The most extreme magnetic fields come from what?

The most extreme magnetic fields come from what?

• A. Red giants
• B. White dwarfs
• C. Black holes
• D. Neutron stars

Answer: (D)

Magnetic fields get amplified when a star collapses, so the strongest fields appear in neutron stars, especially magnetars. During collapse, the stellar radius shrinks dramatically while magnetic flux is roughly conserved, so the field strength rises by many orders of magnitude. Red giants have relatively weak fields because their large size doesn’t concentrate magnetism, and even though white dwarfs are compact, they are larger than neutron stars, so their fields are strong but not as extreme. Black holes don’t have their own intrinsic surface magnetic field in the same way; any field is due to surrounding material rather than the hole itself. Neutron stars end up with the most extreme fields, with magnetars reaching about 10^14 to 10^15 Gauss.

Magnetic fields get amplified when a star collapses, so the strongest fields appear in neutron stars, especially magnetars. During collapse, the stellar radius shrinks dramatically while magnetic flux is roughly conserved, so the field strength rises by many orders of magnitude. Red giants have relatively weak fields because their large size doesn’t concentrate magnetism, and even though white dwarfs are compact, they are larger than neutron stars, so their fields are strong but not as extreme. Black holes don’t have their own intrinsic surface magnetic field in the same way; any field is due to surrounding material rather than the hole itself. Neutron stars end up with the most extreme fields, with magnetars reaching about 10^14 to 10^15 Gauss.