-
转动是影响恒星结构和演化的一个非常重要的物理因素。本文根据零金属丰度恒星演化模型，研究了转动如何影响第一代（星族III）大质量恒星中心氢和氦燃烧阶段的演化。结果发现转动在此阶段演化过程中最主要的影响是提高恒星光度并降低表面温度。光度的增加是由于转动混合导致对流核心增大，而表面温度的下降则是由氢燃烧壳层产生的能量驱动的恒星半径膨胀引起的。星族III恒星的子午环流非常弱，剪切湍流较强。因此星族III恒星传输角动量的效率非常低而混合化学元素的效率较高。转动混合可促进氮元素的表面增丰，然而，在氦燃烧初期，转动混合可能因其引发的能量产生机制变化和恒星结构变化而抑制该过程。转动混合（剪切湍流）作用将包层的氢燃料带入燃烧的核心，扩大核心区尺寸从而提升产能率并延长其主序寿命，最终导致恒星光度增强。在氦燃烧阶段氢燃烧壳层会影响氦核的大小和燃烧强度。氦核的增长会反过来也影响氢燃烧壳层的尺寸和燃烧强度。因而，转动对星族III恒星的演化产生至关重要的影响。We investigate the effects of rotation on the evolution of Population III (Pop III) stars at the stage of core H and He burning. Due to their zero-metallicity nature, these stars are initially unable to burn hydrogen through the CNO cycle. And without this crucial energy supply, they experience a contraction phase during the early main sequence(MS). The lack of CNO elements not only affects the central regions of the star but also leads to energy increase (due to triggering of the CNO cycle) in the stellar envelope due to the outward diffusion of He-burning products. Therefore, rotational mixing has a unique impact on these stars.
· Rotation significantly affects the observable properties of Pop III stars through two main effects. Firstly, rotational mixing brings additional fuel into the nuclear burning core, which increases the luminosity as well as the stellar lifetimes. Secondly, rotational mixing brings He-burning products from the core to the H-burning shell during later evolutionary phases. This changes the temperature profile, and can lead to significant expansion in some models depending on the relative core size. The relative core size is crucial here, because the contribution of the shell and the core to the total energy produced tells us about the structure of the star and what dominates with regard to the evolution of the surface properties. · Despite weaker meridional currents in Pop III stars, angular momentum can accumulate at the surface in fast-rotating massive models because of their negligible mass loss through radiative winds. This spin-up brings models with an initial mass of 40M⊙, initial velocity of υini=400km/s and metallicity of Z=10-4 to critical rotation during the MS which leads to increased mass loss.
· Rotational mixing strongly affects metal enrichment, but does not consistently enhance metal production, different from stars with high metallicity. Rotation leads to an earlier CNO boost to the H shell during He burning, which may hinder metal enrichment. This is true for the core He-burning phase. In these cases the triggering of convection by the CNO boost in the H shell causes a retraction of the He-burning core. As the core grows, the H shell moves outwards faster than the He-burning products can be expelled from the core through rotational mixing, therefore hindering the interaction of these products with the H-burning shell, which is required for metal enrichment. H-He shell interactions after core He burning play a crucial role in metal production, where rotation may enhance enrichment. This highlights the complexity in the metal enrichment processes of these models. A detailed understanding of the interior structure is therefore required to accurately predict metal yields.-
Keywords:
- Stellar Structure and Evolution /
- Rotation /
- Pop III /
- Metallicity
-
[1] Savage B D, Sembach K R 1996 Annu. Rev. Astron. Astrophys. 34 279
