Properties of the Milky Way's Old Populations Based on Photometric Metallicities of the OGLE RR Lyrae Stars

• Autorzy: Pietrukowicz P. , Udalski A. , Soszyński I. , Skowron D. M. , Wrona M. , Szymański M. K. , Poleski R. , Ulaczyk K. , Kozłowski S. , Skowron J. , Mróz P. , Rybicki K. , Iwanek P. , Gromadzki M.

Identyfikatory

DOI

10.32023/0001-5237/70.2.3

• Języki publikacji: EN

Abstrakty

EN

We have used photometric data on almost 91 000 fundamental-mode RR Lyr stars (type RRab) detected by the OGLE survey to investigate properties of old populations in the Milky Way. Based on their metallicity distributions, we demonstrate that the Galaxy is built from three distinct old components: halo, bulge, and disk. The distributions reach their maxima at approximately [Fe/H]_J95=-1.2 dex, -1.0 dex, and -0.6 dex on the Jurcsik's metallicity scale, respectively. We find that, very likely, the entire halo is formed from infalling dwarf galaxies. It is evident that halo stars penetrate the inner regions of the Galactic bulge. We estimate that about one-third of all RR Lyr stars within the bulge area belong in fact to the halo population. The whole old bulge is dominated by two populations, A and B, represented by a double sequence in the period--amplitude (Bailey) diagram. The boundary in iron abundance between the halo and the disk population is at about [Fe/H]_J95=-0.8 dex. Using Gaia DR2 for RRab stars in the disk area, we show that the observed dispersion of proper motions along the Galactic latitude decreases smoothly with the increasing metal content excluding a bump around [Fe/H]_J95=-1.0 dex.

Słowa kluczowe

EN

galaxy: bulge; galaxy: disk; galaxy: halo; stars: variables: RR Lyrae

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 2020
• Tom: Vol. 70, No. 2
• Strony: 121--139
• Opis fizyczny: Bibliogr. 44 poz., rys., wykr.

Twórcy

autor

Pietrukowicz P.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Udalski A.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Soszyński I.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Skowron D. M.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Wrona M.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Szymański M. K.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Poleski R.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Ulaczyk K.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
• Department of Physics, University of Warwick, Coventry CV4 7AL, UK

autor

Kozłowski S.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Skowron J.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Mróz P.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
• Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA

autor

Rybicki K.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Iwanek P.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Gromadzki M.

• Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

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Uwagi

Opracowanie rekordu ze środków MNiSW, umowa Nr 461252 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2021).