scholarly journals The Star Spot Model and the Observations of SZ Piscium

1980 ◽  
Vol 88 ◽  
pp. 415-418
Author(s):  
Shyam M. Jakate
Keyword(s):  
Secondary Minimum ◽  
Primary Minimum ◽  
Photometric Observations ◽  
Spot Model ◽  
Spot Activity

Details of photometric observations during the totalities of the primary and secondary minima of SZ Psc are analysed in the light of the “star spot model” for RS CVn type binaries. Presence of scatter during the totality of primary minimum and its absence during the totality of secondary minimum of SZ Psc provide evidence towards one of the assumptions of the model,i.e. the spot activity confines to one of the hemispheres of the cooler star.

scholarly journals Stellar activity, differential rotation, and exoplanets

2010 ◽  
Vol 6 (S273) ◽  
pp. 89-95 ◽  
Author(s):  
A. F. Lanza
Keyword(s):  
Time Series ◽  
Differential Rotation ◽  
Solar Irradiance ◽  
Giant Planet ◽  
Total Solar Irradiance ◽  
Short Term ◽  
Stellar Activity ◽  
Transiting Planets ◽  
Spot Model ◽  
Spot Activity

AbstractThe photospheric spot activity of some of the stars with transiting planets discovered by the CoRoT space experiment is reviewed. Their out-of-transit light modulations are fitted by a spot model previously tested with the total solar irradiance variations. This approach allows us to study the longitude distribution of the spotted area and its variations versus time during the five months of a typical CoRoT time series. The migration of the spots in longitude provides a lower limit for the surface differential rotation, while the variation of the total spotted area can be used to search for short-term cycles akin the solar Rieger cycles. The possible impact of a close-in giant planet on stellar activity is also discussed.

scholarly journals The Symbiotic Binary System EG Andromedae

1987 ◽  
Vol 93 ◽  
pp. 755-758
Author(s):  
D. Chochol ◽  
A. Skopal ◽  
A. Vittone ◽  
A. Mammano
Keyword(s):  
Binary System ◽  
Symbiotic Star ◽  
Line Profiles ◽  
Primary Minimum ◽  
Photometric Observations ◽  
New Period ◽  
Balmer Lines ◽  
The New Period

AbstractPhotometric observations of the symbiotic star EG and confirm that the binary system is eclipsing. The epoch of primary minimum is computed. The new period 474 days instead of 470 days is estimated by a comparison of line profiles of Balmer lines taken in 1967–69 and 1982–84. The new ephemeris is

Changes in the Period of the Eclipsing System AH Virginis

1982 ◽  
Vol 4 (4) ◽  
pp. 411-413
Author(s):  
H.D. Kennedy
Keyword(s):  
Light Curve ◽  
Secondary Minimum ◽  
Constant Light ◽  
Primary Minimum ◽  
Minimum Light ◽  
The Mean ◽  
Photoelectric Observations ◽  
Orbital Solution

Guthnick and Prager (1929) were the discoverers of the variability of AH Virginis. Prager (1929) produced a photographic light curve the same year. Lause (1934, 1935, 1937) observed the system visually and improved the period as deduced by Prager. Further visual work on the system was done by Zessewitsch (1944). The first photoelectric observations came from Huruhata and Nakamura (1951), followed in 1952 by Kitamura, Tanabe and Nakamura (1957).Lack of their data on ingress and egress at primary eclipse resulted in the mean curve showing a rounded bottom during minimum light. From this, an inclination of the system of 61° was derived by Kopal and Shapley (1956). Two years later, Kwee (1958) revealed primary minimum to be flat bottomed; the light remaining constant for some 40 minutes. This was confirmed by Binnendijk (1960), thus classifying AH Virginis as one of the few W UMa systems which display complete eclipses at an inclination likely to be closer to 90° then to 61°. Observations of the present study confirm constancy of light of 40 minutes duration during primary minimum. Assuming i = 90°, a new orbital solution was derived by Kitamura and Takahashi (1959) showing constant light for both minima. Binnendijk’s observation, however, showed a curved appearance at secondary minimum. The present observations indicate curved as well as flat secondary minima.

Symbiotic Nova PU Vul - 33 Years of Observations

2012 ◽  
Vol 21 (1-2) ◽  
Author(s):  
S. Shugarov ◽  
D. Chochol ◽  
E. Kolotilov
Keyword(s):  
Binary System ◽  
Light Curves ◽  
Secondary Minimum ◽  
Pulsation Period ◽  
Primary Minimum ◽  
Cool Component ◽  
Period Analysis ◽  
Binary Orbit ◽  
Orbit Period

AbstractWe present UBVRI light curves of the symbiotic nova PU Vul after its outburst in 1978. Three observed eclipses of the hot component by the cool one were used to determine the ephemeris of the binary system as JD (Min I) = 2444550(15) + 4897(10) × E days. the 194-day shift of the secondary minimum from its expected positions in 2001 suggests the eccentricity of the binary orbit. Period analysis of the VRI photometry improved the pulsation period of the cool AGB variable in the system to P = 217.7 days. Pulsation of the cool component is detected only in the phases around the primary minimum, when the visible hemisphere of the AGB star is not influenced by the interaction with the hot component.

