Empirical Period-Color and Amplitude-Color Relations for Classical Cepheids and RR Lyrae Variables

Abstract

We analyze Galactic, Large Magellanic Cloud and Small Magellanic Cloud Cepheids and RR Lyrae variables in terms of period-color (PC) and amplitude-color (AC) diagrams at the phases of maximum and minimum light. We compiled Galactic Cepheids $V$- and $I$-band data from the literature. We make use of optical bands light curve data from OGLE-III survey for Cepheids and RR Lyrae variables in the Magellanic Clouds. We apply the $F$-statistical test to check the significance of any variation in the slope of PC and AC relations for Cepheid variables. The PC relation at maximum light for Galactic Cepheids with periods longer than about 7 days is shallow and the corresponding AC relation is flat for the entire period range. For the fundamental mode Cepheids in the Magellanic Clouds, we find significant breaks in the PC and AC relations at both maximum and minimum light for periods around 10 days. The PC relation at maximum light for the Magellanic Clouds is flat for Cepheids with periods greater than 10 days. First overtone Cepheids with periods less than 2.5 days have a shallow PC relation at minimum light. For fundamental mode RR Lyraes, we confirm earlier work supporting a flat PC relation at minimum light and a significant relation between amplitude and color at maximum light. We find that no such relations exist for first overtone RR Lyrae stars. These findings are in agreement with stellar photosphere/hydrogen ionization front interaction considerations. These nonlinearities can provide strong constraints for models of stellar pulsation and evolution.

arXiv commentAccepted for publication in Monthly Notices of Royal Astronomical Society

References in corpus (14)

• New Period-Luminosity and Period-Color Relations of Classical Cepheids: I. Cepheids in the Galaxy
• New Optical Reddening Maps of the Large and Small Magellanic Clouds
• Light curve analysis of Variable stars using Fourier decomposition and Principal component analysis
• Period-color and amplitude-color relations in classical Cepheid variables
• Period-color and amplitude-color relations in classical Cepheid variables III: The Large Magellanic Cloud Cepheid models
• Physical parameters of the Small Magellanic Cloud RR Lyrae stars and the distance scale
• Period-colour and amplitude-colour relations in classical Cepheid variables IV: The multi-phase relations
• Period-colour and amplitude-colour relations in classical Cepheid variables II: the Galactic Cepheid model
• The Detailed Forms of the LMC Cepheid PL and PLC Relations
• Period-color and amplitude-color relations in classical Cepheid variables V: The Small Magellanic Cloud Cepheid models
• Chemical and structural analysis of the Large Magellanic Cloud using the fundamental mode RR Lyrae stars
• Investigations of the Non-Linear LMC Cepheid Period-Luminosity Relation with Testimator and Schwarz Information Criterion Methods
• Period-Color and Amplitude-Color Relations in Classical Cepheid Variables - VI. New Challenges for Pulsation Models
• Period Color and Amplitude Color relations for MACHO project LMC RR Lyraes

Cited by in corpus (14)

• Large Magellanic Cloud Near-Infrared Synoptic Survey. II. The Wesenheit relations and their application to the Distance scale
• On the Variation of Fourier Parameters for Galactic and LMC Cepheids at Optical, Near-Infrared and Mid-Infrared Wavelengths
• High-precision distance measurements with classical pulsating stars
• Large Magellanic Cloud Near-Infrared Synoptic Survey. III. A Statistical Study of Non-Linearity in the Leavitt Laws
• Photometric and radial-velocity time-series of RR Lyrae stars in M3: analysis of single-mode variables
• On the variation of light curve parameters of RR Lyrae variables at multiple wavelengths
• Period-Luminosity Relations Derived From the OGLE-III Fundamental Mode Cepheids II: The Small Magellanic Cloud Cepheids
• The stellar photosphere-hydrogen ionization front interaction in Classical Pulsators: a theoretical explanation for observed period-colour relations
• The Properties of the Magellanic Bridge Based on OGLE IV RR Lyrae Variables
• Period-Luminosity relations derived from the OGLE-III First-overtone mode Cepheids in the Magellanic Clouds
• A multiphase study of theoretical and observed light curves of classical Cepheids in the Magellanic Clouds
• Period-Color and Amplitude-Color Relations at Maximum and Minimum Light for RR Lyrae Stars in the SDSS Stripe 82 Region
• Period-Colour and Amplitude-Colour relations for OGLE-$\delta$ Scuti stars in the Galactic Bulge and LMC
• Multiwavelength light curve analysis of Cepheid variables