2015恒星結(jié)構(gòu)與演化2020

1、恒星結(jié)構(gòu)與演化(2020.2-2020.6)第2部分 恒星物理羅新煉仙林校區(qū)天文樓521房間： xlluo89685982狀態(tài)方程輻射傳能第2部分 恒星物理對(duì)流傳能核過程恒星內(nèi)部核過程參見 Kippenhahns book page 146-1723恒星內(nèi)部的中微子過程恒星內(nèi)部主要的核反應(yīng)電荷效應(yīng)對(duì)核反應(yīng)的影響熱核反應(yīng)率核反應(yīng)截面預(yù)備知識(shí)在天體物理的環(huán)境中,參與核反應(yīng)的原子核幾乎是完全電離的(等離子體)。除了核子之間的庫(kù)侖排斥外,如果所處環(huán)境的密度很高,周圍電子氣體的分布,會(huì)使得反應(yīng)的核子間庫(kù)侖排斥有所降低.從而使得相對(duì) 核的反應(yīng),核反應(yīng)率將有所提高.電子ECoulomb potential效

2、應(yīng).V (r) =+Ecoul Z1Z2 (MeV)Ekin kT(keV)核的庫(kù)侖勢(shì)(排斥)通常人們引入電荷勢(shì)0(吸引) ?因子fjk.rr0nuclear well 30 MeVShielding potential4v ×s (v)= fv ×s (v)screenedjkbaretunneleffectUe (r)Z Z e2 12rElectron Shielding (or Electron screening)留意前面略過的計(jì)算了除電荷自身以外系統(tǒng)內(nèi)部其它所有電荷在它所在位置處產(chǎn)生的電勢(shì)。1. 高溫, 低密情況(Weak Screening)kTn <&

3、lt; ()3離子間庫(kù)侖能<< 熱運(yùn)動(dòng)能量的氫燃燒。要求滿足條件zZ 2e2典型的天體環(huán)境: 如恒星5具體考查了兩種極限情況。 1. 高溫低密情況2. 零溫電離氣體實(shí)際電離氣體(EOS)課后完成 6課后完成 polarized by the charge of the ion通常引入ö1/ 2E / keV æT» 2000ç7÷rD / rc0è z × r / g cm-3Z Zøjk來其中電荷效應(yīng)的強(qiáng)弱.r= Z Z e2 Ec0jk0帶入正常恒星中心的參數(shù),發(fā)現(xiàn)rD / rc0>>1

4、,效應(yīng)很弱E效應(yīng)使得核子間庫(kù)侖相Coulomb potential互作用降低，相對(duì)核而言，Ecoul Z1Z2 (MeV)等效于的核子熱運(yùn)動(dòng)能量增Ekin kT(keV)tunnel effect加ETo first order0Dr0Shielding potentialE = E + (V-V) » E +rccbarnuclear well 30 MeV代入7describe a corrected Coulomb barrierfor the astrophysical environment.¥v ×s (v) = ò0 v ×s (

5、E) f (E)dEZ Z e2 rjkD課后完成效應(yīng)的因子(screening factor), fjk可得電荷，ED / k T << 1。This case applies to stellar densities適用條件，弱< 104 g cm3.， ED / k T1對(duì)于強(qiáng)e 為電子的平均量。-1m = éå X A / Z ùêiii úeë iû整體趨勢(shì)：低溫高密度時(shí)，效應(yīng)越來越重要。8Eéù æ r / g cm-3 ö1/ 3D» 0.02

6、05 (Z + Z )5 / 3 - Z 5/3 - Z 5/3T -1kTêëjkjkúû çm÷7èeøEZ Z e21/ 2 D =jk= 5.92´10-3 Z Z (z × r / g cm-3 ) T -3/2kTr ´ kTjk7Df jk = exp(ED / kT )z = å Zi (Zi +1) XAiii課后完成pycnonuclear reactions密度敏感溫度敏感Thermal nuclear reactionsThe shielding fa

7、ctor for two protons as a function of temperatureFor sufficiently large densities and low temperatures, 9考慮電荷效應(yīng)后的產(chǎn)能率<sv >screened = f jk引入冪率關(guān)系<sv >bare其中n = t - 2 - EDl = 1+ 1 ED3 kTlg T9.033kTt = 19.721×W×T-1/ 31/ 3Thermal nuclear7mjmkW = m=2 Z 22 Z 2ZZjkjkm + mjk8.5jkED()1/ 2

