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Title: The RRc Stars: Chemical Abundances and Envelope Kinematics

Abstract

We analyzed series of spectra obtained for 12 stable RRc stars observed with the echelle spectrograph of the du Pont telescope at Las Campanas Observatory and we analyzed the spectra of RRc Blazhko stars discussed by Govea et al. We derived model atmosphere parameters, [Fe/H] metallicities, and [X/Fe] abundance ratios for 12 species of 9 elements. We co-added all spectra obtained during the pulsation cycles to increase signal to noise and demonstrate that these spectra give results superior to those obtained by co-addition in small phase intervals. The RRc abundances are in good agreement with those derived for the RRab stars of Chadid et al. We used radial velocity (RV) measurements of metal lines and H α to construct variations of velocity with phase, and center-of-mass velocities. We used these to construct RV templates for use in low- to medium-resolution RV surveys of RRc stars. Additionally, we calculated primary accelerations, radius variations, and metal and H α velocity amplitudes, which we display as regressions against primary acceleration. We employ these results to compare the atmosphere structures of metal-poor RRc stars with their RRab counterparts. Finally, we use the RV data for our Blazhko stars and the Blazhko periods of Szczygiełmore » and Fabrycky to falsify the Blazhko oblique rotator hypothesis.« less

Authors:
;  [1];  [2];  [3]
  1. Department of Astronomy and McDonald Observatory, The University of Texas, Austin, TX 78712 (United States)
  2. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
  3. Université Nice Sophia–Antipolis, Observatoire de la Côte dAzur, UMR 7293, Parc Valrose, F-06108, Nice Cedex 02 (France)
Publication Date:
OSTI Identifier:
22679763
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 848; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; ACCELERATION; AMPLITUDES; ATMOSPHERES; CENTER-OF-MASS SYSTEM; COMPARATIVE EVALUATIONS; HYPOTHESIS; METALLICITY; METALS; PULSATIONS; RADIAL VELOCITY; RESOLUTION; SPECTRA; STARS; TELESCOPES

Citation Formats

Sneden, Christopher, Adamów, Monika, Preston, George W., and Chadid, Merieme, E-mail: chris@verdi.as.utexas.edu, E-mail: astromysz@gmail.com, E-mail: gwp@obs.carnegiescience.edu, E-mail: chadid@unice.fr. The RRc Stars: Chemical Abundances and Envelope Kinematics. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8B10.
Sneden, Christopher, Adamów, Monika, Preston, George W., & Chadid, Merieme, E-mail: chris@verdi.as.utexas.edu, E-mail: astromysz@gmail.com, E-mail: gwp@obs.carnegiescience.edu, E-mail: chadid@unice.fr. The RRc Stars: Chemical Abundances and Envelope Kinematics. United States. doi:10.3847/1538-4357/AA8B10.
Sneden, Christopher, Adamów, Monika, Preston, George W., and Chadid, Merieme, E-mail: chris@verdi.as.utexas.edu, E-mail: astromysz@gmail.com, E-mail: gwp@obs.carnegiescience.edu, E-mail: chadid@unice.fr. Tue . "The RRc Stars: Chemical Abundances and Envelope Kinematics". United States. doi:10.3847/1538-4357/AA8B10.
@article{osti_22679763,
title = {The RRc Stars: Chemical Abundances and Envelope Kinematics},
author = {Sneden, Christopher and Adamów, Monika and Preston, George W. and Chadid, Merieme, E-mail: chris@verdi.as.utexas.edu, E-mail: astromysz@gmail.com, E-mail: gwp@obs.carnegiescience.edu, E-mail: chadid@unice.fr},
abstractNote = {We analyzed series of spectra obtained for 12 stable RRc stars observed with the echelle spectrograph of the du Pont telescope at Las Campanas Observatory and we analyzed the spectra of RRc Blazhko stars discussed by Govea et al. We derived model atmosphere parameters, [Fe/H] metallicities, and [X/Fe] abundance ratios for 12 species of 9 elements. We co-added all spectra obtained during the pulsation cycles to increase signal to noise and demonstrate that these spectra give results superior to those obtained by co-addition in small phase intervals. The RRc abundances are in good agreement with those derived for the RRab stars of Chadid et al. We used radial velocity (RV) measurements of metal lines and H α to construct variations of velocity with phase, and center-of-mass velocities. We used these to construct RV templates for use in low- to medium-resolution RV surveys of RRc stars. Additionally, we calculated primary accelerations, radius variations, and metal and H α velocity amplitudes, which we display as regressions against primary acceleration. We employ these results to compare the atmosphere structures of metal-poor RRc stars with their RRab counterparts. Finally, we use the RV data for our Blazhko stars and the Blazhko periods of Szczygieł and Fabrycky to falsify the Blazhko oblique rotator hypothesis.},
doi = {10.3847/1538-4357/AA8B10},
journal = {Astrophysical Journal},
number = 1,
volume = 848,
place = {United States},
year = {Tue Oct 10 00:00:00 EDT 2017},
month = {Tue Oct 10 00:00:00 EDT 2017}
}