Neutron Stars, Pulsars, and Magnetars

By Jeet Parikh

Image Credit: Wikimedia Commons @ ESO/L. Calçada

In the Milky Way galaxy alone, there are about 300 billion stars. That is 300,000,000,000, for scale. With an estimated 125 billion galaxies in the observable universe, the total number of stars is hard to fathom. When the largest of these stars die, gravity pulls the star’s entire mass inwards, creating a massive explosion called a supernova, many of which can outshine entire galaxies. During this process, the force of gravity is so powerful that electrons and protons fuse into neutrons, which are further compressed into pure nuclear matter. What is left is known as a neutron star.

Neutron stars are unimaginably extreme. The nuclear matter that makes up these stars is so dense that just a small object would weigh billions of tons. Due to this immense mass, neutron stars produce some of the strongest gravitational forces, second only to black holes. Their surfaces reach an astonishing 1,000,000 degrees Celsius. For comparison, our Sun only touches about 6,000 degrees Celsius. Most neutron stars observed today generally spin wildly and are called pulsars or magnetars.

Image Credit: Wikimedia Commons @ University of Warwick/Mark Garlick

Pulsars are spinning neutron stars with intense gravitational fields. The fields funnel and eject particles from the magnetic poles of the stars. This creates periodic pulses of radio waves. These pulsars are the most common type of neutron star. Other neutron stars, called magnetars, contain particularly large magnetic fields, some of which can be a quadrillion times larger than that of the Earth’s magnetic field. The beams produced by magnetars are so massive that a recent burst released more energy than the sun has emitted in the last 100,000 years (NASA).

Finally, when two neutron stars are orbiting each other, their orbits gradually decay, and they collapse together. This results in a kilonova explosion, where the conditions are so extreme that atoms are ripped apart into protons and neutrons and quickly reassembled with other neutrons and protons. This phenomenon is how many rare metals like platinum and gold are created.

Citations:

https://www.discovermagazine.com/the-sciences/how-many-galaxies-are-there-astronomers-are-revealing-the-enormity-of-the

https://www.livescience.com/neutron-star.html

https://www.nasa.gov/missions/deepspace/f_magnetars.html

https://imagine.gsfc.nasa.gov/science/objects/neutron_stars1.html

Images:

No changes were made, https://commons.wikimedia.org/wiki/File:Artist%E2%80%99s_impression_of_the_magnetar_in_the_extraordinary_star_cluster_Westerlund_1.jpg , License: Creative Commons — Attribution 4.0 International — CC BY 4.0

No changes were made, https://commons.wikimedia.org/wiki/File:Eso1733s_Artist%27s_impression_of_merging_neutron_stars.jpg , License: Creative Commons — Attribution 4.0 International — CC BY 4.0

What Did You Learn?

Questions:

What is a neutron star?

When the largest stars of the universe die, gravity pulls the star’s entire mass inwards, causing a massive supernova explosion that can outshine entire galaxies. During this process, the force of gravity is so extreme that electrons and protons fuse into neutrons, which are further compressed into pure nuclear matter. This is known as a neutron star.

What are pulsars and magnetars?

Pulsars are spinning neutron stars with intense gravitational fields. The fields funnel and eject particles from the magnetic poles. This creates pulses through beams of radio waves every time they spin. These pulsars are the most common type of neutron star. Magnetars are neutron stars with an even larger magnetic field. Their fields are a quadrillion times larger than that of the Earth. The beams produced by magnetars are so massive that a recent burst released more energy than the Sun has emitted in the last 100,000 years.