scholarly journals Singly-Ionized Iron Emission Lines in the Spectra of Early Type Stars

1976 ◽  
Vol 70 ◽  
pp. 99-103
Author(s):  
R. Viotti ◽  
P. Koubský
Keyword(s):  
Spectroscopic Investigation ◽  
Emission Lines ◽  
Be Stars ◽  
Early Type ◽  
Atomic Processes ◽  
Early Type Stars ◽  
Stellar Envelopes ◽  
Two Parameter

The appearance of singly ionized iron emission lines in the spectra of early type stars is studied, and the results of a spectroscopic investigation of EW Lac and other Be stars are given. We also discuss the atomic processes of excitation of Fe ii in the stellar envelopes using a two-parameter diagram W, NeT−1/2e.

scholarly journals The Connection with B[e] stars

2000 ◽  
Vol 175 ◽  
pp. 26-36 ◽  
Author(s):  
Franz-Josef Zickgraf
Keyword(s):  
Common Property ◽  
Main Sequence ◽  
Emission Lines ◽  
Circumstellar Dust ◽  
Evolutionary Status ◽  
Be Stars ◽  
Early Type ◽  
Circumstellar Envelopes ◽  
Early Type Stars ◽  
Uniform Group

AbstractThe characteristics of the various types of B[e] stars are discussed and compared with those of classical Be stars. Both groups of stars are characterized by the presence of emission lines in their spectra, in particular of hydrogen. However, there are also significant differences between these classes. Classical Be stars lack hot circumstellar dust and strong forbidden low-excitation emission lines, which are typical characteristics produced by B[e]-type stars. While classical Be stars are a rather uniform group of early-type stars, B[e]-type stars form a quite heterogeneous group, very often of poorly known evolutionary status, comprising such diverse types of objects as near main-sequence objects, evolved lowmass proto-planetray nebulae and massive evolved hot supergiants. Even pre-main sequence Herbig Ae/Be stars sometimes find their way into the group of B[e] stars. However, despite these dissimilarities classical Be stars and B[e]-type stars, share a common property, namely the nonsphericity of their circumstellar envelopes.

scholarly journals Observations of stellar winds in early type stars

1981 ◽  
Vol 59 ◽  
pp. 1-18
Author(s):  
Peter S. Conti
Keyword(s):  
Resonance Line ◽  
Optical Spectrum ◽  
Main Sequence ◽  
Emission Lines ◽  
Stellar Winds ◽  
Be Stars ◽  
Early Type ◽  
Main Sequence Stars ◽  
Early Type Stars ◽  
Line P

I have been asked to review the “observations” of winds in “early-type” stars. This normally means stars of spectral type OB and those of the Wolf-Rayet (WR) class. In this paper I will concentrate on the massive population I stars of these types, and primarily the O and WR classes on which most of the recent work has been done. The early B type supergiants share many of the wind properties of the O stars but the later supergiant types, Be stars, and main sequence stars may not. Stellar winds are a ubiquitous phenomenon among these early type stars (Snow and Morton 1976). We see evidence of their winds in the resonance line P Cygni profiles in the UV region, in the emission lines of Hα and λ4686 He II in the optical spectrum, and in the free-free emission from the ionized plasma as observed in the IR and radio regions of the spectrum.

scholarly journals On the Fe II Dielectronic Recombination in Stellar Envelopes

2000 ◽  
Vol 175 ◽  
pp. 492-493 ◽  
Author(s):  
Alicia Cruzado ◽  
Adela E. Ringuelet
Keyword(s):  
Dielectronic Recombination ◽  
Early Type ◽  
Atomic Processes ◽  
Early Type Stars ◽  
Stellar Envelopes

AbstractWe are interested in the atomic processes taking place in the envelopes of early type stars; the first part of our project consists of an investigation of the dielectronic recombination (DR) of metals. In earlier papers, we have studied the DR of Mg II and its contribution to the IR continuum; now, we are interested in accomplishing similar results analysing the Fe II atom.

Some results of the Barbier-Chalonge-Divan system of stellar classification

1966 ◽  
Vol 24 ◽  
pp. 77-90 ◽  
Author(s):  
D. Chalonge
Keyword(s):  
Early Type ◽  
Parameter System ◽  
Early Type Stars ◽  
Two Parameter

Several years ago a three-parameter system of stellar classification has been proposed (1, 2), for the early-type stars (O-G): it was an improvement on the two-parameter system described by Barbier and Chalonge (3).

Infrared Rydberg Emission Lines in Early-Type Stars. I. MG II

1996 ◽  
Vol 461 ◽  
pp. 972 ◽  
Author(s):  
T. A. A. Sigut ◽  
John B. Lester
Keyword(s):  
Emission Lines ◽  
Early Type ◽  
Early Type Stars

scholarly journals Be Phenomena in Young Early-type Stars: Various Forms of Interaction between the Star and the Circumstellar Gaseous Envelope

2000 ◽  
Vol 175 ◽  
pp. 344-347
Author(s):  
M. Pogodin
Keyword(s):  
High Resolution ◽  
Stellar Wind ◽  
Main Sequence ◽  
Stellar Surface ◽  
High Resolution Spectroscopy ◽  
Evolutionary Status ◽  
Be Stars ◽  
Early Type ◽  
Early Type Stars ◽  
Gaseous Envelope

AbstractNew results of high-resolution spectroscopy of four pre-main sequence Ae/Be stars are presented. An analysis of parameters of lines originating in different regions of the circumstellar (CS) envelope (Hα, Hβ, He I 5876, DNal) allows to reconstruct a picture of the interaction between the star and the CS environment which can be displayed in different forms. At least two separate processes seem to impact the structural and kinematical properties of the envelope: the stellar wind from the stellar surface and the matter infall onto the star from the CS media. A possible relation between these two phenomena is discussed in the framework of different models. Some similarity between observational phenomena in Herbig Ae/Be and classical Be stars is noted in spite of their difference in evolutionary status.

scholarly journals A Search for Coronal Emission Lines from Early-Type Stars

1988 ◽  
Vol 132 ◽  
pp. 123-125
Author(s):  
D. Baade ◽  
L. B. Lucy
Keyword(s):  
Stellar Wind ◽  
Controversial Issue ◽  
Emission Lines ◽  
Stellar Winds ◽  
Early Type ◽  
Wind Model ◽  
Coronal Emission ◽  
Early Type Stars ◽  
Hot Corona

For more than ten years now, a controversial issue in studies of stellar winds has concerned the existence or not of a coronal zone (T ∼ 106 K) at the base of the cool winds (T ∼ Teff) of early-type stars. The latest revival of interest in this possibility is due to Wolfire et al. (1985) who showed that Waldron's (1984) recombination stellar wind (RSW) version of the hot corona – cool wind model (Hearn 1975; Cassinelli et al. 1978) yields models for ξ Puppis (O4 If) that are consistent with both IRAS and Einstein IPC data, thus refuting an earlier claim (Lamers et al. 1984) to have excluded the existence of a coronal zone.

Sign in / Sign up

Export Citation Format

Share Document