scholarly journals Theoretical UBVI Light Curves of Pulsating Stars

2000 ◽  
Vol 176 ◽  
pp. 334-337
Author(s):  
Michael U. Feuchtinger ◽  
Ernst A. Dorfi
Keyword(s):  
Radiative Transfer ◽  
Light Curves ◽  
Rr Lyrae Stars ◽  
Fourier Decomposition ◽  
Pulsating Stars ◽  
Rr Lyrae ◽  
Stellar Pulsation ◽  
Sample Application ◽  
Lyrae Stars ◽  
Good Agreement

AbstractBy performing detailed frequency-dependent radiative transfer computations we are able to calculate light curves in particular bandpasses from stellar pulsation models calculated by the Vienna nonlinear convective pulsation code. As a sample application we discuss UBVI light curves of RR Lyrae stars. The properties of these light curves are analyzed by means of standard Fourier decomposition, and a comparison to recent observations is performed. As main results we find a good agreement with important observed RR Lyrae properties like pulsation amplitudes and Fourier parameters in B, V, and I bands. Additionally, from the synthetic color curves we derive linear transformation laws between amplitudes as well as Fourier parameters in the different bandpasses.

scholarly journals RR Lyrae in M15: Fourier Decomposition and Physical Parameters

2006 ◽  
Vol 2 (S240) ◽  
pp. 605-612
Author(s):  
G. García Lugo ◽  
A. Arellano Ferro ◽  
Patricia Rosenzweig
Keyword(s):  
Globular Clusters ◽  
Light Curves ◽  
Physical Parameters ◽  
Rr Lyrae Stars ◽  
Mean Values ◽  
Fourier Decomposition ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
The Mean ◽  
Lyrae Stars

AbstractThe V and R light curves for 30 RR Lyrae stars in M15 were used to calculate their physical parameters. The Blazhko effect, previously reported in V12, was not detected. The determined values of the iron content and distance of the cluster are: [Fe/H] = −1.98 ± 0.24 and d = 8.67 ± 0.41 kpc, respectively. The mean values of the physical parameters determined for the RR Lyrae stars place the cluster precisely into the sequences Oosterhoff type – metallicity and metallicity – effective temperature, valid for globular clusters.

scholarly journals Fourier Decomposition Parameters for the Halo RR Lyrae Variables U and V Caeli

1985 ◽  
Vol 82 ◽  
pp. 272-275
Author(s):  
L. Hansen ◽  
J. O. Petersen
Keyword(s):  
Light Curve ◽  
Light Curves ◽  
Published Data ◽  
Amplitude Ratios ◽  
Rr Lyrae Stars ◽  
Fourier Decomposition ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
Phase Differences

AbstractUBVRI light curves are obtained for the two halo RR Lyrae variables U Caeli with period 0.420 days (73 observations) and V Caeli with period 0.571 days (42 observations). It is shown that their light curve characteristics are very similar to those of field RR Lyrae stars.Fourier decompositions are studied for all five magnitudes and the resulting amplitude ratios and phase differences are discussed. The differences in the Fourier decomposition parameters between the five magnitudes are shown to be relatively small. Comparisons of the Fourier decomposition parameters for the two halo RR Lyrae stars with recently published data for field RR Lyrae stars show no systematic differences.

scholarly journals Comparison of the Pulsation Properties of the Rr Lyrae Stars in ω Centauri with those of Classical Cepheids

1985 ◽  
Vol 82 ◽  
pp. 276-279
Author(s):  
J. O. Petersen
Keyword(s):  
Quantitative Description ◽  
Light Curves ◽  
Powerful Method ◽  
Amplitude Ratios ◽  
Rr Lyrae Stars ◽  
Fourier Decomposition ◽  
Rr Lyrae ◽  
Classical Cepheids ◽  
Lyrae Stars ◽  
Phase Differences

