Astro Unit 3 pt.3
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 more massive than the sun
Stars that include Mercury in their habitable zone are:
About or little less than 0.75 times the mass of the Sun
What doesn't happen when an object approaches a black hole?
It quickly gets sucked in even from a large distance
What is the 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
High- mass stars end up as:
Black holes
The very highest mass stars will end their lives as :
Black holes
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
When it becomes a red giant the star :
Decreases in temperature and increases in luminosity
The habitable zone around the Sun includes?
Earth, & almost Venus and Mars
What is the density at the center of a black hole?
Infinity
Most massive stars burn heavier and heavier elements in the core but that the heaviest thing produced is iron. Why?
Iron is the most stable nucleus
A planetary nebula:
Is the ejected outer layers of a low - to intermediate - mass star
Which is TRUE?
Nothing can travel faster than the speed of light
In a high mass star, why does nuclear burning stop at iron?
Nuclear reactions involving iron do not produce energy
After the variable stage the star :
Produces a planetary nebula
What is at the center of a planetary nebula?
Something that will eventually become a white dwarf and a neutron star
Gold and silver were made in?
Supernova explosions from different types of stars
How do solar-size and smaller stars die? How large are their remnants?
The become white dwarfs, about the size of the earth
What is the main sequence?
The curve on the HR diagram where stars of different masses are located while they are converting hydrogen to helium in their cores
The event horizon of a black hole is:
The minimum distance from which light can escape
Why are things torn apart when they are near the black hole ?
The part of the object closer to the black hole feels a greater force
How do low mass stars end up?
Thy end up as planetary nebulae and then white dwarfs
Medium-mass stars end as :
Type II supernovae then neutron stars
When the core of the Sun-type star shrinks it becomes a :
White dwarf, the size of the Earth Then fades and becomes a black dwarf
Stars less massive than the sun will also end their lives as :
White dwarfs