Blazhko effect in the Galactic bulge fundamental mode RR Lyrae stars II: Modulation shapes, amplitudes and periods

Abstract

The number of stars observed by the Optical Gravitational Lensing Experiment (OGLE) project in the Galactic bulge offers an invaluable chance to study RR Lyrae stars in a statistical manner. We used data of 3141 fundamental-mode RR Lyrae stars showing the Blazhko effect observed in OGLE-IV to investigate a possible connection between modulation amplitudes and periods, light curve and pulsation characteristics. We found that there is no simple monotonic correlation between any combination of two parameters concerning the Blazhko and pulsation amplitudes, periods and the shape of the light curves. There are only systematic limits. There is a bottom limit of the modulation period with respect to the pulsation period. We also found that the possible range of modulation amplitudes decreases with increasing pulsation period which could point towards that the Blazhko effect is suppressed in cooler, larger, more luminous and less metal abundant bulge RR Lyrae stars. Our investigation revealed that the distribution of the modulation periods can be described with two populations of stars with the mean modulation periods of 48 and 186 days. There is a certain region with a low density of the modulated stars, which we call the Blazhko valley, in the pulsation period-modulation period plane. Based on the similarity of the modulation envelopes, basically every star can be assigned to one of six morphological classes. Double modulation was found in 25 per cent of the studied stars. Only 6.3 per cent of modulated stars belongs to the Oosterhoff group II.

arXiv comment14 pages, 15 figures, 2 tables. Accepted for publication in MNRAS

References in corpus (36)

• Scikit-learn: Machine Learning in Python
• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• The K2 Mission: Characterization and Early results
• Metal Abundances, Radial Velocities and other Physical Characteristics for the RR Lyrae Stars in the Kepler Field
• The Konkoly Blazhko Survey: Is light-curve modulation a common property of RRab stars?
• The MACHO Project Large Magellanic Cloud variable star inventory. XI. Frequency analysis of the fundamental mode RR Lyrae stars
• Flavours of variability: 29 RR Lyrae stars observed with Kepler
• On the Blazhko Effect in RR Lyrae Stars
• Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey
• Period doubling bifurcation and high-order resonances in RR Lyrae hydrodynamical models
• Long time-scale behavior of the Blazhko effect from rectified Kepler data
• Blazhko RR Lyrae light curves as modulated signals
• The Blazhko behaviour of RR Geminorum I - CCD photometric results in 2004
• On the Predicted and Observed Color Boundaries of the RR Lyrae Instability Strip as a Function of Metallicity
• Long-term photometric monitoring of RR Lyr stars in M3
• The shortest modulation period Blazhko RR Lyrae star: SS Cnc
• Blazhko effect in the Galactic bulge fundamental mode RR~Lyrae stars I: Incidence rate and differences between modulated and non-modulated stars
• Multicolour CCD photometry of the variable stars in globular cluster M3
• The Multi-periodic Blazhko Modulation of CZ Lacertae
• Long-term photometric monitoring of Messier 5 variables: II. Blazhko stars
• Photometric and radial-velocity time-series of RR Lyrae stars in M3: analysis of single-mode variables
• RR Lyrae stars and the horizontal branch of NGC 5904 (M5)
• The unusually large population of Blazhko variables in the globular cluster NGC 5024 (M53)
• Blazhko modulation in the infrared
• Study of Globular Cluster M53: new variables, distance, metallicity
• On the Oosterhoff dichotomy in the Galactic bulge: I. spatial distribution
• Extended Aperture Photometry of K2 RR Lyrae stars
• Blazhko Effect in the first overtone RR Lyrae stars of the OGLE Galactic bulge collection
• Are all RR Lyrae stars modulated?
• Characteristics of bright ab-type RR Lyrae stars from the ASAS and WASP surveys
• Fitting Blazhko light curves
• The SERMON project: 48 new field Blazhko stars and an investigation of modulation-period distribution
• Blazhko type fundamental-mode RR Lyrae stars in the globular cluster, M3
• The first Baade-Wesselink analysis of Blazhko RR Lyrae stars: discrepancies between photometrically and spectroscopically determined radius variations
• Extended Aperture Photometry of K2 RR Lyrae stars
• On the connection between almost periodic functions and Blazhko light curves

Cited by in corpus (12)

• High-precision distance measurements with classical pulsating stars
• First results on RR Lyrae stars with the TESS space telescope: untangling the connections between mode content, colors and distances
• On the use of field RR Lyrae as Galactic probes: IV. New insights into and around the Oosterhoff dichotomy
• Studies of RR Lyrae Variables in Binary Systems. I.: Evidence of a Trimodal Companion Mass Distribution
• On the Use of Field RR Lyrae as Galactic Probes. VI. Mixed mode RR Lyrae variables in Fornax and in nearby dwarf galaxies
• Two Different Weak Modulations in ab-type RR Lyrae Variable V838 Cyg, and Potential Influence of Metal Abundance on Blazhko Modulation
• A joint 1% calibration of the RR Lyrae & type-II Cepheid Leavitt laws yields homogeneous distances to 93 Galactic globular clusters
• Learning novel representations of variable sources from multi-modal $\text{Gaia}$ data via autoencoders
• A search for photometric variability towards the globular cluster M3 with the TWenty Inch Survey Telescope
• Digging Deeper for RR Lyrae Stars with Low Modulation Amplitudes
• Connections between the cycle-to-cycle light curve and O-C variations of the Blazhko RR Lyrae stars
• Metallicity estimation of RR Lyrae stars from their I-band light curves