Intermediate He Rich Stars

Hunger, K.; Groote, D.; Heber, U.

doi:10.1007/978-94-011-3416-3_16

Cited by 40 publications

(73 citation statements)

References 10 publications

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“…The interesting paper of Hunger & Groote (1999) motivated us to test whether we are also able to predict decoupling of helium on the basis of our multicomponent model. Therefore we introduced two new variables to describe the helium flow, namely helium density ρ He and helium radial velocity v r He .…”

Section: Decoupling Of Heliummentioning

confidence: 99%

“…These results stimulated many authors to study the possible effects of decoupling, however, not by self-consistent solving of the appropriate hydrodynamic equations. Porter & Drew (1995) studied decoupling in the outflow from B stars, Porter & Skouza (1999) using the theory of the decoupled wind pointed out the possibility of the presence of pulsating shells around stars with low-density radiatively driven wind, and Hunger & Groote (1999) studied decoupling of helium in a stellar wind.…”

Section: Introductionmentioning

confidence: 99%

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Multicomponent radiatively driven stellar winds

Krtička

Kubát

2001

A&A

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Abstract.We computed models of a three-component nonisothermal radiatively driven stellar wind for different spectral types of hot B stars. We showed that friction heats mainly the outer parts of the wind and the modified temperature stratification leads to a decrease of the outflow velocity. Contrary to the isothermal case, even the possibility of decoupling of radiatively absorbing ions and (major) nonabsorbing component is excluded for a realistic form of the driving force. Regardless of the actual form of the driving force, we derived general conditions under which decoupling of a stellar wind may occur. We demonstrated that the possibility of decoupling is closely related to the functional dependence of the driving force and to the ratio of the densities of individual components. We discuss several consequences of a multifluid phenomenon in hot star winds, particularly metallicity effects and the implications of possible helium decoupling on chemically peculiar stars. We propose an explanation of the low terminal velocity of τ Sco based on frictional heating.

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Section: Decoupling Of Heliummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multicomponent radiatively driven stellar winds

Krtička

Kubát

2001

A&A

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“…Irrespective of the exact abundances that may eventually be obtained, the following important statement can be expressed: the polar diffusion is well correlated with the magnetic field. W x max coincides with ILff = 0, practically independent of e/m (Hunger et al, 1990 and1991). This is also true for HD 37017 and HD 64740 (both He-rich, Shore and Brown, 1990), and for HD 5737 and HD 79158 (Shore et al, 1990).…”

Section: Polar Diffusionmentioning

confidence: 75%

“…The enrichment near the intersection of rotational and magnetic equators suggests that the wind is controlled by inertial forces (Bohlender, 1988) as well as Lorentz forces (Hunger et al 1990). Centrifugal forces amount to less than 20% in gravity and hence can be neglected.…”

Section: Magneto-rotational Diffusionmentioning

confidence: 99%

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He-Abnormal Stars

Hunger

Groote

1993

International Astronomical Union Colloquium

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The He-rich variable HD 37479 has 2 axes of symmetry, one characterized by the depletion of metals, and one by the enrichment of He. The former is oriented along the axis of the magnetic dipole, while the latter is off set by some 45°. The 2 axes represent 2 different modes of diffusion, the first one being controlled solely by the magnetic field, irrespective of wind, the second one being due to stellar wind that is controlled by the magnetic field and intertial forces. It has been attempted to formulate simple physical conditions that allow to determine the diffusion regions on the surface. It is shown that the resulting surface map can well reproduce the observed phase variations of the equivalent widths of Hel 4471, of UV resonance lines of C IV and Si IV, and the effective magnetic field.

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Chemically Peculiar Hot Stars

Smith¹

1996

Astrophysical and Laboratory Plasmas

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Intermediate He Rich Stars

Cited by 40 publications

References 10 publications

Multicomponent radiatively driven stellar winds

Multicomponent radiatively driven stellar winds

He-Abnormal Stars

Chemically Peculiar Hot Stars

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