The recent announcement of more than 1,200 worlds whirling around other stars has made us accustomed to the reality of a galaxy chock-full of planets.
But the granddaddy of this ballooning field of research is the blazing star Beta Pictoris, located 63 light-years away in the far southern sky.
In 2009, astronomers photographed a planet near the star. Now, new observations show that the planet is indeed orbiting the star according to laws of planetary motion formulated by Johannes Kepler 400 years ago.
What’s so special about Beta Pictoris? 38 years ago — long before exoplanets were ever discovered — the star got astronomers’ attention because it has an odd excess of infrared radiation (IR) for a star of its temperature.
This was interpreted as the IR glow of a warm dust disk encircling the star. Where there’s dust there could be planets too, astronomers reasoned. The idea is that newborn planets would bump and grind though collisions within such disks of dust.
Simply take a look at our solar system; the moon was born out of a grazing blow by a Mars-sized embryonic planet with the newborn Earth.
A ground-based telescopic photo of Beta Pic that blocked out the star’s glare revealed a pair of spike-like appendages on either side of the star. This was interpreted as an edge-on dust disk.
Beta Pic immediately became the poster child for the possibility of exoplanets. All through the 1980s it appeared in nearly every introductory astronomy textbook and popular space books.
'Battle Among Pygmies'
For the whole of the 80s, the disk’s discoverers jealously guarded their data and sometimes got into spats with other astronomers doing follow-up observations of the star. The debate was always: “who saw what first?” This is a common ground for acrimony and competition in cutting-edge science.
“It is a battle among Pygmies!” a Noble Laureate scoffed. “Show me 50 systems like Beta Pictoris,” he told me at the time, “and then we can put together some real science conclusions.”
Through the 1990s the Hubble Space Telescope fulfilled this prerequisite. It scooped up images of numerous dust disks around nearby stars. Later, observations by NASA’s Spitzer Space Telescope found IR excesses around many young stars.
Hubble even gleaned spectroscopic evidence for a snowstorm of comets whirling around Beta Pic. Soon, crisp Hubble pictures showed there were in fact two disks, perhaps altered by the gravitational tug of an unseen planet. Hubble accomplished far more that anyone could have ever imagined when the Beta Pic disk was first imaged.
Finally, the European Southern Observatory photographed the elusive planet just a few years ago.
Lifeless Giant
The latest observations confirm that the planet is in an elliptical orbit about Beta Pic that stretches from 700 million to 1.3 billion miles.
Despite that distance the planet is hot! That’s partly because the planet must still be gravitationally contracting, and because Beta Pic is nearly 10 times brighter than the sun. The planet is more than 2,000 degrees Fahrenheit, making it a place too toasty for life, as we know it. But that’s really a moot point because the system is far too young for life to be present. The star is less than 20 million years old.
Our incomplete understanding of the origin of life on Earth requires that at least a few hundred million years may have to elapse before chemical reactions somehow make the awesome leap to Darwinian evolution. Even if life does start on the Beta Pic giant, it would never have time to evolve beyond the single cell stage because the star is so short-lived.
So today, the much-lauded Beta Pictoris is like an aging movie star. Once the only celebrity in town, its significance is vastly overshadowed by the plethora of exoplanet discoveries. And, it will never be any place to call home, or much less warrant a visit by an interstellar probe looking for E.T.