scholarly journals Helium stars exploding in circumstellar material and the origin of Type Ibn supernovae

2021 ◽  
Author(s):  
L. Dessart ◽  
D. J. Hillier ◽  
H. Kuncarayakti
Keyword(s):  
Circumstellar Material ◽  
Helium Stars

scholarly journals Magnetic Fields and Winds of the Intermediate Helium Stars

1985 ◽  
Vol 87 ◽  
pp. 277-296
Author(s):  
Paul K. Barker
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Stellar Winds ◽  
Be Stars ◽  
Circumstellar Material ◽  
Helium Stars ◽  
Complex Variety ◽  
Hα Emission ◽  
Rapid Rotator ◽  
Ap Stars

AbstractThe intermediate helium stars are exceedingly rare hot analogs of the classical Ap stars, and are the earliest type stars to possess observable global ordered magnetic fields. A recent discovery is the existence of stellar winds which have large scale magnetospheric structure embedded within them. The nature and geometry of the detected fields are summarized, and the modulation of the circumstellar material by the field is illustrated for two examples: the rapid rotator σ Ori E, and the slow rotator HD 184927. The complex variety of stellar wind phenomenology which may be encountered is displayed by a sample of ten helium strong stars. A few of these objects show Hα emission, and thus are the only known magnetic Be stars.

scholarly journals Accretion and Outflow Activity in the Earliest Phases of Star-Formation: CO, Sub-mm Continuum, and Near-Infrared Observations

1997 ◽  
Vol 163 ◽  
pp. 725-726
Author(s):  
K.-W. Hodapp ◽  
E. F. Ladd
Keyword(s):  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Far Infrared ◽  
Point Sources ◽  
Spectral Energy ◽  
Infrared Observations ◽  
Circumstellar Material ◽  
Dense Cores ◽  
Wavelength Radiation ◽  
Main Component

Stars in the earliest phases of their formation, i.e., those accreting the main component of their final mass, are deeply embedded within dense cores of dust and molecular material. Because of the high line-of-sight extinction and the large amount of circumstellar material, stellar emission is reprocessed by dust into long wavelength radiation, typically in the far-infrared and sub-millimeter bands. Consequently, the youngest sources are strong submillimeter continuum sources, and often undetectable as point sources in the near-infrared and optical. The most deeply embedded of these sources have been labelled “Class 0” sources by André, Ward-Thompson, & Barsony (1994), in an extension of the spectral energy distribution classification scheme first proposed by Adams, Lada, & Shu (1987).

scholarly journals Revealing the Mass Loss Structures of Four Key Massive Binaries Using Optical Spectropolarimetry

2014 ◽  
Vol 9 (S307) ◽  
pp. 336-341
Author(s):  
Jamie R. Lomax
Keyword(s):  
Mass Loss ◽  
Binary Systems ◽  
Hot Spot ◽  
Polarized Light ◽  
Opening Angle ◽  
Geometric Information ◽  
Intrinsic Polarization ◽  
Polarization Component ◽  
Circumstellar Material ◽  
Large Opening

AbstractThe majority of massive stars are members of binary systems. However, in order to understand their evolutionary pathways, mass and angular momentum loss from these systems needs to be well characterized. Self-consistent explanations for their behavior across many wavelength regimes need to be valid in order to illuminate key evolutionary phases. I present the results of linear spectropolarimetric studies of three key binaries (β Lyrae, V356 Sgr, V444 Cyg, and WR 140) which reveal important geometric information about their circumstellar material. β Lyrae exhibits a repeatable discrepancy between secondary eclipse in the total and polarized light curves that indicates an accretion hot spot has formed on the edge of the disk in the system. The existence of this hot spot and its relationship to bipolar outflows within the system is important in the understanding of mass transfer dynamics in Roche-lobe overflow binaries. Preliminary work on V356 Sgr suggests the system maybe surrounded by a common envelope. V444 Cyg shows evidence that its shock creates a cone with a large opening angle of missing material around the WN star. This suggests the effects of radiative inhibition or braking, can be significant contributors to the location and shape of the shock within colliding wind binaries. The intrinsic polarization component of WR 140 is likely due to the formation of dust within the system near periastron passages. Continued work on these and additional objects will provide new and important constraints on the mass loss structures within binary systems.

