scholarly journals Spectropolarimetric study of selected cool supergiants

2014 ◽  
Vol 9 (S307) ◽  
pp. 369-370
Author(s):  
V. Butkovskaya ◽  
S. Plachinda ◽  
D. Baklanova
Keyword(s):  
Magnetic Fields ◽  
Stellar Evolution ◽  
Good Opportunity ◽  
Classical Cepheids

AbstractCool supergiants offer a good opportunity to study the interplay of magnetic fields and stellar evolution. We present the results of spectropolarimetric study of the cool supergiants and classical Cepheids η Aql and ζ Gem.

scholarly journals Dynamo-generated magnetic fields in fast rotating single giants

2008 ◽  
Vol 4 (S259) ◽  
pp. 433-434 ◽  
Author(s):  
Renada Konstantinova-Antova ◽  
Michel Aurière ◽  
Klaus-Peter Schröder ◽  
Pascal Petit
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Stellar Evolution ◽  
Red Giants ◽  
Good Opportunity ◽  
Early Results ◽  
First Time ◽  
Fast Rotating

AbstractRed giants offer a good opportunity to study the interplay of magnetic fields and stellar evolution. Using the spectro-polarimeter NARVAL of the Telescope Bernard Lyot (TBL), Pic du Midi, France and the LSD technique we began a survey of magnetic fields in single G-K-M giants. Early results include 6 MF-detections with fast rotating giants, and for the first time a magnetic field was detected directly in an evolved M-giant: EK Boo. Our results could be explained in the terms of α–ω dynamo operating in these giants.

scholarly journals Searching for links between magnetic fields and stellar evolution

2007 ◽  
Vol 470 (2) ◽  
pp. 685-698 ◽  
Author(s):  
J. D. Landstreet ◽  
S. Bagnulo ◽  
V. Andretta ◽  
L. Fossati ◽  
E. Mason ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Stellar Evolution

scholarly journals Observations of evolutionary changes in the pulsation period of cepheids

1984 ◽  
Vol 105 ◽  
pp. 445-448
Author(s):  
L. Szabados
Keyword(s):  
Detailed Analysis ◽  
Stellar Evolution ◽  
Time Scale ◽  
Theoretical Work ◽  
Pulsation Period ◽  
First Approximation ◽  
Evolutionary Changes ◽  
Classical Cepheids ◽  
Cepheid Variables

In spite of the fact that Cepheid variables pulsate quite regularly their pulsation period remains constant only in the first approximation. The pulsation period is subject to variations because of stellar evolution. The calculations made by Hofmeister (1965) predicted that the evolutionary period changes of classical Cepheids should be observed on a time scale of several decades or longer. No detailed analysis of the observed period changes has been made since Hofmeister's fundamental theoretical work.

scholarly journals On Magnetic Mixing and Rotation in Stellar Evolution

1978 ◽  
Vol 80 ◽  
pp. 323-331
Author(s):  
Peter G. Gross
Keyword(s):  
Magnetic Fields ◽  
Stellar Evolution ◽  
Evolutionary Status ◽  
Relevant Parameter ◽  
Stellar Rotation ◽  
Convective Turbulence ◽  
Stellar Interior ◽  
Magnetic Mixing ◽  
Ap Stars

In this paper some thoughts and problems are presented from the viewpoint that the evolution of stars may play a key role in generating magnetic fields which, in turn, may affect the mixing of nuclearly processed elements from the stellar interior to the surface. The relevant parameter is stellar rotation which, upon interaction with convective turbulence driven by thermal instabilities, leads to the generation of magnetic fields. A possible connection to Bidelman's hypothesis on the evolutionary status of Ap stars is also discussed in the context of a post-core-helium-flash hypothesis.

scholarly journals Discovery of kilogauss magnetic fields on the nearby white dwarfs WD 1105–340 and WD 2150+591

