August 22, 2013
Sharpest Night Sky Images Ever Captured Shed New Light On Planetary Formation
redOrbit Staff & Wire Reports - Your Universe Online
Astronomers from the University of Arizona, the Arcetri Observatory in Italy and the Carnegie Observatory have used a new type of telescope camera to capture the highest-resolution images of the night sky ever – answering some longstanding questions about planetary formation in the process.
The technology, which has been in development at Arizona observatories for over two decades, was recently deployed in the high desert of Chile at the Magellan 6.5 meter (21 foot) telescope. The camera made it possible to snap photographs at the theoretical resolution limit for wavelengths of visible light.
“It was very exciting to see this new camera make the night sky look sharper than has ever before been possible,” principle scientist Laird Close of the University of Arizona said in a statement.
“We, for the first time, can make deep images that resolve objects just 0.02 arcseconds across – this is a very small angle – it is like resolving the width of a dime seen from 100 miles away, or like resolving a convoy of three school busses driving together on the surface of the Moon,” he added.
Prior to the development of the new camera, large telescopes were able to only produce sharp pictures in infrared or long-wavelength light, the researchers explained. Even large telescopes equipped with complex adaptive optics imaging cameras were only capable of producing blurry images in visible light.
The new technology, however, can function in the visible spectrum and can make high-resolution photos, because as the resolution moves towards bluer wavelengths, the image sharpness improves. Close’s team developed a powerful adaptive optics system which floats a thin (1/16 of inch thick) curved glass mirror (85 cm across) on a magnetic field 9.2m above the big primary mirror of the telescope.
This system, which the researchers have dubbed the MagAO Adaptive Secondary Mirror (ASM), is capable of changing its shape at 585 points on its surface 1000 times a second. The MagAO ASM is able of removing the “blurring” effects of the atmosphere, the study authors said, and thanks to the high density of the actuators on the mirror, astronomers are able to view the visible sky with greater clarity than ever before.
“As we move towards shorter wavelengths, image sharpness improves,” said Jared Males, a NASA Sagan Fellow at the UA's department of astronomy. “Until now, large telescopes could make the theoretically sharpest photos only in infrared – or long wavelength – light, but our new camera can take photos that are twice as sharp in the visible light spectrum.”
The MagAO adaptive optic system has already led to some important scientific discoveries, the researchers explained. Using it, they analyzed a one-million-year-old binary star known as Theta 1 Ori C, which has approximately 44 times the mass of the Sun and gives the Great Orion Nebulae most of its UV light.
“The team also mapped out all the positions of the brightest nearby cluster stars and was able to detect very small motions as the stars slowly revolved around each other. Indeed a small group of five stars called Theta 1 Ori B was is likely a bound ‘mini-cluster’ of stars, one that may eject the lowest mass star of the five in the near future,” they said.
“The team also managed to address a longstanding question about how planets form,” the authors added. “Scientists have long wondered whether the disks of gas and dust that surround a protoplanet are affected by the strong ionizing light and wind coming from a massive star, one like Theta 1 Ori C.”
They used MagAO and the telescope’s VisAO visible-light camera to look for red light from ionized hydrogen gas to what impact the wind and strong UV light from Theta 1 Ori C affects the disks around its neighboring stars. Their photo showed two stars located some seven arcseconds away from Theta 1 Ori C experienced heavy distortion into “teardrop” shapes as the UV light and wind created shock fronts and dragged gas downwind of the star.
Using VisAO’s special simultaneous/spectral differential imager (SDI), the researchers were also able to shed new light about how dust and gas are redistributed in a young disk during planetary formation. They imaged one of the rare “silhouette” disks in Orion using the SDI instrument, and since the camera allowed the light from the star to be removed at a high level, they were able to see the silhouette clearly for the first time.
The discovery demonstrated MagAO can make visible images of even very faint stars, the researchers said. Close and his colleagues will publish three papers detailing their findings in an upcoming edition of The Astrophysical Journal.