ON THE RR LYRAE STARS IN GLOBULARS. IV. ω CENTAURI OPTICAL UBVRI PHOTOMETRY

被引：53

作者：

Braga, V. F. ^{[1
,2
,3
]}

Stetson, P. B. ^{[4
]}

Bono, G. ^{[1
,3
]}

Dall'Ora, M. ^{[5
]}

Ferraro, I. ^{[3
]}

Fiorentino, G. ^{[6
]}

Freyhammer, L. M. ^{[7
]}

Iannicola, G. ^{[3
]}

Marengo, M. ^{[8
]}

Neeley, J. ^{[8
]}

Valenti, E. ^{[9
]}

Buonanno, R. ^{[1
,10
]}

Calamida, A. ^{[11
]}

Castellani, M. ^{[3
]}

Da Silva, R. ^{[2
,3
]}

Degl'Innocenti, S. ^{[12
,13
]}

Di Cecco, A. ^{[10
]}

Fabrizio, M. ^{[2
,10
]}

Freedman, W. L. ^{[14
]}

Giuffrida, G. ^{[2
,3
]}

Lub, J. ^{[15
]}

Madore, B. F. ^{[16
]}

Marconi, M. ^{[5
]}

Marinoni, S. ^{[2
,3
]}

Matsunaga, N. ^{[17
]}

Monelli, M. ^{[18
]}

Persson, S. E. ^{[16
]}

Piersimoni, A. M. ^{[10
]}

Pietrinferni, A. ^{[10
]}

Prada-Moroni, P. ^{[12
,13
]}

Pulone, L. ^{[3
]}

Stellingwerf, R. ^{[19
]}

Tognelli, E. ^{[12
,13
]}

Walker, A. R. ^{[20
]}

机构：

[1] Univ Roma Tor Vergata, Dept Phys, Via Ric Sci 1, I-00133 Rome, Italy

[2] ASDC, Via Politecn Snc, I-00133 Rome, Italy

[3] INAF Osservatorio Astron Roma, Via Frascati 33, I-00040 Monte Porzio Catone, Italy

[4] Domin Astrophys Observ, NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada

[5] INAF Osservatorio Astron Capodimonte, Salita Moiariello 16, I-80131 Naples, Italy

[6] INAF Osservatorio Astron Bologna, Via Ranzani 1, I-40127 Bologna, Italy

[7] Univ Cent Lancashire, Jeremiah Horrocks Inst Astrophys, Preston PR1 2HE, Lancs, England

[8] Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA

[9] European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany

[10] INAF Osservatorio Astron Teramo, Via Mentore Maggini Snc, I-64100 Teramo, Italy

[11] Natl Opt Astron Observ, 950 N Cherry Ave, Tucson, AZ 85719 USA

[12] Ist Nazl Fis Nucl, Sez Pisa, Largo Pontecorvo 3, I-56127 Pisa, Italy

[13] Univ Pisa, Dipartimento Fis Enrico Fermi, Largo Pontecorvo 3, I-56127 Pisa, Italy

[14] Univ Chicago, Dept Astron & Astrophys, 5640 South Ellis Ave, Chicago, IL 60637 USA

[15] Leiden Univ, Sterrewacht Leiden, POB 9513, NL-2300 RA Leiden, Netherlands

[16] Observ Carnegie Inst Sci, 813 Santa Barbara St, Pasadena, CA 91101 USA

[17] Univ Tokyo, Sch Sci, Inst Astron, Kiso Observ, 10762-30 Mitake, Kiso, Nagano 970101 3, Japan

[18] Inst Astrofis Canarias, Calle Via Lactea S-N, E-38205 Tenerife, Spain

[19] Stellingwerf Consulting, 11033 Mathis Mtn Rd SE, Huntsville, AL 35803 USA

[20] Natl Opt Astron Observ, Cerro Tololo Interamer Observ, Casilla 603, La Serena, Chile

来源：

ASTRONOMICAL JOURNAL | 2016年 / 152卷 / 06期

基金：

日本学术振兴会;

关键词：

globular clusters: individual (omega Cen); stars: distances; stars: horizontal-branch; stars: variables: RR Lyrae; GRAVITATIONAL LENSING EXPERIMENT; PERIOD-LUMINOSITY RELATION; LARGE-MAGELLANIC-CLOUD; EXTREME HORIZONTAL-BRANCH; DWARF SPHEROIDAL GALAXY; CLUSTER AGES EXPERIMENT; OGLE-III CATALOG; METAL-POOR STARS; M4; NGC; 6121; VARIABLE-STARS;

D O I：

10.3847/0004-6256/152/6/170

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

New accurate and homogeneous optical UBVRI photometry has been obtained for variable stars in the Galactic globular cluster omega Cen (NGC 5139). We secured 8202 CCD images covering a time interval of 24 years and a sky area of 84 x 48 arcmin. The current data were complemented with data available in the literature and provided new, homogeneous pulsation parameters (mean magnitudes, luminosity amplitudes, periods) for 187 candidate omega Cen RR Lyrae (RRLs). Among them we have 101 RRc (first overtone) and 85 RRab (fundamental) variables, and a single candidate RRd (double-mode) variable. Candidate Blazhko RRLs show periods and colors that are intermediate between the RRc and RRab variables, suggesting that they are transitional objects. A comparison of the period distribution and the Bailey diagram indicates that RRLs in omega Cen show a long-period tail not present in typical Oosterhoff II (OoII) globulars. The RRLs in dwarf spheroidals and in ultra-faint dwarfs have properties between Oosterhoff intermediate and OoII clusters. Metallicity plays a key role in shaping the above evidence. These findings do not support the hypothesis that omega Cen is the core remnant of a spoiled dwarf galaxy. Using optical period-Wesenheit relations that are reddening-free and minimally dependent on metallicity we find a mean distance to omega Cen of 13.71 +/- 0.08 +/- 0.01 mag (semi-empirical and theoretical calibrations). Finally, we invert the I-band period-luminosity-metallicity relation to estimate individual RRLs' metal abundances. The metallicity distribution agrees quite well with spectroscopic and photometric metallicity estimates available in the literature.

引用

页数：34

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