Helium line emission from Be stars

1994 ◽  
Vol 420 ◽  
pp. 803 ◽  
Author(s):  
Krishna M. V. Apparao ◽  
S. P. Tarafdar
Keyword(s):  
Line Emission ◽  
Be Stars ◽  
Helium Line

Design Considerations and Preliminary Characterizations of a Kilowatt-Plus Microwave-Induced Plasma

1988 ◽  
Vol 42 (6) ◽  
pp. 1061-1065 ◽  
Author(s):  
Kevin B. Cull ◽  
Jon W. Carnahan
Keyword(s):  
Line Emission ◽  
Helical Flow ◽  
Microwave Generator ◽  
Microwave Induced Plasma ◽  
Design Considerations ◽  
Resonator Cavity ◽  
Helium Line ◽  
Intensity Ratios ◽  
Ion Emission ◽  
Generator Output

A high-powered helium microwave-induced plasma was developed, and preliminary characterizations are presented. This kilowatt-plus microwave-induced plasma (KiP-MIP) was contained in a helical flow quartz torch. Power was transferred via waveguides from a 3.0-kW, 2.45-GHz, 120-pulses-per-second microwave generator to a waveguide-to-coaxial converter. A modified Beenakker TM010 resonator cavity was used to focus the energy. Effects of the magnitude of applied power on helium line emission intensities were studied, as well as comparisons of the temporal output of generator output and helium line emission. Introduction of gaseous halogens (Cl2, CBr4) produced intense ion emission which follows the intensity ratios commonly observed in He-MIPs.

Neutral helium line emission for edge plasma conditions

2005 ◽  
Vol 337-339 ◽  
pp. 1101-1105 ◽  
Author(s):  
F.B. Rosmej ◽  
R. Stamm ◽  
S. Fritzsche ◽  
H. Capes ◽  
M. Koubiti ◽  
...  
Keyword(s):  
Line Emission ◽  
Edge Plasma ◽  
Helium Line

Hydrogen and Helium Line Intensities in Some be Stars.

1951 ◽  
Vol 113 ◽  
pp. 84 ◽  
Author(s):  
E. Margaret Burbidge ◽  
G. R. Burbidge
Keyword(s):  
Be Stars ◽  
Line Intensities ◽  
Helium Line

scholarly journals Short and Medium Term Variability of Emission Lines in Selected Southern be Stars

1999 ◽  
Vol 169 ◽  
pp. 36-39
Author(s):  
Thomas Rivinius
Keyword(s):  
Line Emission ◽  
Spectral Lines ◽  
Emission Lines ◽  
Be Stars ◽  
Medium Term ◽  
Monitoring Period ◽  
Stellar Orbit

AbstractWe observed a sample of several southern Be stars from 1995 to 1997 typically for several months in each season using our spectrograph HEROS. One of these stars, μ Cen, was found to be in the process of continued gradual recovery of the Hydrogen emitting disk which had been lost from 1977-1989. During the monitoring period numerous line emission outbursts were observed. A generalized pattern of an outburst cycle is derived from observations of different circumstellar lines at times of various levels of emission from the disk. Relative quiescence in which mostly periodic varaibiltiy is seen, rapid decreases of emission (precursor), outburst, and subsequent relaxation can be distinguished as the main constituing phases, even though there are distinct differences between different groups of spectral lines. Based on this empirical phenomenology, a schematic picture of the associated ejection of matter into a near-stellar orbit is sketched and similarities between μ Cen and other stars will be outlined.

