SIMBAD references

2013AJ....146..119K - Astron. J., 146, 119 (2013/November-0)

The RR Lyrae variables and horizontal branch of NGC 6656 (M22).

KUNDER A., STETSON P.B., CASSISI S., LAYDEN A., BONO G., CATELAN M., WALKER A.R., PAREDES ALVAREZ L., CLEM J.L., MATSUNAGA N., SALARIS M., LEE J.-W. and CHABOYER B.

Abstract (from CDS):

The first calibrated broadband UBVI time-series photometry is presented for the RR Lyrae variable stars in NGC 6656 (M22), with observations spanning a range of 22 years. We have also redetermined the variability types and periods for the RR Lyrae stars identified previously by photographic observations, revising the number of fundamental-mode RR Lyrae variables (RR0) to 10 and the number of first-overtone variables (RR1) to 16. The mean periods of the RR0 and RR1 variables are

RR0= 0.66±0.02 days and

_ RR1_= 0.33±0.01 days, respectively, supporting an Oosterhoff II classification for the cluster. The number ratio of RR1-type to all RR-type variables is N1/NRR= 0.61, also consistent with an Oosterhoff II designation. Both the RR Lyrae stars' minimum light colors and the blue edge of the RR Lyrae instability strip suggest E( B - - V) = 0.36±0.02 mag toward M22. Regarding the HB morphology of M22, we find (B-R)/(B+V+R) = +0.97±0.1 and at least one "gap" located in an unusual part of the blue HB, in the middle of the so-called hot HB stars.


Abstract Copyright: ∼

Journal keyword(s): Galaxy: stellar content - stars: distances - stars: evolution - stars: horizontal-branch - stars: Population II

Nomenclature: Table 2: [KSC2013b] NVN (Nos NV1-NV4).

CDS comments: In introduction, NGC 6556 is a misprint for NGC 6656. In references, Clement et al. 2001, AJ, 121, 2587 is a misprint for 2001, AJ, 122, 2587.

Simbad objects: 66

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