Astro Unit 3 Part 3
When was the first extrasolar planets found?
1992
The habitable zone around the Sun includes?
Earth and Mars
In a high mass star, why does nuclear burning stop at iron?
Nuclear reactions involving iron do not produce energy
What does the Drake Equation estimate?
The number of technological civilizations in the Milky Way
The first extrasolar planet in the habitable zone of its host star was found in:
2001
Stars that include Mercury in their habitable zone are:
About or little less than 0.75 times the mass of the Sun
How can you measure the mass of a black hole?
By measuring the speed of the orbit of a star in a binary system with the black hole
What factor is not in the Drake Equation?
Communication lag due to large distances between stars
What is the main requirement for a habitable zone?
Liquid water
Which statement is true?
Nothing can travel faster than the speed of light
White dwarfs
Stars less massive than the sun will also end their lives as :
How do solar-size and smaller stars die? How large are their remnants?
The become white dwarfs, about the size of the earth
When the planet passes in front of a star as seen from Earth
The brightness of the star diminishes for a time
What is at the center of a planetary nebula?
The core of the dying star and something that will eventually become a white dwarf (Both A and C)
Why are things torn apart when they are near a blackhole?
The part of the object closer to the black hole feels a greater force
Medium-mass stars end as...
Type 2 supernovae then neutron stars
When a star is burning Helium in its core and has puffed out its outer layers, it is...
a red giant
An "onion skin" shell burning structure, with elements up to iron being produced, develops in...
a star much more massive than the Sun
When it becomes a red giant, the star...
decreases in temperature and increases in luminosity
A planetary nebula...
is the ejected outer layers of a low to intermediate mass star
After the variable stage, the star...
produces a planetary nebula
As stars form, they heat up. So they move from...
right to left on the HR diagram, onto the main sequence when their nuclear fusion "engines" turn on
What is the density at the center of a blackhole?
Infinity
The most massive stars burn heavier and heavier elements in the core but that the heaviest thing produced is iron. Why is this?
Iron is the most stable nucleus
Brown dwarf
It is an object with a mass less than 8% of the Sun, which cannot have enough nuclear reactions in its core to be a star.
What doesn't happen when an object approaches a black hole?
It quickly gets sucked in even from a large distance
The most successful early planet finding mission launched in 2009 was called:
Kepler
Do you remember what main sequence means?
The curve on the HR diagram where stars of different masses are located while they are converting hydrogen to helium in their cores. (The position of stars of all different masses
High-mass stars end as...
blackholes
The very highest mass stars will end their lives as...
blackholes
The star must be an M type star to have :
habitable planets at 0.55 AU
A star that is twice the mass of our Sun would have a habitable zone that:
includes Mars but not the Earth
A star that is 75% the mass of our Sun would have a habitable zone that:
includes Venus only
Which of the following is the sequence of events for a 40 solar mass star (one of the most massive stars)?
stellar nursery, protostar, blue star on main sequence, Type II supernova, black hole
The event horizon of a black hole is...
the minimum distance from which light can escape