Exoplanets Archives

December 8, 2014December 23, 2015 by Vanessa Janek

New Research Suggests Better Ways To Seek Out Pale Blue Dots

Artist’s impression of how an an Earth-like exoplanet might look. Credit: ESO.

The search for worlds beyond our own is one of humankind’s greatest quests. Scientists have found thousands of exoplanets orbiting other stars in the Milky Way, but are still ironing out the details of what factors truly make a planet habitable. But thanks to researchers at Cornell University, their search may become a little easier. A team at the Institute for Pale Blue Dots has zeroed in on the range of habitable orbits for very young Earth-like planets, giving astronomers a better target to aim at when searching for rocky worlds that contain liquid water and could support the evolution of life.

The Habitable Zone (HZ) of a star is its so-called “Goldilocks region,” the not-too-hot, not-too-cold belt within which liquid water could exist on orbiting rocky planets. Isolating planets in the HZ is the primary objective for scientists hoping to find evidence of life. Until now, astronomers have mainly been searching for worlds that lie in the HZ of stars that are in the prime of their lives: those that are on the Main Sequence, the cosmic growth chart for stellar evolution. According to the group at Cornell, however, scientists should also be looking at cooler, younger stars that have not yet reached such maturity.

The increased distance of the Habitable Zone from pre-main sequence stars makes it easier to spot infant Earths. Credit: Astrophysical Journal Letters.

As shown in the figure above, cool stars in classes F, G, K, and M are more luminous in their pre-Main Sequence stage than they are once they mature. Planets that circle around such bright stars tend to have more distant orbits than those that accompany dimmer stars, making transits more visible and providing a larger HZ for astronomers to probe. In addition, the researchers found that fledgling planets can spend up to 2.5 billion years in the HZ of a young M-class star, a period of time that would allow ample time for life to flourish.

But just because liquid water could exist on a planet doesn’t mean that it does. A rocky planet must first acquire water, and then retain it long enough for life to develop. The Cornell group found that a watery world could lose its aqueous environment to a runaway greenhouse effect if if forms too close to a cool parent star, even if the planet was on course to eventually stray into the star’s HZ. These seemingly habitable planets would have to receive a second supply of water later on in order to truly support life. “Our own planet gained additional water after this early runaway phase from a late, heavy bombardment of water-rich asteroids,” offered Ramses Ramirez, one author of the study. “Planets at a distance corresponding to modern Earth or Venus orbiting these cool stars could be similarly replenished later on.”

Estimations for the HZs of cool, young stars and probable amounts of water loss for exoplanets orbiting at various distances are provided in a preprint of the paper, available here. The research will be published in the January 1, 2015, issue of The Astrophysical Journal.

December 4, 2014December 23, 2015 by Elizabeth Howell

Yes, You Can Find Exoplanets With A Simple Camera And Telephoto Lens

Artist’s impression of the deep blue planet HD 189733b, based on observations from the Hubble Space Telescope. Credit: NASA/ESA.

If you think exoplanet detections are only in the realm of professional planet-hunting telescopes such as Kepler, take a look at the video above. David Schneider, a senior editor for IEEE Spectrum, explains that it takes little more than a DSLR camera and a camera lens to catch a glimpse.

Schneider told Universe Today that he’s not an experienced amateur observer, nor should his equipment be expected to detect new exoplanets. But the potential for the future is interesting, he explained.

“I was simply trying to detect the signature of a known exoplanet, one that was discovered years ago with far more sophisticated gear,” he wrote in an e-mail. “I knew exactly which star to look at, when the transit occurs, and what the change in brightness would be. I relied on the expertise of professional astronomers to provide all that information.”

Here’s the setup: a Canon EOS Rebel XS DSLR, a 300-millimeter Nikon telephoto lens, an adapter to get the Nikon talking to the Canon, and a self-built “barn door tracker” that he constructed based on descriptions he found on the web. (His IEEE Spectrum article has more details.)

Schneider chose HD 189733, whose hostile-to-life “deep blue” exoplanet is about 63 light-years away and transits the face of the star every 2.2 days. But often these transits take place at inconvenient times (such as during the day, and the star is low on the horizon). He also faced several cloudy nights, meaning it was several weeks until he could take the imagery.

