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Relation between spectral indices and binary fractions in globular clusters

文献类型：期刊论文

作者Zhang FH(张奉辉)1,3,4; Li LF(李立芳)1,3,4; Han ZW(韩占文)1,3,4; Gong XB(龚小波)1,2,3,4
刊名ASTRONOMY & ASTROPHYSICS
出版日期2023-10-30
卷号679
关键词binaries: general globular clusters: general stars: formation galaxies: stellar content galaxies: formation galaxies: fundamental parameters
ISSN号0004-6361
DOI10.1051/0004-6361/202245212
产权排序第1完成单位
文献子类Article
英文摘要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.
学科主题天文学
URL标识查看原文
出版地17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE
WOS关键词HORIZONTAL-BRANCH STARS ; STELLAR POPULATION SYNTHESIS ; SPACE-TELESCOPE OBSERVATIONS ; SUBDWARF-B-STARS ; MAIN-SEQUENCE ; SPECTROSCOPIC BINARIES ; CLOSE BINARIES ; CORE ; SEARCH ; I.
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
WOS研究方向Astronomy & Astrophysics
语种英语
WOS记录号WOS:001096229100007
出版者EDP SCIENCES S A
资助机构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
版本出版稿
源URL[http://ir.ynao.ac.cn/handle/114a53/26517]  
专题云南天文台_大样本恒星演化研究组
云南天文台_中国科学院天体结构与演化重点实验室
作者单位1.International Centre of Supernovae, Yunnan Key Laboratory, Kunming 650216, PR China
2.University of Chinese Academy of Sciences, Beijing 100049, PR China;
3.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming 650216, PR China;
4.Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming 650216, PR China;
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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