Category Archives: Press

MagAO in the news.

MagAO+Clio’s New Apodizing Phase Plate Coronagraphs

During our recent observing run we tested a new set of coronagraphs (devices for blocking star light so we can see planets!), which were developed by our friends Gilles Otten, Frans Snik, and Matt Kenworthy at Leiden University, in the Netherlands. Today Gilles gave a talk at the Spirit of Lyot Conference in Montreal, Canada. The new coronagraphs work spectacularly well! You can read about these results in Dutch, French, and in English.

Here is our announcement of this great news:

Astronomers develop breakthrough optical component for detecting exoplanets close to their host stars

Astronomers from Leiden University (the Netherlands) and the University of Arizona (USA) have successfully commissioned a new type of optic that can reveal the image of an exoplanet next to its parent star. The ‘vector Apodizing Phase Plate’ (vector-APP) coronagraph was installed at the 6.5-m Magellan Clay telescope in Chile in May 2015, and the first observations demonstrated an unprecedented contrast performance very close to the star, where planets are more likely to reside. These results will be presented by PhD student Gilles Otten (Leiden) this Monday to the scientific community at the “Spirit of Lyot” conference in Montreal.

Almost 2000 exoplanets have been detected to date, but only a handful of those have been imaged directly. Exoplanets are typically more than a million times fainter than and are lost in the glare of their parent star as seen from Earth. To directly image exoplanets and to characterize their atmospheres, astronomical instruments at the world’s largest telescopes use coronagraphs to suppress the overwhelming halo of light from the star.
The vector-APP coronagraph[1] uses the wavelike nature of light to cancel out the starlight whilst allowing the planet’s light to shine through.

This manipulation is implemented through a complex phase pattern that can only be manufactured using advanced liquid crystal 3D patterning techniques [2]. This technique creates two images of the star, for which dark D-shaped regions are located on opposite sides of each star image (see Figure 1). In this way, the whole region around the star can be scrutinized for planets. By combining several layers of liquid crystals, the device can be used over a wide range of wavelengths, including the infrared where the contrast between planet and star is more favorable.

On May 6, 2015 a vector-APP coronagraphic device saw first light (at 3.9 um wavelength, in the infrared range of the spectrum) at the MagAO[3] instrument, attached to the 6.5-m diameter Magellan Clay telescope in Chile. The telescope’s integrated adaptive optics system provided the instrument with sharp images of stars, which were consequently split up and modified by the coronagraph to exhibit dark holes in which much fainter planets could be imaged than without the vector-APP coronagraph.

Figure 1: Double image of the star Eta Crucis taken through the vector-APP coronagraph installed at MagAO. The two main images of the star exhibit D-shaped dark holes on complementary sides. Coronagraphic phase pattern designed by Christoph Keller (Leiden). Credit Leiden University, University of Arizona

Frans Snik (Leiden University), who invented the principle behind the new vector-APP coronagraph, says: “It is fantastic to see that after all our design work and lab testing, this new approach works perfectly at the telescope on the very first night!” Gilles Otten adds: “We knew that we were in business as soon as we saw the first picture on the screen in the telescope control room.”

Figure 2: Double image of the star beta Centauri taken through an experimental version of the vector-APP coronagraph installed at MagAO. Both images of the star contain a dark region that covers the complete 360 degrees around the central star. In both cases, the binary companion to beta Centauri is easily detected. Coronagraphic phase pattern designed by Christoph Keller (Leiden). Credit Leiden University, University of Arizona.

Jared Males (NASA Sagan Fellow, University of Arizona) is excited about the opportunities of the vector-APP: “With this new coronagraph we are now looking for planets around nearby stars. We have the capacity to directly detect, or rule out, planets smaller than Jupiter. ” Matthew Kenworthy (Leiden) concludes: “This new coronagraph technology is also excellent news for the extremely large telescopes currently under construction. With a vector-APP coronagraph in the next generation of telescopes, we can search for planets around nearby stars with unprecedented sensitivity.”

The advanced liquid crystal technology that the team adopted also permitted the production of extreme vector-APP designs that are not possible with more traditional manufacturing technologies. These new designs produce dark holes that cover the full 360 degrees around the target stars. The first data from an experimental device already shows the viability of this novel approach (see Figure 2).

Support from the William F. and Elizabeth Lucas Junior Faculty Astronomy Award and the NASA Origins of Solar Systems program made this exciting commissioning possible at the MagAO instrument in Chile. This work was performed in part under contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.

