ESRT Practice — H-R Diagram & Life Cycles of Stars
Welcome back! — your work is saved.
🌟 Student Sign-In
In this lab you will learn to use two key reference table charts: the H-R Diagram (page 14) and the Life Cycles of Stars Model (page 14). Both charts will be available on every question page.
📚 Stellar Vocabulary
Click any card to flip it open. Cards close after 8 seconds — you can reopen any card as many times as you need. Only one card opens at a time.
🔗 Vocabulary Matching
Click a term on the left, then click its matching definition on the right. Correct matches stay green.
0 of 12 matched
Terms
Definitions
📖 Reading: Stellar Classification & Evolution
Reading the H-R Diagram
The Hertzsprung-Russell (H-R) Diagram on page 14 of the Earth and Space Sciences Reference Tables is one of the most important tools in astronomy. It plots stars by their surface temperature on the x-axis and their luminosity (brightness) on the y-axis. Notice that the temperature scale runs backwards: the hottest stars (around 30,000 K) are on the left, and the coolest stars (around 3,000 K) are on the right.
About 90 percent of stars, including our Sun, fall along a diagonal band called the main sequence. Main sequence stars fuse hydrogen into helium in their cores. The hotter and more massive a main sequence star is, the brighter it shines and the shorter it lives. A blue giant like Spica may live only ten million years, while a small red dwarf can live for hundreds of billions of years.
Stars that have left the main sequence are found in other regions of the diagram. Giants and supergiants appear in the upper right — they are cool but extremely luminous because they are huge. White dwarfs are in the lower left — they are hot but very dim because they are tiny. The diagram is essentially a snapshot showing where stars are in their life cycles.
The Life Cycles of Stars Model
Every star begins inside a star-forming nebula, a cloud of gas and dust. Gravity pulls material together to form a protostar. What happens next depends on one factor: mass.
A Sun-like star spends billions of years on the main sequence. When its hydrogen fuel runs low, it expands into a red giant, then sheds its outer layers as a planetary nebula. The hot core left behind cools as a white dwarf.
A massive star (more than 8 to 10 times the Sun's mass) burns through its fuel in only millions of years. It swells into a red supergiant, then explodes as a supernova. The remnant becomes either a neutron star or, if the original star was massive enough, a black hole. The smallest stars, called red dwarfs, burn so slowly they may live for hundreds of billions of years — longer than the current age of the universe.
Together, the H-R Diagram and the Life Cycles model let astronomers identify what stage a star is in just by knowing its temperature and brightness. That is why mastering both reference tables is essential for the Earth and Space Science Regents exam.
✍️ Sentence Practice
Use what you read to complete the sentences below. Each correct response earns 1 point.
1. Astronomers plot stars on the
to compare their
and
.
About 90 percent of stars fall along the
.
Word Bank:
white dwarfsupernovablack holemassneutron star
2. A star's
determines how it dies. A Sun-like star ends as a
, while a massive star explodes in a
and becomes either a neutron star or a
.
3. Drag and click the words below to build the correct sentence.
Available words:
Your sentence:
4. Build the correct sentence below.
Available words:
Your sentence:
5. Expand this bare-bone sentence: "Stars form in nebulae."
Add details that answer When or Where, and Why or How.
6. Expand this bare-bone sentence: "Massive stars become black holes."
Add details that answer When or How.
🎯 Guided Practice 1 — Reading the H-R Diagram
Use the reference charts below to answer each guided question. Toggle between the two charts using the tabs.
Guided Practice Questions
1. Find the Sun on the H-R Diagram. The Sun is located in the
region. Its surface temperature is approximately
.
2. Find Betelgeuse on the H-R Diagram. Betelgeuse is a
. Its surface temperature is much
than the Sun, but it is much
because of its enormous size.
3. Find Sirius B and Procyon B on the H-R Diagram. These two stars are classified as
. They have
surface temperatures but
luminosity.
4. The hottest stars on the H-R Diagram have spectral class
, while the coolest stars have spectral class
. Our Sun has spectral class
.
5. According to the H-R Diagram, a main sequence star with a lifetime of 10⁷ years is
than a star with a lifetime of 10¹⁰ years. This shows that
.
🎯 Guided Practice 2 — Reading the Life Cycles Model
Switch to the Life Cycles of Stars tab below to answer these questions.
