2014AJ....147...31M

Query : 2014AJ....147...31M

2014AJ....147...31M - Astron. J., 147, 31 (2014/February-0)

The RR Lyrae stars: new perspectives.

McNAMARA D.H. and BARNES J.

Abstract (from CDS):

We demonstrate that the Oosterhoff II (Oo II) RR Lyrae ab variables are hotter by ∼270 K, at the same period, than Oo I variables. Or, at the same ( - )0 value the Oo II variables have larger radii than Oo I variables. This accounts for the reason Oo II variables are brighter (0.12-0.20 mag) than Oo I variables. The dependence of the light amplitude of RR Lyrae variables on temperature is independent of Oo type. This makes it possible to derive an accurate set of equations to relate intrinsic (B - V)0color indices to light amplitudes, which in turn can be used to determine the interstellar reddening (E (B - V)). With just a few variables (∼5), it is possible to determine the E (B - V) to an accuracy of <0.01 mag in the absence of systematic photometric errors. We discuss the errors introduced in color excess determinations by including the Blazhko stars in a solution. A comparison of color excess values of 23 globular clusters and two regions of the Large Magellanic Cloud (LMC), determined with the aid of our newly developed equations, are found to compare favorably (∼0.01 mag) with color excess values found in the literature. Four new Oo III variables, some found in metal-poor clusters, are discussed. An analysis of the galactic-field variables indicates the majority are Oo I and Oo II variables, but a few short-period (log P < -0.36) metal-strong variables, so far not found in galactic globular clusters are evidently ∼0.30 mag fainter than Oo I variables. Oo III variables may also be present in the field. We conclude that the RR Lyrae ab variables are primarily restricted to four sequences or groups. If we assume that the Oo I variables' mean absolute magnitude is Mv = 0.61, the mean absolute magnitudes of the other three sequences are: short-period variables Mv ∼ 0.89 mag, Oo II Mv ∼ 0.43 mag, and Oo III Mv ∼ 0.29 mag. The Oo I fundamental RR Lyrae ab red edge (FRE) and fundamental blue edge (FBE) occur at approximately the following temperatures: FRE T ∼ 6180 K and FBE T ∼ 6750 K. There is a strong dependence of Mv on [Fe/H] as we proceed from the short-period variables to the Oo I variables and to the Oo II variables, but there seems to be little or no dependence of Mv on [Fe/H] for stars within a group, at least for the Oo I and Oo II groups. The Oo II variables exhibit a weak period luminosity relation in V in many globular clusters unlike the Oo II-like variables in Oo I clusters which do not exhibit a P-L relation. The properties of some intermediate LMC clusters are discussed.

Abstract Copyright: ∼

Journal keyword(s): globular clusters: general - Magellanic Clouds - stars: variables: RR Lyrae

Simbad objects: 39

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Number of rows : 39
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NGC 12 AG? 00 08 44.7412932648 +04 36 45.267783552   14.5       ~ 48 0
2 SV* HV 810 RR* 00 23 40.5541400088 -72 05 59.945381016   13.76 13.710   13.184 kF1hF4 53 0
3 V* SW And RR* 00 23 43.0896315888 +29 24 03.626531352 9.53 9.34 9.15     A7IIImF0 270 0
4 NGC 104 GlC 00 24 05.359 -72 04 53.20     4.09     ~ 4158 0
5 V* W Tuc RR* 00 58 09.7045404187 -63 23 44.369640880   11.81 11.60     kA2hA5 135 0
6 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7988 0
7 V* X Ari RR* 03 08 30.8846437148 +10 26 45.218712967 9.45 9.25 8.97     F0.5 305 0
8 NGC 1466 GlC 03 44 32.71 -71 40 18.0   11.6 11.59     ~ 166 0
9 NAME Ret GlC 04 36 10.15 -58 51 34.8   14.00 14.25 13.50   ~ 177 1
10 NGC 1841 GlC 04 45 24.38 -83 59 53.3   12.23 11.43     ~ 190 0
11 NGC 1835 Cl* 05 05 09.210 -69 24 20.96   11.314 10.596     ~ 173 0
12 NGC 1851 GlC 05 14 06.76 -40 02 47.6           ~ 1529 0
13 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
14 NGC 2257 Cl* 06 30 12.62 -64 19 40.0   13.24 12.62     ~ 228 0
15 V* RR Gem RR* 07 21 33.5312487888 +30 52 59.459320164   12.34 11.92     kA2hA7.5 217 0
16 NGC 3201 GlC 10 17 36.82 -46 24 44.9           ~ 1001 0
17 V* SU Dra RR* 11 37 56.6071282968 +67 19 47.060102316 9.52 9.37 9.27     kA2.5hA9.5 264 0
18 Cl Ruprecht 106 GlC 12 38 40.20 -51 09 01.0           ~ 413 0
19 M 68 GlC 12 39 27.98 -26 44 38.6     7.96     ~ 1069 0
20 NGC 5053 GlC 13 16 27.09 +17 42 00.9     9.96     ~ 675 0
21 NGC 5139 GlC 13 26 47.28 -47 28 46.1           ~ 3677 0
22 M 3 GlC 13 42 11.62 +28 22 38.2     6.39     ~ 2593 0
23 [ZCS2010] NV12 RR* 13 46 26.63981818194 -51 22 56.8190909065           ~ 3 0
24 NGC 5286 GlC 13 46 26.81 -51 22 27.3           ~ 485 0
25 NGC 5466 GlC 14 05 27.29 +28 32 04.0     9.70     ~ 887 0
26 M 5 GlC 15 18 33.22 +02 04 51.7     5.95     ~ 2095 0
27 M 62 GlC 17 01 12.60 -30 06 44.5           ~ 668 0
28 M 92 GlC 17 17 07.39 +43 08 09.4     6.52     ~ 2240 0
29 NGC 6388 GlC 17 36 17.461 -44 44 08.34           ~ 988 1
30 NGC 6442 AG? 17 46 51.3478765800 +20 45 40.225907376   14.5       ~ 30 0
31 NGC 6441 GlC 17 50 13.06 -37 03 05.2           ~ 940 0
32 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 1164 0
33 M 55 GlC 19 39 59.71 -30 57 53.1     6.49     ~ 913 0
34 M 75 GlC 20 06 04.841 -21 55 20.14     8.26     ~ 394 0
35 M 15 GlC 21 29 58.33 +12 10 01.2           ~ 3274 0
36 M 2 GlC 21 33 27.02 -00 49 23.7     6.25     ~ 1114 1
37 Cl* NGC 7089 SAW V10 RR* 21 33 32.7252231192 -00 48 35.070922116   15.752 16.146     ~ 11 0
38 V* AV Peg RR* 21 52 02.7945264655 +22 34 29.376851146 10.26 10.07 9.87     kF5.5hF6.5 185 0
39 Cl* NGC 6864 CCS V10 RR* ~ ~           ~ 2 0

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