Relation between spectral indices and binary fractions in globular clusters

doi:10.1051/0004-6361/202245212

YNAO OpenIR > 大样本恒星演化研究组

	Relation between spectral indices and binary fractions in globular clusters
	Zhang FH(张奉辉)1,2,4 ; Li LF(李立芳)1,2,4 ; Han ZW(韩占文)1,2,4 ; Gong XB(龚小波)1,2,3,4
发表期刊	ASTRONOMY & ASTROPHYSICS
	2023-10-30
卷号	679
DOI	10.1051/0004-6361/202245212
产权排序	第1完成单位
收录类别	SCI ; EI
关键词	binaries: general globular clusters: general stars: formation galaxies: stellar content galaxies: formation galaxies: fundamental parameters
摘要	Context. We study the relation between the known binary fraction and spectral absorption feature index to judge whether (and potentially which) spectral absorption feature indices are suitable for determining the binary fraction.Aims. The determination of the binary fraction is important in studies of binary star formation, evolutionary population synthesis models, and other works. The number of binary stars is difficult to determine for nearly all stellar systems because the individual stars are need to be resolved photometrically or spectroscopically. By comparison, their integrated spectra or spectral absorption feature indices are relatively easy to obtain.Methods. We used Galactic globular clusters (GCs) as our sample since they have relatively accurate binary fraction measurements and spectroscopic observations along the radial direction. When studying the relation between binary fractions and the spectral absorption feature index, we used three types of binary fractions: one with a mass ratio of q > 0.5 (f(q > 0.5)) and two with a total binary fraction (the methods of counting (f(tot)(mf)) and fitting (f(tot)(mc))), calculated and obtained the equivalent widths or magnitudes of 46 spectral absorption feature indices at three spectral resolutions (FWHMLick/IDS, 5, and 15 & Aring;). Since the regions for the binary fraction measurements (photometric) and the spectroscopic observations are different, we used the method of constructing the radial binary-fraction profile to get the binary fractions corresponding to the regions in the spectroscopic observations. The construction of the radial binary-fraction profile was obtained by using the python curve_fit module to fit the measured and analytic binary fraction values. The analytic value was expressed by taking advantage of the King surface-density profile and the assumed forms with respect to the radial binary-fraction profile (linear, quadratic, exponential, and Gaussian).Results. We find that the low-resolution (15 & Aring;) spectrum is not suitable for this study and the binary fraction type would affect the results: f(q > 0.5) and f(tot)(mc) exhibit better correlations with the spectral absorption feature index than f(tot)(mf) and the difference in metallicity would significantly affect the above relationship. Finally, to eliminate the effects of metallicity, age, and dynamical evolution, we only used those GCs with multiple spectra observed among different regions. We find that OIII-1, OIII-2, H-gamma F, H-delta F, H-gamma A, H-delta A, H-beta, Ca4455, C(2)4668, and TiO1 indices have strong correlations with binary fraction. The two OIII indices are the most sensitive to the binary fraction, followed by four Balmer indices - the two narrower central bandpass Balmer indices (similar to 20 & Aring;, F-definition) are more sensitive than the wider two (similar to 40 & Aring;, A-definition) and, lastly, the Ca4455, C(2)4668, and TiO1 indices. Using the binary fraction-sensitive spectral absorption feature indices in combination with the age- and metallicity-sensitive spectral absorption feature indices, we can determine the ages or metallicities first. Then we can go on to obtain the binary fractions for those stellar systems in which the individual stars cannot be resolved (e.g., dense or distant stellar systems). Furthermore, we are then able to carry out further studies of binary star formation and improve evolutionary population synthesis models.
资助项目	This work was funded by the National Natural Science Foundation of China (Nos. 11973081, 11773065, 11573062, 11521303, 12288102), the Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation (No. 2012048, Y201624), and the Science R[11973081]; This work was funded by the National Natural Science Foundation of China (Nos. 11973081, 11773065, 11573062, 11521303, 12288102), the Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation (No. 2012048, Y201624), and the Science R[11773065]; This work was funded by the National Natural Science Foundation of China (Nos. 11973081, 11773065, 11573062, 11521303, 12288102), the Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation (No. 2012048, Y201624), and the Science R[11573062]; This work was funded by the National Natural Science Foundation of China (Nos. 11973081, 11773065, 11573062, 11521303, 12288102), the Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation (No. 2012048, Y201624), and the Science R[11521303]; This work was funded by the National Natural Science Foundation of China (Nos. 11973081, 11773065, 11573062, 11521303, 12288102), the Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation (No. 2012048, Y201624), and the Science R[12288102]; National Natural Science Foundation of China[2012048]; National Natural Science Foundation of China[Y201624]; Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation[CMS-CSST-2021-A08]; China Manned Space Project[2021YFA1600403]; China Manned Space Project[2021YFA1600400]; National Key Ramp;D Program of China[202302AN360001]; International Centre of Supernovae, Yunnan Key Laboratory
项目资助者	This work was funded by the National Natural Science Foundation of China (Nos. 11973081, 11773065, 11573062, 11521303, 12288102), the Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation (No. 2012048, Y201624), and the Science R[11973081, 11773065, 11573062, 11521303, 12288102] ; National Natural Science Foundation of China[2012048, Y201624] ; Youth Innovation Promotion Association of Chinese Academy of Sciences Foundation[CMS-CSST-2021-A08] ; China Manned Space Project[2021YFA1600403, 2021YFA1600400] ; National Key Ramp ; D Program of China[202302AN360001] ; International Centre of Supernovae, Yunnan Key Laboratory
语种	英语
学科领域	天文学
文章类型	Article
出版者	EDP SCIENCES S A
出版地	17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE
ISSN	0004-6361
URL	查看原文
WOS记录号	WOS:001096229100007
WOS研究方向	Astronomy & Astrophysics
WOS类目	Astronomy & Astrophysics
关键词[WOS]	HORIZONTAL-BRANCH STARS ; STELLAR POPULATION SYNTHESIS ; SPACE-TELESCOPE OBSERVATIONS ; SUBDWARF-B-STARS ; MAIN-SEQUENCE ; SPECTROSCOPIC BINARIES ; CLOSE BINARIES ; CORE ; SEARCH ; I.
EI入藏号	20234615061568
EI主题词	Stars
EI分类号	657.2 Extraterrestrial Physics and Stellar Phenomena - 723.1.1 Computer Programming Languages
引用统计	被引频次：1[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
版本	出版稿
条目标识符	http://ir.ynao.ac.cn/handle/114a53/26517
专题	大样本恒星演化研究组中国科学院天体结构与演化重点实验室
作者单位	1.Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming 650216, PR China; 2.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming 650216, PR China; 3.University of Chinese Academy of Sciences, Beijing 100049, PR China; 4.International Centre of Supernovae, Yunnan Key Laboratory, Kunming 650216, PR China
第一作者单位	中国科学院云南天文台
推荐引用方式 GB/T 7714	Zhang FH,Li LF,Han ZW,et al. Relation between spectral indices and binary fractions in globular clusters[J]. ASTRONOMY & ASTROPHYSICS,2023,679.
APA	张奉辉,李立芳,韩占文,&龚小波.(2023).Relation between spectral indices and binary fractions in globular clusters.ASTRONOMY & ASTROPHYSICS,679.
MLA	张奉辉,et al."Relation between spectral indices and binary fractions in globular clusters".ASTRONOMY & ASTROPHYSICS 679(2023).

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