Which of the following is NOT true about globular clusters?
They contain old stars
There are many of them surrounding the Milky Way
They consist typically of 100,000 to 1,000,000 stars
You cannot find white dwarfs in globular clusters
Their main-sequence turnoff on the HR diagram will be very high and to the left of the plot
47 Tucanae is an example of a globular cluster
They are roughly spherical
The correct answer and explanation is :
The statement that is NOT true about globular clusters is:
“You cannot find white dwarfs in globular clusters.”
Explanation (Approximately 300 words):
Globular clusters are tightly bound collections of stars that orbit the core of galaxies, including the Milky Way. They are among the oldest known stellar populations in the universe, typically containing stars that are around 10 to 13 billion years old. Because of this, they are valuable for studying the early history of galaxies and star formation.
One of the defining features of globular clusters is that they contain old stars, primarily low-mass, Population II stars, which have low metallicity. This fits with the idea that they formed early in the galaxy’s evolution.
These clusters are roughly spherical in shape and are highly concentrated toward their centers, held together by gravity. Each cluster typically contains between 100,000 to 1,000,000 stars, and there are about 150 to 160 globular clusters orbiting the Milky Way.
One famous example is 47 Tucanae, located in the southern sky, which is one of the brightest and most massive globular clusters.
On the Hertzsprung-Russell (HR) diagram, globular clusters show a main-sequence turnoff that is lower and to the right, not high and to the left. This is because their stars are old and of lower mass, so their main-sequence stars are not hot and massive (which would appear high and to the left). Thus, the statement that their main-sequence turnoff is high and to the left is also incorrect.
However, the most clearly incorrect statement is “You cannot find white dwarfs in globular clusters.” In reality, white dwarfs are commonly found in globular clusters. These stellar remnants are the end stage of low- to intermediate-mass stars, which dominate in these clusters due to their age. Over billions of years, many stars have already evolved off the main sequence and ended their lives as white dwarfs.
Thus, the correct answer is:
👉 You cannot find white dwarfs in globular clusters — FALSE.