---
# System prepended metadata

title: Sun
tags: [' ss', ' ncu', Intro to Space and Engineering]

---

---
tags: Intro to Space and Engineering, ss, ncu
author: No-Ball
GA: UA-208228992-1
---

[TOC]

Sun
====

## Multi-waylength Observation
![](https://i.imgur.com/svO2V8L.jpg)
- None of them are real color( Color is added afterwords)
- Ultra violate ray's wavelength is too small that ultra violate can't go through the atmosphere, therefore the observations are made in space (Out of the clouds)

## Basic Parameters of Sun

### Age
- 4.5 x $10^9$ years

### Radius
- 695.5 x $10^6$ m 
- 1$R_S$=0.004649 AU 
- **~$10^2$ radii of Earth**

### Mass (MS)
- 1.989 x $10^30$ kg 
- 332 946 masses of Earth
- **~$10^5$ mass of Earth**

### Mean density
- 1.409 g/cm3 
- 0.256 of mean density of Earth
- **~$10^{-1}$ mean density of Earth**

### Effective temperature
- 5770 К
- **6000K**

### Distance from the Earth
- Mean (1 AU)
- 149.6 x $10^6$ km
- **~$10^8$ km**

### Light travel time to the Earth
- 8.32 min
- ~**8 min**

### Sidereal rotation period (Differential Rotation)
- At equator: 25.05 days
- At poles: 34.4 days

### Chemical composition of photosphere (by mass)
- Hydrogen: 73.46%
- Helium: 24.85%

### Magnetic Field Strengths
- Sunspots: 3000 Gauss
    - **~$10^4$ times of Earth**
- Polar field: 1~2 Gauss
    - **~4 times of Earth**
- Prominences: 10~100 Gauss
    - **~30 times of Earth**
- Earth (for comparison): 0.3~0.6 Gauss

### Temperature
- Interior (center)
    - 15 000 000 K 
- Surface (photosphere)
    - 6050 K 
- Sunspot umbra (typical)
    - 4240 K 
- Penumbra (typical)
    - 5680 K 
- Chromosphere
    - 4300 to 50 000 K
- Corona
    - 800 000 to 3 000 000 K
        
# Layers of Sun

![](https://i.imgur.com/Zmoyhtc.png)

## Core

- Temperature ~ $10^7$K
- Pressure ~ $10^{11}$ of Earth
- Nuclear Fusion at Core

### Engery made by Sun (0~0.25 R~s~)
$$
\Delta E = \Delta m \times c^2 \\[1em]
4\ ^1_1 \text H ⟶ \ ^4_2 \text H + 2\  ^0_1 \beta ^+ \\[1em]
_1^2 \text H + _1^3 \text H ⟶_2^4 \text{He}+2\ ^1_0n
$$

- The Energy comes from Nuclear fusion is too small, the sun has to convert $5 \times 10^9$ kg (Over 10^38^ times of collidtion) to stablelize itself shrinking form it's own gravity

### Hydrostatic Equilibrium

![](https://i.imgur.com/oUpCJwq.png)

$$
F_{gravity} = F_{pressure}
$$


### Conditions of Nuclear Fusion
- Temperature
    - 10^7^ K
- Collidtion time
    - \> 10^38^ (Since the direction need chances to be correct)
- Main Process
    - proton-proton chain (PPChain) 90%
        - ![](https://i.imgur.com/HfCGLGA.jpg)
        - 4 ¹H⁺ → ⁴He²⁺ + 2e⁺(Energy) + 2νₑ

    - Carbon-Nitrogen-Oxygen (CNO) cycle 
        - ![](https://i.imgur.com/gJWBDY8.jpg)

## Radiactive Zone (0.25 ~ 7 R~s~)
- Temperture
    - 10^6^ K
- Energy transfer by radiation, which is,  electromagnetic waves, 
- No Nuclear fusion since the pressure is not enough
- $\gamma$ Ray (High Energy Photon)
    - collides with particle matters and been absorbed 
    - 10^6^ years for a Photon to escape Radiative zone
- $v$ neutrino
    - No reaction with any paritcle matters
    - escape with speed of light

