J/MNRAS/484/4833 Oosterhoff dichotomy in Galactic bulge (Prudil+, 2019)
On the Oosterhoff dichotomy in the Galactic bulge: I. Spatial distribution.
Prudil Z., Dekany I., Catelan M., Smolec R., Grebel E.K., Skarka M.
<Mon. Not. R. Astron. Soc., 484, 4833-4848 (2019)>
=2019MNRAS.484.4833P 2019MNRAS.484.4833P (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, variable ; Photometry
Keywords: Galaxy: bulge - stars: variables: RR Lyrae -
stars: variables: horizontal branch
Abstract:
We present a study of the Oosterhoff (Oo) dichotomy in the Galactic
bulge using 8141 fundamental-mode RR Lyrae stars. We used public
photometric data from the Optical Gravitational Lensing Experiment and
the Vista Variables in the Via Lactea survey. We carefully selected
fundamental-mode stars without modulation and without association with
any globular cluster located towards the Galactic bulge. Subsequently,
we identified and separated the Oosterhoff groups I and II on the
basis of their period-amplitude distribution and using a relation
fitted to the Oosterhoff I locus. Both Oosterhoff groups were then
compared to observations of two bulge globular clusters and with
models of stellar pulsation and evolution. We found that some of the
variables classified as Oo II belong to a third Oo group. The
Oosterhoff II variables are more metal-poor on average, more massive,
and cooler than their Oosterhoff I counterparts. The analysis of their
spatial distribution shows a systematic difference between foreground,
central, and background regions in the occurrence of the Oosterhoff II
group. The difference between the Oo I and II groups is also seen in
their distance distributions with respect to the Galactic bar, but
neither group is associated with the bar.
Description:
We identified and separated the Oo I and II populations among
non-modulated RR Lyrae stars in the Galactic bulge, based on the
period-amplitude space and using manifold learning.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
oobulge.dat 141 8141 Oosterhoff dichotomy in the Galactic bulge
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See also:
J/AcA/64/177 : VI light curves of Galactic Bulge RR Lyrae (Soszynski+, 2014)
Byte-by-byte Description of file: oobulge.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- --- [OGLE-BLG-RRLYR-]
16- 20 I05 --- ID OGLE identification number,
(OGLE BLG-RRLYR-NNNNN in Simbad)
22- 30 F9.5 deg RAdeg Right ascension (J2000)
32- 40 F9.5 deg DEdeg Declination (J2000)
42- 47 F6.3 mag Ksmag Apparent magnitude in K band (VVV survey)
49- 53 F5.3 mag AmpK Amplitude in K band
55 I1 --- Oo [1/2] Oosterhoff type; OoI = 1, OoII = 2
57- 62 F6.3 [-] [Fe/H] Metallicity on JK scale
64- 68 F5.3 [-] e_[Fe/H] Error on metallicity
70- 75 F6.3 [-] [Fe/H]carr Metallicity on Carretta scale
77- 83 F7.5 mag VMAG Absolute magnitude in V band
85- 91 F7.5 mag e_VMAG Error on absolute magnitude in V band
93- 99 E7.1 mag IMAG Absolute magnitude in I band
101-107 F7.5 mag e_IMAG Error on absolute magnitude in I band
109-114 E6.1 mag KMAG Absolute magnitude in K band
116-122 F7.5 mag e_KMAG Error on absolute magnitude in K band
124-128 I5 pc d Distance
130-132 I3 pc e_d Error on distance
134-141 F8.5 mag Ak Extinction in K band
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Acknowledgements:
Zdenek Prudil, prudilz(at)ari.uni-heidelberg.de
(End) Zdenek Prudil [ARI, Germany], Patricia Vannier [CDS] 04-Mar-2020