Exoplanets

Nothing could be more thrilling than to help discover a planet orbiting a distant star.

When we think about detecting these exosolar planets, we imagine powerful instruments like the Hubble Space Telescope keeping an unblinking lens on the heavens, or teams of astronomers in great observatories studying their computer screens.

That’s how most of the 400 or so exoplanets known so far were found and verified. But, surprisingly, the field is open to amateur astronomers too.

Cindy Foote is by far Utah’s most accomplished exoplanets finder. She was working an exo project when a few others and I were guests of her and her husband, Jerry, at their home observatory in Kanab.

Despite a problem with my equipment, those three days and nights in October at the Vermillion Cliffs Observatory were the most pleasant extended astrophotography session of my life. We had balmy skies, excellent company, fine and friendly discussions about topics like global warming, exceptionally kind hosting and delicious homemade meals.

Cindy Foote is cited as co-author of scientific papers announcing exoplanet discoveries. But as her team is sworn to secrecy about ongoing research, she could not tell me what the team was up to currently.

She works with the XO Project, led by Peter McCullough of the Space Telescope Science Institute, the organization controlling the Hubble Space Telescope. According to a presentation she prepared, most of the expenses are paid by a NASA grant and a discretionary fund managed by the institute director. Other team members are six additional professional astronomers and about 11 amateurs worldwide.

On Maui, the XO Observatory monitors “tens of thousands of bright … stars twice every ten minutes on clear nights for more than two months per season of visibility of each particular star,” according to the team. The telescopes note stars whose light output seems to dim periodically; these are candidates for stars whose planets pass between themselves and Earth.

The amateurs then screen candidate stars to weed out flukes and identify which should be studied with follow-up observations using other methods.

Cindy Foote and others will carefully track candidates, taking hundreds of photographs through their telescopes and comparing the stars’ light against that of nearby stars. If they are lucky, they detect a dimming of the starlight when the exoplanets passes in front.

This is a demanding task. On the night of May 30-31, 2006, she captured her first exoplanet light curve by taking 500 guided photographs through her automated telescope, each of one minute duration. The record shows a sharp dip in starlight as an exoplanets moved in, a rise as it cleared away, and then the star’s normal output.

“Amateurs can contribute,” Cindy Foote concluded, but it “takes a lot of work and dedication.”

Her advice for anyone interested in the planet pursuit is to find a mentor, surround oneself with people who are more experienced, join organizations that promote professional-amateur collaboration, and engage in the work.

Patrick Wiggins, NASA solar system ambassador to Utah, is one of those who help with the search for exoplanets. He made trips to Kanab to learn the art, and has the light curves to prove he learned it well.

On Nov. 20, Wiggins recorded the light changes wrought by an exoplanet dubbed WASP-10b. During a 3 hour-session, while he made dozens of photographs, the starlight dropped from its ordinary magnitude of about 12.01 to about 12.05 and then returned to the previous level. A chart of the light curve leaves little doubt about what happened. He said it was “neat” to record the passage of a Jupiter-size planet across its star at the distance of 300 light-years.

[The dimming of starlight recorded by Patrick Wiggins when a planet passed in front of the star]

“It’s an ego boost, especially when your data gets published,” Wiggins said. “And I like the idea that it’s useful.”

With instruments available today, exoplanets that can be detected from Earth are usually big and hot. Many are the size of Jupiter or much larger. They orbit close to their stars; if they were farther away, it would take a longer observing period to confirm their presence — years or decades.

“None of them were anything you’d want to live on,” he said.

But the abundance of exoplanets found in the past few years indicates others are “out there and they’re out there in great numbers.”

The most advanced exoplanet search is carried out by the Kepler probe, a space telescope examining a patch of 100,000 stars in the Cygnus and Lyra regions — minus 9,000 stars that were recently rejected as too variable. Kepler can detect Earth-like planets orbiting sun-like stars, but confirming planets requires three orbits. If they are Earth-like they would be orbiting about as far from the star as we are from the sun, requiring a year per orbit.

If Kepler detects these small planets in the habitable zone of Sol-like stars, their spectra may show evidence of life processes. “That’s going to be the quintessential discovery, second only to making contact,” Wiggins.

Don’t expect these results tomorrow, however.

A NASA website explains, “[I]t will require a minimum of 3 years (and likely longer) to find an Earth-like planet in the habitable zone, and confirm the observations with 3 transits. Kepler launched in 2009, and the soonest we anticipate announcing an Earth-like planet orbiting a Sun-like star would be sometime in 2012-2013.”

Meanwhile, amateurs like Cindy Foote and Wiggins are already helping to discover large planets circling distant stars.

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