scholarly journals Star-streaming from the Stars of Spectral Type B

1954 ◽  
Vol 114 (4) ◽  
pp. 460-466
Author(s):  
T. R. Tannahill
Keyword(s):  
Spectral Type ◽  
Type B

scholarly journals NLTE-Analysis of Three Extremely Helium-Rich O-Type Subdwarfs

1985 ◽  
Vol 87 ◽  
pp. 353-357
Author(s):  
C. Husfeld ◽  
U. Heber ◽  
J.S. Drilling
Keyword(s):  
Spectral Type ◽  
White Dwarf ◽  
Asymptotic Giant Branch ◽  
Evolutionary Status ◽  
Type B ◽  
Hot Stars ◽  
Upper Limits ◽  
Helium Stars ◽  
Effective Temperatures

AbstractThree extremely helium-rich sdO stars (LSE 153, LSE 259 and LSE 263) were analyzed spectroscopically by means of detailed NLTE model atmospheres. These stars are very hot, with effective temperatures ranging from 70000 to 75000 K and gravities between log g = 4.4 and 4.9. Upper limits for the hydrogen abundance were also derived. The evolutionary status of the sdO stars is discussed and it is concluded that they evolve from the asymptotic giant branch towards the white dwarf stage. A possible evolutionary link between these hot stars and the extreme helium stars of spectral type B is discussed.

Semidetached systems of spectral type B : BF Aurigae, mu*1 Scorpii and V Puppis.

1979 ◽  
Vol 84 ◽  
pp. 236 ◽  
Author(s):  
D. P. Schneider ◽  
J. J. Darland ◽  
K.-C. Leung
Keyword(s):  
Spectral Type ◽  
Type B

The genetic control of the two types of mannan produced by Saccharomyces cerevisiae

1971 ◽  
Vol 17 (11) ◽  
pp. 1451-1454 ◽  
Author(s):  
J. F. T. Spencer ◽  
P. A. J. Gorin ◽  
G. H. Rank
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Magnetic Resonance ◽  
Genetic Control ◽  
Spectral Type ◽  
Proton Magnetic Resonance ◽  
Side Chains ◽  
Type B ◽  
Complex Type ◽  
Mendelian Gene ◽  
Different Strains

The two mannans formed by different strains of Saccharomyces cerevisiae give proton magnetic resonance spectra (spectral types A and B), which suggests that they differ principally in the presence of a-(1 → 3)-linked mannopyranosyl end units of the side chains of the more complex type (giving spectral type B). The presence or absence of such end units was under the control of a single mendelian gene, since the two types of mannan segregated independently during sporulation. The gene controlling this type of mannan produced was apparently not linked to those controlling the requirements for adenine, uracil, leucine, or histidine. The implications of the findings concerning the mechanism of biosynthesis of yeast mannan are discussed.

scholarly journals On the Variability of Supergiant Stars

1995 ◽  
Vol 155 ◽  
pp. 395-396
Author(s):  
G. Burki ◽  
F. Kienzle
Keyword(s):  
Radial Velocity ◽  
Spectral Type ◽  
Characteristic Time ◽  
Type B ◽  
Large Dispersion ◽  
Intrinsic Luminosity

The la-type supergiants of spectral type B to G are probably all variable in radial velocity and luminosity; in addition, on the average, the amplitude of the variations increases with increasing intrinsic luminosity and are larger for the earliest and latest spectral types (Abt, 1957; Maeder & Rufener, 1972; Burki et al., 1978; Grenon, 1993). The variations are not strictly periodic, but can be frequently described by a characteristic time Tc, i.e., some kind of ‘most probable periodș (e.g., Sterken, 1977; Rufener et al., 1978; Percy et al., 1979; van Genderen et al., 1992).It is possible to define a Tc-luminosity-colour relation for the supergiant stars (Maeder & Rufener, 1972; Burki, 1978). However, this relation exhibits a large dispersion, due to the imprecise luminosity and colour determinations for these stars and, essentially, to the fact that each supergiant can show very different Tc values. Good determinations of >Tc require very long-term, continuous, photometric monitorings.

scholarly journals R127 and its Surrounding Star Cluster

1991 ◽  
Vol 143 ◽  
pp. 561-562
Author(s):  
Antonella Nota ◽  
Claus Leitherer ◽  
Mark Clampin ◽  
Roberto Gilmozzi
Keyword(s):  
Spectral Type ◽  
Narrow Band ◽  
Star Cluster ◽  
Emission Lines ◽  
Type B ◽  
Circumstellar Material ◽  
Luminous Blue Variable

The LMC star R127 (=HDE 269858) has originally been classified as a late WN type (Walborn 1977). Since then, R127 has developed from spectral type B to A (Wolf et al. 1988) and is now categorized as a Luminous Blue Variable. R127 is embedded in gaseous material and a star cluster which are barely resolvable even on the highest-quality images available. Stahl (1987) studied the circumstellar material using narrow-band CCD images centered on nebular emission lines. No systematic census of the stars in the immediate vicinity of R127 has yet been published.

scholarly journals Luminous blue variables - An evolutionary picture

1987 ◽  
Vol 122 ◽  
pp. 425-427
Author(s):  
S. R. Sreenivasan ◽  
W.J.F. Wilson
Keyword(s):  
Spectral Type ◽  
Variable Stars ◽  
Type B ◽  
Luminous Blue Variables ◽  
Processed Material

A considerable amount of observational information has been gathered on the so-called Hubble-Sandage Variables or S Doradus variable stars, largely due to the efforts of the Heidelberg group (see Wolf, this volume for a review). It is believed that the star P Cygni also belongs to this category. This group of objects is now being referred to as Luminous Blue Variables because they are massive (>10 M⊙), evolved (spectral type B or later) objects showing variability of more than one kind, and evidence of nuclear processed material at the surface.

scholarly journals Statistical Study of the Spin of Algols

1989 ◽  
Vol 107 ◽  
pp. 368-368
Author(s):  
Tan Huisong
Keyword(s):  
Spectral Type ◽  
Statistical Study ◽  
Type A ◽  
Type Systems ◽  
Type B ◽  
Synchronous Rotation

Synchronous rotational velocities have been calculated for 91 Algol-type systems for which the radii of the components and orbital inclinations have been published. New values of V sin i have been measured for some of these systems. The frequency of components rotating near synchronism (F less than 1.5) is found to be higher for unevolved than for evolved systems. For Algols with periods less than 10 days and radii greater than 0.2, synchronous rotation is found to be the rule. There are 50 components of spectral type B and 44 of spectral type A in systems with periods shorter than 10ḍ The shortest period in which synchronism is found is 4 days for the A-type components and 2 days for the B-type.

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