scholarly journals Formation of C2 and CN in nova V2676 Oph around its visual brightness maximum

2015 ◽  
Vol 67 (2) ◽  
Author(s):  
Hideyo Kawakita ◽  
Mitsugu Fujii ◽  
Masayoshi Nagashima ◽  
Tomoyo Kajikawa ◽  
Natsuki Kubo ◽  
...  
Keyword(s):  
Visual Brightness

scholarly journals UV Spectroscopy of the Novalike Variable TT Arietis

1982 ◽  
Vol 69 ◽  
pp. 453-454
Author(s):  
W. Wargau ◽  
H. Drechsel ◽  
J. Rahe ◽  
G. Klare ◽  
B. Wolf ◽  
...  
Keyword(s):  
Uv Spectroscopy ◽  
Wavelength Region ◽  
Apparent Magnitude ◽  
Long Wavelength ◽  
Dwarf Nova ◽  
Tt Ari ◽  
Visual Brightness

TT Ari was detected by Strohmeier et al. (1957) and is classified as a novalike variable. It was hitherto unclear whether TT Ari is a special type of dwarf nova (Warner, 1976) or an old nova (Cowley et al., 1975). Our group obtained a total of four IUE spectra between 1979 and 1981 in the short and long wavelength region. The first spectrum was taken in July 1979, when the system had a visual brightness of 11.3 magnitudes. The following two IUE observations in November 1980 revealed TT Ari in the lowest optical state (V = 14m.3) observed so far. The fourth spectrum was obtained during the rise to maximum in January 1981, when the system had an apparent magnitude of V = 11m.8. From this behavior, Krautter et al. (1981) concluded that TT Ari is a dwarf nova with extremely extended standstills as they are typical for Z Cam stars.

scholarly journals Theory of Dust Formation in R Coronae Borealis Stars

1985 ◽  
Vol 87 ◽  
pp. 441-451
Author(s):  
Yu. A. Fadeyev
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Radial Distance ◽  
Nucleation Theory ◽  
Dust Shell ◽  
M 10 ◽  
R Coronae Borealis Stars ◽  
Homogeneous Nucleation Theory ◽  
Visual Brightness

AbstractApplication of the homogeneous nucleation theory to the problem of R CrB stars shows that the radial distance of the inner boundary of the carbon supersaturation region is at about 12 photospheric radii for a stellar effective temperature Te = 6000 K. Formation of an optically thick dust shell becomes possible at mass loss rates Ṁ ≳ 10−6 M⊙/yr. However, the upper limit of this mass loss rate cannot considerably exceed 10−5 M⊙/yr since, at higher Ṁ, the theoretically predicted rate of the visual brightness decline is larger than that derived from observations. Comparison of the theoretically predicted radii of dust grains with those observed in R CrB and RY Sgr shows that the mass loss rate in these stars should be in the range of 1 × 10−7 M⊙/yr to 3 × 10−6 M⊙/yr.

Reaction Time and Visual Brightness: Within-Subject Correlations

1979 ◽  
Vol 48 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Armand V. Cardello
Keyword(s):  
Reaction Time ◽  
Stimulus Intensity ◽  
Reaction Times ◽  
Visual Reaction Time ◽  
Visual Reaction ◽  
Two Measures ◽  
The Relationship ◽  
Linear Correlations ◽  
Visual Brightness ◽  
Magnitude Estimates

An experiment was conducted to compare visual reaction time and visual brightness within the same subjects. Simple reaction times and magnitude estimates of brightness were obtained in response to 1000-msec. flashes of 60.7, 67.5, 76.4, 85.1, and 93.4 dB re 10−10L white light. The relationship between reaction time and stimulus intensity was best described by a negative logarithmic function, while the relationship between magnitude estimates of brightness and stimulus intensity was best described by a power function. Linear correlations between reaction times and magnitude estimates indicated that visual reaction time and brightness are not proportional within all subjects. Previous reports of proportionality between these two measures were discussed as possibly being the result of inappropriate cross-experiment comparisons.

scholarly journals On the brightness of the corona of April 16, 1893. Preliminary note

1900 ◽  
Vol 66 (424-433) ◽  
pp. 403-409 ◽  
Keyword(s):  
Preliminary Note ◽  
Visual Brightness

The visual brightness of the corona was measured at the total eclipses of August 29, 1886, and April 16, 1893, by Professor T. E. Thorpe, using a method arranged by Sir W. Abney (‘Phil. Trans., A, 1889, p. 363,. and 1896, p. 433). Soon after the first of these eclipses, Sir W. Abney devised a method of measuring the brightness photographically, by exposing a portion of the plate, which was not exposed to the sky, to a standard light passed through a row of small square screens of varying and known thickness.

scholarly journals On the Role of dK and dM Stars in Piling up the Total Mass of Star Clusters

1996 ◽  
Vol 174 ◽  
pp. 359-360
Author(s):  
G. Szécsényi-Nagy
Keyword(s):  
Total Mass ◽  
Star Clusters ◽  
Red Dwarfs ◽  
Visual Brightness

Although many projects were aimed at identifying nearby red dwarfs, the catalogues may be complete up to a limiting distance of 5 pc only and may be reliable to 10 pc. From recent observations it is evident that their absolute visual brightness (MV) ranges from about 6 to at least 18.5 what means that an average dK0 star is at least 100,000 times brighter than red dwarfs of the latest spectral subclasses. The photon detecting efficiency of our instruments is to be increased that these can measure late dM stars from the same distance from which dK stars can be analysed now. Another solution is offered by the flare-active red dwarfs which may be 1000 times brighter during their flare ups than usually.

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