[2] Draine B T 2003 Annu. Rev. Astron. Astrophys. 41 241
[3] Jenkins E B 2009 Astrophys. J. 700 1299
[4] Meynet G, Georgy C, Hirschi R, Maeder A, Massey P, Przybilla N, Nieva M F 2011 Bull. R. Soc. Sci. Liège. 80 266
[5] Cui Z, Wang Z J, Zhu C H 2018 Publ. Astron. Soc. Pac. 130 084202
[6] Peng W G, Song H F, Zhan Q, Wu X H, Jing J H 2019 Acta Phys. Sin. 68 219701 (in Chinese)[彭卫国，宋汉锋，詹琼，吴兴华，景江红 2019 物理学报68 219701]
[7] Wu F W, Song H F, Li Q L, He Y, Qu X Y, Han Z 2024 Chin. Phys. Lett. 41 089701
[8] Marigo P, Chiosi C, Kudritzki R P 2003 Astron. Astrophys. 399 617
[9] Marigo P, Girardi L, Chiosi C, Wood P R 2001 Astron. Astrophys. 371 152
[10] Ekström S, Meynet G, Chiappini C, Hirschi R, Maeder A 2008 Astron. Astrophys. 489 685
[11] Yoon S C, Dierks A, Langer N 2012 Astron. Astrophys. 542 A113
[12] Ekström S, Georgy C, Eggenberger P, Meynet G, Mowlavi N, Wyttenbach A, Granada A, Decressin T, Hirschi R, Frischknecht U,Charbonnel C, Maeder A 2012 Astron. Astrophys. 537 A146
[13] Georgy C, Ekström S, Eggenberger P, Meynet G, Haemmerlé L, Maeder A, Granada A, Groh J H, Hirschi R, Mowlavi N, Yusof N, Charbonnel C, Decressin T, Barblan F 2013 Astron. Astrophys. 558 A103
[14] Groh J H, Ekström S, Georgy C, Meynet G, Choplin A, Eggenberger P, Hirschi R, Maeder A, Murphy L J, Boian I, Farrell E J 2019 Astron. Astrophys. 627 A24
[15] Bromm V, Kudritzki R P, Loeb A 2001 Astrophys. J. 552 464
[16] Abel T, Bryan G L, Norman M L 2002 Sci. 295 93
[17] Heger A, Woosley S E 2002 Astrophys. J. 567 532
[18] Brott I, de Mink S E, Cantiello M, Langer N, de Koter A, Evans C J, Hunter I, Trundle C, Vink J S 2011 Astron. Astrophys. 530 A115
[19] Stacy A, Bromm V, Loeb A 2011 Mon. Not. R. Astron. Soc. 413 543
[20] Stacy A, Greif T H, Klessen R S, Bromm V, Loeb A 2013 Mon. Not. R. Astron. Soc. 431 1470
[21] Hirano S, Bromm V 2018 Mon. Not. R. Astron. Soc. 476 3964
[22] Murphy L J, Groh J H, Ekström S, Meynet G, Pezzotti C, Georgy C, Choplin A, Eggenberger P, Farrell E, Haemmerlé L, Hirschi R, Maeder A, Martinet S 2021 Mon. Not. R. Astron. Soc. 501 2745
[23] Sibony Y, Liu B, Simmonds C, Meynet G, Bromm V 2022 Astron. Astrophys. 666 A199
[24] Aryan A, Pandey S B, Gupta R, Ror A K 2023 Mon. Not. R. Astron. Soc. 521 L17
[25] Tsiatsiou S, Sibony Y, Nandal D, Sciarini L, Hirai Y, Ekström S, Farrell E, Murphy L, Choplin A, Hirschi R, Chiappini C, Liu B, Bromm V, Groh J, Meynet G 2024 Astron. Astrophys. 687 A307
[26] Zahn J P 1992 Astron. Astrophys. 265 115
[27] Maeder A, Zahn J P 1998 Astron. Astrophys. 334 1000
[28] Kippenhahn R, Thomas H C 1969 Mitt. Astron. Ges. 27 168
[29] Maeder A, Meynet G 2004 Proceedings of IAU Symposium Cancun, Yucatan, Mexico, November 11-15, 2002 p500
[30] Kaehler H 1986 Astron. Astrophys. 157 329
[31] Maeder A, Meynet G 2012 Reviews of Modern Physics. 84 25
[32] Heger A, Langer N, Woosley S E 2000 Astrophys. J. 528 368
[33] Maeder A 1995 Astron. Astrophys. 299 84
[34] Maeder A 1997 Astron. Astrophys. 321 134
[35] Vink J S, de Koter A, Lamers H J G L M 2001 Astron. Astrophys. 369 574
[36] lglesias C A, Rogers F J 1996 Astrophys. J. 464 943
[37] Ferguson J W, Alexander D R, Allard F, Hauschildt P H 2001 Astrophys. J. 557 798
[38] Asplund M, Grevesse N, Sauval A J 2005 in Astronomical Society of the Pacific Conference Series Austin, Texas, June17-19, 2004 p25
计量
- 文章访问数: 27
- PDF下载量: 2
- 被引次数: 0
下载:
