◽  
G V Ustyugova ◽  
A V Koldoba ◽  
R V E Lovelace
Keyword(s):  
Magnetic Field ◽  
Time Scale ◽  
Accretion Rate ◽  
Light Curves ◽  
Short Time Scale ◽  
Mhd Simulations ◽  
Representative Model ◽  
Polar Type ◽  
Short Time ◽  
The Magnetic Field

ABSTRACT We have developed a numerical magnetohydrodynamic (MHD) model of the propeller candidate star AE Aqr using axisymmetric MHD simulations. We suggest that AE Aqr is an intermediate polar-type star, where the magnetic field is relatively weak and an accretion disc may form around the white dwarf. The star is in the propeller regime, and many of its observational properties are determined by the disc–magnetosphere interaction. Comparisons of the characteristics of the observed versus modelled AE Aqr star show that the model can explain many observational properties of AE Aqr. In a representative model, the magnetic field of the star is B ≈ 3.3 × 105 G and the time-averaged accretion rate in the disc is 5.5 × 1016 g s−1. Most of this matter is ejected into conically shaped winds. The numerical model explains the rapid spin-down of AE Aqr through the outflow of angular momentum from the surface of the star to the wind, corona, and disc. The energy budget in the outflows, 9 × 1033 erg s−1, is sufficient for explaining the observed flaring radiation in different wavebands. The time-scale of ejections into the wind matches the short time-scale variability in the light curves of AE Aqr.

Sign in / Sign up

Export Citation Format

Share Document