The Excitation of Absorption Lines in Outer Atmospheric Shells of Stars.

Struve, Otto; Wurm, K.

doi:10.1086/143961

Cited by 24 publications

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“…Dilution effects were also found by Struve and his colleagues and collaborators in the spectra of shell stars of both earlier and later spectral type. Thus, the shell of the Bl IVe star £ Tau was revealed by the fact that, in addition to the sharp absorption lines of Fe II and other ionized metals and the Balmer line cores, He I X3965, which arises from a metastable level, is sharp while most other He I lines are broad and diffuse, due to the rapid rotation of the underlying star (Struve and Wurm 1938). The coolest shell stars found during those early years were the A-type expanding shell star 17 Leporis (Struve 1932) and the FO III shell star 14 Comae Berenices (Morgan 1932).…”

Section: Introduction: Early Observationsmentioning

confidence: 99%

The Be stars

Slettebak¹

1988

PASP

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Section: Introduction: Early Observationsmentioning

confidence: 99%

The Be stars

Slettebak¹

1988

PASP

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“…In regard to the lines that indicate dilution effect, we may say that, according to Struve & Wurm's (1938) figures, the diluted layer where the strong and narrow absorption of He I 3889 originates is probably located at a distance of more than 5 stellar radii from the star's centre. This layer is moving away from the system at a velocity of about −180 km s −1 , and its density is probably not higher than 10 11 cm −3 or so.…”

Section: The A4 Absorption System and The Distance To Ry Sctmentioning

confidence: 95%

A Spectrographic Study of the Interacting Eclipsing Binary RY Scuti: An Episode in the Rapid Mass Loss Stage or a Protoplanetary Nebula ?

Sahade¹,

West²,

Skul'Skij³

1992

Evolutionary Processes in Interacting Binary Stars

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RESUMENRY Scuti, la binaria de eclipse de 11 días de período, caracterizada, en su espectro, por presentar líneas de [Fe III], ha sido reinvestigada en base a material espectrográfico obtenido en Chile, en el Observatorio Europeo Austral y en el Observatorio Interamericano de Cerro Tololo, que cubre las regiones 3400-5150Å y 5700-6700Å. Fueron también analizadas observaciones en el ultravioleta obtenidas con el satélite IUE. El espectro de RY Sct es muy complejo y peculiar, y está caracterizado por varios conjuntos de líneas de emisión y de absorción. Entre las emisiones, aparece un grupo de líneas que son características de las nebulosas planetarias. El sistema está formado por una componente B0V y una compañera que parece rodeada por una envoltura opaca que emite en He II λ4686. En la envoltura circumbinaria podemos distinguir: (a) una región de radiación diluida animada de una velocidad de ∼ −178 km s −1 ; (b) regiones donde se originan las líneas de resonancia de Si IV y C IV en el ultravioleta, con velocidades de −1200 y −600 km s −1 ; (c) regiones que dan origen al "espectro nebular" y sugieren la existencia de una triple nebulosidad que rodea al sistema y está caracterizada por un valor de N e probablemente mayor que 10 4 cm −3 , un valor de T e ∼ 15-20,000 K y velocidades de −18, +9 y +48 km s −1 , respectivamente. ABSTRACT RY Scuti, the 11-day [Fe III] eclipsing binary, has been reinvestigated on the basis of spectrographic material obtained in Chile at the European Southern Observatory, La Silla, and at the Cerro Tololo Interamerican Observatory, covering the spectral regions 3400-5150Å and 5700-6700Å. Ultraviolet IUE observations were also analyzed. The spectrum of RY Sct is very complex and peculiar, being characterized by several sets of emission as well as absorption features. Among the emission features, there is a set of lines that are characteristic of planetary nebulae. The system is found to be formed by a B0V component and a companion that appears to be surrounded by an opaque envelope that emits in He II λ4686. In the circumbinary envelope we can distinguish: (a) a region of diluted radiation that suggests a velocity of ∼ −178 km s −1 ; (b) regions of formation of the resonance lines of Si IV and C IV in the IUE UV, characterized by velocities of −1200 and −600 km s −1 ; (c) regions that give rise to the "nebular spectrum" and suggest that there is a triple nebulosity surrounding the system with N e probably larger than 10 4 cm −3 , T e ∼ 15-20,000 K and velocities of −18, +9 and +48 km s −1 , respectively.

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Early-Type Emission-Line Stars

Svolopoulos

1982

Compendium in Astronomy

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The Excitation of Absorption Lines in Outer Atmospheric Shells of Stars.

Cited by 24 publications

References 0 publications

The Be stars

The Be stars

A Spectrographic Study of the Interacting Eclipsing Binary RY Scuti: An Episode in the Rapid Mass Loss Stage or a Protoplanetary Nebula ?

Early-Type Emission-Line Stars

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