Pasadena, CA— A team of astronomers from three institutions has developed a new type of telescope camera that makes higher resolution images than ever before, the culmination of 20 years of effort. The team has been developing this technology at telescope observatories in Arizona and now has deployed the latest version of these cameras in the high desert of Chile at the Magellan 6.5m (21 foot) telescope. Carnegie’s Alan Uomoto and Tyson Hare, joined by a team of researchers from the University of Arizona and Arcetri Observatory in Italy, will publish three papers containing the highest-resolution images ever taken, as well as observations that answer questions about planetary formation, in The Astrophysical Journal.
“It was very exciting to see this new camera make the night sky look sharper than has ever before been possible” said Laird Close of the University of Arizona, who was the project’s principal scientist. “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.”
This improvement results from the use of a large 6.5m telescope for photography at its theoretical resolution limit for wavelengths of visible light. Previously, large telescopes could make sharp photos only in infrared (long wavelength) light. Even large telescopes, those equipped with complex adaptive optics imaging cameras, could only make blurry images in visible light. The new camera can work in the visible spectrum and can make high-resolution photos, because as the resolution moves towards bluer wavelengths, the image sharpness improves.
To correct for atmospheric turbulence, the team developed a very powerful adaptive optics system that floats a thin (1.6 mm –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, so-called Adaptive Secondary Mirror (ASM) can change its shape at 585 points on its surface 1000 times a second. In this manner the “blurring” effects of the atmosphere can be removed, and thanks to the high density of actuators on this mirror, astronomers can see the visible sky more clearly than ever before.
“The Magellan community is delighted to have this powerful new capability, a final addition to our current instrument suite,” said Wendy Freedman, director of the Carnegie Observatories. “It also represents a significant technical milestone for the Giant Magellan Telescope.”
The new adaptive optics system, called MagAO, has already made some important scientific discoveries. As the system was being tested, the team tried to resolve the famous star that gives the Great Orion Nebulae most of its UV light. This 1 million-year-old star is called Theta 1 Ori C and it is about 44 times the mass of the Sun. It was already known to be a binary star (two stars rotating around each other); however, the separation between them is so small that this famous pair has never been resolved into two stars in a direct telescope photo. Once MagAO and VisAO (its visible-light camera) were pointed towards Theta Ori 1 C, the results were exciting and immediate.
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.
The team also managed to address a longstanding question about how planets form. 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. The team used MagAO and VisAO to look for red light from ionized hydrogen gas to trace how the strong UV light and wind from Theta 1 Ori C affects the disks around its neighboring stars. MagAO’s photo shows that a pair of stars some 7 arcseconds away from Theta 1 Ori C was heavily distorted into “teardrop” shapes as the strong UV light and wind create shock fronts and drag gas downwind of the star, a very rare example of a low mass pair of young disks.
Another mystery about planetary formation is how the dust and gas are redistributed in a young disk. The team used VisAO’s special simultaneous/spectral differential imager (SDI) to image one of the rare “silhouette” disks in Orion. The disk is in front of the M42 nebula and so the astronomers could see the dark shadow cast as the dust in the disk absorbed the background light of the nebula. The SDI camera allowed the light from the star to be removed at a very high level, leaving, for the first time, a clear look at the silhouette, demonstrating that MagAO can make visible images of even very faint stars.
Caption: The Magellan Telescope with MagAO’s Adaptive Secondary Mirror (ASM) mounted at the top looking down on the 6.5m (21 foot) diameter Primary Mirror. Photo by Moonlight, taken by Yuri Beletsky, LCO/Magellan Staff. A larger version of the photo is available here.
This work was supported by the National Science Foundation MRI, TSIP, and ATI grant programs.
The ASM itself was produced by Microgate and ADS of Italy, and the University of Arizona’s Steward Mirror Lab. The MagAO pyramid wavefront sensor was developed at the Arcetri Observatory in Italy. The Magellan telescopes are run by a partnership of the Carnegie Institution for Science, University of Arizona, Harvard University, MIT, and the University of Michigan.
A MagAO image of Orion 218-354 silhouette after removal of light from the central star. The left-hand image shows the silhouette (shadow) of the disk against the bright background hydrogen alpha emission of the Orion nebula. The right-hand image is the same, but with contours denoting levels of increasing attenuation of the background nebular light toward the central star. The percentages denote the amount of nebular light passing through the disk. The degree of attenuation probes the amount of dust in the disk at each location. Photo credit Kate Follette, University of Arizona.
The power of visible light adaptive optics. Here we show (on the left) a “normal”photo of the theta 1 Ori C binary star in red light (in the r’ filter, 630 nm). It just looks an unresolved star. Then the middle image shows how if we remove (in real time) the blurring of the atmosphere with MagAO’s adaptive optics’ the resulting photo becomes ~17 times sharper (corrected resolutions range from 0.019-0.029 arcseconds on theta 1 Ori C). Both photos are 60 seconds long, and no post-detection image enhancement has been applied.These are the highest resolution photos taken by a telescope. Photo credit Laird Close,University of Arizona.
The Orion Trapezium is a cluster of young stars still in the process of forming. The top inset image shows MagAO’s photo of the “mini-cluster” of young stars in the Theta 1 OriB group (B1-B4; Top Inset image). There is now clear evidence of relative motion of these stars around B1. The lowest mass member (B4) will likely be ejected in the future. The middle inset photo shows the highest resolution astronomical photo of the Theta 1 Ori C1 C2pair, and the bottom insert shows the LV 1 binary young star pair shaped by the wind from Theta 1 Ori C (in the visible light of hydrogen gas (at 656 nm). Photo Credit: Laird Close and Ya-Lin Wu, University of Arizona. The Background image is a previous HST Orion Trapezium Cluster visible image (NASA, C.R. O'Dell and S.K. Wong, Rice University).
The power of visible light adaptive optics. Here we show (on the left) a “normal” photo of the theta 1 Ori C binary star in red light. Then (to the right) we remove (in real time) the blurring of the atmosphere with MagAO’s adaptive optics and the resulting becomes ~17 times sharper and >50 times brighter. Photo credit Laird Close, University of Arizona.
Different wavelengths and images of the 0.032 arcseconds (or 32 mas) Theta 1 Ori C binary Pair. North is up and East is to the left. The top row is the raw photos and the middle row shows the images after post-detection processing. The last row is just a zoomed and smoothed view of the middle row’s images. Photo Credit Laird Close, University of Arizona.
The binary young star LV 1 in the Orion Nebula some 7” from Theta 1 Ori C. In the light H alpha we can see how the Hydrogen gas makes a bright “bow shock” as the wind and UV light arrives from Theta 1 Ori C. The lack of any image motion between the stars suggests that both the upper and lower stars have low masses. Photo credit Ya-Lin Wu, University of Arizona.
The VisAO camera and MagAO wavefront sensors (all optics inside dark ring) that were used to make the visible wavelength images. Dr. Jared Males (VisAO instrument scientist) and Professor Laird Close (MagAO project scientist) are shown for scale from left to right. Photo credit MagAO postdoctoral fellow Katie Morzinski