scholarly journals The MACHO Project Large Magellanic Cloud Variable Star Inventory. XI. Frequency Analysis of the Fundamental‐Mode RR Lyrae Stars

2003 ◽  
Vol 598 (1) ◽  
pp. 597-609 ◽  
Author(s):  
C. Alcock ◽  
D. R. Alves ◽  
A. Becker ◽  
D. Bennett ◽  
K. H. Cook ◽  
...  
2002 ◽  
Vol 185 ◽  
pp. 412-413
Author(s):  
D.L. Welch ◽  
G. Kovács ◽  
K.H. Cook ◽  
C. Alcock ◽  
R. Allsman ◽  
...  

AbstractWe present the preliminary results of a frequency analysis of 1457 fundamental mode RR Lyrae (RR0) stars in the Large Magellanic Cloud (LMC) from MACHO Project photometry. We find the same classes of pulsational behavior as were found in our earlier survey of first overtone RR Lyrae (RR1) stars. Variables whose prewhitened power spectra contain one or two peaks close to the main frequency component in the original power spectra are commonly known as Blazhko-type variables. The present analysis shows the overall frequency of Blazhko-type stars in the total RR0 population analysed to date to be ≈ 10%. This is lower than the often cited Galactic field/globular rate of 20-30% (Szeidl, 1988).The incidence rate of Blazhko-type variability in the LMC appears to be about three times higher in RR0 stars than in RR1 stars. This puts important constraints on possible models of the Blazhko effect.


2000 ◽  
Vol 176 ◽  
pp. 313-314 ◽  
Author(s):  
G. Kovács ◽  
C. Alcock ◽  
R. Allsman ◽  
D. Alves ◽  
T. Axelrod ◽  
...  

AbstractWe present the first massive frequency analysis of the 1200 first overtone RR Lyrae stars in the Large Magellanic Cloud observed in the first 4.3 yr of the MACHO project. Besides the many new double-mode variables, we also discovered stars with closely spaced frequencies. These variables are most probably nonradial pulsators.


2000 ◽  
Vol 176 ◽  
pp. 172-175 ◽  
Author(s):  
G. Clementini ◽  
A. Bragaglia ◽  
L. Di Fabrizio ◽  
E. Carretta ◽  
R. G. Gratton

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.


2019 ◽  
Vol 490 (3) ◽  
pp. 4254-4270 ◽  
Author(s):  
Jillian R Neeley ◽  
Massimo Marengo ◽  
Wendy L Freedman ◽  
Barry F Madore ◽  
Rachael L Beaton ◽  
...  

ABSTRACT RR Lyrae stars have long been popular standard candles, but significant advances in methodology and technology have been made in recent years to increase their precision as distance indicators. We present multiwavelength (optical UBVRcIc and Gaia G, BP, RP; near-infrared JHKs; mid-infrared [3.6], [4.5]) period–luminosity–metallicity (PLZ), period–Wesenheit–metallicity (PWZ) relations, calibrated using photometry obtained from the Carnegie RR Lyrae Program and parallaxes from the Gaia second data release for 55 Galactic field RR Lyrae stars. The metallicity slope, which has long been predicted by theoretical relations, can now be measured in all passbands. The scatter in the PLZ relations is on the order of 0.2 mag, and is still dominated by uncertainties in the parallaxes. As a consistency check of our PLZ relations, we also measure the distance modulus to the globular cluster M4, the Large Magellanic Cloud and the Small Magellanic Cloud, and our results are in excellent agreement with estimates from previous studies.


2004 ◽  
Vol 193 ◽  
pp. 189-192
Author(s):  
M. Dall’Ora ◽  
G. Bono ◽  
J. Storm ◽  
V. Ripepi ◽  
V. Testa ◽  
...  

AbstractWe present U, B, V, I (SUSI@NTT) and J,Ks (SOFI@NTT) photometry of the Large Magellanic Cloud (LMC) cluster Reticulum. The observing strategy and data reduction (DAOPHOTII/ALLFRAME) allowed us to reach an accuracy of the order of 0.01 – 0.03 mag in all the bands at limiting magnitudes typical of RR Lyrae stars. Reticulum hosts a sizable sample of RR Lyrae stars (32), and we supply an accurate distance estimate using the RR Lyrae K-band Period-Luminosity-Metallicity (PLZK) relation. This method presents several advantages when compared with the MV vs [Fe/H] relation, since it is only marginally affected by off-ZAHB evolutionary effects and reddening corrections.


2009 ◽  
Vol 502 (2) ◽  
pp. 505-514 ◽  
Author(s):  
J. Borissova ◽  
M. Rejkuba ◽  
D. Minniti ◽  
M. Catelan ◽  
V. D. Ivanov

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