Astronomy Flashcards
Does it matter how far away a star is when measuring apparent brightness?
Yes
Does it matter how far away a star is when measuring luminosity?
No
Does it matter how far away a star is when considering the scale of absolute magnitude?
No
Does it matter how far away a star is when considering the scale of apparent magnitude?
Yes
What is luminosity and how do you measure it?
It’s the amount of power generated by a star, and its symbol is L, but its measured in watts
What is apparent brightness in a star?
The brightness a star appears to be from earth
What is apparent brightness?
The apparent brightness scale in which the brightest is. First magnitude, and the dimmest is sixth magnitude visible with the unaided eye. Any magnitudes above six cannot be seen with unaided eyes. The symbol is m
What is the ratio of the brightness in the scale?
Ie: a magnitude 1 star is 100 times brighter than a magnitude 6 star. Diff of five = 100
What is apparent brightness?
The brightness a star appears to be from earth
What is absolute magnitude?
A measure of brightness independent of distance (M)
What is important to know about a stars surface temperature?
- it’s not affected by the distance to the star
- its determined by the stars color
- on a scale from coldest to hottest the star colors are; red, yellow, white, blue
What are the spectral types of hot O stars?
B, A, F, G, K, M in order of declining surface temp
“Oh be a fine girl kiss me”
What are the layers of the earths atmosphere from the lowest to highest?
Troposphere, stratosphere, mesosphere, and thermosphere
What are some properties of the thermosphere?
- hot, up to 2000°C during day, because its near the sun
- exposed to high UV radiation
- its lower parts are protected and cooler
What are some properties of the mesosphere?
- its unstable
- the temp in it decreases with height
- has noctilucent clouds
What are some properties of the stratosphere?
- hottest at top due to formation of ozone
- is stable
- weather balloons here
What are some properties of the troposphere?
- unstable
- weather occurs here
- lowest layer
What is the Coriolis effect?
Changes in direction that appear to be due to an unseen force (coriolis force)
In the coriolis effect, what direction do objects in the northern hemisphere veer to? The southern hemisphere?
In the north they veer right, in the south they veer left
What does keplers first law state?
That a small body orbiting a large body will travel in an elipses with the large body
What does keplers 2nd law state?
That a small body orbiting a large body moves fastest when it’s near the large body
What does keplers 3rd law state?
angular size cubed / Time it takes to orbit squared = G • the mass of the larger / 4 pie squared
What does the universal law of gravitation state?
That the gravitational force between objects, (Fg) = G • the objects masses, (m1 • m2) / the distance between their centers in meters squared
What direction does a low pressure system in the northern hemisphere move?
Counter clockwise
How do most stars start out?
They are formed as a protostar from a nebula
What is true of both small and large main sequence stars?
That in them, fusion and gravity balance out each other, keeping them stable
How does a red giant form?
When hydrogen runs out, helium fusion begins. The energy produced causes its outer layers to cool and glow red
How does a super giant form?
After h runs out, helium fusion begins, and cooler outer layers glow red. Later heavier elements begin to fuse
How does a planetary nebula form?
When Helium fusion overwhelms gravity, the outer layer of a ted giant expand into a gas cloud
How do protostars form from nebulas?
When density waves compress the nebulas gas, it clumps, creating protostars
What is the hottest layer of the suns atmosphere?
The corona
