Exoplanets Can’t Hide Their Secrets From Innovative New Instrument

Artist's conception of the Kepler-13AB binary star system.

The findings not only classify a Jupiter-sized exoplanet in a close binary star system, but also conclusively demonstrate, for the first time, which star the planet orbits. (Image: Gemini Observatory / NSF / AURA / Artwork by Joy Pollard)

In an unprecedented feat, an American research team discovered hidden secrets of an elusive exoplanet using a powerful new instrument at the 8-meter Gemini North telescope on Maunakea in Hawai’i. The findings not only classify a Jupiter-sized exoplanet in a close binary star system, but also conclusively demonstrate, for the first time, which star the planet orbits. Finally, there’s an instrument that can conclusively reveal the secrets of exoplanets.

The breakthrough occurred when Steve B. Howell of the NASA Ames Research Center and his team used a high-resolution imaging instrument of their design — named ‘Alopeke (a contemporary Hawaiian word for fox). The team observed exoplanet Kepler-13b as it passed in front of (transited) one of the stars in the Kepler-13AB binary star system some 2,000 light-years distant.

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Prior to this attempt, the true nature of the exoplanet was a mystery. The research was published in the Astronomical Journal. Howell said:

Chris Davis of the National Science Foundation, one of Gemini’s sponsoring agencies, added:

‘Alopeke performs “speckle imaging,” collecting a thousand 60-millisecond exposures every minute. After processing this large amount of data, the final images are free of the adverse effects of atmospheric turbulence — which can bloat, blur, and distort star images. Howell said:

The team’s analysis revealed a clear drop in the light from Kepler A, proving that the exoplanet orbits the brighter of the two stars. Moreover, ‘Alopeke simultaneously provides data at both red and blue wavelengths, an unusual capability for speckle imagers. Comparing the red and blue data, the researchers were surprised to discover that the dip in the star’s blue light was about twice as deep as the dip seen in red light.

This can be explained by a hot exoplanet with a very extended atmosphere, which more effectively blocks the light at blue wavelengths. Thus, these multi-color speckle observations give a tantalizing glimpse into the appearance of this distant world.

Exoplanets around binary star systems like Kepler-13AB can now be clearly determined.
Artist’s conception of the Kepler-13AB binary star system as revealed by observations including the new Gemini Observatory data. The two stars (A and B) are large, massive bluish stars (center) with the transiting ‘hot Jupiter’ (Kepler-13b) in the foreground (left corner). Star B and its low mass red dwarf companion star are seen in the background to the right. (Image: Artwork by Joy Pollard via Gemini Observatory / NSF / AURA)

Early observations once pointed to the transiting object being either a low-mass star or a brown dwarf (an object somewhere between the heaviest planets and the lightest stars). But Howell and his team’s research almost certainly shows the object to be a Jupiter-like gas-giant exoplanet with a “puffed up” atmosphere due to exposure to the tremendous radiation from its host star.

‘Alopeke has an identical twin at the Gemini South telescope in Chile, named Zorro, which is the word for fox in Spanish. Like ‘Alopeke, Zorro is capable of speckle imaging in both blue and red wavelengths.

Gemini Observatory to resolve thousands of exoplanets

The presence of these instruments in both hemispheres allows Gemini Observatory to resolve the thousands of exoplanets known to be in multiple star systems. Team member and ‘Alopeke instrument scientist Andrew Stephens at the Gemini North telescope said:

First proposed by French astronomer Antoine Labeyrie in 1970, speckle imaging is based on the idea that atmospheric turbulence can be “frozen” when obtaining very short exposures. In these short exposures, stars look like collections of little spots, or speckles, where each of these speckles has the size of the telescope’s optimal limit of resolution.

When taking many exposures, and using a clever mathematical approach, these speckles can be reconstructed to form the true image of the source, removing the effect of atmospheric turbulence. The result is the highest-quality image that a telescope can produce, effectively obtaining space-based resolution from the ground — making these instruments superb probes of extrasolar environments that may harbor planets.

The discovery of planets orbiting other stars has changed the view of our place in the Universe. Space missions like NASA’s Kepler/K2 Space Telescope and the Transiting Exoplanet Survey Satellite (TESS) have revealed that there are twice as many planets orbiting stars in the sky than there are stars visible to the unaided eyes; to date, the total discovery count hovers around 4,000.

While these telescopes detect exoplanets by looking for tiny dips in the brightness of a star when a planet crosses in front of it, they have their limits. Howell said:

Howell added:

Provided by: Gemini Observatory [Note: Materials may be edited for content and length.]

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