8、= 5.92´ Z Zz × r / g cm-3/ 23Tjk7kT致密物質(zhì)核反應(yīng)在極晚期演化中起作用.0510lg10A line of constant energy generation rate for 12C +12C burning.請(qǐng)推導(dǎo).e = e rlTn0v ×s (v)µt 2e-t baref jk = exp(ED / kT )e= rjk ×r X × X× v ×s (v)jkrjk1+ dm mjkscreenedjkjk天文中常用到的形式留意11Density and tempe

9、rature exponents12重要的輔助方程恒星內(nèi)部核過程參見 Kippenhahns13恒星內(nèi)部的中微子恒星內(nèi)部主要的核反應(yīng)到此也差不多夠了電荷效應(yīng)對(duì)核反應(yīng)的影響e = e rlTn0熱核反應(yīng)率核反應(yīng)截面選做習(xí)題:類似電荷效應(yīng)討論,給出共振反應(yīng)的產(chǎn)能率表達(dá)式.預(yù)備知識(shí)1415系恒星主要形成于旋臂上巨大的、冷的致密星際云。的坍縮造成恒星成群形成。恒星形成基本過程：、加熱 原恒星 主序星坍縮、按照virial定理當(dāng)天體自引力收縮時(shí),自引力做功,自引力能的一部分增加系統(tǒng)的內(nèi)能（升溫），另一部分則輻射出去了.16恒星內(nèi)部主要的核反應(yīng)若時(shí)間在各個(gè)演化階段在穿插細(xì)致的核過程else碳燃燒氦燃燒氫燃

10、燒恒星內(nèi)部主要的核反應(yīng)main sequence (MS) phasethe longest phase of stellar evolution, spend 8590% of their nuclear life. (He-burning 1015%, the further stages up to the supernova only 103)Why longest?Produces more nuclear energy per nucleonLess luminous than in later phasesConvective cores, when present, are l

11、arger than in later phases, thus the nuclear reservoirs are larger.氫燃燒 (T > 8106 K)氫燃燒等效為4 1H 4He + EE(4mHmHe) c2(4×1.67×10-246.644×10-24) × c2 26.731 MeV = 4×10-5 erg燃燒效率 0.7 %26.73 Mev230%太陽內(nèi)部每秒都有7750 萬噸的氫在這種過程中轉(zhuǎn)化為氦。氫燃燒 (T > 8106 K)21(2) 碳氮氧循環(huán) (CNO cycle)分界1.1 (1.5)

12、M(1) 質(zhì)子-質(zhì)子鏈 (p-p chain)恒星內(nèi)部氫燃燒的兩種主要的方式如何估算？The three branches of the PP chain.名字由來Main branch PP-I of the proton proton chain.T > 1.4 ´ 107 kT > 2.3 ´ 107 k(1) 質(zhì)子-質(zhì)子鏈 (proton-proton chain)Weak interactionslowest reaction2%4%28%1016 sThe pp chains, with energies and timescales.23(1) 質(zhì)

13、子-質(zhì)子鏈 (proton-proton chain)2He is unstablep + p¾¾®2HeStep 1:Step 2:d + d ¾ ®4Hed abundance is too low3He + p¾ ®4Li3He + d ¾ ®4He + n4Li is unstableStep 3:243He+3He¾ ®4He + 2 pd + p¾ ®3Hep + p ¾ ® d + e+ + veppI原初核。d + d ¾

14、; ®4He25查對(duì)比由第一和第二步核反應(yīng)來命名 1H + 1H 2H +e 2H + 1H 3He +decay,弱相互作用.反應(yīng)率非常低.(bottle neck) 3He到4He可以由不同的方式來完成.26 Why not 2H + 2H 4He ? (2H abundanceis too low)p-p I Why not 1H + 1H 2He ? (2He is unstable)e+ Why does nature use a long complicated chain reaction process to fuse four protons into one he

15、lium nucleus?(1) 質(zhì)子-質(zhì)子鏈 (proton-proton chain) pp13He + 3He 4He + 21H3He + 4He 7Be +如果存在4He pp2 pp37Be + e- 7Li +7Li + 1H 4He + 4Hee7Be +1H 8B +8B 8Be +e+ +e8Be 4He + 4HeTemperature Range (107 K)1 2.33.0Energy release without neutrino26.2025.6719.20ProcessE(MeV)totpp1pp2 pp326.7426.7426.73 W