Once that was finished, Schneider ran the pictures through a piece of astronomical imaging software called Iris. In Schneider’s words, this is how the software helped him pick out the planet:

At the most basic level, Iris allows you to perform the corrections that are customary for really all types of digital astrophotography. In particular, you correct for ‘hot pixels’ in your camera sensor and for variations in the sensitivity of the sensor across the frame. This is standard stuff in astrophotography, requiring that you take images with the lens cap on (so-called “darks”), of a uniformly illuminated background (“flats”), and so forth.

For this project, you also need to use the tools that Iris provides to do what’s called aperture photometry. In a nutshell, you have to adjust the registration of the set of images you collect so that the stars are in the same position in each image. Then you have to set up things in Iris to do photometric measurements of a selected set of stars in one frame. After that, Iris will perform the photometry you want on the whole set of images you have in an automated fashion.

While his equipment isn’t sophisticated enough to account for “false positives” such as a sunspot going across a star — amateurs are more at the stage of confirming professional observations — Schneider pointed out there are many similar projects to his own. Among them are KELT-NORTH (which inspired his search), Evryscope, and this group at the University of Arizona.

“My project merely highlights that you can get your feet wet in this area with some really cheap hardware,” Schneider said. He recommends those that want to do similar work to his read the IEEE Spectrum article, buy the hardware required, read up on astrophotography and Iris, and not be afraid to experiment.

Schneider added he wasn’t trying to do “anything special” — many amateurs have encountered similar success — but he had a lot of fun. “Maybe because I’m a bit of a computer nerd, I found digital astrophotography to be a lot more enjoyable than actually looking through a telescope, which in the few times I’ve done that often involved a lot of squinting and unpleasant vibration.”

November 24, 2014December 23, 2015 by Dan Majaess

Searching for Alien Worlds and Gravitational Lenses from the Arctic

Astronomical observations have been obtained from the Polar Environment Atmospheric Research Laboratory (PEARL), which is located in Northern Canada (image credit: left, Steinbring et al., right, Dan Weaver).

The quest for optimal sites to carry out astronomical observations has taken scientists to the frigid Arctic. Eric Steinbring, who led a team of National Research Council Canada experts, noted that a high Arctic site can, “offer excellent image quality that is maintained during many clear, calm, dark periods that can last 100 hours or more.” The new article by Steinbring and colleagues conveys recent progress made to obtain precise observations from a 600 m high ridge near the Eureka research base on Ellesmere Island, which is located in northern Canada.

The new telescope that Steinbring and his colleagues tested was located at the Polar Environment Atmospheric Research Laboratory (PEARL). The observatory can be accessed in winter by 4 x 4 trucks via a 15 km long road from a base facility at sea-level. That base camp is operated by Environment Canada and serviced by an airstrip and resupply ship in summer. Recently, wide-field cameras developed at the University of Toronto were deployed near Eureka to monitor thousands of stars, with the objective of expanding the exoplanet database.

Earlier work by Steinbring and colleagues indicated that data obtained from PEARL imply that clear weather prevails 68% of the time. After significant testing, the team concluded that the site “can allow reliable, uninterrupted temporal coverage during successive dark periods, in roughly 100 hour blocks with clear skies and good seeing.”

The Polar Environment Atmospheric Research Laboratory (PEARL) is located on Ellesmere Island (image credit: Left, , right, Tobias Kerzenmacher). — The Polar Environment Atmospheric Research Laboratory (PEARL) is located on Ellesmere Island (image credit: left, wikimedia commons, right, Tobias Kerzenmacher).

However, the optimal conditions can be interrupted by brief but potentially intense storms. In the article the team added that, “the primary issue is wind rather than the cold temperatures.” The PEARL facility is equipped with an important weather probe that conveys on-site conditions at 10 minute intervals, thanks to the Canadian Network for the Detection of Atmospheric Change (CANDAC).

There are numerous challenges that arise when observing from the Arctic, but scientists like Steinbring have worked to overcome them, potentially enabling new studies of gravitational lenses and other pertinent phenomena. Indeed, astronomical observations are likewise being obtained from Antarctica. For example, there is the Antarctic Search for Transiting Exoplanets (ASTEP) 40 cm telescope at Dome C, and three 50 cm Antarctic Survey Telescopes (AST3) at Dome A, Antarctica. Steinbring remarked that floorspace is potentially available for up to 5 more telescopes at PEARL, if the compact design they studied was adopted.

