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

[TOC]

Sun
====

## Multi-waylength Observation
- 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


## 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


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

### 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%
- 
- 4 ¹H⁺ → ⁴He²⁺ + 2e⁺(Energy) + 2νₑ

- Carbon-Nitrogen-Oxygen (CNO) cycle
- 

## 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


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


# Sun's atmosphere

- 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


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


### 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


#### Joy's Law
- The more the sunspots is close to the equator, its angular to equator is more less

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


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


- Magnetic


#### Solar Dynamo -- Babcock Model


## Question: Increase of total solar irradiance

- In reality:
- The total solar irradiance (TSI) **increases** by ~0.1% at sunspot maximum

### Faculae



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

### Sunspot are getting lesser




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

### Spicule
- Large convection from photosphere


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

### Pominence and Filament


- 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


- 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

- The black spot is a coronal hole
- Yellow are active regions


### 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

### 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


#### 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
- 
- 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



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


## Interstellar Space


### 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


- The proof of passing termination shock