## Tachocline (0.7 R~s~)
- Transition zone of radiztive zone and the convection zone
- Shear cut $\rightarrow$ Large scale of magnetic field

## Convection zone (0.7 ~ 1 R~s~)
- Energy conduct by convection
- The plasma is either not dense enough or hot enough to radiate energy
    - temperture decreases alot
    - Differential Rotation (Plasma)

### Differential Rotation
- Sidereal rotation period (Differential Rotation)
    - At equator: 25.05 days
    - At poles: 34.4 days

![](https://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Tachocline.svg/600px-Tachocline.svg.png)

### Helioseismology 
- Test structure by **shock wave from sun itself**
- Observe vibrations from Doppler Effect 

![](https://www.nrl.navy.mil/ssd/sites/www.nrl.navy.mil.ssd/files/images/solarFluxEmergence_0.png)

# Sun's atmosphere

![](https://web.njit.edu/~gary/728/assets/solarTemp.gif)
- The Transition region is between chromosphere and corona
- We can clearly see the Corona heats (Coronal heating)
- Density peek is the transition of the photosphere and chromosphere
## Photosphere (500km)
- Temperture 
    - 5800K
- Visible for human eye
- Sunspots and Granulations

![](https://i.imgur.com/mKV5Iy7.png)

### Granulation
- Size
    - 1500 km
- Lifetime
    - 10 min
- Center rise, around drop
    - proof by doppler effect
    - Convection result

![](https://i.imgur.com/U9k7Fk6.png)

### Sunspots 
- Often comes in groups 
- Strong Magnectic Low Temperture zone
- Temperture 
    - 1000 ~ 1500 K
    - Lower than other
    - Center can up to 4000 K
- Magnectic Field is hundred times larger than surface of sun
    - Umbra can up to 1000 ~ 4000 Gauss

#### Reasons
- George Ellery Hale 
    - Magnetic field suppress convection 

![](https://i.imgur.com/jenG5Y5.png)

#### Joy's Law
- The more the sunspots is close to the equator, its angular to equator is more less
![](https://i.imgur.com/CVZn9X9.png)

#### Hale's Ploarity Law
- The pioneer sunspots's magnectic pole is different then the previous sun period

![](https://i.imgur.com/qFy8CrQ.png)

#### Butterfly Diagram 
- The sunspot strips looks like a butterfly 

![](https://upload.wikimedia.org/wikipedia/commons/thumb/9/9e/Sunspot_butterfly_graph.gif/1599px-Sunspot_butterfly_graph.gif)

- Magnetic 

![](https://i.imgur.com/Gmi7eeh.png)

#### Solar Dynamo -- Babcock Model 

![](https://i.imgur.com/e6S6fSG.png)

## Question: Increase of total solar irradiance

![](https://i.imgur.com/T5spFDD.png)
- In reality:
    - The total solar irradiance (TSI) **increases** by ~0.1% at sunspot maximum

### Faculae

![](https://i.imgur.com/OTRLw18.png)
![](https://i.imgur.com/MWphgIM.png)

![](https://www.researchgate.net/profile/Thomas_Woods/publication/238606012/figure/fig1/AS:298733834129415@1448235104875/The-solar-activity-is-waning-and-approaching-its-11-year-solar-cycle-minimum-The.png)

- Sunspots dominate faculae during solar rotation
- Faculae dominate sunspots during 11-year solar cycle

### Sunspot are getting lesser
![](https://i.imgur.com/saj5JXq.png)

![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/28/Sunspot_Numbers.png/660px-Sunspot_Numbers.png)

![](https://i2.wp.com/principia-scientific.com/wp-content/uploads/2018/03/radiation.jpg)

![](https://pbs.twimg.com/media/EF96EliWsAAgDlC?format=jpg&name=medium)