E. Steinbring and his colleagues B. Leckie and R. Murowinski are associated with the National Research Council Canada, Herzberg Astronomy and Astrophysics in Victoria, Canada. An electronic preprint of their article is available on arXiv, and the findings were presented recently at the Adapting to the Atmosphere Conference in Durham, UK.

November 13, 2014December 23, 2015 by Elizabeth Howell

‘Double Earths’ Could Be Fun Exoplanets To Hunt For — If They Exist

Artist's conception of binary Earths. Credit: NASA

One big driver in the search for exoplanets is whether life can exist elsewhere in the Universe. In fact, a major goal of the Kepler space telescope is to discover an Earth-like planet in the habitable zone of a star like our Sun.

But what about having two Earths orbiting close to each other for billions of years? Is this even possible? A new study suggests that yes, this could happen. Imagine the implications for planetary searches if a double Earth is possible.

With current technology it’s hard to spot an Earth-sized planet, let alone resolve two, but if such planets exist it presents interesting questions. Could they be habitable? How do they form? More study is needed.

The study says double Earths can happen if they form at least half a Sun-Earth distance from their star. In what scientists say is the first-ever study considering binary Earths they suggest a scenario where two rocky bodies get close to each other early in their Solar System’s formation. They don’t collide (such as what likely formed our Moon), but they’re close enough to be within three or so radii of each other.

Artist's conception of two celestial bodies smacking into each other. Such a collision is believed to have formed Earth's moon. Credit: NASA/JPL-Caltech — Artist’s conception of two celestial bodies smacking into each other. Such a collision is believed to have formed Earth’s moon. Credit: NASA/JPL-Caltech

“There is a good reason to believe terrestrial binary planetary systems may be possible,” read a press release from the California Institute of Technology. “In a grazing collision the angular momentum is too high to be contained within a single rotating body (it would fission) and if the bodies barely touch then they could retain their identity. However, it requires an encounter where the bodies are initially approaching each other at low enough velocity.”

Scientists simulated these planetary encounters using a simulation, dubbed Smooth Particle Hydrodynamics, which has been used in the past for scenarios such as the collision that created the Moon. The scenarios showed that a collision between two Earth-sized planets would only produce a Moon. However, if the bodies came close enough to produce tidal distortion on each other, the planets could form a binary system.

The research was presented at the Division for Planetary Sciences meeting of the American Astronomical Society this week by undergraduate Keegan Ryan, graduate student Miki Nakajima, and planetary science researcher David Stevenson, all of the California Institute of Technology. A press release did not disclose plans for publication, or if the research is peer-reviewed.

Source: California Institute of Technology

November 11, 2014December 23, 2015 by Elizabeth Howell

Dusty Baby Solar System Gives Clues On How Our Sun And Planets Grew Up

Artist's conception of early planetary formation from gas and dust around a young star. Outbursts from newborn and adolescent stars might drive planetary water beneath the surface of rocky worlds. Credit: NASA/NASA/JPL-Caltech

This isn’t a clone of our Solar System, but it’s close enough. Scientists eagerly scrutinized a young star system called HD 95086 to learn more about how dust belts and giant planets grow up together. This is an important finding for our own neighborhood, where the gas giants of Jupiter, Saturn, Uranus and Neptune are also wedged between dusty areas.

“By looking at other star systems like these, we can piece together how our own Solar System came to be,” stated lead author Kate Su, an associate astronomer at the University of Arizona, Tucson.

The system is about 295 light-years from Earth, and is suspected to have two dust belts: a warmer one (similar to our asteroid belt) and a cooler one (similar to the Kuiper Belt that has icy objects.) The system is host to at least one planet that is five times the mass of Jupiter, and other planets could also be hiding between the dusty lanes. This planet, called HD 95086 b, was imaged by the European Southern Observatory’s Very Large Observatory in 2013.

Planet HD95086 b is shown at lower left in this picture. Astronomers blocked out the light of the star (center) to image the exoplanet. The blue circle represents the equivalent orbit of Neptune in this star system. Credit: ESO/J. Rameau

The next step was a comparison study with another star system called HR 8799, which also has two dusty rings and in this case, at least four planets in between. These planets have also been caught on camera. Comparing the structure of the two systems indicates that HD 95086 may have more planets lurking for astronomers to discover.

