Context:

Recently, astronomers observed a star called M31‑2014‑DS1 in the Andromeda Galaxy collapse directly into a black hole. This is the clearest evidence yet of a star disappearing without a supernova explosion.

How a Star Collapses:

• • • Stars are like a balance between two forces:
      • Outward Pressure: From nuclear fusion in the core (hydrogen turning into helium).
      • Inward Pull: From gravity.
    • When a massive star runs out of fuel, the outward pressure stops. Gravity takes over, and the star’s core collapses.

Different Outcomes for Stars:

• • • What a star becomes depends on the mass of its core:
      • White Dwarf: If core < 1.4 times the Sun’s mass (Chandrasekhar Limit).
      • Neutron Star: If core is 1.4–3 times the Sun’s mass (TOV Limit).
      • Black Hole: If core > 3 times the Sun’s mass, gravity crushes it completely.

Ways a Black Hole Can Form:

• • • Supernova Explosion: Most massive stars explode, leaving behind a dense core that becomes a black hole.
    • Direct Collapse (“Failed Supernova”): Some stars, like M31‑2014‑DS1, collapse quietly without an explosion. Nearby stars can continue orbiting, as seen in the V404 Cygni Black Hole Triple System.

Parts of a Black Hole:

• • • Singularity: The center with infinite density.
    • Event Horizon: The point of no return; nothing can escape.
    • Accretion Disk: Gas and dust around a black hole emit X-rays, helping scientists detect it.

Recent Discoveries:

• • • Gaia BH3: A black hole 33 times the Sun’s mass in the Milky Way.
    • Sagittarius A: The supermassive black hole at our galaxy’s center.
    • Event Horizon Telescope (EHT): Took the first picture of a black hole’s shadow in 2019.

Why It Matters:

This discovery shows that black holes can form without a huge explosion, confirming theories about “silent” star deaths. It helps scientists understand how stars die, how black holes form, and how our universe evolves.