📘 Q.1 IAS Prelims 2024 — Science & Technology (Stellar Evolution)

🧷 Authentic Classroom Explanation by IAS Monk


📌 The Question:

Consider the following statements:

Statement–I: Giant stars live much longer than dwarf stars.
Statement–II: Compared to dwarf stars, giant stars have a greater rate of nuclear reactions.

Which one of the following is correct in respect of the above statements?

(a) Both Statement–I and Statement–II are correct and Statement–II explains Statement–I
(b) Both Statement–I and Statement–II are correct, but Statement–II does not explain Statement–I
(c) Statement–I is correct, but Statement–II is incorrect
(d) Statement–I is incorrect, but Statement–II is correct


Answer: (d)


🧑‍🏫 Classroom Explanation:

A star’s lifetime is governed not just by how much fuel it has, but by how fast it burns that fuel.

🔹 Giant stars are much more massive than dwarf stars.
🔹 Their cores are hotter and denser, leading to a much higher rate of nuclear fusion.
🔹 As a result, they consume their nuclear fuel very rapidly, despite having more of it.

Therefore:

  • Statement–I is incorrect
    → Giant stars do not live longer; they live shorter lives.
  • Statement–II is correct
    → Giant stars indeed have higher nuclear reaction rates.

👉 Hence, option (d) is correct.


🔍 Curiosity Raiser:

💫 Why do the biggest stars die the fastest?
Because in stellar physics, power comes at a price — massive stars burn like raging furnaces, not slow lamps.


📚 Enrichment Notes (UPSC Edge):

  • Dwarf stars (like our Sun) burn fuel slowly and can live billions of years.
  • Massive giant stars may live only a few million years.
  • Giant stars often end their lives as:
    • Supernovae
    • Neutron stars
    • Black holes
  • This concept is called “mass–lifetime inverse relationship” in stellar evolution.

🧘 IAS Monk Whisper:

🌌 In the universe, longevity belongs not to power, but to balance.
Stars teach us that burning slowly often takes us farther.

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