“By knowing where the debris is, plus the properties of the known planet in the system, we can get an idea of what other kinds of planets can be there,” stated Sarah Morrison, a co-author of the paper and a PhD student at the University of Arizona. “We know that we should be looking for multiple planets instead of a single giant planet.”

The researchers presented their work at the Division for Planetary Science Meeting of the American Astronomical Society in Tucson, Arizona. A press release did not disclose publication plans or if the work was peer-reviewed.

Source: NASA

November 10, 2014December 23, 2015 by Matt Williams

NASA’s Next Exoplanet Hunter Moves Into Development

A conceptual image of the Transiting Exoplanet Survey Satellite. Image Credit: MIT

NASA’s ongoing hunt for exoplanets has entered a new phase as NASA officially confirmed that the Transiting Exoplanet Survey Satellite (TESS) is moving into the development phase. This marks a significant step for the TESS mission, which will search the entire sky for planets outside our solar system (a.k.a. exoplanets). Designed as the first all-sky survey, TESS will spend two years of an overall three-year mission searching both hemispheres of the sky for nearby exoplanets.

Previous sky surveys with ground-based telescopes have mainly picked out giant exoplanets. In contrast, TESS will examine a large number of small planets around the very brightest stars in the sky. TESS will then record the nearest and brightest main sequence stars hosting transiting exoplanets, which will forever be the most favorable targets for detailed investigations. During the third year of the TESS mission, ground-based astronomical observatories will continue monitoring exoplanets identified by the TESS spacecraft.

“This is an incredibly exciting time for the search of planets outside our solar system,” said Mark Sistilli, the TESS program executive from NASA Headquarters, Washington. “We got the green light to start building what is going to be a spacecraft that could change what we think we know about exoplanets.”

“During its first two years in orbit, the TESS spacecraft will concentrate its gaze on several hundred thousand specially chosen stars, looking for small dips in their light caused by orbiting planets passing between their host star and us,” said TESS Principal Investigator George Ricker of the Massachusetts Institute of Technology..

Artistic representations of the only known planets around other stars (exoplanets) with any possibility to support life as we know it. Credit: Planetary Habitability Laboratory, University of Puerto Rico, Arecibo. — *Artistic representations of known exoplanets with any possibility to support life. Image Credit: Planetary Habitability Laboratory, University of Puerto Rico, Arecibo.*

All in all, TESS is expected to find more than 5,000 exoplanet candidates, including 50 Earth-sized planets. It will also find a wide array of exoplanet types, ranging from small, rocky planets to gas giants. Some of these planets could be the right sizes, and orbit at the correct distances from their stars, to potentially support life.

“The most exciting part of the search for planets outside our solar system is the identification of ‘earthlike’ planets with rocky surfaces and liquid water as well as temperatures and atmospheric constituents that appear hospitable to life,” said TESS Project Manager Jeff Volosin at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Although these planets are small and harder to detect from so far away, this is exactly the type of world that the TESS mission will focus on identifying.”

Now that NASA has confirmed the development of TESS, the next step is the Critical Design Review, which is scheduled to take place in 2015. This would clear the mission to build the necessary flight hardware for its proposed launch in 2017.

“After spending the past year building the team and honing the design, it is incredibly exciting to be approved to move forward toward implementing NASA’s newest exoplanet hunting mission,” Volosin said.

TESS is designed to complement several other critical missions in the search for life on other planets. Once TESS finds nearby exoplanets to study and determines their sizes, ground-based observatories and other NASA missions, like the James Webb Space Telescope, would make follow-up observations on the most promising candidates to determine their density and other key properties.

*The James Webb Space Telescope. Image Credit: NASA/JPL*

By figuring out a planet’s characteristics, like its atmospheric conditions, scientists could determine whether the targeted planet has a habitable environment.

“TESS should discover thousands of new exoplanets within two hundred light years of Earth,” Ricker said. “Most of these will be orbiting bright stars, making them ideal targets for characterization observations with NASA’s James Webb Space Telescope.”

