Properties of Stars
Stars come in different colors, and their color tells us how hot they are.
TRUE
G-type stars, like our Sun, have surface temperatures around 5,000 to 6,000 degrees Celsius.
TRUE
The Sun's surface temperature is higher than that of blue supergiants.
FALSE
The Hertzsprung-Russell diagram helps astronomers classify stars based on their temperature and luminosity.
TRUE
Each star is represented by a single point on the diagram, based on its specific luminosity and temperature values.
Stars are formed from massive clouds of gas and dust known as nebulae.
TRUE
Stars are born from massive, dense clouds of gas and dust in space called nebulae.
The smallest main-sequence stars are called red dwarfs, and they're about the size of a planet like Mercury.
FALSE
The smallest stars are called red dwarfs, and they're about the size of a planet like Jupiter.
F-type stars are cooler than K-type stars.
FALSE
F-type stars: 6,000 to 7,500 degrees Celsius
K-type stars: 3,500 and 5,000 degrees Celsius
The Sun’s surface temperature reaches about 15 million degrees Celsius.
FALSE
The Sun’s core temperature reaches about 15 million degrees Celsius.
The H-R Diagram was developed by Ejnar Hertzsprung and Henry Norris Russell in the early 20th century.
TRUE
Neutron stars are extremely dense objects primarily made of protons.
FALSE
Neutron stars are extremely dense objects primarily made of neutrons.
What process powers stars and causes them to shine?
a) Nuclear fusion
b) Chemical combustion
c) Electrical discharge
d) Magnetic fields
a) Nuclear fusion
Nuclear fusion is a process that releases an enormous amount of energy, making stars shine brightly.
Which type of stars are the most common in the universe?
a) O-type stars
b) G-type stars
c) M-type stars
d) B-type stars
M-TYPE STARS
How does the Sun’s temperature compare to most other stars?
a) The Sun is cooler than most stars.
b) The Sun is hotter than most stars.
c) The Sun has an average temperature compared to most stars.
d) The Sun’s temperature is unknown.
THE SUN HAS AN AVERAGE TEMPERATURE COMPARED TO MOST STARS.
What does the horizontal axis of the H-R Diagram represent?
a) Luminosity
b) Surface temperature
c) Size
d) Distance from Earth
SURFACE TEMPERATURE
Horizontal axis represents surface temperature, which decreases from left (hotter, blue stars) to right (cooler, red stars).
Which phase of a star's life cycle involves steadily fusing hydrogen into helium in its core?
a) Red giant phase
b) Main sequence phase
c) White dwarf phase
d) Supergiant phase
MAIN SEQUENCE PHASE
What do older stars create through the process of nuclear fusion?
a) Only hydrogen
b) Lighter elements only
c) Carbon and Oxygen
d) Only iron
CARBON AND OXYGEN
As stars age, they begin to fuse helium into heavier elements like carbon and oxygen.
What is the surface temperature range of B-type stars?
a) 3,500 to 5,000 degrees Celsius
b) 5,000 to 6,000 degrees Celsius
c) 10,000 to 30,000 degrees Celsius
d) 30,000 to 40,000 degrees Celsius
10,000 TO 30,000 DEGREES CELSIUS
How does the size of the Sun compare to giant stars?
a) The Sun is larger than giant stars.
b) The Sun is smaller than giant stars.
c) The Sun is the same size as giant stars.
d) The size of the Sun is not comparable to giant stars.
THE SUN IS SMALLER THAN GIANT STARS.
Where are most stars, including the Sun, located on the H-R Diagram?
a) Giants and supergiants region
b) White dwarfs region
c) Main sequence region
d) None of the above
MAIN SEQUENCE REGION
Most stars, including the Sun, are found here, burning hydrogen in their cores.
What phase does a star go into after it runs out of hydrogen in its core?
a) Red giant phase
b) Main sequence phase
c) White dwarf phase
d) Supergiant phase
RED GIANT PHASE
What happens during a supernova explosion?
During a supernova explosion, a massive star explodes, releasing a tremendous amount of energy. This explosion can outshine entire galaxies for a short period. The core that remains can become a neutron star or a black hole, depending on its mass.
What happens to red supergiants at the end of their life cycle?
At the end of their life cycle, red supergiants typically undergo a supernova explosion. This massive explosion can result in the creation of either a neutron star or a black hole, depending on the mass of the original star.
How does the Sun generate energy?
The Sun generates energy through nuclear fusion reactions in its core. During these reactions, hydrogen atoms are fused into helium, releasing a tremendous amount of energy in the form of light and heat. This process powers the Sun and makes it shine brightly.
How does the Hertzsprung-Russell (H-R) Diagram help astronomers determine the evolutionary stage of a star?
Astronomers use the H-R Diagram to determine a star's evolutionary stage by examining its position on the diagram. As stars move off the main sequence and become giants or supergiants, they indicate the depletion of hydrogen fuel and progression into later evolutionary stages.
What are some observable consequences of a star entering the red giant phase?
First, the star expands and becomes significantly larger in size compared to its previous state. This expansion can lead to the engulfment of nearby planets or moons in some cases. Additionally, the surface temperature of the star decreases, causing it to emit redder light compared to its hotter, younger phase. These changes in size and temperature are visible indicators of a star's transition into the later stages of its life cycle.