OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge using RR Lyrae Stars

• Autorzy: Jacyszyn-Dobrzeniecka A. M. , Skowron D. M. , Mróz P. , Soszyński I. , Udalski A. , Pietrukowicz P. , Skowron J. , Poleski R. , Kozłowski S. , Wyrzykowski Ł. , Pawlak M. , Szymański M. K. , Ulaczyk K.

Identyfikatory

DOI

10.32023/0001-5237/67.1.1

• Języki publikacji: EN

Abstrakty

EN

We present a three-dimensional analysis of a sample of 22 859 type ab RR Lyr stars in the Magellanic System from the OGLE-IV Collection of RR Lyr stars. The distance to each object was calculated based on its photometric metallicity and a theoretical relation between color, absolute magnitude and metallicity. The LMC RR Lyr distribution is very regular and does not show any substructures. We demonstrate that the bar found in previous studies may be an overdensity caused by blending and crowding effects. The halo is asymmetrical with a higher stellar density in its north-eastern area, which is also located closer to us. Triaxial ellipsoids were fitted to surfaces of a constant number density. Ellipsoids farther from the LMC center are less elongated and slightly rotated toward the SMC. The inclination and position angle change significantly with the $a$ axis size. The median axis ratio is 1:1.23:1.45. The RR Lyr distribution in the SMC has a very regular, ellipsoidal shape and does not show any substructures or asymmetries. All triaxial ellipsoids fitted to surfaces of a constant number density have virtually the same shape (axis ratio) and are elongated along the line-of-sight. The median axis ratio is 1:1.10:2.13. The inclination angle is very small and thus the position angle is not well defined. We present the distribution of RR Lyr stars in the Magellanic Bridge area, showing that the Magellanic Clouds' halos overlap. A comparison of the distributions of RR Lyr stars and Classical Cepheids shows that the former are significantly more spread and distributed regularly, while the latter are very clumped and form several distinct substructures.

Słowa kluczowe

EN

stars: fundamental parameters; stars: variables: RR Lyrae; Magellanic Clouds; galaxies: statistics; galaxies: structure

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 2017
• Tom: Vol. 67, No. 1
• Strony: 1--35
• Opis fizyczny: Bibliogr. 48 poz., rys., tab., wykr.

Twórcy

autor

Jacyszyn-Dobrzeniecka A. M.

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

autor

Skowron D. M.

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

autor

Mróz P.

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

autor

Soszyński I.

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

autor

Udalski A.

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

autor

Pietrukowicz P.

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

autor

Skowron J.

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

autor

Poleski R.

• Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
• Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210, USA

autor

Kozłowski S.

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

autor

Wyrzykowski Ł.

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

autor

Pawlak M.

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

autor

Szymański M. K.

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

autor

Ulaczyk K.

• Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK

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Uwagi

Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2019).