Astronomy final

Name the 6 layers of the sun

Core

Radiation zone

Convection zone

Photosphere

Chromosphere

Corona

Describe the Suns composition

71% hydrogen

27%helium

2% heavier elements

According to Nasa

Key point: Mostly hydrogen and helium with minuscule amounts of heavier elements

Describe light's path from being made to "escaping"?

1.Photons are created in the (CORE) as gamma rays

2. In the a(Radiative Zone)Gamma rays travel outward but are repeatedly absorbed and re-emitted by ions in the dense plasma

3. in the (Convection zone)energy is transferred through the movement of hot gas, rather than by direct light travel

4. In the (Photosphere) Photons emitted as visible light

5.then it take approximately 8 minutes to reach earth(extra)

Key:Created in the core

Light is absorbed and re-emmited losing energy in the radiative zone

Convection zone: photons are transferred to the photosphere through convection currents

Photosphere: Photons are emitted as visible light

Define Solar activity

phenomena on the Sun driven by its magnetic field

What are the 4 categories of Solar activity?

1. Sunspots

2. Solar Flares

3. Coronal Mass Ejections(CME)

4. Solar Wind

draw a diagram that accurately represents the relative thickness of the layers (roughly, not perfectly)

Explain what a star is

A giant round ball of ionized gas that shines under its own power through nuclear fusion

Outline and define 4 key properties of stars & units/variables?

Mass:Determines a star’s evolution and lifespan, measured in Solar masses

Radius:Physical size. Measured in solar radius

Luminosity:Rate of energy production, Energy output per(secs,mins,hours ect) measured in Solar luminosities or watts

Temperature:: Surface temperature affecting color and spectrum. Measured in kelvin (K).

define hydro static equilibrium and stellar balance?

A constant battle between 2 forces, inward force of gravity and outward for of nuclear fusion

Outline nuclear fusion

Nuclear fusion is when atomic nuclei merge to form heavier nuclei a small amount of mass is converted into a energy

H+H +2 neutron = helium + energy(extra)

Whats the difference between Brightness and luminosity?

Luminosity is the total energy a star emits per unit time. Brightness is how bright a star appears from a location.

apply Wien’s law to determine stellar temperature?

Values will be given on test

Draw a simple HR diagram

Luminosity

Temperature

Mass

Radius

Main Sequence line

Explain Spectral types

Spectral types classify stars by temperature, based on spectra. Examples

O: 30k kelvin

B: 20k kelvin

A: 10k kelvin

F: 7k kelvin

G: 6k kelvin(our sun sits here)

K: 4k kelvin

M: 3k kelvin

O-BAF-GKM

absorption/emission spectra for rough temperature:

Line patterns and strengths depend on temperature:

• Hot stars (>10,000 K): Strong ionized helium or hydrogen lines.

• Medium stars (~5,000–10,000 K): Prominent hydrogen Balmer lines.

• Cool stars (<5,000 K): Molecular bands, neutral metals.

Explain the magnitude system and apparent vs. absolute magnitude

The magnitude system measures star brightness. Lower numbers = brighter; higher numbers = dimmer.

Apparent magnitude (m): How bright a star appears from Earth. Depends on luminosity and distance

Absolute magnitude (M): How bright a star would appear at 10 parsecs (32.6 light-years)

Use the inverse square law

b=1/d²

define star-forming region

A star-forming region is a dense area within a molecular cloud where gravity causes gas(hydrogen) and dust to collapse, forming new stars. example Pillars of creation

summarize star formation

Cloud collapse under gravity

Gas and dust heat up forming proto-star

Accretion disk forms

Critical mass is reached

Hydrogen fusion ignites

Stars born onto the main sequence

outline and describe key stages of low mass star evolution from formation to death

• illustrate these stages on an HR diagram

draw this

outline and describe key stages of high mass star evolution from formation to death

• illustrate these stages on an HR diagram