On THE RR LYRAE STARS IN GLOBULARS. IV. Ω CENTAURI OPTICAL UBVRI PHOTOMETRY*

Braga, V. F.; Stetson, P. B.; Bono, G.; Dall’Ora, M.; Ferraro, I.; Fiorentino, G.; Freyhammer, L. M.; Iannicola, G.; Marengo, Massimo; Neeley, J.; Valenti, E.; Buonanno, R.; Calamida, A.; Castellani, M.; Silva, R. da; Degl’Innocenti, S.; Cecco, A. Di; Fabrizio, M.; Freedman, Wendy L.; Giuffrida, G.; Lub, J.; Madore, Barry F.; Marconi, M.; Marinoni, S.; Matsunaga, Noriyuki; Monelli, M.; Persson, S. E.; Piersimoni, A. M.; Pietrinferni, A.; Prada-Moroni, P.; Pulone, L.; Stellingwerf, R. F.; Tognelli, E.; Walker, A. R.

doi:10.3847/0004-6256/152/6/170

Cited by 63 publications

(102 citation statements)

References 130 publications

(233 reference statements)

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“…The quoted circumstantial evidence indicates that we still lack a homogenous and detailed analysis of the Bailey diagram as a function of the metal content. In this context it is worth mentioning that we are neglecting the metallicity estimates based either on photometric indices such as the inversion of the PL relation (Braga et al 2016;Martínez-Vázquez et al 2016;Bono et al 2019) or the Fourier decomposition of the light curve (Jurcsik & Kovacs 1996;Nemec et al 2013;Elorrieta et al 2016;Hajdu et al 2018). Data plotted in Fig.…”

Section: The Fine Structure Of the Bailey Diagrammentioning

confidence: 99%

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On the Use of Field RR Lyrae as Galactic Probes. I. The Oosterhoff Dichotomy Based on Fundamental Variables*

Fabrizio

Bono

Braga

et al. 2019

ApJ

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We collected a large data set of field RR Lyrae stars (RRLs) by using catalogues already available in the literature and Gaia DR2. We estimated the iron abundances for a sub-sample of 2,382 fundamental RRLs (∆S method: Ca II K, Hβ, Hγ and Hδ lines) for which are publicly available medium-resolution SDSS-SEGUE spectra. We also included similar estimates available in the literature ending up with the largest and most homogeneous spectroscopic data set ever collected for RRLs (2,903). The metallicity scale was validated by using iron abundances based on high resolution spectra for a fundamental field RRL (V Ind), for which we collected X-shooter spectra covering the entire pulsation cycle. The peak ([Fe/H]=-1.59±0.01) and the standard deviation (σ=0.43 dex) of the metallicity distribution agree quite well with similar estimates available in the literature. The current measurements disclose a well defined metal-rich tail approaching Solar iron abundance. The spectroscopic sample plotted in the Bailey diagram (period vs luminosity amplitude) shows a steady variation when moving from the metal-poor ([Fe/H]=-3.0/-2.5) to the metal-rich ([Fe/H]=-0.5/0.0) regime. The smooth transition in the peak of the period distribution as a function of the metallicity strongly indicates that the longstanding problem of the Oosterhoff dichotomy among Galactic globulars is the consequence of the lack of metal-intermediate clusters hosting RRLs. We also found that the luminosity amplitude, in contrast Corresponding author: Michele Fabrizio michele.fabrizio@ssdc.asi.it * Partially based on observations collected under ESO programmes 297.D-5047 (PI. G. Bono) and 083.B-0281 (PI. D. Romano). arXiv:1908.02064v2 [astro-ph.SR] 7 Aug 2019 M. Fabrizio et al.with period, does not show a solid correlation with metallicity. This suggests that period-amplitudemetallicity relations should be cautiously treated.

