Bibcode
Braga, V. F.; Stetson, P. B.; Bono, G.; Dall’Ora, M.; Ferraro, I.; Fiorentino, G.; Iannicola, G.; Marconi, M.; Marengo, M.; Monson, A. J.; Neeley, J.; Persson, S. E.; Beaton, R. L.; Buonanno, R.; Calamida, A.; Castellani, M.; Di Carlo, E.; Fabrizio, M.; Freedman, W. L.; Inno, L.; Madore, B. F.; Magurno, D.; Marchetti, E.; Marinoni, S.; Marrese, P.; Matsunaga, N.; Minniti, D.; Monelli, M.; Nonino, M.; Piersimoni, A. M.; Pietrinferni, A.; Prada-Moroni, P.; Pulone, L.; Stellingwerf, R.; Tognelli, E.; Walker, A. R.; Valenti, E.; Zoccali, M.
Bibliographical reference
The Astronomical Journal, Volume 155, Issue 3, article id. 137, 27 pp. (2018).
Advertised on:
3
2018
Citations
48
Refereed citations
39
Description
We present a new complete near-infrared (NIR, JHK s ) census
of RR Lyrae stars (RRLs) in the globular ω Cen (NGC 5139). We
collected 15,472 JHK s images with 4–8 m class
telescopes over 15 years (2000–2015) covering a sky area around
the cluster center of 60 × 34 arcmin2. These images
provided calibrated photometry for 182 out of the 198 cluster RRL
candidates with 10 to 60 measurements per band. We also provide new
homogeneous estimates of the photometric amplitude for 180 (J), 176 (H)
and 174 (K s ) RRLs. These data were supplemented with
single-epoch JK s magnitudes from VHS and with single-epoch
H magnitudes from 2MASS. Using proprietary optical and NIR data together
with new optical light curves (ASAS-SN) we also updated pulsation
periods for 59 candidate RRLs. As a whole, we provide JHK s
magnitudes for 90 RRab (fundamentals), 103 RRc (first overtones) and one
RRd (mixed-mode pulsator). We found that NIR/optical photometric
amplitude ratios increase when moving from first overtone to fundamental
and to long-period (P > 0.7 days) fundamental RRLs. Using predicted
period–luminosity–metallicity relations, we derive a true
distance modulus of 13.674 ± 0.008 ± 0.038 mag
(statistical error and standard deviation of the median) based on
spectroscopic iron abundances, and of 13.698 ± 0.004 ±
0.048 mag based on photometric iron abundances. We also found evidence
of possible systematics at the 5%–10% level in the zero-point of
the period–luminosity relations based on the five calibrating RRLs
whose parallaxes had been determined with the HST.
This publication makes use of data gathered with the Magellan/Baade
Telescope at Las Campanas Observatory, the Blanco Telescope at Cerro
Tololo Inter-American Observatory, NTT at La Silla (ESO Program IDs:
64.N-0038(A), 66.D-0557(A), 68.D-0545(A), 073.D-0313(A), ID
073.D-0313(A) and 59.A-9004(D)), VISTA at Paranal (ESO Program ID:
179.A-2010) and VLT at Paranal (ESO Program ID: ID96406).
Related projects
Galaxy Evolution in the Local Group
Galaxy formation and evolution is a fundamental Astrophysical problem. Its study requires “travelling back in time”, for which there are two complementary approaches. One is to analyse galaxy properties as a function of red-shift. Our team focuses on the other approach, called “Galactic Archaeology”. It is based on the determination of galaxy
Matteo
Monelli