Exoplanet Stepping Stones

Astronomers have gleaned some of the best data yet on the composition of a planet known as HR 8799c — a young giant gas planet about 7 times the mass of Jupiter that orbits its star every 200 years.

The team used state-of-the art instrumentation at the W. M. Keck Observatory on Maunakea, Hawaii to confirm the existence of water in the planet’s atmosphere, as well as a lack of methane.

While other researchers had previously made similar measurements of this planet, these new, more robust data demonstrate the power of combining high-resolution spectroscopy with a technique known as adaptive optics, which corrects for the blurring effect of Earth’s atmosphere.

“This type of technology is exactly what we want to use in the future to look for signs of life on an Earth-like planet. We aren’t there yet but we are marching ahead,” says Dimitri Mawet, an associate professor of astronomy at Caltech and a research scientist at JPL, which Caltech manages for NASA.

Mawet is co-author of a new paper on the findings published today in the Astronomical Journal. The lead author is Ji Wang, formerly a postdoctoral scholar at Caltech and now an assistant professor at Ohio State University.

Taking pictures of planets that orbit other stars — exoplanets — is a formidable task. Light from the host stars far outshines the planets, making them difficult to see.

More than a dozen exoplanets have been directly imaged so far, including HR 8799c and three of its planetary companions. In fact, HR 8799 is the only multiple-planet system to have its picture taken. Discovered using adaptive optics on the Keck II telescope, the direct images of HR8799 are the first-ever of a planetary system orbiting a star other than our sun.

Once an image is obtained, astronomers can use instruments, called spectrometers, to break apart the planet’s light, like a prism turning sunlight into a rainbow, thereby revealing the fingerprints of chemicals. So far, this strategy has been used to learn about the atmospheres of several giant exoplanets.

The next step is to do the same thing only for smaller planets that are closer to their stars (the closer a planet is to its star and the smaller its size, the harder is it to see).

The ultimate goal is to look for chemicals in the atmospheres of Earth-like planets that orbit in the star’s “habitable zone” — including any biosignatures that might indicate life, such as water, oxygen, and methane.

Mawet’s group hopes to do just this with an instrument on the upcoming Thirty Meter Telescope, a giant telescope being planned for the late 2020s by several national and international partners, including Caltech.

But for now, the scientists are perfecting their technique using Keck Observatory — and, in the process, learning about the compositions and dynamics of giant planets.

“Right now, with Keck, we can already learn about the physics and dynamics of these giant exotic planets, which are nothing like our own solar system planets,” says Wang.

In the new study, the researchers used an instrument on the Keck II telescope called NIRSPEC (near-infrared cryogenic echelle spectrograph), a high-resolution spectrometer that works in infrared light.

They coupled the instrument with Keck Observatory’s powerful adaptive optics, a method for creating crisper pictures using a guide star in the sky as a means to measure and correct the blurring turbulence of Earth’s atmosphere.

This is the first time the technique has been demonstrated on directly imaged planets using what’s known as the L-band, a type of infrared light with a wavelength of around 3.5 micrometers, and a region of the spectrum with many detailed chemical fingerprints.

“The L-band has gone largely overlooked before because the sky is brighter at this wavelength,” says Mawet. “If you were an alien with eyes tuned to the L-band, you’d see an extremely bright sky. It’s hard to see exoplanets through this veil.”

The researchers say that the addition of adaptive optics made the L-band more accessible for the study of the planet HR 8799c. In their study, they made the most precise measurements yet of the atmospheric constituents of the planet, confirming it has water and lacks methane as previously thought.

“We are now more certain about the lack of methane in this planet,” says Wang. “This may be due to mixing in the planet’s atmosphere. The methane, which we would expect to be there on the surface, could be diluted if the process of convection is bringing up deeper layers of the planet that don’t have methane.”

The L-band is also good for making measurements of a planet’s carbon-to-oxygen ratio — a tracer of where and how a planet forms. Planets form out of swirling disks of material around stars, specifically from a mix of hydrogen, oxygen, and carbon-rich molecules, such as water, carbon monoxide, and methane.

These molecules freeze out of the planet-forming disks at different distances from the star — at boundaries called snowlines. By measuring a planet’s carbon-to-oxygen ratio, astronomers can thus learn about its origins.

