2007A&A...476..779B


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.21CEST15:34:36

2007A&A...476..779B - Astronomy and Astrophysics, volume 476, 779-790 (2007/12-3)

RR Lyrae stars in Galactic globular clusters. VI. The period-amplitude relation.

BONO G., CAPUTO F. and DI CRISCIENZO M.

Abstract (from CDS):

This work uses nonlinear convective models of RR Lyrae stars and evolutionary predictions of low-mass helium burning stellar structures to constrain the properties of cluster and field RR Lyrae variables. In particular, we address two problems: is the Period-Amplitude (PAV) plane of fundamental (RRab) variables a good diagnostic for the metal abundance? Is the MV(RR)-[Fe/H] relation of field and cluster variables linear over the whole metal abundance range of [Fe/H]~-2.5 to ∼0? We perform a detailed comparison between theory and observations for fundamental RR Lyrae variables in the solar neighborhood and in both Oosterhoff type I (OoI) and type II (OoII) Galactic globular clusters. We show that the distribution of cluster RRab variables in the PAV plane depends not only on the metal abundance, but also on the cluster Horizontal Branch (HB) morphology. We find that on average the observed pulsation parameter kpuls connecting the period to the visual amplitude increases when moving from metal-poor to metal-rich GGCs. However, this parameter shows marginal changes among OoI clusters with intermediate to red HB types and iron abundances -1.8≤[Fe/H]≤-1.1, whereas its value decreases in OoII clusters with the bluer HB morphology, although these clusters are also the less metal-poor ones of the group. Moreover, at [Fe/H]=-1.7±0.1 the OoI clusters present redder HB types and larger <kpuls> values than the OoII clusters. The RRab variables in ω Cen and in the solar neighborhood further support the evidence that the spread in [Fe/H], at fixed kpuls, is of the order of ±0.5dex. Using the results of synthetic HB simulations, we show that the PAV plane can provide accurate cluster distance estimates. We find that the RRab variables in OoI and in OoII clusters with very blue HB types obey a well-defined MV(RR)-kpuls relation, while those in OoII clusters with moderately blue HB types present a zero-point that is ∼0.05mag brighter. Regarding field variables, we show that with [Fe/H]≥-1.0 a unique MV(RR)-kpuls relation can be adopted, independently of the color distribution of the parent HB star population. Current findings suggest that the PAV distribution is not a robust diagnostic for the metal abundance of RRab variables. However, the same observables can be used to estimate the absolute magnitude of globular cluster and field RRab variables. We show that over the metallicity range -2.4≤[Fe/H]≤0.0 the MV(RR)-[Fe/H] relation is not linear but has a parabolic behavior.

Abstract Copyright:

Journal keyword(s): Galaxy: globular clusters: general - stars: evolution - stars: horizontal-branch - stars: oscillations - stars: variables: RR Lyr

Simbad objects: 34

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Number of rows : 34

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11051 1
2 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5758 1
3 NGC 1851 GlC 05 14 06.76 -40 02 47.6   8.80 7.23     ~ 1252 0
4 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14989 1
5 NGC 3201 GlC 10 17 36.82 -46 24 44.9   9.18 8.24     ~ 734 0
6 NGC 4147 GlC 12 10 06.149 +18 32 31.78   11.45 10.74     ~ 499 0
7 M 68 GlC 12 39 27.98 -26 44 38.6   10.26 7.96     ~ 886 0
8 M 53 GlC 13 12 55.25 +18 10 05.4   8.95 7.79     ~ 722 0
9 NGC 5053 GlC 13 16 27.09 +17 42 00.9     9.96     ~ 542 0
10 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3032 0
11 2MASS J13272171-4723331 Al* 13 27 21.71 -47 23 33.2 17.654 17.884 17.262 16.778 16.370 ~ 36 0
12 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2277 0
13 NGC 5466 GlC 14 05 27.29 +28 32 04.0   10.5 9.70     ~ 727 0
14 IC 4499 GlC 15 00 18.57 -82 12 49.6     8.56     ~ 312 0
15 M 5 GlC 15 18 33.22 +02 04 51.7   7.34 5.95     ~ 1782 0
16 M 4 GlC 16 23 35.22 -26 31 32.7           ~ 1685 0
17 M 107 GlC 16 32 31.86 -13 03 13.6   9.96 8.85     ~ 708 0
18 NGC 6229 GlC 16 46 58.641 +47 31 36.38   9.38 9.86     ~ 315 0
19 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 1916 0
20 M 9 GlC 17 19 11.78 -18 30 58.5   9.36 8.42     ~ 279 0
21 NGC 6362 GlC 17 31 54.99 -67 02 54.0   9.72 8.86     ~ 493 0
22 NGC 6426 GlC 17 44 54.71 +03 10 12.5           ~ 189 0
23 NGC 6441 GlC 17 50 13.06 -37 03 05.2   9.26 8.00     ~ 772 0
24 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 914 0
25 NGC 6723 GlC 18 59 33.15 -36 37 56.1           ~ 432 0
26 V* RR Lyr RR* 19 25 27.9123232234 +42 47 03.690634101   7.36   7.6   A8-F7 883 0
27 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 764 0
28 M 75 GlC 20 06 04.841 -21 55 20.14     8.26     ~ 316 0
29 NGC 6934 GlC 20 34 11.37 +07 24 16.1   10.48 9.75     ~ 363 0
30 M 72 GlC 20 53 27.70 -12 32 14.3   9.95 8.96     ~ 368 0
31 NGC 7006 GlC 21 01 29.465 +16 11 16.49     10.46     ~ 486 0
32 M 15 GlC 21 29 58.33 +12 10 01.2   3       ~ 2922 0
33 M 2 GlC 21 33 27.02 -00 49 23.7     6.25     ~ 906 1
34 NAME Local Group GrG ~ ~           ~ 7071 0

    Equat.    Gal    SGal    Ecl

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2020.10.21-15:34:36

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