2019 ◽  
Vol 623 ◽  
pp. A46 ◽  
Author(s):  
J. D. Landstreet ◽  
S. Bagnulo
Keyword(s):  
Magnetic Fields ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Weak Field ◽  
Field Structure ◽  
Small Sample ◽  
Dipolar Field ◽  
Surface Field ◽  
Clear Link ◽  
Statistical Studies

Magnetic fields are present in roughly 10% of white dwarfs. These fields affect the structure and evolution of such stars, and may provide clues about their earlier evolution history. Particularly important for statistical studies is the collection of high-precision spectropolarimetric observations of (1) complete magnitude-limited samples and (2) complete volume-limited samples of white dwarfs. In the course of one of our surveys we have discovered previously unknown kG-level magnetic fields on two nearby white dwarfs, WD 1105–340 and WD 2150+591. Both stars are brighter than mV = 15. WD 2150+591 is within the 20 pc volume around the Sun, while WD 1105–340 is just beyond 25 pc in distance. These discoveries increase the small sample of such weak-field white dwarfs from 21 to 23 stars. Our data appear consistent with roughly dipolar field topology, but it also appears that the surface field structure may be more complex on the older star than on the younger one, a result similar to one found earlier in our study of the weak-field stars WD 2034+372 and WD 2359–434. This encourages further efforts to uncover a clear link between magnetic morphology and stellar evolution.

scholarly journals Magnetic fields in white dwarfs and stellar evolution

2004 ◽  
Vol 355 (3) ◽  
pp. L13-L16 ◽  
Author(s):  
C. A. Tout ◽  
D. T. Wickramasinghe ◽  
L. Ferrario
Keyword(s):  
Magnetic Fields ◽  
Stellar Evolution ◽  
White Dwarfs

scholarly journals An Essay on Stellar Oscillations and Evolution

1983 ◽  
Vol 66 ◽  
pp. 457-467
Author(s):  
Icko Iben
Keyword(s):  
Stellar Evolution ◽  
Evolution Theory ◽  
Agb Stars ◽  
Solar Oscillation ◽  
High Luminosity ◽  
Stellar Oscillations ◽  
Classical Cepheids ◽  
Neutrino Fluxes ◽  
Oscillation Characteristics

AbstractIt is cautioned that solar models adjusted in such a way as to achieve a match between theoretical solar oscillation characteristics and observed ones may produce neutrino fluxes inconsistent with the observations and that this is likely to be explicable as a deficiency in modeling that portion of the envelope which is most strongly affected by uncertainties in the treatment of convection. Then follows a summary of how the results of pulsation theory and of stellar evolution theory have been used together to learn about the structure and evolution of RRLyrae stars, classical Cepheids, and high luminosity AGB stars.

scholarly journals Physics under the bonnet of a stellar evolution code

2015 ◽  
Vol 11 (A29B) ◽  
pp. 600-607
Author(s):  
Richard J. Stancliffe
Keyword(s):  
Magnetic Fields ◽  
Stellar Evolution ◽  
Reaction Rates ◽  
Computational Method ◽  
Atomic Diffusion ◽  
Stellar Models ◽  
Convective Boundaries ◽  
The Way

AbstractJust how good are modern stellar models? Providing a rigorous assessment of the uncertainties is difficult because of the multiplicity of input physics. Some of the ingredients are reasonably well-known (like reaction rates and opacities). Others are not so good, with convection standing out as a particularly obvious example. In some cases, it is not clear what the ingredients should be: what role do atomic diffusion, rotation, magnetic fields, etc. play in stellar evolution? All this is then compounded by computational method. In converting all this physics into something we can implement in a 1D evolution code, we are forced to make choices about the way the equations are solved, how we will treat mixing at convective boundaries, etc. All of this can impact the models one finally generates. In this review, I will attempt to assess the uncertainties associated with the ingredients and methods used by stellar evolution modellers, and what their impacts may be on the science that we wish to do.

Sign in / Sign up

Export Citation Format

Share Document