In the last few years several studies have shown that Fourier decomposition technique is a powerful method for quantitative description of light curves of pulsation variables. This technique was introduced by Simon & Lee (1981), who showed that amplitude ratios and phase differences provide a very useful description of the Hertzsprung progression for classical Cepheids. Recently, Simon & Teays (1982) discussed 70 RR Lyrae field stars.In the present study I analyse 130 photographic mean light curves of RR Lyrae variables in ω Centauri taken from Martin (1938). I wish (i) to compare the Fourier decomposition parameters of the ω Cen RR Lyrae stars with those of the field variables as studied by Simon & Teays, (ii) to discuss the evidence for progression sequences among the ω Cen variables and (iii) to compare the basic pulsation properties of the RRab variables in ω Cen with those of classical Cepheids.

scholarly journals The Unusual Period Distribution of the RR Lyrae Variables in NGC 5897

1989 ◽  
Vol 111 ◽  
pp. 287-287
Author(s):  
Amelia Wehlau
Keyword(s):  
Light Curves ◽  
Instability Strip ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Period Distribution ◽  
Unusual Distribution ◽  
Photoelectric Observations ◽  
Lyrae Stars ◽  
Branch Star ◽  
Central Concentration

AbstractAttention is called to the rather unusual distribution of the periods of the RR Lyrae variables in NGC 5897, a metal-poor halo globular cluster with a very low central concentration. Of the seven RR Lyrae stars known in the cluster, three have periods between 0.797 and 0.856 day and two have periods of 0.45 and 0.42 day. The other two have periods of 0.34 and 0.35 day with much lower amplitudes of variation. Due to the lack of crowding in this cluster photoelectric observations and Fourier decompositions of the resulting light curves should be possible for at least six of the RR Lyrae variables. In addition, the cluster appears to contain a non-variable horizontal branch star, SK 120, lying within the instability strip. As this is the only well documented case of such a star, photoelectric observations of this star would also be desirable.

scholarly journals Luminosity variation in the extended one-zone RR Lyrae model

2005 ◽  
pp. 57-64
Author(s):  
D. Pricopi
Keyword(s):  
Ideal Gas ◽  
Stellar Model ◽  
Nonlinear Analyses ◽  
Uniform Rotation ◽  
Factors Affecting ◽  
Pulsating Stars ◽  
Rr Lyrae ◽  
Stellar Pulsation ◽  
Pulsation Model ◽  
Good Agreement

The Stellingwerf one-zone stellar model is extended by assuming, a slow and uniform rotation that leads to a very small oblateness of the star. The matter in the core-surrounding shell is supposed to consists of a mixture of ideal gas and radiation. This one-zone stellar pulsation model is proposed as a tool to investigate the factors affecting luminosity variations of pulsating stars. Linear and nonlinear analyses of the resulting equations are described. The results are in very good agreement with the observed RR Lyrae light curves. .

scholarly journals Light Curves and Metal Abundances of RR Lyrae Variables in the Bar of the Large Magellanic Cloud

2000 ◽  
Vol 176 ◽  
pp. 172-175 ◽  
Author(s):  
G. Clementini ◽  
A. Bragaglia ◽  
L. Di Fabrizio ◽  
E. Carretta ◽  
R. G. Gratton
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Photometric System ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Visual Magnitude ◽  
Metal Abundance ◽  
Definition Of ◽  
Lyrae Stars

AbstractThe Large Magellanic Cloud (LMC) is widely considered a corner-stone of the astronomical distance scale. However, a difference of 0.2−0.3 mag exists in its distance as predicted by the short and long distance scales. Distances to the LMC from Population II objects are founded on the RR Lyrae variables. We have undertaken an observational campaign devoted to the definition of the average apparent luminosity, and to the study of the mass–metallicity relation for RR Lyrae stars in the bar of the LMC. These are compared with analogous quantities for cluster RR Lyrae stars. The purpose is to see whether an intrinsic difference in luminosity, possibly due to a difference in mass, might exist between field and cluster RR Lyrae stars, which could be responsible for the well-known dichotomy between short and long distance scales. Preliminary results are presented on the V and B − V light curves, the average apparent visual magnitude, and the pulsational properties of 102 RR Lyrae stars in the bar of the LMC, observed at ESO in January 1999. The photometric data are accurately tied to the Johnson photometric system. Comparison is presented with the photometry of RR Lyrae stars in the bar of the LMC obtained by the MACHO collaboration (Alcock et al. 1996). Our sample includes 9 double-mode RR Lyrae stars selected from Alcock et al. (1997) for which an estimate of the metal abundance from the ΔS method is presented.

