On a thermonuclear origin for the 1980-81 deep light minimum of the symbiotic nova PU VUL

1993 ◽  
Vol 106 ◽  
pp. 298 ◽  
Author(s):  
Edward M. Sion
Keyword(s):  
Light Minimum

Polarimetry of R CrB at visual light minimum.

1973 ◽  
Vol 186 ◽  
pp. 961 ◽  
Author(s):  
G. V. Coyne ◽  
S. J. Shawl
Keyword(s):  
Light Minimum ◽  
Visual Light

scholarly journals On the Existence of Solar-type Activity in the Secondary Components of Cataclysmic Variables

1991 ◽  
Vol 130 ◽  
pp. 384-385
Author(s):  
E.S. Dmitrienko
Keyword(s):  
White Dwarf ◽  
Cataclysmic Variables ◽  
Recurrence Time ◽  
Late Type ◽  
Light Minimum ◽  
Type Activity ◽  
Solar Type ◽  
Cyclic Variations ◽  
The Difference

AbstractCyclic variations of the parameter O-C (the difference between observed and calculated times of the light minimum in eclipse) have been detected for Nova 1934 DQ Her in the U BV RI-bands during 1982-89 with a recurrence time of about 5-6 years and amplitudes of about 2-4 min. No O-C oscillations for the nova-like AC Cnc have been discovered with the resolution of 45 sec in 1985-89. Both systems consist of a white dwarf and a late-type dwarf component. Some possibilities to explain their O-C-behaviour are discussed.

Absorption Spectrum of RCrB During the Light Minimum

1989 ◽  
Vol 106 ◽  
pp. 403-403
Author(s):  
N. Kameswara Rao ◽  
S. Giridhar ◽  
B.N. Ashoka
Keyword(s):  
Absorption Spectrum ◽  
Molecular Band ◽  
Maximum Light ◽  
Light Minimum

Observations of RCrB obtained during the 1986 and early part of 1963 light minima show the following changes relative to the spectrum obtained at maximum light.The molecular band of C2 (Swan System), CN bands at λ4215 and low excitation metal lines are enhanced in absorption.

scholarly journals R Coronae Borealis at the 2003 light minimum

2006 ◽  
Vol 370 (2) ◽  
pp. 941-953 ◽  
Author(s):  
N. K. Rao ◽  
D. L. Lambert ◽  
M. D. Shetrone
Keyword(s):  
Light Minimum

scholarly journals A Theoretical Period-Luminosity Relation of Dwarf Cepheids

1993 ◽  
Vol 138 ◽  
pp. 437-438
Author(s):  
D.H. McNamara ◽  
John M. Powell
Keyword(s):  
Large Amplitude ◽  
High Accuracy ◽  
Fundamental Period ◽  
Instability Strip ◽  
Light Minimum ◽  
F Stars ◽  
Light Maximum ◽  
Very High

Dwarf Cepheids (large-amplitude δ Sct variables and SXPhe variables in the GCVS) are late A-type stars near light maximum and early-F stars near light minimum. In the lower part of the instability strip where these stars are found the pulsation constant Q varies only slightly. As pointed out by Andreasen, Hejlesen, and Petersen (1983) this makes it easy to transform a theoretical HR or alternatively a (logTe, logg) diagram to a theoretical logTe, logP0) diagram by the use of the relation. This follows from the equations:where P0 is the fundamental period of pulsation. The periods, of course, can be determined with very high accuracy.

scholarly journals The Unprecedented Light Variations of NGC 2346

1983 ◽  
Vol 103 ◽  
pp. 59-60
Author(s):  
R.H. Méndez ◽  
R. Gathier ◽  
V. S. Niemela
Keyword(s):  
Spectral Type ◽  
Planetary Nebula ◽  
Orbital Motion ◽  
Central Star ◽  
Primary Component ◽  
Radial Velocities ◽  
Spectroscopic Binary ◽  
Light Minimum ◽  
Photoelectric Measurements ◽  
Light Maximum

The central star of the planetary nebula NGC 2346 is now well confirmed as a single-lined spectroscopic binary, with P = 16d (Méndez and Niemela 1981, Ap. J., 250, 240). Unexpected photometric variations were recently reported by L. Kohoutek (1982, IAU Circular 3667). From additional photoelectric measurements and visual estimates we have found that these variations are periodic, with the same period as the orbital motion of the A-type primary component. From previous observations we can ascertain that such variations did not exist before, and must have started in 1981. The light minimum occurs at phase 0.75, that is to say when the A-type component is moving towards us. Radial velocities measured on spectrograms obtained during the light minimum are more positive, by about 40 km s−1, than expected from the orbital motion; while the radial velocities corresponding to the light maximum agree with what is expected from the orbital motion. The spectral type of the A-type star does not change significantly as a function of brightness.

IV-Th Great Visual Light Minimum of R CrB. I. UBVRCIC Photometry

Astrophysics ◽  
2016 ◽  
Vol 59 (2) ◽  
pp. 183-198 ◽  
Author(s):  
A. E. Rosenbush
Keyword(s):  
Light Minimum ◽  
Visual Light

scholarly journals The Photometric Investigation of V921 Her Using the Lunar-Based Ultraviolet Telescope of Chang’e-3 Mission

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Xiao Zhou ◽  
Sheng-Bang Qian ◽  
Jia Zhang ◽  
Lin-Jia Li ◽  
Qi-Shan Wang
Keyword(s):  
Binary System ◽  
Thermal Contact ◽  
Primary Star ◽  
Light Minimum ◽  
Evolutionary Scenario ◽  
Total Luminosity ◽  
Massive Component ◽  
Contact Binary ◽  
Photometric Investigation ◽  
First Time

The light curve of V921 Her in ultraviolet band observed by the Lunar-based Ultraviolet Telescope (LUT) is analyzed by the Wilson-Devinney code. Our solutions conclude that V921 Her is an early type marginal contact binary system with an additional close-in component. The binary system is under poor thermal contact with a temperature difference of nearly 700 K between the two components. The close-in component contributes about 19% of the total luminosity in the triple system. Combining the radial velocity study together with our photometric solutions, the mass of the primary star and secondary one is calculated to beM1=1.784  (±0.055)M⊙,M2=0.403  (±0.012)M⊙. The evolutionary scenario of V921 Her is discussed. All times of light minimum of V921 Her available in the bibliography are taken into account and theO-Ccurve is analyzed for the first time. The most probable fitting results are discussed in the paper, which also confirm the existence of a third component (P3=10.2year) around the binary system. The period of V921 Her is also undergoing a continuously rapid increase at a rate ofdP/dt=+2.79×10-7  day·year-1, which may be due to mass transfer from the less massive component to the more massive one.

Optical Spectroscopy at Deep Light Minimum of R Coronae Borealis

2013 ◽  
Vol 125 (930) ◽  
pp. 879-888 ◽  
Author(s):  
Steve B. Howell ◽  
Travis A. Rector ◽  
Donald Walter
Keyword(s):  
Optical Spectroscopy ◽  
Light Minimum
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