Helium line emission spectroscopy in recombining detached plasmas

2018 ◽  
Vol 25 (6) ◽  
pp. 063303 ◽  
Author(s):  
Shin Kajita ◽  
Kensuke Suzuki ◽  
Hirohiko Tanaka ◽  
Noriyasu Ohno
Keyword(s):  
Emission Spectroscopy ◽  
Line Emission ◽  
Helium Line

scholarly journals Measurements of Ion Temperature and Flow Velocity in Divertor Simulator MAP-II from Hydrogenic Helium Line Emission

2003 ◽  
Vol 79 (9) ◽  
pp. 841-843 ◽  
Author(s):  
Shinichiro KADO ◽  
Taiichi SHIKAMA
Keyword(s):  
Flow Velocity ◽  
Line Emission ◽  
Ion Temperature ◽  
Helium Line

H? line emission and infrared excess in Be stars

1985 ◽  
Vol 113 (2) ◽  
pp. 373-381 ◽  
Author(s):  
P. S. Goraya ◽  
B. S. Rautela
Keyword(s):  
Line Emission ◽  
Be Stars ◽  
Infrared Excess

scholarly journals Continuous spectra of circumstellar envelopes of Be stars

1994 ◽  
Vol 162 ◽  
pp. 425-426
Author(s):  
D. Rohe-Koths ◽  
J. Dachs
Keyword(s):  
Line Emission ◽  
Circumstellar Disks ◽  
Balmer Line ◽  
Be Stars ◽  
Continuous Emission ◽  
Circumstellar Envelopes ◽  
Recombination Radiation ◽  
Infrared Spectral ◽  
Be Star ◽  
Central Stars

Line emission in Be star spectra is accompanied by continuous emission both in the Balmer continuum and in the infrared spectral region, due to the same process that is responsible for Balmer line emission, i.e. to recombination radiation from ionized hydrogen in the extended circumstellar disks surrounding the hot central stars.

scholarly journals Short-term variability and mass loss in Be stars

2020 ◽  
Vol 635 ◽  
pp. A140 ◽  
Author(s):  
C. C. Borre ◽  
D. Baade ◽  
A. Pigulski ◽  
D. Panoglou ◽  
A. Weiss ◽  
...  
Keyword(s):  
Spiral Structure ◽  
Line Emission ◽  
Amplitude Distribution ◽  
Optical Variability ◽  
Radial Pulsation ◽  
Be Stars ◽  
Short Term ◽  
Period Range ◽  
Rapid Rotation ◽  
X Ray

Context. Be stars are physically complex systems that continue to challenge theory to understand their rapid rotation, complex variability, and decretion disks. γ Cassiopeiae (γ Cas) is one such star but is even more curious because of its unexplained hard thermal X-ray emission. Aims. We aim to examine the optical variability of γ Cas and thereby to shed more light on its puzzling behaviour. Methods. We analysed 321 archival Hα spectra from 2006 to 2017 to search for frequencies corresponding to the 203.5 day orbit of the companion. Space photometry from the SMEI satellite from 2003 to 2011 and the BRITE-Constellation of nano-satellites from 2015 to 2019 were investigated in the period range from a couple of hours to a few days. Results. The orbital period of the companion of 203.5 days is confirmed with independent measurements from the structure of the Hα line emission. A strong blue versus red asymmetry in the amplitude distribution across the Hα emission line could hint at a spiral structure in the decretion disk. With the space photometry, the known frequency of 0.82 d−1 is confirmed in data from the early 2000s. A higher frequency of 2.48 d−1 is present in the data from 2015 to 2019 and possibly in the early 2000s as well. A third frequency at 1.25 d−1 is proposed to exist in both SMEI and BRITE data. Seemingly, only a non-radial pulsation interpretation can explain all three variations. The two higher frequencies are incompatible with rotation.

scholarly journals The continuing saga of Sakurai's object (V4334 Sgr): dust production and helium line emission

2000 ◽  
Vol 315 (3) ◽  
pp. 595-599 ◽  
Author(s):  
V. H. Tyne ◽  
S. P. S. Eyres ◽  
T. R. Geballe ◽  
A. Evans ◽  
B. Smalley ◽  
...  
Keyword(s):  
Line Emission ◽  
Dust Production ◽  
Helium Line
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