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Բյուրականի աստղադիտարանի հաղորդումներ: Երևանի աստղադիտարանի բյուլետեն = Сообщения Бюраканской обсерватории. Бюллетень ереванской Астрономической обсерватории = Contributions from the Burakan observatory. Bulletin of the Erevan astronomical observatory

Nucleosynthesis ; r-process- Galaxy ; halo-stars ; abundances-stars ; Chemically peculiar-stars ; Population III- stars ; Orbits- stars ; individual (LAMOST J1109+0754)

We report a comprehensive Chemo-dynamical analysis of LAMOST J1109+0754, a relatively bright (V = 12.8), extremely metal-poor ([Fe/H] = -3:17), and prograde (Jф and Vф > 0) star, with a strong r-process enhancement ([Eu/Fe] = +0.94 ± 0.12, [Ba/Fe] = -0.52 ± 0.15). 31 chemical abundances (from Lithium to Thorium) were derived. We suggest a possible progenitor with stellar mass of 13.4-29.5Mo. We argue that J1109+0754 is representative of the main r-process component due to the well agreement with the scaled-solar r-process component. We analyze the orbital history of this star in a time-varying Galactic potential, based on a Milky-Way analogue model extracted from Illustris-TNG simulations. Using this model, we carry out a statistical estimation of the phase-space coordinates of J1109+0754 at a young cosmic age. Collectively, the calculated motions, the derived chemistry, and the results from the cosmological simulations suggest that LAMOST J1109+0754 most likely formed in a low-mass dwarf galaxy, and belongs to the Galactic outer-halo population.

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Communications of the Byurakan Astrophysical Observatory (ComBAO) is a peer-reviewed scientific journal, which publishes research in observational and theoretical astronomy/astrophysics and presents recent advances in these fields. It is being published by the NAS RA V. Ambartsumian Byurakan Astrophysical Observatory (BAO) in English in electronic form. The journal publishes original papers, review papers, brief reports, book reviews, special communications, observational and theoretical results in various fields of astronomy and related sciences, and some editorial notes, including anniversaries and obituaries. Under the heading “Legacy”, the renewed magazine will republish some old articles of high value in English. The heading “Guest articles” will bring to the attention of readers the articles of researchers who are not employees of BAO. ComBAO was founded in 1946 and regularly published in 1946-1990. However, the publication was interrupted because of the economic situation after the disintegration of the Soviet Union in 1991.

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