Mawet’s team is now gearing up to turn on their newest instrument at Keck Observatory, called the Keck Planet Imager and Characterizer (KPIC). It will also use adaptive optics-aided high-resolution spectroscopy but can see planets that are fainter than HR 8799c and closer to their stars.

“KPIC is a springboard to our future Thirty Meter Telescope instrument,” says Mawet. “For now, we are learning a great deal about the myriad ways in which planets in our universe form.”

The Violent Solar Storms That Threaten Earth

A violent storm on the Sun could cripple communications on Earth and cause huge economic damage, scientists have warned. Why are solar storms such a threat?

In 1972, dozens of sea mines off the coast of Vietnam mysteriously exploded.

It was recently confirmed the cause was solar storms, which can significantly disrupt the Earth’s magnetic field.

Today, the effects of a similar event could be much more serious – disrupting the technology we rely on for everything from satellites to power grids. The cost to the UK economy alone of an unexpected event has been estimated at £16bn.

There are good reasons why we are vulnerable to events taking place millions of miles from Earth.

What causes an extreme solar event?
The Sun is a star, a seething mass of electrified hydrogen. As this fluid moves around, it builds up energy within its complex magnetic field.

This magnetic energy is released through intense flashes of light known as solar flares and through vast eruptions of material and magnetic fields known as coronal mass ejections or solar storms.

While flares can disrupt radio communication on Earth, solar storms pose the greatest threat.

Each storm contains the energy equivalent to 100,000 times the world’s entire nuclear arsenal, although this is spread throughout an enormous volume in space.

The Sun rotates like a vast spinning firework, launching eruptions into space in all directions.

If one of these heads towards our planet, with a magnetic field aligned opposite to the Earth’s, the two fields can merge together. As the solar storm washes past, some of the Earth’s magnetic field is distorted into a long tail.

And when this distorted magnetic field eventually snaps back, it accelerates electrified particles towards the Earth. Here, they strike the upper atmosphere, heating it and causing it to glow in a spectacular display known as the northern and southern lights.

But this distortion of the Earth’s magnetic field has other, more significant effects.

It is thought to have triggered the sea mines back in 1972. The mines were designed to detect small variations in the magnetic field caused by the approach of metal-hulled boats. But their engineers hadn’t anticipated that solar activity could have the same effect.

When will the next extreme weather event happen?
Scientists are looking for clues as to what triggers these vast eruptions and, once they have been launched, how to track them through interplanetary space.

Our records of the Earth’s magnetic field go back as far as the mid-19th Century. They suggest an extreme space weather event is likely to occur once every 100 years, although smaller events will happen more frequently. In 1859, the Carrington Event – most extreme solar storm recorded to date – caused telegraph systems to spark and for the northern lights to be spotted as far south as the Bahamas.

The next time it happens, the effects are likely to be far more serious.

With every solar cycle, our global community has become more reliant on technology.

In 2018, space satellites are central to global communication and navigation, while aeroplanes connect continents and extensive power grids crisscross the world.

All of these could be badly affected by the aftermath of extreme solar events.

Electronic systems on spacecraft and aeroplanes could be harmed as their miniaturised electronics are zapped by energetic particles accelerated into our atmosphere, while power networks on the ground can be overwhelmed by excess electrical currents.

Planning ahead
Enough satellites and power grids have failed during past space weather events to make it clear that the Sun must be closely monitored, to help predict when a solar storm will affect Earth.

Forecasters are working on this all over the world, from the UK’s Met Office to the Australian Met Bureau and the Noaa Space Weather Prediction Center in the US.

All being well, they can detect when a storm is heading towards Earth and predict its arrival time within six hours. That still leaves relatively little time to prepare but forecasting would cut the cost to the UK economy from £16bn to £3bn.

Space weather now appears on the UK government’s risk register, alongside other, more familiar risks such as a flu pandemic and severe flooding. It has been rated at the equivalent risk as a severe heatwave or the emergence of a new infectious disease.

Government agencies are now speaking to power companies, spacecraft and airline operators to ensure they have plans in place to limit the impact of an extreme space weather event.

It is vital, for example, to make sure enough power is available to refrigerate supplies of food and medicine as well as to make sure water and fuel can be pumped as needed.

If communication with some satellites is lost, familiar technologies such as sat-navs and satellite television could stop working.

