輔仁大學 太空物理 ( space physics )

第一章 太陽Chapter 1 The Sun

大綱 第 1.1 節 結構與能量

內部構造與能量傳播

第 1.2 節 太陽輻射太陽光與太陽風太陽風暴

太空是什麼

1977 年

Termination Shock

Heliopause

Heliosphere

Bow Shock

Voysger 1 & 2 http://voyager.jpl.nasa.gov/

大氣—地球表面至地表 80公里 太空—地球表面 50公里到太陽系 ( 太陽風終極震

波 )

天文—太陽、恆星、星系以至銀河科學—數學、生物、物理、化學與自然科學科技—電機、機械、土木…等工業技術

太空環境

太空科學

太空旅行 太空科技

更新：航海家 1,2 已接近日磁層頂

太陽的基本資料 年齡：快 50 億歲了 體重： 3.3×105個地球重

大小： 100 個地球半徑

密度： 1.4 g/cm3

重力： 2.7 ×102 m/s2

自轉週期：平均為 27 天

•地球重： 5.97×1027Kg

•地球半徑： 6400 Km

核 心 : 能量的來源 ( 核融合 )0.3R⊙, 1.5×107K

輻射層 : 先吸收再以輻射傳遞0.5R ⊙ , 5.0×105K

對流層 : 利用對流方式傳遞0.2R ⊙ , 6.6×105K

光球層 : 肉眼所看到的部份0.001R ⊙ , 5750K

彩球層 : 最薄的一層10000KM , 4500-500000K

日 冕 : 相當於太陽的大氣層>R ⊙ ,1.5×106K

The source of the Sun’s energy is nuclear fusionProton-proton cycle, four protons merges to one α-particle, the mass difference between the four protons and the α-particle corresponds to an energy of 4.3*10-12J or 26.2 MeV.

The first step: Two protons merge to a deuteron, emitting a positron and a neutrino.

The second step: A proton collides and merges with the deuteron, forming a 3He-nuclei under emission of a γ-quant.

The third step:Two 3He-nuclei collide, they merge to an α-particle, emitting two protons and a γ-quant .

The time scale of the proton-proton cycle basically is by the first step, half of the hydrogen initially present is converted into deuteron within 1010 year.

Although a photon travels with the speed of light, it needs about 100000 years to diffuse from the Sun’s core to its surface.

Wiki

不同波段下的太陽

EIT195 EIT284 EIT3041.5 million 2 million 80,000

MDI EIT1716000 1million

The Sun’s composition:

hydrogen 92% in terms of particle number or 72% in terms of masshelium 8%oxygen 0.06%carbon 0.03%the rest<0.01%.

The Sun radiates as a black body at about 6000 K.

The flux of visible solar energy varies very little and, however, the emissions at shorter wavelengths, the EUV and X-ray, vary by orders of magnitude depending on sunspot number and solar activity.

Differential rotation

Sunspot characteristics:

(i) Low temperature: 3900°K(ii) Intense magnetic field: 200gauss(iii) Pair (iv) Cycle~11.25 years

Wolf Sunspot number (Solar activity index, SSN,R)

Wolf number: R=k(10*g+f)f: number of individual spot g: number of groupk: comparison constant ~1 Solar min R~0 Solar max R~200

R12: 將 12 個月所觀測到的 R 值 ( 太陽黑子數 ) 相加起來除以 12R12=(0.5R-6 +R-5 +R-4 +R-3 +R-2 +R-1 +R0+R1+R2+R3+R4+R5 +0.5R6)/12

The 1st cycle: 1755~1766Now: 24th cycle, 2008.01.04 ~The Maunder Minimum: 1645~1715

不同波段的太陽黑子

近距離觀測太陽黑子

太陽的自轉—差動式自轉

太陽光譜

The solar windThe solar wind is a continuous flow of charged particle.Slow solar wind 250-400 km/s, 8ions/cm3 at 1AU, Streamer belt Strongly overexpending flux tubes.Fast solar wind 400-800 km/s, 3ions/cm3 at 1AU, Coronal hole

太陽活動強度不同之差異

tanθ=rω/Vsw

Solar index, F10.7: 以太陽表面所輻射出來之波長為 10.7cm(2800MHz) 的電磁波強度作為太陽活動強弱的參考。下圖為 F10.7 與太陽黑子數的比較。

The active Sun

Flare A flare is a burst of “light” (easily observed at red Hα

6563A) occurring in the chromosphere near a sunspot. Life time 3 min up to 2 hr.

Hα-flares are ranked in the size (importance, 1-4) and brilliance (f, n, b).

X-ray flares are classified by power flux level of 1-8A (C, M, X).

Radio burst Radio bursts are generally associated with flares

and originate from all levels of the solar atmosphere.

Class Peak (W/m2)between 1 and 8 Angstroms

 B  I < 10-6  C  10-6 < = I < 10-5  M  10-5 < = I < 10-4  X  I > = 10-4

•X-RAY FLARE的強度區分如下表所示：

太陽黑子爆炸

太陽閃焰

日冕物質拋射

日冕物質拋射

太陽閃焰與日冕物質拋射

Exclusive views of Comet 96P/Machholz swinging past the Sun

Comet Hyakutake