The effects of magnetic fields on the winds from luminous hot stars

2008 ◽  
pp. 169-177
Author(s):  
Joseph P. Cassinelli ◽  
Nathan A. Miller
Keyword(s):  
Magnetic Fields ◽  
Hot Stars

scholarly journals X-Ray Emission from Magnetically Confined Winds

1999 ◽  
Vol 169 ◽  
pp. 187-190
Author(s):  
Jacques Babel
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Hot Stars ◽  
X Ray ◽  
Magnetically Confined ◽  
Circumstellar Environment

AbstractWe consider the effect of large scale magnetic fields on the circumstellar environment of hot stars. In these stars, magnetic fields of order of 100 G lead to magnetically confined wind shocks (MCWS) and then to the existence of large X-ray emitting region. MCWS lead also to the presence of corotating cooling disks around hot stars.We discuss the case of θ1 Ori C, which is perhaps the hottest analog to Bp stars and consider the effect from rotation and instabilities. We finally discuss the case of the Herbig Ae-Be HD 104237 and show that MCWS might also explain the X-ray emission from this star.

scholarly journals The evolution of magnetic fields in hot stars

2016 ◽  
Vol 12 (S329) ◽  
pp. 141-145
Author(s):  
Mary E. Oksala ◽  
Coralie Neiner ◽  
Cyril Georgy ◽  
Norbert Przybilla ◽  
Zsolt Keszthelyi ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Main Sequence ◽  
Stellar Structure ◽  
Surface Magnetism ◽  
Hot Stars ◽  
Life Project ◽  
Surface Magnetic Field ◽  
First Order ◽  
Structure Changes ◽  
The Impact

AbstractOver the last decade, tremendous strides have been achieved in our understanding of magnetism in main sequence hot stars. In particular, the statistical occurrence of their surface magnetism has been established (~10%) and the field origin is now understood to be fossil. However, fundamental questions remain: how do these fossil fields evolve during the post-main sequence phases, and how do they influence the evolution of hot stars from the main sequence to their ultimate demise? Filling the void of known magnetic evolved hot (OBA) stars, studying the evolution of their fossil magnetic fields along stellar evolution, and understanding the impact of these fields on the angular momentum, rotation, mass loss, and evolution of the star itself, is crucial to answering these questions, with far reaching consequences, in particular for the properties of the precursors of supernovae explosions and stellar remnants. In the framework of the BRITE spectropolarimetric survey and LIFE project, we have discovered the first few magnetic hot supergiants. Their longitudinal surface magnetic field is very weak but their configuration resembles those of main sequence hot stars. We present these first observational results and propose to interpret them at first order in the context of magnetic flux conservation as the radius of the star expands with evolution. We then also consider the possible impact of stellar structure changes along evolution.

scholarly journals Observations of Magnetic Fields in B Stars

1994 ◽  
Vol 162 ◽  
pp. 155-166
Author(s):  
David A. Bohlender
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Effective Temperature ◽  
Be Stars ◽  
Hot Stars ◽  
Photometric Variability ◽  
B Stars ◽  
Peculiar Stars ◽  
Thermal Radio Emission ◽  
Circumstellar Environments

Globally ordered magnetic fields are known to exist in non-degenerate stars with spectral types between approximately F0 and B2. Among the B stars, and in order of increasing effective temperature, these include the Bp Si stars, helium-weak stars, and the helium-strong stars. These rather remarkable objects present us with an excellent opportunity to quantitatively examine the possible effects of magnetic fields on the photospheres, winds, and circumstellar environments of hot stars. In this paper we review some of the observations of the magnetic fields and field geometries of magnetic B stars, and also briefly discuss the success of attempts to measure magnetic fields in hotter OB and Be stars. We point out some of the interesting observational similarities of the helium-weak and helium-strong stars to Be and other hot stars, including their spectroscopic and photometric variability, variable winds as demonstrated by the UV resonance lines of C IV and Si IV, and their non-thermal radio emission. Continuing work also suggests that a considerable fraction of the rapidly rotating magnetic helium-peculiar stars are in fact variable Be and Be shell stars.

scholarly journals Observations of magnetic fields in hot stars

2010 ◽  
Vol 6 (S272) ◽  
pp. 106-117 ◽  
Author(s):  
Véronique Petit
Keyword(s):  
Magnetic Properties ◽  
Magnetic Fields ◽  
Massive Stars ◽  
Current Understanding ◽  
High Mass ◽  
Hot Stars ◽  
Precise Information ◽  
Ob Stars ◽  
Modern Methods ◽  
New Generation

AbstractThe presence of magnetic fields at the surfaces of many massive stars has been suspected for decades, to explain the observed properties and activity of OB stars. However, very few genuine high-mass stars had been identified as magnetic before the advent of a new generation of powerful spectropolarimeters that has resulted in a rapid burst of precise information about the magnetic properties of massive stars. During this talk, I will briefly review modern methods used to diagnose magnetic fields of higher-mass stars, and summarize our current understanding of the magnetic properties of OB stars.

Constraints on the surface magnetic fields of hot stars with winds

1992 ◽  
Vol 386 ◽  
pp. 695 ◽  
Author(s):  
Murugesapillai Maheswaran ◽  
Joseph P. Cassinelli
Keyword(s):  
Magnetic Fields ◽  
Hot Stars

scholarly journals Evidence for spots on hot stars suggests major revision of stellar physics

2019 ◽  
Vol 490 (2) ◽  
pp. 2112-2116 ◽  
Author(s):  
L A Balona
Keyword(s):  
Magnetic Fields ◽  
Hot Stars ◽  
B Stars ◽  
Considerable Fraction ◽  
Rotation Periods ◽  
Major Revision ◽  
Stellar Envelopes ◽  
Space Observations

ABSTRACT It has long been thought that starspots are not present in the A and B stars because magnetic fields cannot be generated in stars with radiative envelopes. Space observations show that a considerable fraction of these stars varies in light with periods consistent with the expected rotation periods. Here we show that the photometric periods are the same as the rotation periods and that starspots are the likely cause for the light variations. This discovery has wide-ranging implications and suggests that a major revision of the physics of hot stellar envelopes may be required.

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