Guided Practice Questions
1. All stars begin their lives in a
. The early stage of any star is called a
.
2. A Sun-like star spends
on the main sequence. After this it becomes a
, sheds its outer layers as a
, and finally cools as a
.
3. Massive stars (more than 8 to 10 times the Sun's mass) live for only
. They expand into a
, then explode in a
.
4. After a supernova explosion, the remnant left behind becomes either a
or a
, depending on the original star's mass.
5. The smallest stars on the model are
. These stars have lifetimes of
of years — longer than the current age of the universe.
🎓 Regents Practice 1 — H-R Diagram Questions
These questions mimic Earth & Space Science Regents formats. Use the reference charts below to find the best answer.
1. The H-R Diagram shows the relationship between which two characteristics of stars?
(1)mass and distance from Earth
(2)surface temperature and luminosity
(3)age and color
(4)diameter and rotation period
2. A newly observed star has a surface temperature of 3,500 K and a luminosity of 10⁴ solar units. According to the H-R Diagram, this star would be classified as a
(1)main sequence star
(2)white dwarf
(3)supergiant
(4)red dwarf
3. A student compares the stars Sirius and Polaris using the H-R Diagram. Which statement best describes their differences?
(1)Both stars have the same temperature, but Polaris is dimmer.
(2)Polaris is cooler and far more luminous than Sirius.
(3)Sirius is a white dwarf and Polaris is a main sequence star.
(4)Both stars are giants located in the same H-R region.
4. Which combination of statements correctly describes our Sun based on the H-R Diagram?
Letter
Statement
I
The Sun is on the main sequence.
II
The Sun has spectral class G.
III
The Sun has a luminosity of about 1 solar unit.
IV
The Sun has a surface temperature near 30,000 K.
(1)I, II, and IV
(2)II, III, and IV
(3)I, II, and III
(4)I, III, and IV
🎓 Regents Practice 2 — Life Cycles Questions
Continue using the reference charts. Switch tabs as needed.
5. Use the word list below to complete the passage. Each word may be used only once.
Word List:
supernovanebulaprotostarmain sequencesupergiant
Every star begins inside a star-forming
.
Gravity pulls material together to form a
,
which eventually begins fusing hydrogen and joins the
.
A massive star later expands into a red
,
and finally explodes as a
.
6. According to the Life Cycles of Stars Model, what is the final stage of a star with a mass similar to our Sun?
(1)black hole
(2)white dwarf
(3)neutron star
(4)red supergiant
7. A student compares two stars labeled Star X and Star Y. Star X has a surface temperature of 25,000 K and Star Y has a surface temperature of 4,000 K. Both stars are on the main sequence.
Star
is more massive because it has a
surface temperature, which means it will have a
lifetime and end its life as a
.
A
B
C
D
X or Y
hotter or cooler
shorter or longer
white dwarf or black hole or neutron star
8. Which statement best explains why massive stars have shorter lifetimes than less massive stars?
(1)Massive stars burn through their fuel much faster due to higher core temperatures.
(2)Massive stars have less hydrogen fuel available to begin with.
(3)Massive stars are cooler, so they cannot sustain fusion reactions.
(4)Massive stars are farther from Earth, so we observe them less.
📊 Star Data Analysis
Use both reference charts to classify each star below. Completing this table is worth 4 points.
Star Name
Surface Temp (K)
Luminosity (solar units)
Classification (you)
Likely fate (you)
Sun
~6,000
1
Betelgeuse
~3,500
~10⁵
Sirius B
~25,000
~0.03
Proxima Centauri
~3,000
~0.001
Graph: Lifetime vs Mass
The graph below uses data from the H-R Diagram showing the relationship between stellar mass and main-sequence lifetime.
9. What pattern does the graph show between stellar mass and main-sequence lifetime?
(1)As mass increases, lifetime increases.
(2)As mass increases, lifetime decreases.
(3)Mass and lifetime are unrelated.
(4)Lifetime stays constant for all masses.
⭐ Boss Battle: Stellar Jeopardy
Choose a category and point value. Higher points = harder questions.
Score: 0 points
Question
📝 Final Quiz — 5 Random Regents-Style Questions
You will see 5 questions drawn from a bank of 20. Pass with 60% mastery (3 of 5). You may retry with fresh questions if you do not pass.