Exam 3 Flashcards
Photosphere
The surface of a star, where the plasma is thin enough that light can escape freely into space
Corona
A stars upper atmosphere, where thin plasma is heated to millions of Kelvin by the stars magnetic field
Fusion
The process where small nuclei are merged to form a heavier element, which can release energy
Envelope
The interior part of a star where fusion doesn’t occur and where the composition stays the same since the star was formed
Fission
When a heavy unstable nucleus breaks apart to form nuclei of lighter elements, which can release energy
Core
The part of the star where energy is generated
The sun shines because it is
Hot like a stove
Heat is generated in the suns core by
Nuclear fusion of hydrogen into helium
Nuclear ____ involves merging atoms while nuclear ____ involves splitting them
Fusion= merge Fission= split
The sun has been shining for __ years and is..
4.5 billion years; halfway through its life
Sometimes the sun throws a ball of plasma and magnetic field out into the solar system. This is called a
Coronal mass ejection (CME)
What causes sunspots and solar cycles
The suns magnetic field reverses polarity
Fusion powers the core, changes on the surface are c if the magnetic field
There are more sunspots, flares, and CMEs during
The middle of a sunspot cycle
Th corona glows in X-rays while the photosphere only glows in visible light, so we know the corona is ___ than the photosphere
Hotter
The ___ is heated by fusion while the ___ is heated by magnetic fields
Core= fusion Corona= magnetic fields
If you were to dive into the sun, you would hit a solid surface at the..
… actually, the plasma would just get thicker and thicker as you fell in
You can tell the temperature of a star by looking at its
Color
Lost the spectral types from hottest to coolest
OBAFGKM
How would you tell a K type red giant from a K type red dwarf?
The giant is more luminous
True or false: as a star loses mass due to the stellar wind, it goes from being a main sequence O star to being a main sequence G star to finally being a main sequence M star
False; a star lands somewhere on the main sequence depending on its mass, and doesn’t move from there until it leaves the main sequence entirely
On the main sequence compared to low mass stars, high mass stars are hotter
More luminous, and have shorter lifetimes
High mass stars can fuse carbon but the sun cannot because
It’s core is not hot enough
Stars on the main sequence range in luminosity and temperature, but they are all
Fusing hydrogen into helium in their cores
Stars become larger once they leave the main sequence because
They are producing more energy, which makes the surface expand more
List stellar corpses based on the mass of the star that formed from the lowest to the highest
White dwarf, neutron star, black hole
When stars become red giants or red supergiants, they turn red because
The surface is farther from the center of the star
Which kind of star will die by going supernova?
A star with more mass than our sun
You see a bright star in the night sky. You have enough information to determine:
Nothing
When a large gas cloud has clumps that form stars, you would tend to find
More low mass stars like K and M stars
2 stars are the same mass. Star A is fusing hydrogen into helium, star B is fusing hydrogen into helium and helium into carbon and oxygen. Which star is older?
B; it’s fusing heavier elements
List the stages that a low mass star goes through in chronological order
Main sequence, red giant, planetary nebula, white dwarf
As a red isn’t the sun will fuse hydrogen in a shell around the core. What phase comes after this?
The sun fuses helium in the core and hydrogen in a shell around the core
How can you measure the age of a star cluster?
Determine what mass the star is just about to leave the main sequence
Your friend says, “this thing keeps publishing bright faint bright faint, and is giving me a headache.” What object is this?
Neutron star
A supernova is when
A massive star dies, a white dwarf gains too much mass
Parallax allows us to measure a stars
Distance
You measure the pulsation period of a variable star in a star cluster. You can now estimate the?
Clusters distance
Over its lifetime and death, a star creates ___ heavier elements than it uses, so it ___ the amount of heavy elements present in a galaxy’s gas
More, increases
You observe a red supergiant and a red giant. Which is more polluted with heavier elements?
Red supergiant
A habitable planet is one that
Is the right temperature for water to be liquid
Why are exoplanets difficult to detect?
They’re far from earth, net to bright stars, and dim
When we observe an exoplanet using the Doppler shift, the planets signal is
.. actually, we never see the planet itself
A hot Jupiter exoplanet is a Jovian planet that
Is in very small orbit
You see a star moving toward and away from you in a periodic manner. Which detection method is this?
Radial velocity
Most of the planets in the exoplanet database are Jovian planets because
Our detection methods are biased toward finding Jovian planets
The Drake equation allows us to estimate there are __ alien civilizations whose radio signals we could detect in the Milky Way
.. actually, we have no idea how many
If you want to detect a planet like earth that is orbiting a star, you should observe it for a minimum of..
3 years