16、ith increasing T, pp2 and pp3 will dominate more andmore over pp127pp鏈氫燃燒的產(chǎn)能率1 / 3e= 2.38´106y fg r X T-2-2 / 333.80 /Te6pp1111H6g= 1+ 0.0123×T1/3 + 0.0109 ×T 2/3 + 0.0009 ×T11666其中f11為因子,表示, pp2 , pp3對(duì)產(chǎn)能率的修正.的數(shù)值在1到2之間,與化學(xué)成分,溫度有關(guān).28不必在意29pp neutrino<E> = 0.27 MeV14%2%CNO cy

17、cle84%7Be neutrino8BneutrinoE=0.39,0.86 MeV<E>=6.74 MeV1 eV =energy of an electron passing through one volt of potential.=1.602 ´ 10-19 J.30思考：如何計(jì)算分支比？太陽內(nèi)部. 太陽中微子的譜Water7Be+e-à7Li+可研究太陽的物理性質(zhì).31CNO循環(huán)名字的由來，32(2) 碳氮氧循環(huán) (CNO cycle)T = 2.5107 KslowestCoulomb barriers and S-factors33(2) 碳氮

18、氧循環(huán) (CNO cycle)initially恒星內(nèi)部氫燃燒的另一種主要方式. (24.97 MeV 扣除中微子后)T 2×10 7 K, M 1.1 M碳氮氧起到催化劑的作用?CN cycle 12C + 1H 13N + 13N 13C + e+e 13C + 1H 14N + 15O 15N + e+e 15N + 1H 12C + 4Hemain cycle 16O +Secondary cycle (10-4 )bottle neck343414N + 1H 15O +(2) 碳氮氧循環(huán) (CNO cycle)cycle limited by b decay of 13N

19、 (t 10 min) and 15O (t 2 min) ？(e+n)(p,g)(p,g)(e+n)(p,a)The CN cycle in the atomic weightenergy plane.35(p,g)3637真實(shí)過程復(fù)雜得多恒星內(nèi)部碳氮氧循環(huán)要比CN循環(huán)遠(yuǎn)遠(yuǎn)來得復(fù)雜.CN cycle (99.9%)O Extension 1 (0.1%)O Extension 2O Extension 3O(8)N(7)C(6)3456789NO cycle16O + 1H ® 17F + gneutron number17F ® 17O + e+ n17O + 1H &

20、#174; (18F) -® 14N+ 4He¯ ® 18F + g38請(qǐng)留意:novae, X-ray bursts(T > 8×10 7 K)環(huán)境中的高溫碳氮氧循環(huán)反應(yīng).Ne(10)F(9)許多不同形式CNO循環(huán)的產(chǎn)能率1 / 3e= 8.67 ´1027 gr X2 / 3-152.28 /TXTe6CNO14,1CNOH6=1+ 0.0027×T1/3 - 0.00778×T 2/3 - 0.000149×Tg14,1666其中XCNO為碳氮氧三種核素的質(zhì)量豐度之和.20 M starTypical

21、CNO abundance ratios (inmass fractions) overall rate of CNO-cycle determinedreaction apart from 4He, 14N is the major product of the CNO-cycleby the 14N(p, )15O39不必在意假想(conversion of all hydrogen to helium)0.9950.005 apart from4He, 14N is the major product of the CNO-cycle40宇宙中絕大部分14N產(chǎn)生于CNO循環(huán)質(zhì)子-質(zhì)子鏈與

22、碳氮氧循環(huán)核反應(yīng)的比較恒星內(nèi)部的核反應(yīng)速率對(duì)溫度十分敏感，因庫(kù)侖位壘的關(guān)系CNO循環(huán)需要更高溫。41ppX12T41.1(1.5) M T6 > 17CNOX1 X14 T18nthe log of the rates of nuclear energy as a function of T in different stars on the ZAMS and for the present Sun.the exponent as a function of T42選做習(xí)題: 選其中任何一種特殊天體環(huán)境中的氫燃燒過程做簡(jiǎn)單的調(diào)研報(bào)告. NeNa and MgAl Cycles, rp-p

23、rocess .43else碳燃燒氦燃燒氫燃燒恒星內(nèi)部主要的核反應(yīng)宇宙中主要的C，O來源To build elements heavier than 4He, it would seem normal to first consider proton or captures by helium nuclei; however the absence of stable nuclei of atomic mass A = 5 and 8 makes this kind of building problematic.Nothing was supposed to halt the collaps