“The Webb telescope and other teams will focus on understanding the atmospheres and surfaces of these distant worlds, and someday, hopefully identify the first signs of life outside of our solar system,” Volosin said.

TESS will use four cameras to study sections of the sky’s north and south hemispheres, looking for exoplanets. The cameras would cover about 90 percent of the sky by the end of the mission.

This makes TESS an ideal follow-up to the Kepler mission, which searches for exoplanets in a fixed area of the sky. Because the TESS mission surveys the entire sky, TESS is expected to find exoplanets much closer to Earth, making them easier for further study.

In addition, Ricker said TESS would provide precision, full-frame images for more than 20 million bright stars and galaxies.

“This unique new data will comprise a treasure trove for astronomers throughout the world for many decades to come,” Ricker said.

Now that TESS is cleared to move into the next development stage, it can continue towards its goal of being a key part of NASA’s search for life beyond Earth.

“I’m still hopeful that in my lifetime, we will discover the existence of life outside of our solar system and I’m excited to be part of a NASA mission that serves as a key stepping stone in that search,” Volosin said.

Further Reading: NASA

November 7, 2014December 23, 2015 by Jason Major

Will Gaia Be Our Next Big Exoplanet Hunter?

ESA's Gaia is currently on a five-year mission to map the stars of the Milky Way. Image credit: ESA/ATG medialab; background: ESO/S. Brunier.

Early on the morning of Dec. 19, 2013, the pre-dawn sky above the coastal town of Kourou in French Guiana was briefly sliced by the brilliant exhaust of a Soyuz VS06 rocket as it ferried ESA’s “billion-star surveyor” Gaia into space, on its way to begin a five-year mission to map the precise locations of our galaxy’s stars. From its position in orbit around L2 Gaia will ultimately catalog the positions of over a billion stars… and in the meantime it will also locate a surprising amount of Jupiter-sized exoplanets – an estimated 21,000 by the end of its primary mission in 2019.

And, should Gaia continue observations in extended missions beyond 2019 improvements in detection methods will likely turn up even more exoplanets, anywhere from 50,000 to 90,000 over the course of a ten-year mission. Gaia could very well far surpass NASA’s Kepler spacecraft for exoplanet big game hunting!

“It is not just the number of expected exoplanet discoveries that is impressive”, said former mission project scientist Michael Perryman, lead author on a report titled Astrometric Exoplanet Detection with Gaia. “This particular measurement method will give us planet masses, a complete exoplanet survey around all types of stars in our Galaxy, and will advance our knowledge of the existence of massive planets orbiting far out from their host stars”.

Watch: ESA’s Gaia Launches to Map the Milky Way

Artist's impression of a Jupiter-sized exoplanet orbiting an M-dwarf star — Artist’s impression of a Jupiter-sized exoplanet orbiting an M-dwarf star

The planets Gaia will be able to spot are expected to be anywhere from 1 to fifteen times the mass of Jupiter in orbit around Sun-like stars out to a distance of about 500 parsecs (1,630 light-years) from our own Solar System. Exoplanets orbiting smaller red dwarf stars will also be detectable, but only within about a fifth of that distance.

While other space observatories like NASA’s Kepler and CNES/ESA’s CoRoT were designed to detect exoplanets through the transit method, whereby a star’s brightness is dimmed ever-so-slightly by the silhouette of a passing planet, Gaia will detect particularly high-mass exoplanets by the gravitational wobble they impart to their host stars as they travel around them in orbit. This is known as the astrometric method.

A select few of those exoplanets will also be transiting their host stars as seen from Earth – anywhere from 25 to 50 of them – and so will be observable by Gaia as well as from many ground-based transit-detection observatories.

After some issues with stray light sneaking into its optics, Gaia was finally given the green light to begin science observations at the end of July and has since been diligently scanning the stars from L2, 1.5 million km from Earth.

With the incredible ability to measure the positions of a billion stars each to an accuracy of 24 microarcseconds – that’s like measuring the width of a human hair from 1,000 km – Gaia won’t be “just” an unprecedented galactic mapmaker but also a world-class exoplanet detector! Get more facts about the Gaia mission here.

The team’s findings have been accepted for publication in The Astrophysical Journal.

Source: ESA

November 6, 2014December 23, 2015 by Tammy Plotner

ALMA Shows Off Baby Pictures… Baby Planets, That Is!

