The lives of stars: Ashes to ashes, dust to dust, nebula to nebula

Wittenberg prof continues program ahead of total solar eclipse April 8.

Credit: Bill Lackey

Credit: Bill Lackey

When it’s time to add a sweet topping to our peanut butter Rice Krispies bars, we turn the heat on under a pot, add semi-sweet chocolate and butterscotch chips, then stir.

Under the influence of heat, the chips melt away, their flavors freed to recombine in a way that could not occur at room temperature. In the oven at the sun’s core, with temperatures up to 27,000,000 degrees Fahrenheit and pressure tens of thousands of times greater than Earth’s atmospheric pressure, hydrogen and helium undergo a similar transformation.

Solids, liquids and gases give way to a state of matter called plasma, and atoms come apart like Lego pieces in a tornado.

In the main maelstrom, the atomic parts collide and combine with complementary bits.

When that happens — when the parts fuse like Legos locking together — interesting things happen: New matter is created, energy is released and all of existence hits the Powerball lottery.

Credit: Bill Lackey

Credit: Bill Lackey

Although the mass lost in the creation of each new Lego is tiny, the energy given off by its production is huge, following the formula E = mc squared.

The E represents the amount of energy created. To get that total, we start by taking the mass lost in the production of each new Lego assembly and multiply it by a constant called “c”. But, get this, the constant c is the speed of light — 3 times 10 to the eighth power or 186,500 miles per second.

As though that multiplier alone weren’t enough to run us out of numbers, the product of the mass times the speed of light is then multiplied not by 10, 100, 1,000 or a million, but by itself (again)! That’s right, it has to be squared so that it can express the incredible amount of energy created.

As dramatic as the numbers, says Dan Fleisch, professor emeritus of physics at Wittenberg University, is the scale at which this happens.

“The sun is converting millions of tons of hydrogen into helium every second,” he said.

The result: “4 times 10 to the 26th power joules of energy every second – that’s 400 milllion billion billion watts of power.”

For hockey and soccer fans, Fleisch offers this offers this illustration: “One gram of mass (about the weight of paperclip) makes about as much energy as 300 billion shots on goal by a world-class athlete.”

GOOOOOAAAAAAALLLLL!!!!!

Still, Fleisch adds, if the energy produced by this process couldn’t ride to earth in the form of a stream of photons,” the sun would be doing its thing but we would be frozen solid.”

So, how does that happen?

In the core of every internal combustion car’s alternator, spinning magnets are surrounded by coils. The magnets create a magnetic field and spinning them creates an electrical field adjacent to it. Coils absorb energy from the electrical field and route it to the car’s electrical system so it can spark the spark plugs, light the headlights and charge the battery.

Well, every photon of light departing from the surface of the sun is an “electromagnetic wave” made up of electric and magnetic fields that change over time and space. These fields repeat without interruption for the 8-plus minutes it takes a photon to cover the 93 million miles to the Earth — and goes on longer if it misses earth and heads for someplace like Saturn.

In their dash to our door, photons deliver not only every bit of sunshine we’ll ever see — let’s call that a pizza — but also extra toppings that include ultraviolet and infrared light, X-rays and radio waves.

And we don’t even have to have the coupon or fork out a tip.

Now a look at other stars.

Space accountants seem lightyears away from a solid estimate on the number of stars in our galaxy let alone our universe. Estimates for the Milky Way — from 200 billion to 400 billion — seem as reassuring as the prediction that the next person you see will have either one or two noses.

Before taking away their kevlar pocket protectors, however, we might entertain that the current state of affairs says more about the revolutionary eye-opening nature of the Hubble and James Webb space telescopes than the faults of astral accountants.

In this revolutionary time, one rule of thumb still applies to stars: The hotter they burn, the sooner they burn out.

At its surface (not a solid crust, just a “photosphere” from which light shines), a yellow-dwarf star like our sun burns at a modest 10,000 degrees Fahrenheit. That’s a candle in the solar wind to a stunning electric blue star’s 50,000 degrees. To their great credit and our benefit, stars that have more mass and higher temperature than the sun manufacture the elements essential to life on Earth. In contrast, our sun’s legacy will be a lump of carbon. Well, that and all the products of our existence.

