Extreme Cosmic Physics
Do not go gentle into that good night. Rage, rage against the dying of the light! — Dylan Thomas
What happens to massive stars as they near the end of their lives? Some go supernova, generating one of the most powerful explosions in the universe. The fiery fury of a supernova releases more energy in a few seconds than our star, the sun, will generate in its entire 10-billion-year lifespan.
The aftermath leaves behind the core of the old star, now a neutron star. These neutron stars are so dense that a teaspoonful of this matter would weigh a billion tons. One NASA scientist described it as taking Mount Everest and squeezing it into the size of a sugar cube. Only about ten percent of neutron stars with exceptionally strong magnetic fields become magnetars. These are some of the most puzzling objects in the cosmos with a magnetic pull trillions of times stronger than the Earth’s magnetic field.
But now a unique star discovered over a century ago may shed new light on how magnetars form. This star, HD 45166, is 3000 light-years from Earth with a mass twice that of our Sun. According to a study published in the journal Science in August 2023, Tomar Shenar and his team found that HD 45166 has the strongest magnetic field of any known star, 43,000 times stronger than our Sun. Do stars like these become magnetars after they go supernova?
The magnetic fields of magnetars are so strong they can distort atoms and can crack the star’s crust, leading to “starquakes.” These starquakes, along with the overall magnetic activity, can cause the magnetar to emit high-energy electromagnetic radiation, like X-rays and gamma rays.
All neutron stars rotate rapidly on their axes, with some of them spinning at an incredible rate of hundreds of times a second. Magnetars rotate more slowly than regular neutron stars, with rotation periods ranging from one to ten seconds. This difference in rotation rate is one of the distinguishing features between magnetars and other kinds of neutron stars. Their strong magnetic fields may brake the rotational speed of magnetars. In comparison, our Sun, which rotates much more slowly, takes about 25 days at its equator and up to about 35 days near its poles to complete one rotation.
Astronomers think the extreme magnetic field of a magnetar decays relatively quickly over time, and the intense radiation fades. The active lifetimes of magnetars only span thousands to tens of thousands of years, a blink of a cosmic eye. They live fast and die young.
Astronomers hypothesize the highly magnetic environments of magnetars could cause some Fast Radio Bursts (FRBs). These FRBs are intense bursts of radio waves that last for just a few milliseconds but release an enormous amount of energy.
Our last post Unraveling Cosmic Mysteries: The Fascinating Discovery of FRB 20220610A explored these are intriguing cosmic puzzles. If a starquake or a giant flare occurs, a magnetar could release a burst of energy that includes radio waves detectable over vast intergalactic distances. In 2020, astronomers linked an FRB to a known magnetar within the Milky Way, strengthening the case for this theory of FRB origin.
Despite our growing understanding, magnetars remain mysterious objects. They represent an extreme state of matter and an opportunity to study the laws of physics under conditions that are not possible on Earth. Each new observation of magnetars and their behaviors contributes valuable data that can help us unravel the enigmatic nature of these cosmic powerhouses. The physics of magnetars stars reveals much about the behavior of matter under extreme conditions, making them a fascinating subject of study in astrophysics. As the noted astronomer Carl Sagan said, “Somewhere, something incredible is waiting to be known.”
Next post is on February 16th.