Speculations on a Neutron Star

Could life use other types of energy beside electromagnetic radiation?

Artist's conception of a neutron star. (Casey Reed, Penn State University)

In a recent paper published in The Astrophysical Journal, a research team led by Bettina Posselt from Pennsylvania State University reported an unexplained heat signature around the neutron star RXJ0806.4–4123.

Neutron stars are the collapsed cores of massive stars. Only 10 to 20 kilometers in diameter, they have enormous gravitational and magnetic fields— so strong, in fact, that electrons are ripped from their nuclei, and protons and neutrons come in close proximity. In such a bizarre environment, the strong nuclear force is dominant, not the electromagnetic force that predominates in our own part of the universe.

The infrared (heat) emissions detected near RXJ0806.4–4123 with the Hubble Space Telescope are puzzling, because they are much stronger than what we’d expect based on the observed optical and ultraviolet emissions from neutron stars. Posselt and colleagues offer two explanations. The infrared excess could be due to particles accelerated by the neutron star’s huge magnetic field (“a pulsar wind,” so to speak). Or we could be observing a supernova fallback disk— remnant dust from the neutron star’s formation that is heating up the star and slowing its rotation.

Both possibilities are tantalizing, but what does it have to do with life? Long ago, forward thinkers like Gerald Feinberg and Bob Shapiro suggested that life on a neutron star could be based on the strong interaction (strong nuclear force) rather than electromagnetic energy. Malvin Ruderman from Columbia University even surmised that magnetic forces might reshape “normal” atoms into strange configurations exhibiting long, polymer-like chains in which the nuclei lie along a central line and the electrons occupy elongated bands. Magnetically formed polymers could then align to form larger structures.

These are quite fanciful speculations, of course, and even though they help us envision how dynamic complexity can be established, they most likely have nothing to do with life.

Still, neutron stars might have planets. And life on such a planet could use the extremely strong magnetic field of its star as a primary energy source. On Earth, visible light plays that role, because of the power output of our Sun, a G dwarf star. But life on our planet is still sensitive to magnetic fields—pigeons, for example, find their way by orienting themselves using Earth’s magnetic field.

The energy available from magnetic fields on Earth is much lower than the energy available from visible light, but the situation is reversed near a neutron star. Could life on such a planet harvest the massively powerful magnetic field of a neutron star? It’s an intriguing idea.

There might be other explanations for the infrared excess seen around RXJ0806.4–4123. It could be the signature of a Dyson’s sphere, a hypothetical megastructure constructed by a technologically very advanced civilization that has figured out how to capture a large percentage of its star’s power output. Brooks Harrop and I have shown that a single, giant structure of this kind is not possible, as it requires too much matter to build and too much energy to stabilize. But other versions, with many smaller satellites harvesting the energy of a star, would be possible in theory.

One thing is certain, in this fanciful scenario: A neutron star would have enormous energy to offer.

About Dirk Schulze-Makuch
Dirk Schulze-Makuch

Dirk Schulze-Makuch is a Professor at the Technical University Berlin, Germany, and an Adjunct Professor at Arizona State University and Washington State University. He has published seven books and nearly 200 scientific papers related to astrobiology and planetary habitability. His latest book (2017) is The Cosmic Zoo: Complex Life on Many Worlds.

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