HAT-P-10b: Light, Cold Planet with Two Names

ASTRO LINK EXCLUSIVE
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Two teams of scientists have discovered one of the lightest and coldest transiting planets to ever be discovered orbiting a star outside our solar system, but there may be some disagreement about who gets credit for its discovery, or what its fundamental properties might be.

Transiting planets are those that appear to cross the disk of their parent star, as observed from earth. They are important because they reveal the physical properties of planetary atmospheres. As the planets pass across the face of the star, light from the star becomes absorbed by the planet's atmosphere. By measuring which wavelengths of light are absorbed, and which are scattered, scientists can determine the chemical properties of that planet.

Transiting planets can also be used to measure the "wobble" of a parent star, thus revealing characteristics about the planet's orbit, which in turn can be used to understand the planet's basic properities, such as whether it is made up of rock, ice or gas.

The newly discovered planet is a gas giant that orbits around a very cool K-dwarf star every 3.72 earth days. From earth, the K-dwarf star appears moderately bright (v=11), making follow up studies of this system easy in the future.

The European team that first discovered the planet (R. G. West et al) calls it "WASP -11b," after the SuperWASP survey that found planet. They say the planet seems to be less than 1-2 billion years old, though acknowledge that the measurement is "poorly constrained" and that the planet may be much older. In comparing their data to current models of planetary evolution, West and his team say the planet has a dense core.

The SuperWASP survey uses two identical 2-meter telescopes, one pointed to the Northern sky in La Palma, Spain, and another pointed at the Southern sky in Sutherland, South Africa.

However, U.S. observations with the HATNet survey, which has access to a larger telescope, show the gas giant planet is probably around 4.5 billion years old and entirely made up of hydrogen and helium, with no core at all.

The HATNet survey uses six wide-field instruments (four in Arizona and two in Hawaii), then follows up on the most promising candidates with the 10-meter Keck I telescope in Hawaii.

The HATNet team (G. ´A. Bakos et al) wants to claim credit for the newly discovered planet and call it "HAT-P-10b," saying that although the SuperWASP team published a press release about the discovery in April 2008, they did not publish such basic details about the planet, such as its coordinates or parameters.

However, the SuperWASP team recently submitted their findings to the European journal "Astronomy and Astrophysics" on Sept. 17th, almost a week before the HATNet team, which just submitted their paper Sept. 24th.

Some astronomers familiar with both discoveries scold the WASP team of holding on too tightly to their data. They say they should have released their peer-reviewed science paper with the press release, as is common practice in the research field.

But SuperWASP supporters say the publishing process takes too long and the scientific community benefits from the rapid release of information. Besides, they say, history shows peer-review of science is no guarantee of accuracy or quality.

Whether the planet will ultimately be known as WASP-11b or HAT-P-10b is still to be determined. Despite the different acceptance dates for each paper, both were made public simultaneously on Sept. 26th.