scholarly journals The effect of stellar evolution on the light curves’ shapes of RR Lyrae stars in M3

2004 ◽  
Vol 193 ◽  
pp. 171-175
Author(s):  
Johanna Jurcsik
Keyword(s):  
Light Curve ◽  
Stellar Evolution ◽  
Light Curves ◽  
Horizontal Branch ◽  
Homogeneous Sample ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

AbstractThe light curve characteristics of a homogeneous sample of variables in M3 are studied in detail. Accurate light curves and mean magnitudes of about 100 RRab and 50 RRc stars which do not show any type of modulation are analyzed. According to their mean magnitudes and Fourier parameters the variables can be sorted into four groups, representing different stages of the horizontal branch stellar evolution.

K-band light curves for RR Lyrae stars in the globular clusters M5 and M92

1992 ◽  
Vol 104 ◽  
pp. 159 ◽  
Author(s):  
Jesper Storm ◽  
Bruce W. Carney ◽  
David W. Latham
Keyword(s):  
Globular Clusters ◽  
Light Curves ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
K Band

scholarly journals Calibration of the Cepheid Distance Scale

1993 ◽  
Vol 139 ◽  
pp. 72-80
Author(s):  
Wolfgang P. Gieren ◽  
Pascal Fouqué
Keyword(s):  
Large Magellanic Cloud ◽  
Distance Scale ◽  
Absolute Calibration ◽  
Rr Lyrae Stars ◽  
Sn 1987A ◽  
Rr Lyrae ◽  
Calibration Sets ◽  
Lyrae Stars ◽  
Zero Points ◽  
Good Agreement

AbstractThe absolute calibration of the Cepheid period-luminosity (PL) relation with galactic Cepheids is discussed. Various methods, most importantly the cluster ZAMS-fitting scale and the Baade-Wesselink scale are found to yield PL zero points which agree within ∼ ± 0.1 mag. The present Cepheid calibration sets the Large Magellanic Cloud at μ0 (LMC) = 18.6 ± 0.1 mag, in good agreement with the distance derived from SN 1987A and other methods except RR Lyrae stars which seem to give a shorter distance scale.

scholarly journals Humps and bumps: the effects of shocks on the optical light curves of fundamental-mode RR Lyrae stars

2020 ◽  
Vol 635 ◽  
pp. A66 ◽  
Author(s):  
Z. Prudil ◽  
I. Dékány ◽  
R. Smolec ◽  
M. Catelan ◽  
E. K. Grebel ◽  
...  
Keyword(s):  
Main Shock ◽  
Period Change ◽  
Light Curves ◽  
Horizontal Branch ◽  
Instability Strip ◽  
Rr Lyrae Stars ◽  
Change Rate ◽  
Rr Lyrae ◽  
Red Edge ◽  
Lyrae Stars

We present the most extended and homogeneous study carried out so far of the main and early shocks in 1485 RR Lyrae stars in the Galactic bulge observed by the Optical Gravitational Lensing Experiment. We selected nonmodulated fundamental-mode RR Lyrae stars with good-quality photometry. Using a self-developed method, we determined the centers and strengths of main and early shock features in the phased light curves. We found that the positions of both humps and bumps are highly correlated with the pulsation properties of the studied variables. Pulsators with a pronounced main shock are concentrated in the low-amplitude regime of the period–amplitude diagram, while stars with a strong early shock have average and above-average pulsation amplitudes. A connection between the main and early shocks and the Fourier coefficients is also observed. In the color–magnitude diagram, we see a separation between stars with strong and weak shocks. Variables with a pronounced main shock cluster close to the fundamental red edge of the instability strip (IS), while stars with a strong early shock tend to clump in the center and near the fundamental blue edge of the IS. The appearance of shocks and their properties appear to be independent of the direction of evolution estimated from the period change rate of the studied stars. In addition, the differences in the period change rate between the two main Oosterhoff groups found in the Galactic bulge suggest that stars of Oosterhoff type I are located close to the zero-age horizontal branch while Oosterhoff type II variables are on their way toward the fundamental red edge of the instability strip, and have therefore already left the zero-age horizontal branch.

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