This is the sharpest image ever taken by ALMA — sharper than is routinely achieved in visible light with the NASA/ESA Hubble Space Telescope. It shows the protoplanetary disc surrounding the young star HL Tauri. These new ALMA observations reveal substructures within the disc that have never been seen before and even show the possible positions of planets forming in the dark patches within the system. Credit: ALMA (ESO/NAOJ/NRAO)

In a test of its new high resolution capabilities, the Atacama Large Millimeter/submillimeter Array (ALMA) is happily sharing some family snapshots with us. Astronomers manning the cameras have captured one of the best images so far of a newly-forming planet system gathering itself around a recently ignited star. Located about 450 light years from us in the constellation of Taurus, young HL Tau gathers material around it to hatch its planets and fascinate researchers.

Thanks to ALMA images, scientists have been able to witness stages of planetary formation which have been suspected, but never visually confirmed. This very young star is surrounded by several concentric rings of material which have neatly defined spacings. Is it possible these clearly marked gaps in the solar rubble disc could be where planets have started to gel?

“These features are almost certainly the result of young planet-like bodies that are being formed in the disk. This is surprising since HL Tau is no more than a million years old and such young stars are not expected to have large planetary bodies capable of producing the structures we see in this image,” said ALMA Deputy Director Stuartt Corder.

“When we first saw this image we were astounded at the spectacular level of detail. HL Tauri is no more than a million years old, yet already its disc appears to be full of forming planets. This one image alone will revolutionize theories of planet formation,” explained Catherine Vlahakis, ALMA Deputy Program Scientist and Lead Program Scientist for the ALMA Long Baseline Campaign.

Let’s take a look at what we understand about solar system formation…

Through repeated research, astronomers suspect that all stars are created when clouds of dust and gas succumb to gravity and collapse on themselves. As the star begins to evolve, the dust binds together – turning into “solar system soup” consisting of an array of different sized sand and rocks. This rubble eventually congeals into a thin disc surrounding the parent star and becomes home to newly formed asteroids, comets, and planets. As the planets collect material into themselves, their gravity re-shapes to structure of the disc which formed them. Like dragging a lawn sweeper over fallen leaves, these planets clear a path in their orbit and form gaps. Eventually their progress pulls the gas and dust into an even tighter and more clearly defined structure. Now ALMA has shown us what was once only a computer model. Everything we thought we knew about planetary formation is true and ALMA has proven it.

“This new and unexpected result provides an incredible view of the process of planet formation. Such clarity is essential to understand how our own solar system came to be and how planets form throughout the universe,” said Tony Beasley, director of the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, which manages ALMA operations for astronomers in North America.

“Most of what we know about planet formation today is based on theory. Images with this level of detail have up to now been relegated to computer simulations or artist’s impressions. This high resolution image of HL Tauri demonstrates what ALMA can achieve when it operates in its largest configuration and starts a new era in our exploration of the formation of stars and planets,” says Tim de Zeeuw, Director General of ESO.

The major reason astronomers have never seen this type of structure before is easy to envision. The very dust which creates the planetary disc around HL Tau also conceals it to visible light. Thanks to ALMA’s ability to “see” at much longer wavelengths, it can image what’s going on at the very heart of the cloud. “This is truly one of the most remarkable images ever seen at these wavelengths. The level of detail is so exquisite that it’s even more impressive than many optical images. The fact that we can see planets being born will help us understand not only how planets form around other stars but also the origin of our own solar system,” said NRAO astronomer Crystal Brogan.

How does ALMA do it? According to the research staff, its new high-resolution capabilities were achieved by spacing the antennas up to 15 kilometers apart. This baseline at millimeter wavelengths enabled a resolution of 35 milliarcseconds, which is equivalent to a penny as seen from more than 110 kilometers away. “Such a resolution can only be achieved with the long baseline capabilities of ALMA and provides astronomers with new information that is impossible to collect with any other facility, including the best optical observatories,” noted ALMA Director Pierre Cox.

