RR Lyrae Atmospherics: Wrinkles Old and New. A Preview

Abstract

I report some results of an echelle spectroscopic survey of RR Lyrae stars begun in 2006 that I presented in my Henry Norris Lecture of January 4, 2010. Topics include (1) atmospheric velocity gradients, (2) phase-dependent envelope turbulence as it relates to Peterson's discoveries of axial rotation on the horizontal branch and to Stothers' explanation of the Blazhko effect, (3) the three apparitions of hydrogen emission during a pulsation cycle, (4) the occurrence of He I lines in emission and absorption, (5) detection of He II emission and metallic line-doubling in Blazhko stars, and finally (6) speculation about what helium observations of RR Lyrae stars in omega Centauri might tell us about the putative helium populations and the horizontal branch of that strange globular cluster.

13 pages, 10 Figures, submitted to AJ

References in corpus (4)

• Fashionably Late? Building up the Milky Way's Inner Halo
• Multiperiodic Galactic field RR Lyrae stars in the ASAS catalog
• New Metallicities of RR Lyrae Stars in omega Centauri: Evidence for a Non He-Enhanced Metal-Intermediate Population
• An extensive photometric study of the Blazhko RR Lyrae star MW Lyr: II. Changes in the physical parameters

Cited by in corpus (30)

• Metal Abundances, Radial Velocities and other Physical Characteristics for the RR Lyrae Stars in the Kepler Field
• The Chemical Compositions of Variable Field Horizontal Branch Stars: RR Lyrae Stars
• Fitting Analysis using Differential Evolution Optimization (FADO): Spectral population synthesis through genetic optimization under self-consistency boundary conditions
• Spectroscopic Comparison of Metal-Rich RRab Stars of the Galactic Field with Their Metal-Poor Counterparts
• Chemical abundances of solar neighborhood RR Lyrae stars
• Template RR Lyrae H alpha, H beta, and H gamma Velocity Curves
• Radial Velocities and Pulsation Ephemerides of 11 Field RR Lyrae Stars
• Metallicities from high resolution spectra of 49 RR Lyrae Variables
• Photometric and radial-velocity time-series of RR Lyrae stars in M3: analysis of single-mode variables
• Blazhko modulation in the infrared
• The Absolute Magnitude of RRc Variables From Statistical Parallax
• Variable turbulent convection as the cause of the Blazhko effect - testing the Stothers model
• Chemical abundances in a high velocity RR Lyrae star near the bulge
• Spectroscopic properties of a two-dimensional time-dependent Cepheid model II. Determination of stellar parameters and abundances
• SMHASH: Anatomy of the Orphan Stream using RR Lyrae stars
• Dynamical structure of the pulsating atmosphere of RR Lyr - I. A typical pulsation cycle
• Metal-Rich RRc stars in the Carnegie RR Lyrae Survey
• The Axial Rotation and Variable Macroturbulence of RR Lyrae and Red Horizontal Branch Stars
• Hydrogen lines in LAMOST low resolution spectra of RR Lyrae stars
• First observation of H$\alpha$ redshifted emission in RR Lyr
• The first Baade-Wesselink analysis of Blazhko RR Lyrae stars: discrepancies between photometrically and spectroscopically determined radius variations
• Spectroscopic and photometric time series of the bright RRc star T Sex
• Axial rotation and turbulence of RR ab stars: the Peterson Conundrum revisited
• Possible evidence of hydrogen emission in the first-overtone and multi-mode RR Lyrae variables
• Hydrogen and Helium Shock Phenomena during Rising Light in RR Lyrae Fundamental Mode Pulsators
• Field Blue Stragglers and Related Mass Transfer Issues
• Atmospheric dynamics and shock waves in RR Lyr -- I. The three H$\alpha$ emissions
• Blazhko effect in Cepheids and RR Lyrae stars
• Blueshifted hydrogen emission and shock wave of RR Lyrae variables in SDSS and LAMOST
• rrlfe: Software for Generating and Applying Metallicity Calibrations for RR Lyrae Variable Stars Across a Wide Range of Phases and Temperatures