[1] For an introduction to the principles behind the vector-APP coronagraph, see Snik et al. (2012) and Otten el al. (2014). The name “vector-APP” stems from “Apodizing Phase Plate” based on polarization (vector) techniques. The original optical theory was developed by Johanan Codona at the University of Arizona.

[2] The vector-APP coronagraph devices for MagAO were developed in collaboration with the group of Dr. Michael Escuti at North Carolina State University, and were produced by ImagineOptix.

[3] The MagAO instrument is introduced in Morzinski et al. (2014). See visao.as.arizona.edu/

Contacts:
Dr. Frans Snik (in the Netherlands)
Leiden Observatory, Leiden University
snik@strw.leidenuniv.nl

Dr. Matthew Kenworthy (at the “Spirit of Lyot”) conference
Leiden Observatory, Leiden University
Kenworthy@strw.leidenuniv.nl

Dr. Jared Males
University of Arizona
jrmales@email.arizona.edu

Posted in Press | Comments Off

Eyepiece Observing With MagAO

Welcome APOD and Sky and Telescope readers. This post was written while MagAO was mounted on the Clay 6.5 m telescope, and we post daily updates throughout the run on the main page. You can also find out about some of our scientific results using the In The News and Results pages.

You can also read about our eyepiece observations in a post by Tom Beal at the Arizona Daily Star.


On our first night on-sky in 2015A, our infrared camera Clio wasn’t quite ready to mount on the telescope. We also needed to test operating the AO system with a different camera, since there are several new instrument concepts in the works (Clio’s entrance window is the dichroic which sends light to the Pyramid and VisAO). The result of these fortunate circumstances is that we mounted the eyepiece for the very first time.

Laird presents the MagAO eyepiece. It is mounted where Clio normally goes.

The night started out poorly. It was cloudy, a guider communications cable failed deep inside the telescope, and one of VisAO’s hard drives failed.

Our first night started out cloudy. (Picture by Yuri Beletsky, click for larger image)

The telescope staff went to work on the cable, and Jared tore apart the VisAO electronics. Meanwhile, Laird was doing some last minute alignment checks on the eyepiece. At around midnight, all the problems were fixed and the sky magically began to clear.

Once we opened, we immediately pointed at alpha Centauri A which is a very bright star and so makes a good alignment target. Working out on the platform in near freezing temperatures, we moved the MagAO Pyramid wavefront sensor around until it was aligned to the star with the eyepiece dichroic.

Eyepiece alignment was done on the platform. At left is a cellphone image of alpha Cen A&B imaged on a card through the eyepiece. At right is the simultaneous image on the VisAO camera (on a laptop screen on the platform). These are open-loop images (before we turned on the AO).

Then, on the first try, we closed the loop at 1000 Hz controlling 300 modes.

Proof that the loop was closed while we were observing.

At that point, we were observing the alpha Centauri system at the diffraction limit of a 6.5 meter telescope! Luckily the moon was out, giving Yuri Beletsky plenty of light to document the whole thing.

Laird Close, the MagAO PI, observes alpha Cen at the diffraction limit of the 6.5 meter Clay telescope. The inset shows an image recorded with VisAO, MagAO’s visible wavelength science camera, at nearly the same wavelength (i’). Reports from all observers indicate that it looks just like this through the eyepiece! (Photo by Yuri Beletsky, click for larger image)

The eyepiece had a very red filter installed, passing wavelengths longer than 685 nm. This means the sharpest details in the image were as small as 22 milli-arcseconds. We’re pretty sure that this is the highest angular resolution image ever formed on a human retina. We compared what we saw to images recorded on the VisAO science camera at nearly the same wavelength, and it was very gratifying to see the similarities.

Katie tried her hand at drawing the image. You can see the 22-milliarcsecond core of A, the control radius around A, the chromatically elongated speckles, some atmospheric dispersion is evident, and you can see that anisoplanatism is affecting the image of B.

Jared, Katie, and Laird pose next to the eyepiece. Katie is holding The Book. (Photo by Yuri Beletsky, click for bigger version)

During the night, 9 people looked through the eyepiece. These astronomers are the inaugural members of an exclusive club: “L’Ordine degli Astronomi al Limite di Diffrazione” (The Order of Astronomers at the Limit of Diffraction). In this moonlit timelapse you can see most of them take their turn.

Special thanks to Yuri Beletsky for documenting this great night.