Spacecraft engineers study extreme events so they can build resilience into spacecraft, protecting vulnerable electronics and installing backup systems.

An accurate space weather forecast would enable operators to further protect their assets by ensuring they were in a safe state as the storm passed.

Many planes fly over the north pole en route from Europe to North America. During space weather events, aircraft operators re-route aeroplanes away from the polar skies, where most of the energetic particles enter Earth’s atmosphere.

This is to limit exposure to enhanced radiation doses and ensure reliable radio communication.

We have learned much about space weather since the events of 1972 but as modern technologies evolve, we need to make sure they can withstand the worst the Sun can throw at us.

Earth’s Magnetotail: First-Ever Views Of Elusive Energy Explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving “magnetic reconnection” — the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion — in the Earth’s magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can have — sparking auroras and possibly wreaking havoc on power grids in the case of extremely large events — but they haven’t completely understood the details. In a study published in the journal Science, the scientists outline the first views of the critical details of how this energy conversion process works in the Earth’s magnetotail.

“This was a remarkable event,” said Roy Torbert of the Space Science Center at UNH and deputy principal investigator for NASA’s Magnetospheric Multiscale mission, or MMS. “We have long known that it occurs in two types of regimes: asymmetric and symmetric but this is the first time we have seen a symmetric process.”

Magnetic reconnection occurs around Earth every day due to magnetic field lines twisting and reconnecting. It happens in different ways in different places, with different effects. Particles in highly ionized gases, called plasmas, can be converted and cause a single powerful explosion, just a fraction of a second long, that can lead to strong streams of electrons flying away at supersonic speeds. The view, which was detected as part of the scientists’ work on the MMS mission, had enough resolution to reveal its differences from other reconnection regimes around the planet like the asymmetric process found in the magnetopause around Earth which is closer to the sun.

“This is important because the more we know and understand about these reconnections,” said Torbert, “the more we can prepare for extreme events that are possible from reconnections around the Earth or anywhere in the universe.”

Magnetic reconnection also happens on the sun and across the universe — in all cases forcefully shooting out particles and driving much of the change we see in dynamic space environments — so learning about it around Earth also helps us understand reconnection in other places in the universe which cannot be reached by spacecraft. The more we understand about different types of magnetic reconnection, the more we can piece together what such explosions might look like elsewhere.

For the first reported asymmetrical event on October 16, 2015, and now this symmetrical event on July 11, 2017, NASA’s MMS mission made history by flying through magnetic reconnection events near the Earth. The four MMS spacecrafts launched from a single rocket were only inside the events for a few seconds, but the instruments which UNH researchers helped to develop were able to gather data at an unprecedented speed of one hundred times faster than ever before. As a result, for the first time, scientists could track the way the magnetic fields changed, new electric fields presented, as well as the speeds and direction of the various charged particles.

Could Yesterday’s Earth Contain Clues For Making Tomorrow’s Medicines?

Several billion years ago, as the recently formed planet Earth cooled down from a long and brutal period of heavy meteor bombardment, pools of primordial muck began to swirl with the chemical precursors to life.

Today, scientists are devising chemical reactions that mimic early Earth not only to learn about how life developed, but also to unlock new capabilities for modern medicine.

“If you can get chemistries that encode information, then maybe you can design new drugs,” says John Yin, a professor of chemical and biological engineering at the University of Wisconsin-Madison.

In a paper published recently in the journal Origins of Life and Evolution of Biospheres, Yin and colleagues described initial steps toward achieving chemistries that encode information in a variety of conditions that might mimic the environment of prehistoric Earth.

“I view this as systems chemistry,” says Yin. “How do we take store-bought chemicals and combine them in such a way that they display emergent properties like the ability to store information or copy themselves?”

The compounds the researchers combined were molecules called amino acids, which are the molecular building blocks for the proteins that perform much of the structural and chemical work inside living cells. There are 20 different amino acids that combine to form the essential proteins for life, but Yin and colleagues focused on just two: alanine and glycine, which are among the simplest examples of these molecules.

Also in the mix was an energy molecule called triphosphate, believed to be available on early earth.

The researchers “cooked” together the mixture over a range of different temperatures and variously acidic conditions. In mixtures without the energy molecule, amino acids only joined together under the most hot and harsh conditions. When triphosphate was present, however, short chains of alanine and glycine formed at more moderate temperatures.