The tradeoff is that a hot, massive star’s time on the main sequence —the prime of its life — lasts only about 10 million years. Although that’s a lot of birthdays, it’s just a few percent of the sun’s 7- to 10-billion-year life expectancy. Cooler, lower mass stars can last 100 billion years or more, many times the current age of the universe.

But the life cycles of all stars have certain similarities.

They begin in the creative dust and mist of giant nebular clouds. These wombs of stars are the recycling center of universe, where the leftovers of previous generations of stars and planets are drawn together.

The word nebulous perfectly describes the disorganized state of matter in the clouds. But that doesn’t prevent them from becoming what Fleisch describes as “the most gorgeous structures” in the universe, the thunderstorms of galaxies.

Gravity being what it is, atoms within the clouds are attracted to other atoms, molecules to molecules and clumps to clumps. For those clumps, Fleisch says, “it’s a case of the rich getting richer.” Having greater density and gravity than the clumps around it them, the big clumps draw in matter like Oscar winners draw audiences. Some of those large clumps gain enough mass to become proto-stars, often orbited by smaller clumps that become proto-planets.

After about 50 million years, a protostar with about the mass of the sun lights up nuclear burning in its core, and matures onto the main sequence where it will spend the majority of its life.

During that prime time, the gravity that holds the star together and the pressure caused by thermonuclear burning in the furnace of its core is in balance like the outward pressure of the air inside a fully inflated basketball and the inward forces provided by its leather shell. And while that balance can be maintained for millions or even billions of years, its internal flames are not eternal flames.

Fleisch said that as it fuel runs out, our sun will “produce a core of pure carbon with a little helium and unburned hydrogen around it.

“That core of carbon is not burning, which causes a fundamental disturbance in the force that has sustained the sun. As a result, the core collapses, then blows out its outer layers, which become a “planetary nebula” — a cloud of dust originally thought to be a proto-planet but now known to be the material ejected by a dying star like the sun. The carbon core left behind by this process becomes a glowing ember that astronomers call a white-dwarf star.

Larger stars hot enough to burn metals have a slightly different and much more violent fate.

To the sun’s core of carbon, the larger hotter burning stars will add additional metals that oxygen, neon, magnesium, and silicon, which surround the carbon core “like the layers of an onion,” Fleisch said.

That happens until the star’s core is converted entirely into iron, which cannot produce energy by nuclear fusion.

Unable to produce outward pressure, the core collapses and produces a violent explosion called a supernova, causing the dying star to briefly outshine the hundreds of billions of other stars in its galaxy. The dust cloud produced by this process seeds the universe with the raw materials that will collect in the next nebula, and those nebulas will produce the next generation of stars and planets. This is how the Earth inherited its metals.

Of course, we have much more to learn about the details of the birth, life, and death of stars.

But, for now, let’s entertain one more thought.

While the life story of a star has a familiar ring — ashes to ashes, dust to dust and nebula to nebula — we would be wrong to overlook the main sequence in which stars are in their elements, lighting up the universe and giving life a chance to take advantage of the Powerball ticket it was lucky enough to hit.

Next Sunday: Planets.

The second in a series by Tom Stafford.


Wittenberg University Professor Dan Fleisch, adviser to this series, will give a free companion on talk on stars at 1 p.m. today at Wittenberg University’s Weaver Observatory. Presentations on “Planets” and “Cathedrals as Solar Observatories” will follow on March 24 and March 31. The Main Branch of the Clark County Library, the Westcott House and the Springfield Museum of Art also are hosting displays Fleisch created about the solar system. Fleisch also will present “Eclipse Tips and Safety recommendations in separate presentations a 1 p.m. Saturday, April 6 and Sunday, April 7 at Weaver Observatory. All are part of the university’s WittClipse project, which will culminate with an event that will be held from 11 a.m. to 4 p.m. eclipse day, April, 8, weather permitting, at Edwards-Maurer Field. For information about eye safety during the eclipse go to https:/eclipse.aas.org.safety.

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