Light Curves Of Variable Stars Research Articles

Light curves of variable stars: a pictorial atlas

Light curves of variable stars: a pictorial atlas

Nonperiodic variations in astrophysical systems: Investigating frequency evolution

view Abstract Citations (11) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Nonperiodic Variations in Astrophysical Systems: Investigating Frequency Evolution Boyd, Patricia T. ; Carter, Patricia H. ; Gilmore, Robert ; Dolan, Joseph F. Abstract We present a method related to the wavelet transform, the Gabor transform, for investigating astronomical time series containing non-consistent frequencies. Instances in which such data sets may arise include variable star light curves, numerical studies of the gravitational three-body problem, X-ray binaries, and signals from more exotic objects such as planets around pulsars and mass infall from accretion structures onto compact objects. As an illustration of its power, we apply the technique to a numerical data set of a gravitational three-body interaction and to photometry of the rapidly oscillating peculiar A star HD 60435. In the three-body example, the method provides an insightful shorthand that allows for the determination of episodes where the system behaves as two nearly Keplerian orbits. For HD 60435, the power in the main frequency exhibits unusual evolution over the duration of the observation. Publication: The Astrophysical Journal Pub Date: June 1995 DOI: 10.1086/175746 Bibcode: 1995ApJ...445..861B Keywords: Celestial Mechanics; Frequency Distribution; Peculiar Stars; Periodic Variations; Stellar Oscillations; Time Series Analysis; Wavelet Analysis; Gravitational Effects; Light Curve; Time Dependence; Transformations (Mathematics); X Ray Binaries; Astrophysics; CELESTIAL MECHANICS; STELLAR DYNAMICS; METHODS: ANALYTICAL; STARS: OSCILLATIONS; STARS: INDIVIDUAL HENRY DRAPER NUMBER: HD 60535; STARS: PECULIAR full text sources ADS | data products SIMBAD (2)

Application of cubic splines to the spectral analysis of unequally spaced data

view Abstract Citations (29) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Application of Cubic Splines to the Spectral Analysis of Unequally Spaced Data Akerlof, C. ; Alcock, C. ; Allsman, R. ; Axelrod, T. ; Bennett, D. P. ; Cook, K. H. ; Freeman, K. ; Griest, K. ; Marshall, S. ; Park, H. -S. ; Perlmutter, S. ; Peterson, B. ; Quinn, P. ; Reimann, J. ; Rodgers, A. ; Stubbs, C. W. ; Sutherland, W. Abstract In the absence of a priori information, nonparametric statistical techniques are often useful in exploring the structure of data. A least-squares fitting program, based on cubic B-splines has been developed to analyze the periodicity of variable star light curves. This technique takes advantage of the limited domain within which a particular B-spline is nonzero to substantially reduce the number of calculations needed to generate the regression matrix. By using simple approximations adapted to modern computer workstations, the computational speed is competitive with most other common methods that have been described in the literature. Since the number of arithmetic operations increases as N2, where N is the number of data points, this method cannot compete with the fast Fourier transformations (FFT) modification of the Lomb-Scargle algorithm. However, for data sets with N less than 104, it should be quite useful. Examples are shown, taken from the Massive Compact Halo Object (MACHO) experiment. Publication: The Astrophysical Journal Pub Date: December 1994 DOI: 10.1086/174954 Bibcode: 1994ApJ...436..787A Keywords: Astronomical Spectroscopy; Cubic Equations; Data Processing; Data Structures; Least Squares Method; Spectroscopic Analysis; Spline Functions; Statistical Analysis; Variable Stars; Algorithms; Applications Programs (Computers); Fast Fourier Transformations; Light Curve; Astronomy; METHODS: DATA ANALYSIS; METHODS: NUMERICAL; METHODS: STATISTICAL full text sources ADS | data products SIMBAD (2)

CCD ENSEMBLE PHOTOMETRY ON AN INHOMOGENEOUS SET OF EXPOSURES

ABSTRACT A method is described to perform ensemble stellar photometry on a series of CCD images for which the number and identity of the comparison stars vary throughout the set of exposures. The technique is particularly useful for the production of light curves of variable stars from long-term photometric programs where the inhomogeneity of the data set can be large. The linear least squares solution is derived, paying particular attention to the evaluation of errors. Examples are presented of the use of two interactive computer programs which implement this technique.

CCD photometry with small telescopes

CCD photometry with small telescopes often complements the use of such detectors on larger telescopes and in addition it is ideally suited to projects, such as determining variable star light curves, that require considerable amounts of observing time. Following a discussion of some of the techniques found useful for producing accurate CCD photometry, the results of several projects carried out with the SAAO 1m CCD camera are presented.

Periods and Light-Curves of Variable Stars in NGC 121

82 photographs of the globular cluster NGC 121 on the outskirts of the Small Magellanic Cloud, covering a total range of 9 years but mostly concentrated in three consecutive seasons, are used to derive periods and light-curves of 5 variables within |$1^{\prime}$| of the cluster. Of these, three are short-period variables (periods between 0.50 and 0.64 days) of Bailey a and b type with the usual relations between period, amplitude and shape of light-curve. The other two, among the reddest and brightest of the cluster-stars, have periods of 140.2 and 112.4 : days. The light-variations are presented in the form of step-estimates on a “ basic ” sequence. Four other short-period variables have been found on the plates which are too far from the cluster to be members. They are sufficiently faint to be regarded as possibly the first instance of RR Lyr variables in the general field of the Small Magellanic Cloud.

Note on the Relation Between the Visual and Photographic Light Curves of Variable Stars of Short Period

Note on the Relation Between the Visual and Photographic Light Curves of Variable Stars of Short Period

Our Astronomical Column

FUZZINESS OF SOME VARIABLE STARS.—Mr. Cuthbert G. Peek has, during the last six years, used his 6¼-imch achromatic for the investigation of the light-curves of variable stars. In this month's Knowledge he describes some observations of changes in appearance of a few variable stars at different epochs. Three variables—T Cassiopeia, R Cassiopeiæ, and S Herculis—have been frequently observed as (a) remarkably well defined, almost planetary, disks; (b) well-defined stars, surrounded by a more or less dense, ruddy atmosphere; (c) large, woolly, ill-defined images, resembling a small but bright planetary nebula; (d) at minimum, in place of the variable, a slight bluish nebulosity. The changes appear to be real, for stars near the places of the variables have been seen clear and sharp when the haziness of the variables was unmistakable. Other stars with regard to which Mr. Peek has made similar observations are S Cassiopeiæ, R Tauri, R Aurigæ, V Cancri, R Ursæ Majoris, S Ursæ Majoris, R Camelopardi, R Boötis, S Coronæ, R Aquilæ, and S Cephei.