Category Archives: Astronomy

Video: Breaking the Seeing Barrier for Planetary Astronomy

The SETI Institute posts this video of a talk by Franck Marchis, about Breaking the Seeing Barrier for Planetary Astronomy

Caption:

When Galileo Galilei pointed his telescope toward Jupiter in 1609 and discovered what we now call the Galilean moons, he did not realized that he had just established a new research field in astronomy. In the past four centuries, planetary astronomy, the study of our solar system bodies using telescopes, has increased our knowledge of the environment of Earth, the evolution of the planets, the origin of comets and asteroids and the formation of our solar system. Space exploration accelerated planetary astronomy in the 1960s by allowing planetary scientists to access in-situ and detailed data.

In this talk, I will discuss the contributions of telescopic observation over the past 50 years to planetary science, particularly the recent developments like adaptive optics which renewed interest in ground-based observations of planets. I will explore the contribution of all-sky surveys like Pan-STARRS and LSST, which provide several terabytes of data a week, changing radically the way we do astronomy. Looking to the future of space-based astronomy, I will consider whether the James Webb Space Telescope and ATLAST are potential successors to the successful Hubble Space Telescope.

Finally I’ll explore the way in which specialized low-cost telescopes designed to search and study exoplanets, planets around other stars, constitutes a paradigm shift in our field.

Telescope system corrects for atmospheric distortions in visible light observations

The announcement below is quite interesting. Previously, using adaptive optics to correct for atmospheric distortions only worked for infrared observations. Now it is being applied to visible light astronomy:

UA Astronomers Take Sharpest Photos Ever of the Night Sky

Thanks to new technology developed in part at the UA, astronomers can now view objects in the sky at unprecedented sharpness in visible light. Using a telescope mirror that vibrates a thousand times each second to counteract atmospheric flickering, the team has achieved image resolution capabilities that could see a baseball diamond on the moon.

A close-up of the central region of the Orion nebula, taken with the Schulman Telescope at the UA's Mount Lemmon SkyCenter. (Photo: Adam Block/UA SkyCenter)

A close-up of the central region of the Orion nebula, taken with the Schulman
Telescope at the UA’s Mount Lemmon SkyCenter. (Photo: Adam Block/UA SkyCenter)

Astronomers at the University of Arizona, the Arcetri Observatory near Florence, Italy and the Carnegie Observatory have developed a new type of camera that allows scientists to take sharper images of the night sky than ever before. The team has been developing this technology


(Click image to enlarge)

The Magellan Telescope with MagAO’s Adaptive Secondary Mirror (ASM)
mounted at the top looking down some 30 feet onto the 21-foot diameter primary
mirror, which is encased inside the blue mirror cell.
(Photo: Yuri Beletsky, Las Campanas  Observatory)

for more than 20 years at observatories in Arizona, most recently at the Large Binocular Telescope, or LBT, and has now deployed the latest version of these cameras in the high desert of Chile at the Magellan 6.5-meter telescope.

“It was very exciting to see this new camera make the night sky look sharper than has ever before been possible,” said UA astronomy professor Laird Close, the project’s principal scientist. “We can, for the first time, make long-exposure images that resolve objects just 0.02 arcseconds across – the equivalent of a dime viewed from more than a hundred miles away. At that resolution, you could see a baseball diamond on the moon.”

The twofold improvement over past efforts rests on the fact that for the first time, a telescope with a large diameter primary mirror is being used for digital photography at its theoretical resolution limit in visible wavelengths – light that the human eye can see.

“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.”

(Click image to enlarge)
Equipped with the newly developed MagAO adaptive optics system, the
Magellan Telescope revealed details about the Orion nebula. The background image,
taken with the Hubble Space Telescope, shows the Trapezium cluster of young
stars (pink) still in the process of forming. The middle inset photo reveals the
binary nature of the Theta Ori C star pair. The bottom insert shows a different
binary young star pair shaped by the stellar wind from Theta 1 Ori C.
 (Photo credits: Laird Close and Ya-Lin Wu; NASA, C.R. O’Dell and S.K. Wong)

 These images are also at least twice as sharp as what the Hubble Space Telescope can make, because with its 21-foot diameter mirror, the Magellan telescope is much larger than Hubble with its 8-foot mirror. Until now, Hubble always produced the best visible light images, since even large ground-based telescope with complex adaptive optics imaging cameras could only make blurry images in visible light.