“Triphosphate facilitates reactions in conditions where most life is found to occur,” says Yin.

Intriguingly, the alanine and glycine did not combine at random. Instead, the amino acids linked up into chains with specific sequences, depending on temperature and pH.

“What we have shown is that you are a product of your environment,” says Yin.

Key to the study was the ability to determine the composition of different amino acid chains with sophisticated analytical chemistry. For the molecular characterizations, Yin collaborated with Lingjun Li, a UW-Madison professor of pharmacy and chemistry.

“People have been cooking amino acids since 1940 or so,” says Yin. “But now we can identify what’s actually in there.”

What they identified hints at the first glimmers of information storage that arose so many billions of years ago.

The scientists speculate that, with increased “cooking” time, even greater complexity might appear. Their reactions only proceeded for 24 hours — a mere blink of an eye compared to the history of the planet. Additionally, the scientists plan to add a greater variety of molecules into the mixture.

Eventually, they hope to create mixtures where complicated molecules spontaneously come together from simpler components and create self-driving chemical reactions that interact and feed off of each other.

Those reactions could contain the keys to creating new drugs or synthesizing existing compounds more efficiently.

“We’ll figure out how to close the loop,” says Yin.

Scientists Discover New ‘Pinwheel’ Star System

An international team of scientists has discovered a new, massive star system — one that also challenges existing theories of how large stars eventually die.

“This system is likely the first of its kind ever discovered in our own galaxy,” says Benjamin Pope, a NASA Sagan fellow at New York University’s Center for Cosmology and Particle Physics and one of the researchers.

Specifically, the scientists detected a gamma-ray burst progenitor system — a type of supernova that blasts out an extremely powerful and narrow jet of plasma and which is thought to occur only in distant galaxies.

“It was not expected such a system would be found in our galaxy — only in younger galaxies much further away,” adds Pope. “Given its brightness, it is surprising it was not discovered a lot sooner.”

The discovery of the system, reported in the journal Nature Astronomy and dubbed “Apep,” also included scientists from the Netherlands Institute for Radio Astronomy, the University of Sydney, the University of Edinburgh, the University of Sheffield, and the University of New South Wales.

The system, an estimated 8,000 light years away Earth, is adorned with a dust “pinwheel” — whose strangely slow motion suggests current theories on star deaths may be incomplete.

When the most massive stars in our universe near the end of their lives, they produce fast winds — typically moving at more than 1,000 kilometers per second — that carry away large amounts of a star’s mass. These fast winds should carry away the star’s rotational energy and slow it down long before it dies.

“These massive stars are often found with a partner, in which the fast winds from the dying star can collide with its companion to produce a shock that emits at X-ray and radio frequencies and produces exotic dust patterns,” explains Joseph Callingham, a postdoctoral fellow at the Netherlands Institute for Radio Astronomy and lead author of the paper.

“Apep’s dust pinwheel moves much slower than the wind in the system,” he adds. “One way this can occur is if one of the massive stars is rotating so quickly that it is nearly tearing itself apart. Such a rotation means that when it runs out of fuel and begins to explode as a supernova, it will collapse at the poles before the equator, producing a gamma-ray burst.”

950-Mile-Long Cloud Spotted Over Martian Volcano. And It Has Staying Power.

A mysterious white-colored plume extending some 950 miles (just over 1,500 kilometers) has been spotted on the leeward side of the Arsia Mons volcano on Mars.

Unlike other Martian cloud structures that seem to poof in and out of existence, this one has staying power, with the lengthy plume hovering near Arsia Mons since Sept. 13 and seen as recently as Nov. 12, according to the European Space Agency. The agency’s Mars Express camera has been recording images of the mountainous cloud.

“Montane clouds are very common on Mars, but it was the length of the cloud and its duration that makes it interesting,” said Francois Forget, a senior research scientist at the National Center for Scientific Research (CNRS) in Paris. “Usually, it is more localized to the volcano.”

Forget and his colleagues could rule out volcanic spewing as the cause of the cloud: The Arsia Mons volcano has been inactive for at least 10 million years, and its peak activity occurred even longer ago — about 150 million years ago. At approximately 12 miles (20 km) high, Arsia Mons is the southernmost volcano of a group of three ancient volcanoes located on an elevated plateau known as the Tharsis regionon Mars.

