scholarly journals Line Profile Variations of Rotating Pulsating Stars

1993 ◽  
Vol 139 ◽  
pp. 182-182
Author(s):  
C. Aerts ◽  
M. De Pauw
Keyword(s):  
Line Profile ◽  
Be Stars ◽  
Line Profiles ◽  
Rotating Stars ◽  
Early Type ◽  
Pulsating Stars ◽  
Doppler Image ◽  
Early Type Stars ◽  
Almost All ◽  
High Degree

Line-profile variations (LPVs) are often seen in early-type stars. They were first detected in the β Cephei stars, where they are due to radial as well as to nonradial pulsations (NRP). It is still a matter of debate whether NRP is also the cause of LPVs in broad-lined B- and Be stars.The study of LPVs of nonradially pulsating stars is often considered to be especially interesting in the case of rapid rotators, because in such stars the line profiles may offer a Doppler image of the stellar surface. Almost all investigators conclude that only sectorial modes with high -values can properly account for the observations of LPVs in broad-lined stars; on the other hand, high-degree modes are almost never seen in slowly rotating stars.We point out here that the expression for the velocity field which is usually adopted, is not valid for rapid rotators.

scholarly journals NRP Modes in a Be Star Zeta Oph

1995 ◽  
Vol 155 ◽  
pp. 301-302
Author(s):  
E. Kambe ◽  
R. Hirata ◽  
M. Kato ◽  
H. Ando ◽  
E. J. Kennelly ◽  
...  
Keyword(s):  
Line Profile ◽  
Early Type ◽  
Period Analysis ◽  
Be Star ◽  
Early Type Stars ◽  
Almost All

AbstractTwo large sinusoidal variations with periods of 3.337 hrs and 2.018 hrs and other smaller variations have been detected from the period analysis of Hel Λ 6678 spectra obtained by our multi-site campaign for ζ Oph in May, 1993. The resultant periodgram is considerably improved (aliasing free) from those in previous publications. The periodicity may be consistent with previous studies except ambiguities of aliasing. It is surprising that almost all detected periods have a common superperiodicity of about 10.05 hrs. We emphasise the importance of multi-site campaign for the study of line-profile variations (lpv) in early-type stars.

scholarly journals Nonradial Oscillations in Zeta Ophiuchi in 1991

1993 ◽  
Vol 134 ◽  
pp. 219-221
Author(s):  
E. Kambe ◽  
H. Ando ◽  
R. Hirata
Keyword(s):  
Line Profile ◽  
Be Stars ◽  
Early Type ◽  
Early Type Stars ◽  
Nonradial Oscillations

The line-profile variations have been found in many early-type stars surrounding the classical β Cephei variables in the H-R diagram. The feature of the variations has not been known enough mainly because of their periods of about one day. To specify the cause of the variations, however, it is necessary to make clear their features such as the multi-periodicity, the relation between the photometric variations and the spectroscopic ones, and the cause of existence or non-existence of mode (or period) switching (Balona 1991, Smith 1991). In Be stars, the correlation of the amplitude of the variations with their emission cycle is also important (Ando 1986).

scholarly journals Unified NRP-Modelling of Be Stars

2002 ◽  
Vol 185 ◽  
pp. 240-243 ◽  
Author(s):  
Th. Rivinius ◽  
D. Baade ◽  
S. Štefl ◽  
M. Maintz
Keyword(s):  
Line Profile ◽  
Inclination Angle ◽  
Be Stars ◽  
Rotating Stars ◽  
Early Type ◽  
Rapidly Rotating Stars ◽  
Nonradial Pulsation ◽  
Low Order

AbstractRecently, the line profile variability (lpv) of two low-v sin i Be stars, μ Cen and ω (28) CMa was successfully modelled as nonradial pulsation (nrp) of rapidly rotating stars seen pole-on. In this work, it is shown that the lpv of low-v sin i early-type Be stars in general closely resembles these two cases, and is therefore explainable by the same mechanism. The lpv of intermediate to high-v sin i Be stars can be explained by the same model if the inclination angle of the model alone is increased. Consequently, early-type Be stars form a distinct, fairly homogeneous class of non-radial low-order g-mode pulsators.

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.

Problems in the Formation of Neutral Helium Lines in Early Type Stars

1970 ◽  
Vol 1 (7) ◽  
pp. 326-328
Author(s):  
R. W. Simpson
Keyword(s):  
Absorption Coefficient ◽  
Electron Scattering ◽  
Growth Analysis ◽  
Line Profiles ◽  
Early Type ◽  
Line Absorption ◽  
Early Type Stars ◽  
Made In ◽  
The Continuum

The aim of this work is to investigate certain assumptions that have been made in calculating line profiles and equivalent widths of neutral helium lines in early type stars. The effect of electron scattering on the continuum flux is investigated and a curve of growth analysis carried out to study this effect. The theories involved in calculating the line absorption coefficient are also investigated.

Hβ Line Profiles for Rapidly Rotating Early- Type Stars.

1965 ◽  
Vol 70 ◽  
pp. 320
Author(s):  
George W., II Collins ◽  
J. Patrick Harrington
Keyword(s):  
Line Profiles ◽  
Early Type ◽  
Early Type Stars

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.

Sign in / Sign up

Export Citation Format

Share Document