This is a composite image of the young star HL Tauri and its surroundings using data from ALMA (enlarged in box at upper right) and the NASA/ESA Hubble Space Telescope (rest of the picture). This is the first ALMA image where the image sharpness exceeds that normally attained with Hubble. Credit: ALMA (ESO/NAOJ/NRAO)

The long baselines spell success for the ALMA observations and are a tribute to all the technology and engineering that went into its construction. Future observations at ALMA’s longest possible baseline of 16 kilometers will mean even more detailed images – and an opportunity to further expand our knowledge of the Cosmos and its workings. “This observation illustrates the dramatic and important results that come from NSF supporting world-class instrumentation such as ALMA,” said Fleming Crim, the National Science Foundation assistant director for Mathematical and Physical Sciences. “ALMA is delivering on its enormous potential for revealing the distant universe and is playing a unique and transformational role in astronomy.”

Pass them baby pictures our way, Mama ALMA… We’re delighted to take a look!

Original Story Source: “Revolutionary ALMA Image Reveals Planetary Genesis” – ESO Press Release

November 4, 2014December 23, 2015 by Matt Williams

VLTI Detects Exozodiacal Light Around Exoplanets

Artist's impression of zodiacal light viewed from the surface of an exoplanet. Credit: ESO/L. Calçada

If you’ve ever stood outside after twilight has passed, or a few hours before the sun rises at dawn, then chances are you’ve witnessed the phenomenon known as zodiacal light. This effect, which looks like a faint, diffuse white glow in the night sky, is what happens when sunlight is reflected off of tiny particles and appears to extend up from the vicinity of the Sun. This reflected light is not just observed from Earth but can be observed from everywhere in the Solar System.

Using the full power of the Very Large Telescopic Interferometer (VLTI), an international team of astronomers recently discovered that the exozodiacal light – i.e., zodiacal light around other star systems – close to the habitable zones around nine nearby stars was far more extreme. The presence of such large amounts of dust in the inner regions around some stars may pose an obstacle to the direct imaging of Earth-like planets.

The reason for this is simple: even at low levels, exozodiacal dust causes light to become amplified intensely. For example, the light detected in this survey was roughly 1000 times brighter than the zodiacal light seen around the Sun. While this exozodiacal light had been previously detected, this is the first large systematic study of this phenomenon around nearby stars.

The team used the VLTI visitor instrument PIONIER which is able to interferometrically connect all four Auxiliary Telescopes or all four Unit Telescopes of the VLTI at the Paranal Observatory. This led to not only extremely high resolution of the targets but also allowed for a high observing efficiency.

The Very Large Telescoping Interferometer firing it's adaptive optics laser. Credit: ESO/G. Hüdepohl — *The Very Large Telescoping Interferometer firing its adaptive optics laser.*
*Credit: ESO/G. Hüdepohl*

In total, the team observed exozodiacal light from hot dust close to the habitable zones of 92 nearby stars and combined the new data with their earlier observations.

In contrast to these earlier observations – which were made with the Center for High Angular Resolution Astronomy (CHARA) array at Georgia State University – the team did not observe dust that will later form into planets, but dust created in collisions between small planets of a few kilometers in size – objects called planetesimals that are similar to the asteroids and comets of the Solar System. Dust of this kind is also the origin of the zodiacal light in the Solar System.

As a by-product, these observations have also led to the discovery of new, unexpected stellar companions orbiting around some of the most massive stars in the sample. “These new companions suggest that we should revise our current understanding of how many of this type of star are actually double,” says Lindsay Marion, lead author of an additional paper dedicated to this complementary work using the same data.

“If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars,” said Steve Ertel, lead author of the paper, from ESO and the University of Grenoble in France. “Detecting and characterizing this kind of dust around other stars is a way to study the architecture and evolution of planetary systems.”

A portrait of the HR8799 planetary system as imaged by the Hale Telescope. Credit: NASA/JPL-Caltech/Palomar Observatory. — *A portrait of the HR8799 planetary system as imaged by the Hale Telescope.*
*Credit: NASA/JPL-Caltech/Palomar Observatory.*

However, the good news is that the number of stars containing zodiacal light at the level of our Solar System is most likely much higher than the numbers found in the survey.

“The high detection rate found at this bright level suggests that there must be a significant number of systems containing fainter dust, undetectable in our survey, but still much brighter than the Solar System’s zodiacal dust,” explains Olivier Absil, co-author of the paper, from the University of Liège. “The presence of such dust in so many systems could therefore become an obstacle for future observations, which aim to make direct images of Earth-like exoplanets.”

