Mid-infrared period–luminosity relations for globular cluster RR Lyraeстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 19 июня 2014 г.
Аннотация:The period–metallicity–WISE W1- and W2-band luminosity relations are derived for RR
Lyrae stars based on WISE epoch photometry for 360 and 275 stars in 15 and 9 Galactic
globular clusters, respectively. Our final relations have the form MW1 = γ W1− (2.381 ±
0.097) log PF + (0.096 ± 0.021)[Fe/H] and MW2 = γ W2 −(2.269 ± 0.127)log PF +
(0.108 ± 0.021)[Fe/H], where [Fe/H] values are on the scale of Carretta et al.We obtained two
appreciably discrepant estimates for the zero-points γ W1 and γ W2 of both relations: one based
on a statistical-parallax analysis – γ W1 = −0.829 ± 0.093 and γ W2 = −0.776 ± 0.093 and
another, significantly brighter one, based on Hubble Space Telescope (HST) Fine Guidance
Sensor (FGS) trigonometric parallaxes – γ W1,HST =−1.150 ± 0.077 and γ W2,HST =−1.105 ±
0.077. The period–metallicity–luminosity relations in the two bands yield highly consistent
distance moduli for the calibrator clusters and the distance moduli computed using the W1-
and W2-band relations with the HST zero-points agree well with those computed by Sollima,
Cacciari&Valenti based on their derived period–metallicity–K-band luminosity relationwhose
zero-point is tied to the HST trigonometric parallax of RR Lyrae itself (DM0 = 0.04 and
0.06, respectively, with a scatter of only 0.06).