Question 1: Define a nebula and explain its role in star formation.

Answer: A nebula is a vast cloud of gas and dust in space where new stars are born during gravitational collapse.

Question 2: Describe the process by which a protostar evolves into a main-sequence star.

Answer: A protostar forms from collapsing gas and dust; as nuclear fusion ignites in its core, it becomes a main-sequence star.

Question 3: What is a supernova and how does it relate to the formation of a black hole?

Answer: A supernova is a massive explosion of a dying star; if the remnant's core is sufficiently dense, it can collapse into a black hole.

Question 1: Calculate the approximate luminosity of a star with a radius of 1.5 times that of the Sun and a surface temperature of 6000 K. Use the Stefan-Boltzmann Law: L = 4πR^2σT^4. (σ = 5.67×10^-8 W/m^2K^4)

Answer: Luminosity ≈ 2.66×10^26 Watts

Question 2: If a star has a mass of 10 times the Sun's mass, estimate its lifespan on the main sequence using the relation: lifespan ∝ 1/M^2, where M is mass in solar masses. Given the Sun's lifespan is about 10 billion years.

Answer: Lifespan ≈ 1 billion years

Question 1: Outline a theoretical experiment to observe the effects of supernova explosions on surrounding space. Include variables to measure and safety precautions.

Answer: An experiment could involve simulating supernova shockwaves in a controlled environment using high-energy lasers or plasma chambers, measuring variables like shockwave speed and energy dispersion, while ensuring safety protocols for high-energy equipment and radiation shielding are followed.

Question 1: A star's core collapses after exhausting its nuclear fuel. Describe the sequence of events leading to the formation of a black hole based on observational data of supernova remnants.

Answer: The core collapses under gravity, causing a supernova explosion; if the remnant core's mass exceeds the Tolman–Oppenheimer–Volkoff limit (~3 solar masses), it continues collapsing into a black hole, observable through X-ray emissions and gravitational effects.

Question 1: Explain the processes involved in a star's transition from a main-sequence star to a supernova and subsequently to a black hole, highlighting the key differences at each stage.

Answer: A star remains stable during its main-sequence phase by fusing hydrogen into helium. When hydrogen is exhausted, it expands into a red giant or supergiant. Massive stars then undergo supernova explosions; if the remnant core's mass exceeds a certain limit, it collapses into a black hole, involving intense gravitational forces and event horizon formation.

Question 1: Discuss how knowledge of stellar evolution has contributed to advancements in astrophysics technology, such as telescopes and space probes.

Answer: Understanding stellar evolution has led to the development of powerful telescopes and space probes that allow detailed observation of stars and supernovae, improving our knowledge of the universe and enabling technologies like adaptive optics and spectroscopy.