March 6, 2014
Digital Camera-Like Technology Used To Image Exoplanet From Earth
redOrbit Staff & Wire Reports - Your Universe Online
A team of researchers from the University of Arizona’s Department of Astronomy have managed to use an Earth-based telescope to capture images of a world outside of our solar system, according to research scheduled to be published in an upcoming edition of The Astrophysical Journal.
“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,” lead author and NASA Sagan Fellow Jared Males explained in a statement Tuesday.
While the image was taken at a wavelength that is not quite visible to the human eye, using a digital camera-type imaging sensor (otherwise known as a charge-coupled device or CCD) means that it is possible to image planets in visible light – something that was previously impossible using with Earth-based telescopes.
Co-author and UA astronomy professor Laird Close called the advancement “exciting to astronomers” because it brings them “a small step closer to being able to image planets outside our solar system in visible light.”
All other Earth-based images of exoplanets near their stars are infrared images that detect the planet’s heat, limiting the technology to the massive young plants known as gas giants. While gas giants still shed heat, older planets that are potentially habitable have cooled since being formed are not as visible in infrared images. Essentially, in order to properly image these planets, scientists will have to rely on visible light-detecting cameras.
The planet photographed using the CCD technology is known as Beta Pictoris b, and it orbits its star at just nine times the distance between the Earth and the Sun. In the images, it appears approximately 100,000 times fainter than its host star, which makes it the faintest object imaged at such a relative proximity to its star to date.
These images, which also indicate that Beta Pictoris b is the faintest object imaged at such a high contrast, confirms that it has an atmospheric temperature of approximately 2600 degrees Fahrenheit (1700 Kelvin). Males, Close and their colleagues estimate that Beta Pictoris b is approximately 12 times more massive than Jupiter.
“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 explained. “Our image has the highest contrast ever achieved on an exoplanet that is so close to its star.”
The team also imaged the planet using The Magellan Adaptive Optics (MagAO) technology in order to help remove the blurring or turbulence caused by a combination of the host star’s brightness and the Earth’s atmosphere. By imaging the planet using both CCD and MagAO cameras, the astronomers were able to obtain two completely independent simultaneous images of Beta Pictoris b in both infrared and bluer light.
“An important part of the signal processing is proving that the tiny dot of light is really the planet,” said MagAO team member and Sagan Fellow Katie Morzinski. “I obtained the second image in the infrared spectrum… to serve as an unequivocal control that we are indeed looking at the planet. Taking the two images simultaneously helps to prove the planet image on the CCD is real and not just noise.”
In related news, researchers from the University of Washington have unveiled a new way to study planetary atmospheres by searching for dimers – pairs of atoms that are bound together, such as two oxygen molecules. This technique could help astronomers identify some of the characteristics associated with potentially habitable planets.
By looking for dimers, the authors explain that scientists might be able to uncover evidence that a planetary atmosphere possesses a minimum density. In this instance, molecular oxygen indicates that the world has an atmosphere that is at least 25 percent that of Earth’s atmospheric pressure – the threshold beneath which it is unlikely that molecules would form, according to redOrbit.com’s John P. Millis, Ph.D.
Astronomers search for dimer oxygen by performing a spectral analysis on the atmosphere, seeking out specific patterns in the data. By doing this for another planet, they could search for these patterns to identify dimer molecules, and their presence could also alert them to conditions conducive to life. The study was published last month in the journal Astrobiology.
Image 2 (below): An image of the exoplanet Beta Pictoris b taken with the Magellan Adaptive Optics VisAO camera. This image was made using a CCD camera, which is essentially the same technology as a digital camera. The planet is nearly 100,000 times fainter than its star, and orbits its star at roughly the same distance as Saturn from our Sun. Credit: Jared Males/UA