To overcome atmospheric turbulence, which plagues earth-based telescopes by causing the image to blur, Close’s team developed a very powerful adaptive optics system that floats a thin (1/16th of an inch) curved glass mirror (2.8 feet across) on a magnetic field 30 feet above the telescope’s primary mirror.

This so-called Adaptive Secondary Mirror (ASM) can change its shape at 585 points on its surface 1,000 times each second, counteracting the blurring effects of the atmosphere.

“As a result, we can see the visible sky more clearly than ever before,” Close said. “It’s almost like having a telescope with a 21-foot mirror in space.”

The new adaptive optics system, called MagAO for “Magellan Adaptive Optics,” has already made some important scientific discoveries, published today in three scientific papers in the Astrophysical Journal. As the system was being tested and received what astronomers call “first light,” the team pointed it to a famous and well-studied massive star that gives the Great Orion Nebula (Object M42) most of its UV light. The Orion Nebula, located just below Orion’s Belt visible as smudge of light even with regular binoculars.

UA NASA Sagan Fellow and VisAO instrument scientist Jared Males (left) and UA Astronomy Professor and MagAO project scientist Laird Close with the VisAO camera and MagAO wavefront sensors at the focus of the 6.5m Magellan telescope that were used to make

(Click image to enlarge)

UA NASA Sagan Fellow and VisAO instrument scientist Jared Males (left) and
UA Astronomy Professor and MagAO project scientist Laird Close with the
VisAO camera and MagAO wavefront sensors at the focus of the 6.5m Magellan
telescope that were used to make the visible wavelength images.
(Photo: Katie Morzinski)

Considered young at about 1 million years old, this star, called Theta 1 Ori C, has been previously known to be in fact a binary star pair made up of two stars called C1 and C2. However, the separation between the two is so small – about the average distance between Earth and Uranus – that astronomers had never been able to resolve the famous pair in a direct telescope photo.

Once MagAO and its visible science camera called VisAO were pointed towards Theta Ori 1 C, the results were immediate.

“I have been imaging Theta 1 Ori C for more than 20 years and never could directly see that it was in fact two stars,” Close said. “But as soon as we turned on the MagAO system it was beautifully split into two stars.”

In another result, MagAO has shed light on another mystery: How do how planets form from disks of dust and gas affected by the strong ionizing light called stellar wind coming from a massive star like Theta 1 Ori C, which has about 44 times the mass of the sun?

The team used MagAO and VisAO to look for red light from ionized hydrogen gas to trace out how the strong UV radiation and stellar wind from Theta 1 Ori C affects the disks around its neighboring stars.

“Close to Theta 1 Ori C, there are two very young stars surrounded by disks of gas and dust,” said Ya-Lin Wu, a graduate student and lead author on one of the publications. “Theta 1 Ori C pummels those disks with stellar wind and UV light. It looks like they are being bent backwards by a strong wind.”

MagAO’s photo revealed that the two stars and their protoplanetary disks are heavily distorted into teardrop shapes as the strong UV light and wind create shock fronts and drag gas downwind of the pair.

The distribution of gas and dust in young planetary systems is another unsolved problem in planet formation. The team used VisAO’s simultaneous/spectral differential imager, or SDI, to estimate the mass of another intriguing object in the Orion Nebula: one of a few stars in Orion sporting a rare “silhouette disk.” The SDI camera allowed the light from the star to be removed at a very high level—offering, for the first time, a clear look at the inner regions of the silhouette.

(Click image to enlarge)
The power of visible light adaptive optics: On the left is a “normal” photo of the
theta 1 Ori C binary star in red light. The middle image shows the same object,
but with MagAO’s adaptive optics system turned on.  Eliminating the atmospheric
blurring, the resulting photo becomes about 17 times sharper, turning a blob into
a crisp image of a binary star pair.  These are the highest resolution photos taken
by a telescope. (Photo: Laird Close/UA)

“The disk lies in front of the bright Orion nebula, so we see the dark shadow cast as the dust in the disk absorbs background light from the nebula,” said Kate Follette, a graduate student and lead author of one of the three papers published in the Astrophysical Journal. “Picture a moth flying across a bright movie screen: Its body will appear opaque, while the wings will be partially transparent. Our SDI instrument allows us to peer into the silhouette and trace how much dust is at each location in the disk based on how transparent or opaque it is.”

