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Tiny telescope's big discovery: Saturn-like planet orbiting an unlikely star

The Saturn-like planet has a well-studied cousin – the first alien planet found using the transit approach – to which it can be compared, right down to the makeup of its atmosphere.

By Staff writer / June 4, 2013

Astronomers have discovered a statistical odd-ball of a planet – one orbiting a star most planets its size typically don't call home. And they found it with what's been dubbed "the little telescope that could."

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The planet, about the size of Saturn, orbits a star some 700 light-years away near the constellation Leo. Dubbed KELT-6b, the planet orbits its host star once every 7.8 days. It's the fourth of six discoveries (two of which remain works in progress) by a planet-hunting project called KELT – Kilodegree Extremely Little Telescope.

Yes, in this day and age of the mighty Keck and Very Large Telescopes, the Hubble Space Telescope, and other sizable "light buckets," there is room in the planet-hunting arsenal for "telescopes" whose optics are nothing more than high-end telephoto and wide-angle lenses typically used by professional photographers.

More on that later. First, the planet.

KELT-6b is of special interest because it has a well-studied cosmic cousin – the first extrasolar planet discovered using the transit approach – to which KELT-6b can be compared, right down to the makeup of its atmosphere.

The cousin, a planet called HD209458b, orbits a star 150 light-years away in the constellation Pegasus. It has 220 times Earth's mass and orbits its star once every 3.5 days. Its host star is so bright and close that researchers have been able to detect and begin to describe the planet's atmosphere, right down to the presence of oxygen and a super storm similar to Jupiter's Great Red Spot. Although more distant, KELT-6b's star also is bright enough to allow for similar studies of the planet.

The differences between these two systems hold the promise of providing astronomers interested in the birth and evolution of solar systems with rich insights because HD209458b orbits a metal-rich star, one with a relatively high abundance of elements heavier than hydrogen and helium. KELT-6b's star is among the poorest of known metal-poor stars.

Metal content, at least as astronomers define metal, is important since elements heavier than hydrogen and helium are vital to building the molecules needed for the emergence, care, and feeding of organic life.

The new planet was discovered by Karen Collins, an electronics engineer-turned-astronomy PhD candidate at the University of Louisville and a member of the KELT research team.

As with other extrasolar planet searches, including NASA's Kepler mission, KELT researchers hunt for a planet by detecting the faint dimming that occurs when the planet passes in front of its host star – the transit method.

In this case, the hunt was "really like an adventure," said Ms. Collins at a press briefing Tuesday during the spring meeting of the American Astronomical Society, which runs through Thursday in Indianapolis.

Initially, the data hinted at the presence of a planet. But when the team followed up the discovery using a more-capable telescope and a different planet-hunting technique in an effort to determine the mass of the purported companion, the results came back as no mass.



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