scholarly journals Cataclysmic Variables: Structure and Evolution

1994 ◽  
Vol 147 ◽  
pp. 420-442
Author(s):  
J.-M. Hameury
Keyword(s):  
Equation Of State ◽  
Internal Structure ◽  
Observational Data ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Main Sequence Star

AbstractI discuss the structure and evolution of cataclysmic variables, with a particular emphasis on the influence of the physics used in calculating the internal structure of the secondary. The available observational data is very rich, and can, in principle, be used to constrain the stellar physics. It is found that, in order to explain the lack of systems with periods in the range 2 – 3 hr, it is required that main sequence star become convective for masses below 0.3 M⊙. This has little consequences on the equation of state, but constrains the opacities and the treatment of subphotospheric layers.

scholarly journals Boundaries of the δ Scuti Instability Region

2000 ◽  
Vol 176 ◽  
pp. 443-443
Author(s):  
Alexei A. Pamyatnykh
Keyword(s):  
Equation Of State ◽  
Observational Data ◽  
Main Sequence ◽  
Instability Region ◽  
Instability Strip

With new data on stellar opacity and equation of state, we computed the theoretical blue edges of the classical instability strip in the vicinity of the main sequence. The results were compared with observational data on δ Scuti variables using various diagrams (HR, log g – log Teff, Mv – (b – y)0 and so on). An example of these diagrams is shown in Fig. 1. Detailed results can be found in Pamyatnykh (2000).

scholarly journals Problems in Common Envelope Evolution as a Pre-Stage of Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 520-520
Author(s):  
F. Meyer ◽  
E. Meyer-Hofmeister
Keyword(s):  
Angular Momentum ◽  
Thermal Instability ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Main Sequence Star ◽  
Common Envelope ◽  
Angular Momentum Transport ◽  
Binary Separation ◽  
Low Mass ◽  
Red Giant

We follow the evolution of an originally widely separated red-giant in orbit with a low mass main sequence star to a cataclysmic binary system. Angular momentum transport via differential rotation leads to a common envelope around the red giant core and the main sequence star. The internal binary separation shrinks by frictional transfer of angular momentum to the extended red giant envelope. This shrinkage continues at nearly constant luminosity until after several hundred years the binary “Roche lobe” cuts into the dense layers of the main sequence star. The envelope will then be lost by a thermal instability. Method and computations for a 5 M⊙ + 1 M⊙ binary are presented elsewhere (Astron. Astrophys. 1979, in press).

scholarly journals Some Aspects of the Evolutionary Status Of W Ursae Majoris Binaries Deduced from Observational Data

1982 ◽  
Vol 69 ◽  
pp. 301-304
Author(s):  
Walter Van Hamme
Keyword(s):  
Observational Data ◽  
Spectral Type ◽  
Main Sequence ◽  
Type A ◽  
Type Systems ◽  
Primary Component ◽  
Main Sequence Star ◽  
Evolutionary Status ◽  
Evolutionary Stage ◽  
Evolutionary State

AbstractWe have developed a test for the evolutionary state of W Ursae Majoris binaries by comparing the observed spectral type of 31 of these systems (14 of type W and 17 of type A) with the expected one when their primary component is an unevolved main sequence star. It appears that both the W- and A-type systems have a primary with a mass and radius too large to be compatible with the observed spectral type,so there is no indication that each type should mark a different evolutionary stage.

scholarly journals Population Synthesis Studies of White Dwarf Binaries

2004 ◽  
Vol 194 ◽  
pp. 101-103
Author(s):  
U. Kolb ◽  
B. Willems
Keyword(s):  
White Dwarf ◽  
Main Sequence ◽  
Cataclysmic Variables ◽  
Eclipsing Binaries ◽  
Main Sequence Star ◽  
Population Synthesis

AbstractWe present population synthesis studies of white dwarf - main-sequence star binaries, of cataclysmic variables that are driven by circumbinary discs, and of eclipsing binaries in the exoplanet transit search SuperWASP.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

A large rotating structure around AB Doradus A at VLBI scale

2019 ◽  
Vol 15 (S354) ◽  
pp. 189-194
Author(s):  
J. B. Climent ◽  
J. C. Guirado ◽  
R. Azulay ◽  
J. M. Marcaide
Keyword(s):  
Magnetic Reconnection ◽  
Main Sequence ◽  
Complex Structure ◽  
Main Sequence Star ◽  
Polar Cap ◽  
Vlbi Observations ◽  
Rotating Structure ◽  
Source Structure ◽  
Expected Position

AbstractWe report the results of three VLBI observations of the pre-main-sequence star AB Doradus A at 8.4 GHz. With almost three years between consecutive observations, we found a complex structure at the expected position of this star for all epochs. Maps at epochs 2007 and 2010 show a double core-halo morphology while the 2013 map reveals three emission peaks with separations between 5 and 18 stellar radii. Furthermore, all maps show a clear variation of the source structure within the observing time. We consider a number of hypothesis in order to explain such observations, mainly: magnetic reconnection in loops on the polar cap, a more general loop scenario and a close companion to AB Dor A.

scholarly journals PHIBSS: MOLECULAR GAS CONTENT AND SCALING RELATIONS INz∼ 1-3 MASSIVE, MAIN-SEQUENCE STAR-FORMING GALAXIES

2013 ◽  
Vol 768 (1) ◽  
pp. 74 ◽  
Author(s):  
L. J. Tacconi ◽  
R. Neri ◽  
R. Genzel ◽  
F. Combes ◽  
A. Bolatto ◽  
...  
Keyword(s):  
Main Sequence ◽  
Gas Content ◽  
Main Sequence Star ◽  
Scaling Relations ◽  
Molecular Gas ◽  
Star Forming

scholarly journals Pulsars in Globular Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 291-300 ◽  
Author(s):  
Scott M. Ransom
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Globular Clusters ◽  
Main Sequence ◽  
Galactic Disk ◽  
Nuclear Density ◽  
Millisecond Pulsars ◽  
Eccentric Orbits ◽  
The Masses ◽  
Current Record

AbstractGlobular clusters produce orders of magnitude more millisecond pulsars per unit mass than the Galactic disk. Since the first cluster pulsar was uncovered 20 years ago, at least 138 have been identified – most of which are binary millisecond pulsars. Because their origins involve stellar encounters, many of the systems are exotic objects that would never be observed in the Galactic disk. Examples include pulsar-main sequence binaries, extremely rapid rotators (including the current record holder), and millisecond pulsars in highly eccentric orbits. These systems are allowing new probes of the interstellar medium, the equation of state of material at supra-nuclear density, the masses of neutron stars, and globular cluster dynamics.

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