unit 8 Flashcards
2/22/24
The star’s apparent motion
- a star’s position once, then again 6 months later
stellar parallax
distance that light travels in one year
light year
a unit of length or distance
- used to measure the large distances to astronomical objects outside the Solar System
parsec
any massive self-luminous celestial body of gas that shines by radiation derived from its internal energy sources
star
a measure of the total amount of energy radiated by a star or other celestial object per second
luminosity
- depends on its its distance from Earth
- the total energy emitted by a star per second
- how bright a star appears from the perspective of observers on Earth
apparent brightness
a number that tells how bright that star appears at its great distance from Earth
apparent magnitude
the magnitude that a star would appear to have if it were located at a standard distance of 10 parsecs
absolute magnitude
the relationship between the stars’ absolute magnitudes or luminosities versus their stellar classifications or effective temperatures.
HR diagram
an enormous cloud of dust and gas occupying the space between stars and acting as a nursery for new stars.
nebula
looks like a star but its core is not yet hot enough for fusion to take place
prostar
fuse hydrogen to form helium in their cores - including our Sun.
main sequence stars
- when main sequence stars run out of hydrogen fuel
- dying stars
- the most massive and most luminous stars
supergiants and giant stars
- blue/white core of the star that is left behind
- a small very dense star that is typically the size of a planet.
- dead main sequence stars
- hot and dim
white dwarfs
a white dwarf that has cooled sufficiently to no longer emit significant heat or light
black dwarfs
