@article{7eee25f32aa94109940ccd67900c2930,
title = "The distance from the Sun to the centre and the shape of the old bulge in the Galaxy: 16 221 OGLE RR Lyrae stars",
abstract = "A statistical method is used to determine both the Sun's distance r0 from the Galactic Centre and the 3D structure of the old stellar population of the Galactic bulge. The space distribution of 16 221 high latitude type-RRab RR Lyrae stars from the optical OGLE survey located towards the bulge is explored. An estimate by using RR Lyraes leads to a mean r0 = 8.28 ± 0.14 kpc within the effective bulge radius of rbulge = 2-3 kpc. The distribution of RR Lyraes within rbulge has the shape of an ellipsoid slightly elongated almost towards the Sun with a major axis of its symmetry a and two minor axes b and c of about the same length. The axial ratio is a: b: c ~ 1: 0.7: 0.7. These age-old, metal-poor, and kinematically hot stars do not trace a strong bar-like structure in the direction of the bulge at distances >1 kpc from the Galactic Centre, as b/a ~ 1.",
keywords = "Galaxy: bulge, Galaxy: fundamental parameters, Galaxy: kinematics and dynamics, Galaxy: structure",
author = "Evgeny Griv and Michael Gedalin and Pawel Pietrukowicz and Daniel Majaess and Jiang, {Ing Guey}",
note = "Funding Information: We would like to express our gratitude to our colleagues from the Department of Physics, at the Ben-Gurion University and the Department of Physics and Institute of Astronomy, at the National Tsing-Hua University who have discussed with us many of the problems considered in the paper. We are grateful to Irena Zlatopolsky for valuable technical assistance. The authors thank the anonymous referee for the helpful comments, numerous suggestions, and sharp criticisms of some preliminary results that helped us to improve the quality of this paper. The study described here was partially carried out at the NTHU in 2019 November. EG thanks Ing-Guey Jiang for the hospitality he and his colleagues extended to him during a three-weeks long visit in Hsin-Chu. EG is also thankful to the Israeli Ministry of Immigrant Absorption for partial financial support in the framework of the program 'KAMEA'. This study was supported in part by the Israel Science Foundation, the United States-Israel Binational Science Foundation, and the Ministry of Science and Technology of Taiwan. Funding Information: We would like to express our gratitude to our colleagues from the Department of Physics, at the Ben-Gurion University and the Department of Physics and Institute of Astronomy, at the National Tsing-Hua University who have discussed with us many of the problems considered in the paper. We are grateful to Irena Zlatopolsky for valuable technical assistance. The authors thank the anonymous referee for the helpful comments, numerous suggestions, and sharp criticisms of some preliminary results that helped us to improve the quality of this paper. The study described here was partially carried out at the NTHU in 2019 November. EG thanks Ing-Guey Jiang for the hospitality he and his colleagues extended to him during a three-weeks long visit in Hsin-Chu. EG is also thankful to the Israeli Ministry of Immigrant Absorption for partial financial support in the framework of the program {\textquoteleft}KAMEA{\textquoteright}. This study was supported in part by the Israel Science Foundation, the United States-Israel Binational Science Foundation, and the Ministry of Science and Technology of Taiwan. Publisher Copyright: {\textcopyright} 2020 The Author(s).",
year = "2020",
month = nov,
day = "1",
doi = "10.1093/mnras/staa2845",
language = "English",
volume = "499",
pages = "1091--1098",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "1",
}