Vocab
Define Absolute magnitude
What is magnitude that stars would appear to have if it was located at a standard distance of 10 parsecs.
Novas
What is star that suddenly and dramatically increases in brightness, and then fades away over time?
Hertzsprung- Russel (H-R) diagram
separates the effects of temperature and surface area on stellar luminosities (a graph)
- one of the most important analysis and reference tools in stellar astronomy
Explain gravity and who discovered it.
Gravity is a fundamental force of nature
It's responsible for keeping planets in orbit and objects on Earth's surface
Sir Isaac Newton first described gravity mathematically
Inner planets vs outer planets
Inner planets: Mercury, Venus, Earth, Mars
Outer planets: Jupiter, Saturn, Uranus, Neptune
Inner planets are smaller and rocky
Outer planets are larger and gaseous
Neutron star
What is the collapsed core of a massive supergiant star?
Helium fusion
What is a nuclear fusion reaction that occurs when helium nuclei fuse together to form a heavier element?
Luminosity, Temperature, and Diameter
an H-R diagram has luminosity on the vertical axis and temperature on the horizontal axis.
- a star is represented by a point on a graph that shows its luminosity.
-the diagram also contains a scale of spectral types across the top.
-Note the symbol Θ: it refers to the Sun.
What are the Variables Affecting Gravity's Strength?
Mass of objects: More mass means stronger gravitational pull
Distance between objects: Gravity weakens with increased distance
The gravitational constant G
Explain the Asteroid Belt and Kuiper Belt.
Asteroid belt: located between Mars and Jupiter
Kuiper belt: beyond Neptune's orbit
Both contain smaller objects left over from solar system formation
Spectral class
What is the represent a temperature sequence; a way to categorize stars based on their absorption lines and surface temperature?
Hydrogen fusion
What is a reaction that the nuclear reaction in which hydrogen nuclei are fused into helium nuclei (nucleus) releasing large amounts of energy?
What can the the H-R diagram reveal about a star?
- Its distance
- Its evolutionary (relative) age
- Its size
-Its mass
-Its density
-Its surface temperature
Explain Gravity in our solar system
Sun's gravity keeps planets in orbit
Each planet also has its own gravitational field
Moons orbit planets due to gravity
What are the three laws of planetary motion?
Three laws describing how planets move around the Sun
1. Planets orbit in ellipses with the Sun at one focus
2. Planets sweep out equal areas in equal times
3. The square of the orbital period is proportional to the cube of the semi-major axis
Apparent magnitude
What is how bright an object appears in the sky from Earth?
Main Sequence Stars
What is a star that fuses hydrogen into helium in its core?
Red dwarfs
at the lower end of the main sequence are not only cool but also small, giving them low luminosities.
Explain Calculating planetary orbits
Use Newton's law of universal gravitation: F = G(m₁m₂/r²)
Kepler's laws of planetary motion also apply
Orbit calculations consider mass, distance, and velocity
Newton laws of motion
Newton's laws explain motion and forces in the universe
1. Objects in motion stay in motion unless acted upon by a force
2. Force equals mass times acceleration (F = ma)
3. For every action, there is an equal and opposite reaction
Protostars
What is the first stage of the stars life cycle, nebula, a giant cloud of gas that collapsed under gravity?
Luminosity
What is brightness; the amount of light or energy that something gives off?
Color Rule
Blue stars: Red Stars:
Hot cooler
Bright dimmer
Massive less faster
burn fast burn slow
shorter lives longer lives
Explain red shift and the expanding universe theory
Red shift: Light from distant galaxies appears redder
Indicates galaxies are moving away from us
Evidence for the expanding universe theory
Explain planetary motion patterns.
All planets orbit counterclockwise around the Sun
Orbits are on roughly the same plane (the ecliptic)
Planets follow predictable, elliptical paths