“We were surprised to find that the amount of attenuated light from the nebula never reached an opaque point,” she said. “It seems as though the outer parts of this disk have less dust than we would have expected.”

“It is important to understand how dust is laid out in these objects because that dust and gas is what nature uses to build planets,” Close explained. “Our new imaging capabilities revealed there is very little dust and gas in the outer part of the disk.”

A Magellan Adaptive Optics image of Orion 218-354 silhouette after removal of light from the central star. The image on the left shows the dark silhouette of the disk against the bright background light of the Orion nebula. The image on the right shows ho

A Magellan Adaptive Optics image of Orion 218-354 silhouette after removal
of light from the central star. The image on the left shows the dark silhouette

of the disk against the bright background light of the Orion nebula. The image on
the right shows how the new capabilities allowed astronomers to probe of nebular
light passing through the disk, telling them about the distribution of gas and dust.

(Photo: Kate Follette/UA)

According to Close, the silhouette disk might have been close to the massive star Theta 1 Ori C at some point, which might have blown away its outer dust and gas.

“This tells us something about planet-forming disks in these dense, stellar nurseries,” Close said. “There appears to be a limit to the formation of massive planets very far away from their parent stars. One possible explanation might be the presence of a massive star like Theta 1 Ori C stripping away the outer gas and dust.”

The MagAO system was developed with support of the National Science Foundation MRI, TSIP and ATI grant programs. The Adaptive Secondary Mirror itself was produced by Microgate and ADS of Italy, with the UA’s Steward Observatory Mirror Lab. The MagAO pyramid wavefront sensor was developed at the Arcetri Observatory, Italy.

The Magellan telescopes are operated by a partnership between the Carnegie institute, the UA Harvard University, MIT and the University of Michigan. The work of NASA Sagan Fellows Jared Males and Katie Morzinski was performed in part under contract with the California Institute of Technology and was funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute. The work of Kate Follette was funded in part by the NSF Graduate Research Fellowship program.

Kepler must switch to other missions – no reaction wheel fix found

Efforts to resurrect the broken reaction wheels on the Kepler space observatory have failed. The spacecraft can still do useful science but not exoplanet transit searches, which requires the extremely stable and precise pointing capabilities provided by 3 working reaction wheels.

Video: Advice on selecting a telescope

The Slashdot technology forum site posted this two part introduction to telescopes for amateur astronomy:

Bruce Berger is an IT guy, but he’s also an amateur astronomer who takes at least one aspect of astronomy more seriously than most sky-watchers. Not content with what he could buy when he first wanted a telescope of his own, Berger set out to make one — it turned out so well, he says he’ll never part with it, and he’s made several others since, and taught many other people to do the same. In this pursuit, he’s also been a long-time member of the Amateur Telescope Makers of Boston, including a stint as the group’s president. (Berger’s custom license plate reads “SCPMKR.”)

In the video Berger discusses what to look for in telescopes.

Amateur Astronomer Bruce Berger Talks About Meteors and Telescopes (Video) – Slashdot

In the next video, Berger continues with advice

on telescope selection and purchasing. He mentions Orion, a telescope vendor he seems to respect, along with other sources for both new and used equipment. Which should you buy (or build): A reflector or a refractor telescope? Bruce talks about how you should make your selection based on what you want to view, your skill level, and how much time and/or money you have available.

Amateur Astronomer Bruce Berger Talks About Telescopes, Part II (Video) – Slashdot

A beginners guide to astronomy

Astronomy newbies should check out the Beginners Guide To Astronomy at Learn Astronomy HQ:

This guide covers how to get started cheaply in astronomy and then progresses to a guide to telescopes and what to consider when buying a telescope. Once you have your equipment the guide covers setting up a telescope, what to start out observing, how to develop your knowledge of the night sky and provides a list of uk astronomy equipment to begin expanding your range and skills.