The Challenge of Explaining the Nonlinear Features in the Light Curve of the ZZ Ceti Star G117-B15A

2010 ◽  
Author(s):  
G. Fontaine ◽  
P. Brassard ◽  
Klaus Werner ◽  
T. Rauch
Keyword(s):  
Light Curve ◽  
Nonlinear Features ◽  
Ceti Star

The light curve of the ZZ Ceti star G226-29

1983 ◽  
Vol 271 ◽  
pp. 744 ◽  
Author(s):  
S. O. Kepler ◽  
E. L. Robinson ◽  
R. E. Nather
Keyword(s):  
Light Curve ◽  
Ceti Star

scholarly journals G117-B15A: How is it Evolving?

1989 ◽  
Vol 114 ◽  
pp. 341-345
Author(s):  
S.O. Kepler ◽  
G. Vauclair ◽  
R.E. Nather ◽  
D.E. Winget ◽  
E.L. Robinson
Keyword(s):  
Light Curve ◽  
Direct Measurement ◽  
White Dwarf ◽  
Galactic Disk ◽  
Period Change ◽  
Rate Of Change ◽  
Independent Measurement ◽  
Ceti Star

AbstractThe measurement of the rate of change of period with time for the g-mode pulsations in ZZ Ceti stars is a direct measurement of the cooling timescale for a DA white dwarf, which in turn can give a totally independent measurement of the age of the galactic disk. Using asteroseismology, we have obtained a rate of change of the period of the dominant pulsation in the light curve of the ZZ Ceti star G117-B15A of dP/dt = (12.5 ± 5.5) × 10−15s/s, equivalent to a timescale for period change of P/P = (5.5 ± 2.4) × 108 yr, which is consistent with the theoretical value for the cooling timescale of a DA white dwarf around 11,000 K.

scholarly journals An improved limit for the rate of period change in the ZZ Ceti star G117-B15A or The Most Stable Optical Clock Known

1988 ◽  
Vol 123 ◽  
pp. 325-328
Author(s):  
S.O. Kepler ◽  
D.E. Winget ◽  
E.L. Robinson ◽  
R.E. Nather
Keyword(s):  
Light Curve ◽  
Confidence Level ◽  
White Dwarf ◽  
Period Change ◽  
Rate Of Change ◽  
Optical Clock ◽  
Upper Limit ◽  
Ceti Star ◽  
Image Position

The rate of change of period with time for the g-mode pulsations in ZZ Ceti stars depends directly on the cooling timescale for a DA white dwarf, and therefore a measurement of its value can yield an evolutionary timescale for the white dwarf. We have obtained an upper limit for the rate of change of the period of the dominant pulsation in the light curve of the ZZ Ceti star G117-B15A of |dP/dt| ≤ 9.9 × 10−15 s/s at the 68% confidence level, equivalent to a timescale for period change of

The Eclipsing Binary WX Eridani

1979 ◽  
Vol 46 ◽  
pp. 385
Author(s):  
M.B.K. Sarma ◽  
K.D. Abhankar
Keyword(s):  
Light Curve ◽  
Spectral Type ◽  
Orbital Period ◽  
Primary Component ◽  
Light Curves ◽  
Absorption Feature ◽  
Primary Star ◽  
Eclipsing Binary ◽  
The Times ◽  
Phase Angles

AbstractThe Algol-type eclipsing binary WX Eridani was observed on 21 nights on the 48-inch telescope of the Japal-Rangapur Observatory during 1973-75 in B and V colours. An improved period of P = 0.82327038 days was obtained from the analysis of the times of five primary minima. An absorption feature between phase angles 50-80, 100-130, 230-260 and 280-310 was present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with primary to be transit and secondary, an occultation. Elements derived from the solution of the light curve using Russel-Merrill method are given. From comparison of the fractional radii with Roche lobes, it is concluded that none of the components have filled their respective lobes but the primary star seems to be evolving. The spectral type of the primary component was estimated to be F3 and is found to be pulsating with two periods equal to one-fifth and one-sixth of the orbital period.

RSCVn Stars in the Southern Hemisphere

1979 ◽  
Vol 46 ◽  
pp. 371-384 ◽  
Author(s):  
J.B. Hearnshaw
Keyword(s):  
Light Curve ◽  
Southern Hemisphere ◽  
Orbital Period ◽  
Binary Stars ◽  
Small Amplitude ◽  
Light Variation ◽  
Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

A Radial Velocity and Light Curve Study of Pulsations and Binarity in Proto-Planetary Nebulae

2015 ◽  
Vol 71-72 ◽  
pp. 127-128
Author(s):  
B.J. Hrivnak ◽  
W. Lu ◽  
G. Van de Steene ◽  
H. Van Winckel ◽  
J. Sperauskas ◽  
...  
Keyword(s):  
Light Curve ◽  
Radial Velocity ◽  
Planetary Nebulae

SN2017ein: bolometric light curve and physical parameters

2017 ◽  
Vol 4 (1) ◽  
pp. 15-19
Author(s):  
P.S. Tadjimuratov ◽  
◽  
D. Mirzakulov ◽  
Keyword(s):  
Light Curve ◽  
Physical Parameters

Optical Light Curve of the Type I[CLC]a[/CLC] Supernova 1998[CLC]bu[/CLC] in M96 and the Supernova Calibration of the Hubble Constant

1999 ◽  
Vol 117 (3) ◽  
pp. 1175-1184 ◽  
Author(s):  
Nicholas B. Suntzeff ◽  
M. M. Phillips ◽  
R. Covarrubias ◽  
M. Navarrete ◽  
J. J. Pérez ◽  
...  
Keyword(s):  
Light Curve ◽  
Hubble Constant ◽  
Type I ◽  
Optical Light Curve

scholarly journals An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr*

2012 ◽  
Vol 423 (2) ◽  
pp. 993-1005 ◽  
Author(s):  
J. Jurcsik ◽  
Á. Sódor ◽  
G. Hajdu ◽  
B. Szeidl ◽  
Á. Dózsa ◽  
...  
Keyword(s):  
Light Curve ◽  
Light Curves ◽  
Stellar Structure ◽  
Time Base ◽  
Photometric Method ◽  
Physical Parameters ◽  
Component Solution ◽  
Rr Lyrae ◽  
Curve Variation ◽  
Type Variable

Abstract The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation. On the time base of ∼110 yr, a strict anticorrelation between the pulsation- and modulation-period changes is established. The light curve of RZ Lyr shows a remarkable bump on the descending branch in the small-amplitude phase of the modulation, similarly to the light curves of bump Cepheids. We speculate that the stellar structure temporally suits a 4:1 resonance between the periods of the fundamental and one of the higher order radial modes in this modulation phase. The light-curve variation of RZ Lyr can be correctly fitted with a two-modulation-component solution; the 121-d period of the main modulation is nearly but not exactly four times longer than the period of the secondary modulation component. Using the inverse photometric method, the variations in the pulsation-averaged values of the physical parameters in different phases of both modulation components are determined.

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