Fluctuating Helium Emission in Optically Thick Divertor Plasmas

2008 ◽  
Vol 48 (1-3) ◽  
pp. 243-248 ◽  
Author(s):  
F. B. Rosmej ◽  
N. Ohno ◽  
S. Takamura ◽  
S. Kajita
Keyword(s):  
Helium Emission

scholarly journals Infrared helium emission lines from Cygnus X-3 suggesting a Wolf-Rayet star companion

Nature ◽  
1992 ◽  
Vol 355 (6362) ◽  
pp. 703-705 ◽  
Author(s):  
M. H. van Kerkwijk ◽  
P. A. Charles ◽  
T. R. Geballe ◽  
D. L. King ◽  
G. K. Miley ◽  
...  
Keyword(s):  
Emission Lines ◽  
Rayet Star ◽  
Helium Emission

scholarly journals Nitrogen as the carrier gas for helium emission along an active fault in NW Taiwan

2010 ◽  
Vol 25 (4) ◽  
pp. 593-601 ◽  
Author(s):  
Wei-Li Hong ◽  
Tsanyao Frank Yang ◽  
Vivek Walia ◽  
Shih-Jung Lin ◽  
Ching-Chou Fu ◽  
...  
Keyword(s):  
Active Fault ◽  
Carrier Gas ◽  
Helium Emission

Absolutmessung der kontinuierlichen Strahlung des Heliums im Lichtbogen von λ = 109 bis 540 nm / Measurement of the Helium Continuum Radiation from λ = 109 to 540 nm in an Arc Plasma

1980 ◽  
Vol 35 (8) ◽  
pp. 808-819 ◽  
Author(s):  
P. Thoma
Keyword(s):  
Energy Balance ◽  
Theoretical Calculations ◽  
Continuum Emission ◽  
Kinetic Temperature ◽  
Arc Plasma ◽  
Plasma Parameters ◽  
Continuum Radiation ◽  
Theoretical Results ◽  
Helium Emission ◽  
Good Agreement

Abstract Absolute helium emission coefficients have been measured from 540 nm down to 109 nm in the near vuv. The radiation originates from the axis of a cylindrical He-arc of 2 mm ∅ at one atmosphere with electron temperatures between 25000 K and 26500 K. The electron densities range from 3.0 · 1016 cm-3 to 4.0 · 1016 cm-3 and have been determined independently from other plasma parameters by means of line shape measurements. The density of atoms and their kinetic temperature have been calculated from the energy balance of the electrons and Dalton's law. Comparison of the measured helium continuum emission coefficients with theoretical calculations in the wavelength range from 540 nm to 400 nm shows that, in this experiment, the radiation due to bremsstrahlung in the field of atoms must not be neglected. Taking into account this contribution very good agreement with theoretical calculations over the whole investigated spectral range from 540 nm down to 109 nm has been found. Thus the present experiment confirms the theoretical results for the photoionisation coefficients from the n = 2 and n = 3 levels. On the basis of these results the helium continuum radiation may be used for calibration purposes, which is of particular interest in the vuv.

scholarly journals Helium Emission Lines in the Type I[CLC]c[/CLC] Supernova 1999[CLC]cq[/CLC]

2000 ◽  
Vol 119 (5) ◽  
pp. 2303-2310 ◽  
Author(s):  
Thomas Matheson ◽  
Alexei V. Filippenko ◽  
Ryan Chornock ◽  
Douglas C. Leonard ◽  
Weidong Li
Keyword(s):  
Emission Lines ◽  
Type I ◽  
Helium Emission

scholarly journals Identification of the Spurious D3 Helium Emission from the Solar Corona.

1964 ◽  
Vol 69 ◽  
pp. 565 ◽  
Author(s):  
Harold Zirin ◽  
Robert James ◽  
D. Keith Watson
Keyword(s):  
Solar Corona ◽  
Helium Emission

scholarly journals Detection of circumstellar helium in Type Iax progenitor systems

2019 ◽  
Vol 487 (2) ◽  
pp. 2538-2577 ◽  
Author(s):  
Wynn V Jacobson-Galán ◽  
Ryan J Foley ◽  
Josiah Schwab ◽  
Georgios Dimitriadis ◽  
Shawfeng Dong ◽  
...  
Keyword(s):  
Spectral Synthesis ◽  
Early Time ◽  
Late Time ◽  
Independent Evidence ◽  
Hydrogen Emission ◽  
Upper Limits ◽  
The Common ◽  
Star Binary ◽  
Circumstellar Environment ◽  
Helium Emission

ABSTRACT We present direct spectroscopic modelling of 44 Type Iax supernovae (SNe Iax) using spectral synthesis code SYNAPPS. We confirm detections of helium emission in the early-time spectra of two SNe Iax: SNe 2004cs and 2007J. These He i features are better fit by a pure-emission Gaussian than by a P-Cygni profile, indicating that the helium emission originates from the circumstellar environment rather than the SN ejecta. Based on the modelling of the remaining 42 SNe Iax, we find no obvious helium features in other SN Iax spectra. However, ${\approx } 76{{\ \rm per\ cent}}$ of our sample lack sufficiently deep luminosity limits to detect helium emission with a luminosity of that seen in SNe 2004cs and 2007J. Using the objects with constraining luminosity limits, we calculate that 33 per cent of SNe Iax have detectable helium in their spectra. We examine 11 SNe Iax with late-time spectra and find no hydrogen or helium emission from swept-up material. For late-time spectra, we calculate typical upper limits of stripped hydrogen and helium to be 2 × 10−3 M⊙ and 10−2 M⊙, respectively. While detections of helium in SNe Iax support a white dwarf–He star binary progenitor system (i.e. a single-degenerate [SD] channel), non-detections may be explained by variations in the explosion and ejecta material. The lack of helium in the majority of our sample demonstrates the complexity of SN Iax progenitor systems and the need for further modelling. With strong independent evidence indicating that SNe Iax arise from an SD channel, we caution the common interpretation that the lack of helium or hydrogen emission at late-time in SN Ia spectra rules out SD progenitor scenarios for this class.

scholarly journals New Models for Massive Star Populations in Young Starbursts: Summary of the Models and Applications

1999 ◽  
Vol 186 ◽  
pp. 285-285
Author(s):  
Daniel Schaerer ◽  
William D. Vacca
Keyword(s):  
Emission Line ◽  
Stellar Evolution ◽  
Massive Star ◽  
Optical Emission ◽  
Emission Lines ◽  
Evolutionary Synthesis ◽  
Stellar Spectra ◽  
New Models ◽  
Helium Emission ◽  
Line Strengths

Using the latest stellar evolution models, theoretical stellar spectra, and a compilation of observed emission line strengths from Wolf-Rayet (WR) stars, we have constructed evolutionary synthesis models for young starbursts (Schaerer & Vacca 1997; see also Schaerer 1996). We provide detailed predictions of UV and optical emission line strengths for both the WR stellar lines and the major nebular hydrogen and helium emission lines, as a function of several input parameters related to the starburst episode.

G61 - 29, a Helium Emission-Line Star

1971 ◽  
Vol 170 ◽  
pp. L39 ◽  
Author(s):  
E. M. Burbidge ◽  
P. A. Strittmatter
Keyword(s):  
Emission Line ◽  
Helium Emission
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