24、e at the end of H burning until supernova explosion intervenes at T > 109 K氦燃燒(Helium Burning)Saha like equilibriumX (8Be) 1.4×108 at T = 108 KSalpeter:Saha equationsacapture12CHoyle showed that the triple- reaction would not be fast enough at T = 2×108 K to account for all the C, O and

25、 Ne observed in the Universe without a resonance of the reaction 8Be(, )12C, which was effectively found subsequently.共振MeV0.29 MeV45不必在意細(xì)節(jié)氦燃燒(Helium Burning) He燃燒 (3反應(yīng) the triple alpha reaction)T 10 8 K3 4He 12C + 4He + 4He 8Be(Q = - 92.1 keV) 8Be + 4He 12C* (- 286 keV) 12C +(Q = 7.66 MeV)Q = 7.27

26、MeV隨著溫度增加1) 4He + 4He 反應(yīng)率增加Þ 8Be 豐度增加;2) 8Be + 4He 反應(yīng)率增加Þ 12C豐度增加C12的某共振能級(jí)46 在高溫高密度環(huán)境下8Be 再俘獲一個(gè)a粒子形成12C. 8Be 的10-16 s 衰變時(shí)標(biāo)仍然比其與 粒子的某種非共振方式散射時(shí)標(biāo)高出5個(gè)量級(jí). 8Be 是一個(gè)極不穩(wěn)定的核素,在10-16 s 內(nèi)衰變?yōu)閮蓚€(gè)a粒子.氦燃燒(Helium Burning) 問：為何原初核無3反應(yīng)? builds up small equilibrium concentration of 8Bereaction rate is uncertai

27、n affects final C/O ratio becomes possible at T 108K due to a resonance in12C(predicted by Fred Hoyle in1954) net effect3 4He 12C + (Q = 7.275 MeV)(Q = 7.126 MeV)4712C + 16O + 氦燃燒階段, 還得考慮其它a粒子俘獲反應(yīng):3 a® ¹2 C + gscreening factorC + a ® 16O + g¹2efr X3-3-= 5.09´1011244.027 /TTe

28、83a3aa816O + a ® 20Ne + g2æö1+ 0.134 ×T2 / 3以及效率更低的20Ne + a ® 24Mg + g24Mg + a ® 28Si + g1 / 3e= 1.3´1027 fr XX T-2-69.20 /T8eç÷812,a12,a12a 81+ 0.01×T 2/3èø81/ 3e=fr XX 1.82´10 Te27-2 / 3 -85.65/T816,a16,a16a8+ 9.22´1019 T -3/ 2e

29、-103.59 /T8 8Y 為4He 質(zhì)量豐度48產(chǎn)能率公式參見Kippenhahn書不必在意495051溫度逐升到108 K，3-alpha反一旦應(yīng)可以進(jìn)行，恒星由紅巨星進(jìn)入另一個(gè)演化階段.Helium flashhorizontal branch5253HR diagram showing the location of the carbon stars. These are stars inside which the s-process operates. The process responsible for the synthesis may also bring the fre

30、shly synthesized elements to the surface of the star, so that they can be observed. The s-process elements thus observed where not synthesized in a previous generation of stars氦燃燒場(chǎng)所？54細(xì)節(jié)暫不討論具體參見：第五章AGB 演化55細(xì)節(jié)暫不討論課后請(qǐng)閱讀else碳燃燒氦燃燒氫燃燒恒星內(nèi)部主要的核反應(yīng)58M > 8 MM >12M59Evolution of the central T and r cond

31、itions60碳燃燒(Carbon Burning)T 6×10 8 K12C +12C 24Mg + 23Na + p 20Ne + 4He 23Mg + n 16O + 2 4He(Q = 13.931 MeV)(Q = 2.238 MeV) 50 % (Q = 4.616 MeV) 50 % (Q = -2.605 MeV)(Q = -0.114 MeV)61產(chǎn)能率公式參見Kippenhahn書dominates碳燃燒(Carbon Burning)T 5×108 K r 3×106 g cm3光之裂解20Ne + 16O + 4He(Q = -4.7 M

32、eV)產(chǎn)生的a粒子20Ne +4He 24Mg +(Q = 9. 3 MeV)62氖燃燒(Neon Burning)T 109 K16O + 16O 32S + 31P + p 28Si + 4He 31S + n 24Mg + 2 4He(Q = 16.541 MeV) (Q = 7.677 MeV) (Q = 9.593 MeV) (Q = 1.453 MeV) (Q = -0.393 MeV)6312C/16O BURNING12C ashes = Ne, Na, Mg16O ashes = Al, Simajor ash 28SiSUPER RED-GIANT STARS氧燃燒(Oxy

