Two New Discoveries

Two discoveries occurred this month: one confirmed a way to make basic particles, another found out that the misnomer “planetary nebula” may not be such a misnomer after all.

Physicists at the Cornell Electron Storage Ring accelerator said they saw the subatomic particle “charmed-strange meson” decay into a proton and an anti-neutron. This is news because they’ve never seen this happen before, though it has been predicted. Seeing it happen in this direction means it could have happened the other way. This gives physicists new clues on how the universe formed, and how particles first came together.

“It’s the sort of thing that, for many years, people have known should happen,” said John Yelton, a physicist at the University of Florida, one of many institutions that are part of the collaboration. “What we have done is show that it does, and how often.”

The accelerator smashes electrons with positrons at extremely high energies (3-5 billion electron volts; an electron volt is the kinetic energy gained by an electron passing through a potential difference of one volt). This produces rare and short-lived particles physicists can then study.

I love the particle physics discoveries. If you think of physics as the science that gets at the bottom of it all, then particle physics is one of the true fields in physics that still tries to tear apart the world into its composite parts. Do you think we’ll ever find the last indivisible particle? Or do you think that going smaller is just as infinite as space and every time we think we’re at the end, there’s more there to split?

At the other end of the spectrum, astronomers now believe that small stars and even Jupiter-sized planets are actually responsible for those beautiful planetary nebulae. Those planetary nebulae that for years and years we have been told have nothing to do with planets. The name “planetary nebulae” was given hundreds of years ago, but even in the 19th century astronomers realized they were only large clouds of dust, but by then it was too late and the name had stuck.

In a paper in Astrophysical Journal Letters, researchers at the University of Rochester say that planets orbiting a dying star may be the things responsible for creating the appearance of the nebulae (“pillars of creation”).

“Few researchers have explored how something as small as a very low-mass star, a brown dwarf, or even a massive planet can produce several flavors of nebulae and even change the chemical composition of the dust around these evolved stars,” says Eric Blackman professor of physics and astronomy at the University of Rochester. “If the companions can be this small, it’s important because low-mass stars and high-mass planets are likely quite common and could go a long way toward explaining the many dusty shapes we see surrounding these evolved stars.”

Most stars, when they die, will end as nebulae. The bigger ones end up as black holes, pulsars or neutrons stars, or fizzle out as brown dwarfs if they’re too small. When the star runs out of fuel, the core contracts and its envelope expands, throwing its “envelope” out into space. This is what we are made of: star stuff. That’s how larger elements are created, within stars. Then when a star exploded like that, those elements get flung out into space to be collected in a new solar system, like ours.

In their research, Blackman showed that when the planet in orbit with the star is in a wide enough orbit, the planet’s gravity begins to drag some of the star material around with it. Blackman says it looks a lot like a twisted wagon wheel. Eventually a torus of this dust forms, like this: Dumbbell Nebula.

The team is now calculating for more models with more precision to better map out what astronomers see in nebulae. It might turn out that most of the patterns we now see in planetary nebulae are actually from planets.