scholarly journals New Clues on the Model of YY Her After Two Seasons

2004 ◽  
Vol 194 ◽  
pp. 222-222
Author(s):  
L. Hric ◽  
R. Gális ◽  
A. Dobrotka ◽  
V. Śimon ◽  
K. Petrík ◽  
...  
Keyword(s):  
Binary System ◽  
Line Emission ◽  
Photometric Data ◽  
Secondary Minimum ◽  
Photometric Observations ◽  
Symbiotic Binaries ◽  
Light Variability

During two observational seasons of international campaign of YY Her we secured photometric data which covered the primary as well as the secondary minima and revealed unexpected outburst activity of this system.YY Her belongs to the classical symbiotic binaries with nova-like outbursts. Recently Mikolajewska et al. (2002) explained the light variability of YY Her by combining the ellipsoidal changes and sinusoidal variations of the nebular continuum and line emission. In 2001 (Hric et al. 2001) we discovered in the binary system YY Her the presence of the secondary minimum that was indicated, however, by only three photometric observations from one observatory.

Probing DLVO Forces Using Interparticle Magnetic Forces:  Transition from Secondary-Minimum to Primary-Minimum Aggregation

Langmuir ◽  
2001 ◽  
Vol 17 (20) ◽  
pp. 6065-6071 ◽  
Author(s):  
Ching-Ju Chin ◽  
Sotira Yiacoumi ◽  
Costas Tsouris
Keyword(s):  
Secondary Minimum ◽  
Primary Minimum ◽  
Magnetic Forces

scholarly journals Discovery of a pre-cataclysmic binary with unusual chromaticity of the eclipsed white dwarf by the GPX survey

2020 ◽  
Vol 493 (4) ◽  
pp. 5208-5217 ◽  
Author(s):  
Vadim Krushinsky ◽  
Paul Benni ◽  
Artem Burdanov ◽  
Igor Antokhin ◽  
Eleonora Antokhina ◽  
...  
Keyword(s):  
White Dwarf ◽  
Main Sequence ◽  
Accretion Rate ◽  
Binary Star ◽  
Mass Ratio ◽  
Orbital Inclination ◽  
Common Envelope ◽  
Secondary Star ◽  
Photometric Observations ◽  
Spot Activity

ABSTRACT We report the discovery of a relatively bright eclipsing binary system, which consists of a white dwarf (WD) and a main-sequence K7 star with clear signs of chromospheric and spot activity. The light curve of this system shows ∼0.2 mag ellipsoidal variability with a period of 0.297549 d and a short total eclipse of the WD. Based on our analysis of the spectral and photometric data, we estimated the parameters of the system. The K7V star is tidally deformed but does not fill its Roche lobe (the filling factor is about 0.86). The orbital inclination is i = $73{_{.}^{\circ}}1 \pm 0{_{.}^{\circ}}2$, and the mass ratio is q = M2/M1 ≈ 0.88. The parameters of the K7V star are M2 ≈ 0.64 M⊙, R2 = 0.645 ± 0.012R⊙, and T2 ≈ 4070 K. The parameters of the WD are M1 ≈ 0.72 M⊙, R1 = 0.013 ± 0.003R⊙, and T1 = 8700 ± 1100 K. Photometric observations in different bands revealed that the maximum depth of the eclipse is in the SDSS r filter, which is unusual for a system of a WD and a late main-sequence star. We suspect that this system is a product of the evolution of a common-envelope binary star, and that the WD accretes the stellar wind from the secondary star (the so-called low-accretion-rate polar, hereafter LARP).

scholarly journals Observations of Dwarf Novae

1976 ◽  
Vol 73 ◽  
pp. 85-140 ◽  
Author(s):  
B. Warner
Keyword(s):  
Hot Spot ◽  
Variable Stars ◽  
Accretion Disc ◽  
Cataclysmic Variable ◽  
Dwarf Novae ◽  
X Ray ◽  
Classical Novae ◽  
Photometric Observations ◽  
Spot Model ◽  
Hot Spot Model

Spectroscopic and photometric observations relevant to the structure of classical novae, recurrent novae and dwarf novae are collected together. Details are given of optical, infrared, satellite ultraviolet, X-ray and radio observations. Most of these can be understood in terms of the hot spot model of cataclysmic variable stars. Estimates are made of luminosities, temperatures and rates of mass transfer. Observations made during eruptions of dwarf novae imply large changes taking place in the accretion disc.

The trials and tribulations of the Hawaii hot spot model

2021 ◽  
Vol 215 ◽  
pp. 103544
Author(s):  
Zhaoxia Jiang ◽  
Sanzhong Li ◽  
Qingsong Liu ◽  
Jianli Zhang ◽  
Zaizheng Zhou ◽  
...  
Keyword(s):  
Hot Spot ◽  
Spot Model ◽  
Hot Spot Model
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