Exoplanet Imaged in Visible Light Using Basic Digital Camera Technology

Astronomers have used what amounts to basic digital camera technology to obtain images of distant exoplanets in visible light, an important step necessary in the quest to capture images of Earth-like planets around stars.

Writing in The Astrophysical Journal, the researchers detail their observations, which are the first to image a distant planet from a terrestrial telescope using the visible light wavelength.

"This is an important next step in the search for exoplanets because imaging in visible light instead of infrared is what we likely have to do if we want to detect planets that might be suitable for harboring life," said lead study author Jared Males of the University of Arizona.

Males and his colleagues used a telescope mounted with what's known as a charge-coupled device (CCD), an image sensor not unlike those found in modern digital cameras. With the CCD, the astronomers imaged an exoplanet at a wavelength just shy of being visible to the human eye in the visible light spectrum.

"This is exciting to astronomers because it means we now are a small step closer to being able to image planets outside our solar system in visible light," said study co-author Laird Close, an astronomy professor at University of Arizona.

Most exoplanets are imaged using infrared wavelengths, which rely on a planet's heat to process the image. However, only gas giants - massive planets still young enough to shed heat - can be imaged reliably with infrared. Older planets emitting less heat are not always visible in infrared, so developing technology that can image cooler planets in visible light has been a goal of astronomers.

"Our ultimate goal is to be able to image what we call pale blue dots," Close said. "After all, the Earth is blue. And that's where you want to look for other planets: in reflected blue light."

The astronomers used the CCD to image a planet known as Beta Pictoris b, a distant planet that appears about 100,000 times fainter than its host star. Beta Pictoris b is the faintest object imaged so far at such high contrast and at such relative proximity to its star, the researchers said.

"Because the Beta Pictoris system is 63.4 light years from Earth, the scenario is equivalent to imaging a dime next right next to a lighthouse beam from more than four miles away," Males said. "Our image has the highest contrast ever achieved on an exoplanet that is so close to its star."