What is the Chandrasekhar limit? A. the maximum mass that a black hole can contain B. the maximum density of a black dwarf star C. the maximum mass of a white dwarf star D. the minimum density of a black hole

Stars, like humans, have life cycles. Stellar evolution refers to the process by which a star changes over the course of time. This journey is driven by the principles of nuclear fusion and is determined by the star's initial mass.
Here's a brief overview of stellar life stages:

• **Stellar Nebula**: A cloud of gas and dust where stars are born.
• **Protostar**: Formed from collapsing gases in the nebula.
• **Main Sequence Star**: Where a star spends most of its life, fusing hydrogen into helium.
• **Red Giant/Supergiant**: Occurs when the star runs out of hydrogen in its core.
• **End Stages**: Depending on the mass, a star can become a white dwarf, neutron star, or black hole.

Our Sun will one day become a white dwarf star, but more massive stars can end in spectacular supernovae and potentially form black holes or neutron stars.

Stars come in various sizes and masses, which significantly impact their lifecycles. The mass of a star determines how hot and bright it will be, as well as its fate.
Here are key points about mass limits:

• **Low-Mass Stars**: Less than 8 solar masses. They typically end up as white dwarf stars after shedding outer layers.
• **Intermediate-Mass Stars**: Between 8 and 25 solar masses. These stars usually end in supernovae, leaving behind neutron stars.
• **High-Mass Stars**: Greater than 25 solar masses. They often explode as supernovae and can form black holes.

One fundamental mass limit in astrophysics is the Chandrasekhar limit. It specifies the maximum mass (approximately 1.4 times the mass of our Sun) that a white dwarf can have before collapsing into a denser state, like a neutron star or black hole.

A white dwarf is the remnant of a low to medium mass star that has exhausted its nuclear fuel. These remnants are incredibly dense and hot but will gradually cool over time.
Key characteristics of white dwarf stars include:

• **Density**: They pack a mass comparable to the Sun in a volume similar to Earth.
• **Size**: White dwarfs are quite small but incredibly dense.
• **Temperature**: Initially very hot, but they cool down as they age.

The Chandrasekhar limit is critical when studying white dwarfs. It's the threshold of 1.4 solar masses, beyond which the white dwarf cannot support itself against gravitational collapse using electron degeneracy pressure. This limit is named after the astrophysicist Subrahmanyan Chandrasekhar, who discovered it in 1930. Understanding this helps astrophysicists predict the fate of stars and the evolution of binary systems where stars can transfer mass to one another.