TY - JOUR
T1 - On a New Theoretical Framework for RR Lyrae Stars. II. Mid-infrared Period-Luminosity-Metallicity Relations
AU - Neeley, Jillian R.
AU - Marengo, Massimo
AU - Bono, Giuseppe
AU - Braga, Vittorio F.
AU - Dall'ora, Massimo
AU - Magurno, Davide
AU - Marconi, Marcella
AU - Trueba, Nicolas
AU - Tognelli, Emanuele
AU - Moroni, Pier G.Prada
AU - Beaton, Rachael L.
AU - Freedman, Wendy L.
AU - Madore, Barry F.
AU - Monson, Andrew J.
AU - Scowcroft, Victoria
AU - Seibert, Mark
AU - Stetson, Peter B.
PY - 2017/6/1
Y1 - 2017/6/1
N2 - We present new theoretical period-luminosity-metallicity (PLZ) relations for RR Lyræ stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range of metal abundances (Z = 0.0001-0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, μ 0, and extinction, A V, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia's first data release. For M4, we find a distance modulus of μ 0 = 11.257 ± 0.035 mag with A V = 1.45 ± 0.12 mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ∼0.02 mag at mid-infrared wavelengths.
AB - We present new theoretical period-luminosity-metallicity (PLZ) relations for RR Lyræ stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range of metal abundances (Z = 0.0001-0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, μ 0, and extinction, A V, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia's first data release. For M4, we find a distance modulus of μ 0 = 11.257 ± 0.035 mag with A V = 1.45 ± 0.12 mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ∼0.02 mag at mid-infrared wavelengths.
KW - infrared: stars
KW - stars: horizontal-branch
KW - stars: variables: RR Lyrae
UR - http://www.scopus.com/inward/record.url?scp=85020750935&partnerID=8YFLogxK
UR - http://dx.doi.org/10.3847/1538-4357/aa713d
U2 - 10.3847/1538-4357/aa713d
DO - 10.3847/1538-4357/aa713d
M3 - Article
AN - SCOPUS:85020750935
SN - 0004-637X
VL - 841
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 84
ER -