The light curves of RR Lyrae field stars

Abstract

Fourier decompositions have been made of the light curves of a large sample of RR Lyrae field stars. The coefficients have been tabulated. Following the scheme of an earlier investigation of classical Cepheids, certain combinations of the low-order coefficients-</>21' R 21' and </>31-are plotted against period. The Bailey-type c pulsators stand out from the type ab stars, particularly on the R21 plot which is found to be a more sensitive discriminator of Bailey type than is the traditionally employed amplitude-period diagram. We compare the RR Lyrae plots of </>21' R 21 , and </>31 with those previously obtained for classical Cepheids. It is noted that, while the Cepheid plots display a tightly defined progression with period, reflecting the influence of a modal resonance, in the RR Lyrae case there is much more scatter. However, some evidence is shown to exist for a Cepheid-like progression appearing among the longer period RR Lyrae pulsators and culminating in the unique small-amplitude variable XZ Ceti. New observations will be required to confirm the reality of such a progression.

Long term light curve variations of theKeplerCepheid V 1154 Cyg

“…We characterised the light curve shapes with the Fourier parameters [5]. Particular results for R 21 = A 2 /A 1 and R 31 = A 3 /A 1 are presented in fig1.…”

Variable Stars and Stellar Populations in Andromeda XXVII. IV. An Off-centered, Disrupted Galaxy*

“…Right: Period-amplitude diagram of the RR Lyrae stars in the field of And XXVII (orange filled circles) compared with the RR Lyrae stars in And XIX (blue asterisks, from Paper I), And XXI (cyan squares, from Paper II)), And XXV (magenta pentagons, from Paper III)) and in three HST fields in the M31 halo from Sarajedini et al (2009;gray dots) and Brown et al (2004, dark-gray dots), respectively. ity can also be derived from the φ 31 parameter of the Fourier decomposition of the light curve (see, e.g., Simon & Teays 1982, Jurcsik & Kovacs 1996, Cacciari et al 2005). We performed a sine Fourier decomposition of the V -band light curves of the RRab stars in our sample deriving the normalized Fourier parameter φ 31 and the deviation parameter D m , which measures the regularity of the light curve (Jurcsik & Kovacs 1996).…”

Improving the cosmic distance ladder. Distance and structure of the Large Magellanic Cloud

“…According to Simon & Teays (1982) the light curve of a RR Lyrae star can be fitted with a Fourier function of the form:…”

“…The shape of the light curves can be quantified by the low order coefficients of the fit: R i1 = A i /A 1 and φ i1 = φ i − iφ 1 . The A 1 , A 2 and the φ 21 , φ 31 parameters of the Fourier decomposition can be used to classify the RR Lyrae stars (see e.g., Simon & Teays 1982). Jurcsik & Kovacs (1996) derived a relation between the Fourier parameter φ 31 of the V -band light curve of field ab-type RR Lyrae stars, the period and the star metallicity on the Jurcsik (1995) metallicity scale:…”