Dynamical orbital classification of selected N-rich stars with Gaia Data Release 2 astrometry

Author(s)

Fernandez-Trincado, Jose G. ^[1] ; Chaves-Velasquez, Leonardo ^{[2, 3]} ; Perez-Villegas, Angeles ^[4] ; Vieira, Katherine ^[1] ; Moreno, Edmundo ^[5] ; Ortigoza-Urdaneta, Mario ^[1] ; Vega-Neme, Luis ^{[6, 7]}

Affiliation

^[1] Univ Atacama, Inst Astron & Ciencias Planetarias, Copayapu 485, Copiapo - Chile

^[2] Univ Narino, Univ Narino Observ, Ave Panamer, Pasto, Narino - Colombia

^[3] Univ Narino, Dept Fis, Torobajo Calle 18 Carrera 50, Pasto, Narino - Colombia

^[4] Univ Sao Paulo, IAG, Rua Matao 1226, BR-05508900 Sao Paulo - Brazil

^[5] Univ Nacl Autonoma Mexico, Inst Astron, Apdo Postal 70264, Mexico City 04510, DF - Mexico

^[6] Consejo Nacl Invest Cient & Tecn, Inst Astron Teor & Expt, Cordoba - Argentina

^[7] Univ Nacl Cordoba, Observ Astron Cordoba, Cordoba - Argentina

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 495, n. 4, p. 4113-4123, JUL 2020.
• Web of Science Citations: 0

Abstract

We have used the galaxy modelling algorithm GRAVPOT16, to explore the most probable orbital elements of a sample of 64 selected N-rich stars across the Milky Way. We use the newly measured proper motions from Gaia Data Release 2 with existing line-of-sight velocities from the second generation of the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) and spectrophotometric distance estimations from STARHORSE. We adopted a set of high-resolution particle simulations evolved in the same steady-state Galactic potential model with a bar, in order to identify the groups of N-rich stars that have a high probability of belonging to the bulge/bar, disc and stellar halo component. We find that the vast majority of the N-rich stars show typically maximum height from the Galactic plane below 3 kpc, and develop eccentric orbits (e > 0.5), which means that these stars appear to have bulge/bar-like and/or halo-like orbits. We also show that similar to 66 per cent of the selected N-rich stars currently reside in the inner Galaxy inside the corotation radius, whilst similar to 14 per cent are in halo-like orbits. Among the N-rich stars in the inner Galaxy, similar to 27 per cent share orbital properties in the boundary between bulge/bar and disc, depending on the bar pattern speeds. Our dynamical analysis also indicates that some of the N-rich stars are likely to be halo interlopers, which suggests that halo contamination is not insignificant within the bulge area. (AU)

• FAPESP's process: 17/15893-1 - Globular cluster orbits of bulge: the formation and evolution of the Milky Way
• Grantee: Maria de Los Angeles Perez Villegas
• Support Opportunities: Scholarships in Brazil - Post-Doctoral