Artist's rendition of a supposed black hole. Credit: ESO/L. Calçada/M.Kornmesser.

Blowing Hot Air
Jul 21, 2010

When hot air is injected into a cool, lower pressure environment, it expands. Stars appear to be exempt from that rule.

Imagine a soccer ball filled with hot air. Imagine it being punctured on a winter’s day. What do you think will happen? Hot air…cold surroundings…lower pressure…even without knowing Boyle’s Law, one would expect expansion.

Now imagine that the soccer ball is scaled up to the size of a star. Imagine it is a star. Imagine that the hot air is really hot, so hot that it’s ionized, and the winter’s day is as cold and low-pressure as the vacuum of interstellar space. Now what do you think will happen? Um…I’d guess expansion.

Astronomers have found a star in a nearby galaxy that has “collimated jets of fast moving particles” and “a huge bubble of hot gas.” One astronomer compares it to a soccer ball with jets that reach to the orbit of Pluto. The standard model of stars assumes that they are isolated balls of really hot air bound by gravity. The hot air is escaping from this newfound star, and it’s expanding into a bubble. So far, so good.

Unfortunately for the model, the hot air is refusing to expand until it gets hundreds of light-years away from the star. Then suddenly it expands into a bubble a thousand light-years wide that “contains a mixture of hot gas and ultra-fast particles at different temperatures.” Another astronomer remarked, “We have been astonished by how much energy is injected into the gas.”

Obviously, stars blow hot air according to rules that are different from those that govern soccer balls. Maybe, just maybe, it’s not stars that blow hot air, but astronomers. Boyle’s Law may be universally true after all; it just doesn’t apply to stars and their jets and bubbles. Astronomers have used the wrong law to build their model.

After all, stars are not composed of hot air, not even really hot air: they’re composed of plasma. Plasma is electromagnetically active. The fast-moving particles are really ions; their movement is otherwise known as an electrical current. That current generates an inwardly directed magnetic force that constricts the current into a filament—called a jet by plasma-impaired astronomers and a Birkeland current by plasma physicists. Electrical forces accelerate the ions, electrons, and charged dust to different velocities, which astronomers interpret as different temperatures.

If the standard model used the wrong law for the star’s composition and the wrong mechanism for its containment, it’s probably wrong about the star’s energy. With plasma and Birkeland currents, stars cannot be isolated or internally powered.

Moving charged particles must continue moving around a circuit; if they stop, they will quickly build up an electric field that stops the current. The jets are part of galaxy-wide circuits, and the stars are loads on a galaxy’s power grid. The magnetic maps of galaxies trace these circuits. The energy supplied to the bubbles is only astonishing if it must be supplied by the internal resources of the star. It’s a minuscule portion of a galactic generator’s output.

Mel Acheson