33、gen Burning)T 1.5×10 9 KT 2109 KT 1.5×10 9 K28Si + 28Si 56Ni +56Ni 56Fe + 2e+major ash = 56Fe+ 2e64硅燃燒(Silicon Burning)T 3109 K當(dāng)恒星內(nèi)部形成Fe后，由于Fe的聚變反應(yīng)吸熱而不是放熱，恒星內(nèi)部的熱核反應(yīng)至此停止。High ( > 812 M)Mass Starsonion模型Ne Photodisintegration66The onion skin structure of a massive star with 25 M67Structur

34、e and evolution of a 25M star of solar mlicity, as predicted by one-dimensional, spherically symmetric ms8平穩(wěn)燃燒for T > 4109 K almost nuclear statistical equilibrium (NSE) may bereachedPre-SupernovaSuper Giant 3x104 yO, Ne Red Giant 3x108 yMain Sequence 1010 yCHeHfinal compositionmay be mostly56FeG

35、ravitational Contractionbecause p/n < 1 (due to -decays and e- captures)>photodisintegrations69補(bǔ)充The main parameters in the advancedevolution of a 15Mstar.Physics Formation and Evolution of Rotating Stars70photonsneutrino emission1. 宇宙元素豐度注意,在此提到的僅僅是重子物質(zhì),沒有涉及暗物質(zhì),暗能量.71元素粒子數(shù)相對(duì)豐度（%）H（1個(gè)核子）90He（4

36、個(gè)核子）9Li族（7.1個(gè)核子）0.000001C族（12個(gè)核子）0.2Si族（23.8個(gè)核子）0.01Fe族（50.2個(gè)核子）0.01中等質(zhì)量元素（63個(gè)核子）0.00000001重元素（>100個(gè)核子）0.000000001恒星演化與元素宇宙元素豐度宇宙中的各種元素是如何形成的？72在星際介質(zhì)中高能宇宙射線一代又一代恒星演化、不斷地累積的結(jié)果。原初核。2. 原初元素H, He和少量的Li, B, Be，形成于宇宙大爆炸初期。3. 恒星內(nèi)部的核(nuclear synthesis)73問： 14N 在哪形成？燃燒過程產(chǎn)物溫度(K)最小質(zhì)量(M )H燃燒He2×1070.1He

37、燃燒C, O2×1081C燃燒O, Ne, Na,Mg8×1081.4Ne燃燒O, Mg1.5×1095O燃燒Mg-S2.0×10910Si燃燒Fe峰元素3.0×10920比Fe 峰元素更重元素的形成中子俘獲反應(yīng)(Z, A) + n (Z, A+1) +衰變：(Z, A+1) (Z+1, A+1) + e- +ne2) 快過程 (r-process)1) 慢過程(s-process)中子俘獲過程比衰變快中子俘獲過程比發(fā)生在恒星內(nèi)部，衰變慢發(fā)生在超爆發(fā)，形成 251Cf（锎）元素。形成 209Bi（鉍）元素。一代又一代恒星演化的結(jié)果。74講義第1

38、2章內(nèi)容.見彭75查ZN76重元素77Schematic representation (mass versus time) of a low- or intermediate-mass (M 9 M), thermally pulsing AGB star.7880Stellar sitesNuclear processesBig Bang (primordial nucleosynthesis)Reactions between the lightest elements p, d, He, Be, LiHydrogen burningproton-proton chain, CNO cy

39、cle,Ne-Na cycle, Mg-Al cycleMain sequence(ex. Sun)Helium burning3a-process, 12C(a,g)16OOther (a,g) and (a, n) reactionsRed giant stars, stars of the Asymptotic branchSuper giant stars, Wolf-Rayet stars and Pre-supernovaeAdvance burning stages Reactions of C, O, N, Ne, SiExplosive burning Hot CNO cyc

40、leRapid proton capture (rp process)Novae, supernovae,X-ray burstsAGB stars, supernovae II, Neutrons starsNucleosynthesis beyond iron Slow neutron capture (s-process) Rapid neutron capture (r-process)photodisintegration and proton capture (p-process)81Ø hot burning in massive AGB stars (> 4 M

