Abundance anomalies in low-mass field mergers as evidence of a merger origin for the second-generation stars in globular clusters

Kravtsov, V.; Dib, S.; Calderon, F.

Авторы: Kravtsov V., Dib S., Calderon F.
Журнал: Astronomy and Astrophysics
Том: 703
Год издания: 2025
Издательство: Springer Verlag
Местоположение издательства: Germany
Первая страница: 1
Последняя страница: 9
Номер статьи: A191
DOI: 10.1051/0004-6361/202556481
Аннотация: The canonical formation of second-generation (G2) stars in globular clusters (GCs) from gas enriched and ejected by G1(primordial) polluters faces substantial challenges, namely (i) a mass-budget problem and (ii) uncertainty in the source(s) of the abundance anomaly of light elements (AALE) in G2 stars. The merger of G1 low-mass main-sequence (MS) binaries can overcome (i), butits ability to result in AALE remains unverified.We present evidence of the merger process to explain AALE, based on highly probable merger remnants in the Galactic disc.Methods. We focus on carbon-deficient red clump giants with low masses of 1.0 M⊙ < M ≲ 2.0 M⊙, and hot He-intermediate subdwarfs of super-solar metallicity, both exhibiting G2-like AALE that are incompatible with a GC origin.The origin of such rare core He-burning stars as mergers of [MS star (MSS)]+[He white dwarf (HeWD)] binaries, whichevolved from low-mass, high-mass ratio (MSS+MSS) binaries, is supported by models that evolve them to either horizontal branch(HB) stars or He subdwarfs via the red giant branch (RGB). Such binaries in the GC NGC 362 contain very young (∼4 Myr), extremelylow-mass HeWDs, in contrast to much older (∼100 times) counterparts in open clusters. This agrees with the impact of the GC environment on the lifetime of hard binaries: (MSS+HeWD) systems merge there soon after forming from (MSS+MSS) binaries that haveundergone the common envelope stage of evolution. Based on the number and lifetime of the (MSS+HeWD) binaries uncovered inNGC 362, the expected fraction of their progeny G2 RGB stars is estimated to be ≲10%.The field merger remnants with G2-like AALE support the merger nature of at least a fraction of G2 stars in GCs. Thespecific channel [(MSS+MSS) – (MSS+HeWD) – merger product], supported by observations and models, is tentatively identified asthe formation channel of the extreme G2 RGB component in GCs.
Добавил в систему: Кравцов Валерий Витальевич

	ИСТИНА	Войти в систему Регистрация
	ИСТИНА ПсковГУ
	Главная Поиск Статистика О проекте Помощь

ИСТИНА

ИСТИНА ПсковГУ

Abundance anomalies in low-mass field mergers as evidence of a merger origin for the second-generation stars in globular clustersстатья

Прикрепленные файлы