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Section: The Fine Structure Of the Bailey Diagrammentioning

confidence: 99%

“…Later on, it was also recognised that the population ratio, i.e. the ratio between RRc and the total number of RRLs, is smaller in OoI (N c /N tot ≈0.29) than in OoII (N c /N tot ≈0.44) globulars (Stobie 1971;Braga et al 2016;Bono et al 2016).…”

Section: Introductionmentioning

confidence: 99%

On the Use of Field RR Lyrae as Galactic Probes. I. The Oosterhoff Dichotomy Based on Fundamental Variables*

Fabrizio

Bono

Braga

et al. 2019

ApJ

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“…The amplitude modulation ranges from a few tenths to more than half a magnitude (Piersimoni et al 2002;Braga et al 2016). The pulsation characteristics available in the literature do not allow us to assess whether the Fornax cluster RRLs located below the HASP region (green circles in Fig.…”

Section: The Bailey Diagrammentioning

confidence: 99%

Weak Galactic halo-Fornax dSph connection from RR Lyrae stars

Fiorentino

Monelli

Stetson

et al. 2017

A&A

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Aims. For the first time accurate pulsation properties of the ancient variable stars of the Fornax dwarf spheroidal galaxy (dSph) are discussed in the broad context of galaxy formation and evolution. Methods. Homogeneous multi-band BV I optical photometry of spanning twenty years has allowed us to identify and characterize more than 1400 RR Lyrae stars (RRLs) in this galaxy. Results. Roughly 70% are new discoveries. We investigate the period-amplitude distribution and find that Fornax shows a lack of high amplitude (A V 0.75 mag) short period fundamental-mode RRLs (P 0.48 d, HASPs). These objects occur in stellar populations more metal-rich than [Fe/H] ∼ −1.5 and they are common in the Galactic halo (hereafter Halo) and in globulars. This evidence suggests that old Fornax stars (older than 10 Gyr) are relatively metal poor. A detailed statistical analysis of the role of the present-day Fornax dSph in reproducing the Halo period distribution shows that it can only account for up to 20% of the Halo when combined with RRLs in massive dwarf galaxies (Sagittarius dSph, Large Magellanic Cloud). This finding indicates that Fornax-like systems played a smaller role than massive dwarfs in building up the Halo. Conclusions. We also discuss the occurrence of HASPs in connection with the luminosity and the early chemical composition of nearby dwarf galaxies. We find that, independently of their individual star formation histories, bright (M V −13.5 mag) galaxies have HASPs, whereas faint ones (M V −11 mag) do not. Interestingly enough, Fornax belongs to a luminosity range (−11 < M V −13.5 mag) in which the occurrence of HASPs appears to be correlated with the early star formation and chemical enrichment of the host galaxy.

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“…The RR Lyrae stars in the globular cluster Rup 106 are shown as green squares. (Bottom) Same as above but the background in this case are RR Lyrae stars in selected dwarf galaxies as compiled byBraga et al (2016) and scaled to the g band (see text).…”

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confidence: 99%

A DECam view of the diffuse dwarf galaxy Crater II – Variable stars

Vivas

Walker

Martı́nez-Vázquez

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Time series observations of a single dithered field centered on the diffuse dwarf satellite galaxy Crater II were obtained with the Dark Energy Camera (DECam) at the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile, uniformly covering up to two half-light radii. Analysis of the g and i time series results in the identification and characterization of 130 periodic variable stars, including 98 RR Lyrae stars, 7 anomalous Cepheids, and 1 SX Phoenicis star belonging to the Crater II population, and 24 foreground variables of different types. Using the large number of ab-type RR Lyrae stars present in the galaxy, we obtained a distance modulus to Crater II of (m − M) 0 = 20.333 ± 0.004 (stat) ±0.07 (sys). The distribution of the RR Lyrae stars suggests an elliptical shape for Crater II, with an ellipticity of 0.24 and a position angle of 153 • . From the RR Lyrae stars we infer a small metallicity dispersion for the old population of Crater II of only 0.17 dex. There are hints that the most metal-poor stars in that narrow distribution have a wider distribution across the galaxy, while the slightly more metal rich part of the population is more centrally concentrated. Given the features in the color-magnitude diagram of Crater II, the anomalous Cepheids in this galaxy must have formed through a binary evolution channel of an old population.

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On THE RR LYRAE STARS IN GLOBULARS. IV. Ω CENTAURI OPTICAL UBVRI PHOTOMETRY*

Cited by 63 publications

References 130 publications

On the Use of Field RR Lyrae as Galactic Probes. I. The Oosterhoff Dichotomy Based on Fundamental Variables*

On the Use of Field RR Lyrae as Galactic Probes. I. The Oosterhoff Dichotomy Based on Fundamental Variables*

Weak Galactic halo-Fornax dSph connection from RR Lyrae stars

A DECam view of the diffuse dwarf galaxy Crater II – Variable stars

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