Posted in eyepiece, Press | Comments Off

VisAO takes the first optical image of an exoplanet from the ground

Today the MagAO team, along with our collaborators from the NICI team, published a paper on the extrasolar planet beta Pictoris b. We used our CCD camera VisAO to take a picture of the planet, the first time such a camera has been used to image an extrasolar planet from the ground.

You can read more about this achievement at UA News, the NASA Exoplanet Science Institute, and PlanetQuest.

Here is our announcement:

A Small Step Toward Discovering Habitable Earths

University of Arizona researchers snapped images of a planet outside our solar system with an Earth-based telescope using essentially the same type of imaging sensor found in digital cameras instead of an infrared detector. Although the technology still has a very long way to go, the accomplishment takes astronomers a small step closer to what will be needed to image earth-like planets around other stars

An artist’s impression of a young, giant exoplanet orbiting its host star. (Image: NASA/JPL-Caltech)

“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 Jared Males, a NASA Sagan Fellow in the UA’s Department of Astronomy and Steward Observatory and lead author on a report to be published in The Astrophysical Journal.

Even though the image was taken at a wavelength that is just shy of being visible to the human eye, the use of a digital camera-type imaging sensor – called a charge-coupled device or CCD – opens up the possibility of imaging planets in visible light, which has not been possible previously with Earth-based telescopes.

“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 Laird Close, a professor in the Department of Astronomy, who co-authored the paper.

He explained that all the other Earth-based images taken of exoplanets close to their stars are infrared images, which detect the planets’ heat. This limits the technology to Gas Giants – massive, hot planets young enough to still shed heat. In contrast, older, possibly habitable planets that have cooled since their formation don’t show up in infrared images as readily, and to image them, astronomers will have to rely on cameras capable of detecting visible light.

“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 photographed planet, called Beta Pictoris b, orbits its star at only nine times the Earth-Sun distance, making its orbit smaller than Saturn’s. In the team’s CCD images, Beta Pictoris b appears about 100,000 times fainter than its host star, making it the faintest object imaged so far at such high contrast and at such relative proximity to its star. The new images of this planet helped confirm that its atmosphere is at a temperature of roughly 2600 degrees Fahrenheit (1700 Kelvin). The team estimates that Beta Pictoris b weighs in at about 12 times the mass of Jupiter.

An image of the exoplanet Beta Pictoris b made with the Magellan Adaptive Optics (MagAO) VisAO camera. This image was made using a CCD camera, which is essentially the same technology as a cell phone 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.

“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.”

The contrast in brightness between the bright star and the faint planet is similar to the height of a 4-inch molehill next to Mount Everest, Close explained.

In addition to the host star’s overwhelming brightness, the astronomers had to overcome the turbulence in Earth’s atmosphere, which causes stars to twinkle and telescope images to blur. The success reported here is mostly due to an adaptive optics system developed by Close and his team that eliminates much of the atmosphere’s effect. The Magellan Adaptive Optics technology is very good at removing this turbulence, or blurring, by means of a deformable mirror changing shape 1,000 times each second in real time.

The Magellan Telescope with MagAO’s Adaptive Secondary Mirror (ASM) mounted at the top looking down (some 9 meters) onto the 6.5m (21 foot) diameter Primary Mirror (not visible, inside blue mirror cell). Moonlight image, credit: Yuri Beletsky, Las Campanas Observatory.

Adaptive optics have been used for more than 20 years at observatories in Arizona, most recently at the Large Binocular Telescope, and the latest version has now been deployed in the high desert of Chile at the Magellan 6.5-meter telescope.

The team also imaged the planet with both of MagAO’s cameras, giving the scientists two completely independent simultaneous images of the same object in infrared as well as bluer light to compare and contrast.

“An important part of the signal processing is proving that the tiny dot of light is really the planet and not a speckle of noise,” said Katie Morzinski, who is also a Sagan Fellow and member of the MagAO team. “I obtained the second image in the infrared spectrum – at which the hot planet shines brightly – 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.”

Males added: “In our case, we were able to record the planet’s own glow because it is still young and hot enough so that its signal stood out against the noise introduced by atmospheric blurring.”

“But when you go yet another 100,000 times fainter to spot much cooler and truly earthlike planets,” Males said, “we reach a situation in which the residual blurring from the atmosphere is too large and we may have to resort to a specialized space telescope instead.”

Development of the MagAO system was made possible through the strong support of the National Science Foundation MRI, TSIP and ATI grant programs. The Magellan telescopes are operated by a partnership of the Carnegie institute, the University of Arizona, Harvard University, Massachusetts Institute of Technology 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 funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.

Posted in Press | Comments Off