Therefore, these observations are only a first step towards more detailed studies of exozodiacal light, and need not dampen our spirits about discovering more Earth-like exoplanets in the near future.

Further Reading: ESO

October 29, 2014December 23, 2015 by Tammy Plotner

Double Disc Found Feeding Each Other In Binary Star System

This wide-field view shows the sky around the young multiple star system GG Tauri, which appears very close to the centre of this picture. This view also shows a dust cloud and evidence of star formation near the top of the picture. Credit: ESO/Digitized Sky Survey 2. Acknowledgement: Davide De Martin

Deep within the Taurus Dark Cloud complex, one of the closest star-forming regions to Earth has just revealed one of its secrets – an umbilical cord of gas flowing from the expansive outer disc toward the interior of a binary star system known as GG Tau-A. According to the ESO press release, this never-before-seen feature may be responsible for sustaining a second, smaller disc of planet-forming material that otherwise would have disappeared long ago.

A research group led by Anne Dutrey from the Laboratory of Astrophysics of Bordeaux, France and CNRS used the Atacama Large
Millimeter/submillimeter Array (ALMA) to observe the distribution of
dust and gas in the unusual GG Tau-A system. Since at least half of
Sun-like stars are the product of binary star systems, these type of
findings may produce even more fertile grounds for discovering
exoplanets. However, the 450 light year distant GG Tau system is even more complex than previously thought. Through observations taken with the VLTI, astronomers have discovered its primary star – home to the inner disc – is part of a more involved multiple-star system. The secondary star is also a close binary!

“We may be witnessing these types of exoplanetary systems in the midst of formation,” said Jeffrey Bary, an astronomer at Colgate University in Hamilton, N.Y., and co-author of the paper. “In a sense, we are learning why these seemingly strange systems exist.”

Let’s take a look…

This artist’s impression shows the dust and gas around the double star system GG Tauri-A. Researchers using ALMA have detected gas in the region between two discs in this binary system. This may allow planets to form in the gravitationally perturbed environment of the binary. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets.

“Like a wheel in a wheel, GG Tau-A contains a large, outer disc
encircling the entire system as well as an inner disc around the main central star. This second inner disc has a mass roughly equivalent to that of Jupiter.” says the research team. “Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.”

Thanks to studies done with ALMA, the researchers made an exciting discovery in these disc structures… gas clumps located between the two. This observation could mean that material is being fed from the outer disc to feed the inner. Previously observations done with ALMA show that a single star pulls its materials inward from the outer disc. Is it possible these gas pockets in the double disc GG Tau-A system are creating a sustaining lifeline between the two?

“Material flowing through the cavity was predicted by computer
simulations but has not been imaged before. Detecting these clumps
indicates that material is moving between the discs, allowing one to
feed off the other,” explains Dutrey. “These observations demonstrate that material from the outer disc can sustain the inner disc for a long time. This has major consequences for potential planet formation.”

As we know, planets are created from the materials leftover from
stellar ignition. However, the creation of a solar system occurs at a snail’s pace, meaning that a debris disc with longevity is required for planet formation. Thanks to these new “disc feeding” observations from ALMA, researchers can surmise that other multiple-star systems behave in a similar manner… creating even more possibilities for exoplanet formation.

“This means that multiple star systems have a way to form planets, despite their complicated dynamics. Given that we continue to find interesting planetary systems, our observations provide a glimpse of the mechanisms that enable such systems to form,” concludes Bary.

During the initial phase of planetary searches, the emphasis was placed on Sun-like, single-host stars. Later on, binary systems gave rise to giant Jupiter-sized planets – nearly large enough to be stars on their own. Now the focus has turned to pointing our planetary discovery efforts towards individual members of multiple-systems.

Emmanuel Di Folco, co-author of the paper, concludes: “Almost half the Sun-like stars were born in binary systems. This means that we have found a mechanism to sustain planet formation that applies to a significant number of stars in the Milky Way. Our observations are a big step forward in truly understanding planet formation.”

Original Story Source: Planet-forming Lifeline Discovered in a Binary Star System ALMA Examines Ezekiel-like “Wheel in a Wheel” of Dust and Gas – ESO Science News Release.