scholarly journals A search for variability in intermediate helium stars

1994 ◽  
Vol 269 (1) ◽  
pp. 33-36 ◽  
Author(s):  
D. Kilkenny ◽  
E. Luvhimbi ◽  
M. Harrop-Allin
Keyword(s):  
Helium Stars

scholarly journals Unidentified emission features in the R Coronae Borealis star V854 Centauri

2018 ◽  
Vol 610 ◽  
pp. L6 ◽  
Author(s):  
L. C. Oostrum ◽  
B. B. Ochsendorf ◽  
L. Kaper ◽  
A. G. G. M. Tielens
Keyword(s):  
Near Infrared ◽  
Physical Nature ◽  
The Other ◽  
Large Telescope ◽  
Circumstellar Material ◽  
Spatially Resolved ◽  
Broad Emission ◽  
Very Large Telescope ◽  
New Feature ◽  
Molecular Nature

During its 2012 decline, the R Coronae Borealis star (RCB) V854 Cen was spectroscopically monitored with X-shooter on the ESO Very Large Telescope. The obscured optical and near-infrared spectrum exhibits many narrow and several broad emission features, as previously observed. The envelope is spatially resolved along the slit and allows for a detailed study of the circumstellar material. In this Letter, we report on the properties of a number of unidentified visual emission features (UFs), including the detection of a new feature at 8692 Å. These UFs have been observed in the Red Rectangle (RR), but their chemical and physical nature is still a mystery. The previously known UFs behave similarly in the RR and in V854 Cen, but are not detected in six other observed RCBs. Some hydrogen might be required for the formation of their carrier(s). The λ8692 UF is present in all RCBs. Its carrier is likely of a carbonaceous molecular nature, presumably different from that of the other UFs.

scholarly journals A search for circumstellar material around B-type stars in the Galactic halo

2002 ◽  
Vol 336 (4) ◽  
pp. 1147-1154 ◽  
Author(s):  
H. R. M. Magee ◽  
W. R. J. Rolleston ◽  
P. L. Dufton ◽  
F. P. Keenan ◽  
C. J. Mooney
Keyword(s):  
Galactic Halo ◽  
Circumstellar Material

scholarly journals Extreme helium stars: non-LTE matters

2005 ◽  
Vol 443 (3) ◽  
pp. L25-L28 ◽  
Author(s):  
N. Przybilla ◽  
K. Butler ◽  
U. Heber ◽  
C. S. Jeffery
Keyword(s):  
Helium Stars

Comparison of oxygen with the extra lines in the spectra of the helium Stars β crucis, &c.; also summary of the spectra of southern Stars to the 3 1/2 magnitude and their distribution

1898 ◽  
Vol 62 (379-387) ◽  
pp. 417-423 ◽  
Keyword(s):  
Type I ◽  
Gaseous Nebulae ◽  
Helium Stars

In a previous paper read before the Society on April 8, 1897, I suggested that the special lines present in spectra of the first division of helium stars (Type I, Divison la) might possibly be clue to oxygen. These stars are associated by their position and distribution with the gaseous nebulae, and some of the lines in their spectra correspond with bright lines observed by Campbell in nebulae. The suggestion from this was that these stars are in the first stage of tellar development from gaseous nebulæ.

scholarly journals New results on the Galactic Center Helium stars

2007 ◽  
pp. 303-307
Author(s):  
Thibaut Paumard ◽  
Jean-Pierre Maillard ◽  
Susan Stolovy
Keyword(s):  
Galactic Center ◽  
Helium Stars
Sign in / Sign up

Export Citation Format

Share Document