## Chromosphere (200km)
- Temperture decrease through height
    - 1000 ~ 10^7^ K
- Pominence, Filament, Super-granulation, Spicule

### Spicule
- Large convection from photosphere

![](https://i.imgur.com/E2W39Oa.png)

### Super-granulation
- Larage convection from photosphere
- Large scale of granulation

### Pominence and Filament

![](https://i.imgur.com/UwkzqeD.png)

- The Pominence is dark compare to light from sun (H-$\alpha$ Light) so it is also called filament (Dark Pattern)
- Low temperature, high dense structure that is made by bonded plasma 

![](https://i.imgur.com/aLwvvhM.png)
![](https://i.imgur.com/j0HV1T5.png)
![](https://i.imgur.com/uCqcWGd.png)

- We can see the direction of the magnetic field is vertical to the direction of the Pominence

## Corona
- Temperature
    - 10^6^ K
- Low dense
- Only observe when solar eclipse
- Coronal hole and coronal loops

### Coronal hole 
- Open magnetic line
- Low density of plasma 
- Fast Solar Wind

![](https://i.imgur.com/t2fVjCo.jpeg)
- The black spot is a coronal hole
- Yellow are active regions

![](https://i.imgur.com/jnEvh4r.png)

### Solar Flare
- Large energy released in a short period of time
- Almost happens at sunspots
- Irradiance peek 
- 10^20^ ~ 10^25^ J of energy
- Observation
![](https://hpde.gsfc.nasa.gov/LWS_Space_Weather/GOES_20050121_xray.gif)

### Coronal Mass Ejection (CME)

- Large amount of plasma eject from coronal
- Most of the CME are happend in Active regions
- Mass of ejection
    - 10^14^ ~ 10^17^ grams
- Velocity of ejection 
    - 20 $km/s$ ~ 3200 $km/s$
- Cause shock wave while traveling through space
    - plasma shound speed 10^2^ km/s

![](https://i.imgur.com/ZO1nRNw.png)

#### Coronagraph (SOHO LASCO)
- Telesope equipped with occulting disk that blocks out the sunlight 

### Solar Wind
- A plasma flow blow out from sun's surface
- Electron, Proton, Ions and so on have seperate movment
    - average of 400 km/s
    - Electrical neutrality
- The extend of Solar atmosphere
- Prove of solar wind
    - Ion tail
        - made by ion gass
        - didn't effect by sun's radiation pressure and gravity
        - CO ion is blue while absorbing ultra-light
        - will break and rebuild
    - dust tail
        - made by dust
        - Effect by sun's radiation pressure and sun's gravity
        - curve and yellow
    - ![](https://tw.spaceschool.org/wp-content/uploads/sites/13/2019/06/02-7-300x294.png)
- Have its sown mangectic field
    - Interplanetary Magnetic Field (IMF)
- Bow Shock 
    - Over plasma sound speed
- End of Solar Wind
    - Interstellar Space

#### Parker Spiral 
- Results from suns own rotation

![](https://i.imgur.com/f056OQJ.png)

![](https://i.imgur.com/tgkPTT7.png)
![](https://cdn.sci.esa.int/documents/33816/35255/1567220605676-12399-screen2.jpg)

### Ulysses Satellite
- A polar orbitting satellite of sun
- Observe corona's datas

![](https://i2.read01.com/SIG=17lfqvr/304565485a4d394f7a64.jpg)

## Interstellar Space

![](https://www.thesun.co.uk/wp-content/uploads/2018/12/cl-graph-voyager-3.jpg)

### Termination Shock
- Paricles streaming from sun slow to subsonic speed

### Heliosphere 
- Extended bubble of solar paricles

### HelioPause
- The boundary of the Solar System
- outward pressure is in balance with the inward push of the interstellar medium

### Bow shock?
- Shock wave of ionized gas
- Perhaps not fast enough to make one

## Voyager
- A Satellite that shoots outword from sun

![](https://i.imgur.com/pF4keQv.png)
![](https://i.imgur.com/gcUFgMH.png)


- The proof of passing termination shock
