Measurement
This is the distance between the Earth and the sun.
How are the luminosity and period of a Cepheid star related?
The higher the luminosity the longer the period
What is interstellar matter?
gas and dust between stars
What is a nebula?
cloud of dust and gas
What does a light curve measure?
the change in a star's brightness over time
This is one ten-millionth of the distance between the Earth's equator and pole.
original definition of meter
What happens to the spectroscopy of a pulsating variable star that is expanding and contracting?
Doppler Effect - red and blue shifts in spectral lines at regular intervals
This is the zone around hot stars where hydrogen atoms are ionized.
H II
What is a dark nebula?
a cloud of dust and gas that blocks light from stars behind it
How are distances to Venus and Mars measured?
radar
1/2 of the diameter of the Earth's orbit around the sun
These stars have a high luminosity, a period of 5 days or more, and their luminosity changes by a factor of 10.
Cepheid Variable Stars
cold cloud of dust and gas containing molecules
What is a reflection nebula?
cloud of dust and gas that reflects light from nearby stars
What tells the type of star (supergiant, giant, main sequence)?
luminosity
How is triangulation used to find distances?
An object is observed from two points (separated by a known distance). The angle that the object appears to change position is measured. The triangle is solved.
These stars have a luminosity of about 50L, a period of less than one day, and luminosity changes by a factor of 2.
RR Lyrae Variable Stars
What are interstellar grains made of?
silicon or graphite core surrounded by ice
What is an emission nebula?
cloud of dust and gas that gives off light
What element makes a nebula appear red?
hydrogen
How is the size of the parallax related to the distance of a star?
The parallax decreases as the distance increases.
Which type of variable star is large and yellow?
Cepheid
How is interstellar matter heated to over one million degrees?
Shock waves from supernova heat matter that they come in contact with.
Name one nebula.
Orion, Crab, Horesehead
What are cosmic rays made of?
fast moving nuclei, electrons, positrons