Unit E Section 1.3 Flashcards
WHAT IS A STAR?
A star is a hot, glowing ball of gas (main hydrogen) that gives off tremendous light energy
What is the weight of the Sun compared to Earth?
Our Sun has a mass 300 000 times greater than Earth, with an average density of 1.4 times that of water.
What is the size and weight of the Betelgeuse compared to the sun?
In diameter, Betelgeuse is 670 times larger than our Sun but only 1/10-millionth as dense
What does the color of the star depend on?
The color of a star depends on its surface
temperature.
What do hot stars look like?
Very hot stars look blue
What do cooler stars look like?
Cooler stars look red.
What is the “Hertzsprung-Russell diagram”?
Shows the stars fall into several distinct groupings
Which star grouping does the sun belong to?
Main sequence
How much percent of stars fall into the main
sequence?
Ninety percent of
all stars fit into this grouping.
What do nebulae mean?
Stars form in regions of space where there are huge
accumulations of gas and dust called nebulae
What gases are nebulae formed of?
75% hydrogen
23% helium
The other 2% is oxygen, nitrogen,
carbon, and silicate dust
What is interstellar matter
is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays
What is protostar?
the first stage in a star’s formation
What is fusion?
This process, known as fusion, releases great quantities of energy and radiation.
What does the star depend on to figure out if it is a Sun-like or massive?
Depending on the mass of the star formed from a particular nebula,
What do Sun-like (in terms of mass) or massive spend most of their lives doing?
Both types of stars spend most of their lives in this main sequence, converting hydrogen to helium in their cores.
What makes the stars in a stable state?
The outward pressure of radiation on the stellar
material is counteracted by gravity
When does the stable state of the star shrink?
-When the hydrogen in the core has been used up, the stable state star shrinks in size, heating the helium core so that it first starts fusing to carbon, then to other elements
How does a star become a red giant or a red supergiant?
- After the stable state, when hydrogen is used up and turns into other elements,
- As gravity causes the star to contract, further nuclear reactions occur, leading to expansion of the outer layers.
What is the difference between a red giant and a red supergiant?
- red giant if it is a Sun-like star
- red supergiant if it is a massive star
When will our sun become a red giant?
- Our Sun will become a red giant in about 5 billion years.
- At that time, the Sun’s diameter may extend out past the present orbit of Mars.
When does the final stage in a star’s life occur?
when the fusion reaction stops
When does the fusion reaction end for a Sun-like star?
-fusion ends when the core temperature in the star is
no longer hot enough to keep the reaction going.
-With no heat input from fusion, the decreasing pressure is unable to prevent gravity from causing the star to collapse slowly on itself
What happens to a sun-like star after its last stage occurs as a giant red star
The Sun-like star continues to shrink, gradually becoming a WHITE DWARF, no larger than Earth
Eventually, the star will fade completely until it evolves into a cold, dark BLACK DWARF?