41、)(T9 0.08)Ø nova explosions on accreting white dwarfs(T9 0.4)Ø X-ray bursts on accreting neutron stars(T9 2)Ø accretion disks around low mass black holesØ neutrino driven wind in core collapse supernovaeØ neutron star mergers請(qǐng)留意特殊天體環(huán)境下的氫燃燒過程.(溫度,密度與通常恒星內(nèi)部很不一樣)A schematic dia

42、gram showing the principal products of the collision of a high energy proton with a nucleus.請(qǐng)留意特殊天體環(huán)境下的氫燃燒過程.(溫度,密度與通常恒星內(nèi)部很不一樣)Schematic of the thermonuclear flashmof an X-ray burstTheoretical mof an X-ray burst and its evolution with time.87問題：形成的proton-rich 核素如何脫離中子星表面？88需要Nuclear data:Masses (pro

43、ton separation energies)-decay ratesReaction rates (p, n -capture and ,p)Nucleosynthesis is a gradual, still ongoing process:H, He, LiStar FormationBig Bangcontineous enrichment, increasingEjection of envelope into ISMLife of astarmlicityDeath of a star (Supernova, planetary nebula)Remnants(WD,NS,BH

44、)BH: Black Hole NS: Neutron StarWD: White Dwarf StarISM Interstellar Medium星系化學(xué)演化Nucleosynthesis !Nucleosynthesis !Illustration of the two principal stages of the formation of the elements showing how the first- generation stars contained only the light elements from the Big Bang, while second-gener

45、ation stars contain the heavier elements from the supernovae explosions.90 No CNO cycles working initially. Only the pp chains are present opacities are generally lower, which makes a larger outgoing luminosity and a smaller radius, lower mass and angular momentum losses. Without CO molecules to pro

46、vide cooling, the clouds that formed the first stars had to be considerably warmer than todays molecular clouds The first stars must therefore have been more massive than most of todays stars, for gravity to overcome pressureBIRTHgravitationalcontractionInterstellar gasStarsexplosionejectionDEATHmix

47、ing of interstellar gasthermonuclearreactionsabundance distribution energy production stability against collapse synthesis of “ms”9192Giant molecular cloudsHomework:(選做)請(qǐng)登陸, 任選其中一個(gè)核反應(yīng)網(wǎng)絡(luò)進(jìn)行計(jì)算,分析計(jì)算結(jié)果并做出相關(guān)圖形.93Homework:(選做)請(qǐng)登陸, 對(duì)星系化學(xué)演化進(jìn)行試算,并大致說明星系化學(xué)演化以及這個(gè)程序編寫的基本思路,如果你來做,會(huì)做哪些改進(jìn)?2.7 Neutron capture reacti

48、ons949596恒星內(nèi)部核過程參見 Kippenhahns book page 146-17297恒星內(nèi)部的中微子過程恒星內(nèi)部主要的核反應(yīng)電荷效應(yīng)對(duì)核反應(yīng)的影響熱核反應(yīng)率核反應(yīng)截面預(yù)備知識(shí)估算中微子的平均自由程 For “normal” stellar matter with r »1 g cm-3,ln » 1020cm » 100 pc » 1.4´109 R For r » 106 g cm-3, one hasln » 3000 R For r » 1014 g cm-3,one hasln »

49、 20 kmDuring the H- and He-burning phases, the energy goes out from the stars in the form of electromagnetic radiation. In later phases including supernova explosions, most of the energy goes out in the form of neutrinos and we also examine here these processes of energy losses.JPress, 1989-process

50、, WoosleyJ., Vol. 356, p. 272, 1990., Astrophys.99此節(jié)內(nèi)容參見Kippenhahn的P169-172頁(yè)內(nèi)容?；?“Physics Formation and Evolution. N. Bahcall, Neutrino Astrophysics, Cambridge: Cambridge University恒星內(nèi)部的中微子過程有的同學(xué)補(bǔ)充整理Star is transparent to neutrinosThe star, once driven by photon losses, is now driven by neutrino los

51、ses.The time scale of evolution shortensdramaticallyto becombefore thNeutrino luminosity and photonluminosity in a 15Mstar as asupernovfunction of the central temperature in 109 K. Above 0.5 × 109 K, the neutrino luminosity takes over and controls the evolution of the starexplosio100a few hourserg g-1s-1A comparison between the neutrino losses and various nuclear energygeneration reactions according to Hayashi. (1962).101Plasma NeutrinoPhotoneutrinoPair AnnihilationThe core cools fast, while the envelope, still dominated by photons, hardly notices what