The development of the plume, called an orographic or lee cloud, is due to a combination of factors that are common in mountain regions on Mars and even on Earth.

Dust and cooler air are the main ingredients. The images of the plume were taken after a global dust storm had finally subsided on Mars. While dust storms occur, sometimes they develop into global storms, as happened this year.

“The dust storms create darkened conditions and reduced heat at the planet surface and increased absorption of solar radiation and heating by the dust particles high in the atmosphere,” Forget said. “Just like tropical air on Earth, when this unusually warm air encounters a topographic feature such as a mountain or ancient volcano such as Arsia Mons, disturbance in the air parcel is created as it is forced upward and over the volcano to even higher elevation.”

At higher elevations, the air temperatures are cooler and the atmosphere is thinner, he added.

When the air cools to its dew point, the water condenses and water-ice clouds form.

“Given the conditions, the ice particles do not sublimate [transition directly from ice to water vapor]. As a result, the cloud transports water ice a long way, constantly being renewed by the wind,” Forget said. He added that”the plume on Mars is similar to the varying duration of contrails from airplanes.”

These hot exhaust trails from airplanes are also rich in water vapor. If the air is cold and humid, the exhaust condenses and may freeze, similar to what happens with the warm, humid Martian air when it hits these higher topographic features.

As for why the Martian plume is so long-lasting, Forget suggested it has to do with high humidity. The more humid the air, the more likely that the lee cloud can renew itself on the waves of air for such a long distance on the leeward side of the volcano. “We can speculate that before encountering the volcano, the air was ‘supersaturated’ with water vapor so that once condensed the water-ice cannot sublimate,” he added.

“The fact that the same formations did not replicate themselves farther north to the other volcanoes may be an indication that the northern hemisphere is just starting its winter solstice and is typically a more cloud-free period,” Forget said. “The southern hemisphere, where Arsia Mons is located, is just starting its summer.”

Trans-Galactic Streamers Feeding Most Luminous Galaxy In The Universe

The most luminous galaxy in the universe has been caught in the act of stripping away nearly half the mass from at least three of its smaller neighbors, according to a new study published in the journal Science. The light from this galaxy, known as W2246-0526, took 12.4 billion years to reach us, so we are seeing it as it was when our universe was only about a tenth of its present age.

New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) reveal distinct streamers of material being pulled from three smaller galaxies and flowing into the more massive galaxy, which was discovered in 2015 by NASA’s space-based Wide-field Infrared Survey Explorer (WISE). It is by no means the largest or most massive galaxy we know of, but it is unrivaled in its brightness, emitting as much infrared light as 350 trillion Suns.

The connecting tendrils between the galaxies contain about as much material as the galaxies themselves. ALMA’s amazing resolution and sensitivity allowed the researchers to detect these remarkably faint and distant trans-galactic streamers.

“We knew from previous data that there were three companion galaxies, but there was no evidence of interactions between these neighbors and the central source,” said Tanio Díaz-Santos of the Universidad Diego Portales in Santiago, Chile, lead author of the study. “We weren’t looking for cannibalistic behavior and weren’t expecting it, but this deep dive with the ALMA observatory makes it very clear.”

Galactic cannibalism is not uncommon, though this is the most distant galaxy in which such behavior has been observed and the study authors are not aware of any other direct images of a galaxy simultaneously feeding on material from multiple sources at those early cosmic times.

The researchers emphasize that the amount of gas being devoured by W2246-0526 is enough to keep it forming stars and feeding its central black hole for hundreds of millions of years.

This galaxy’s startling luminosity is not due to its individual stars. Rather, its brightness is powered by a tiny, yet fantastically energetic disk of gas that is being superheated as it spirals in on the supermassive black hole. The light from this blazingly bright accretion disk is then absorbed by the surrounding dust, which re-emits the energy as infrared light.

This extreme infrared radiation makes this galaxy one of a rare class of quasars known as Hot, Dust-Obscured Galaxies or Hot DOGs. Only about one out of every 3,000 quasars observed by WISE belongs to this class.

Much of the dust and gas being siphoned away from the three smaller galaxies is likely being converted into new stars and feeding the larger galaxy’s central black hole. This galaxy’s gluttony, however, may lead to its self-destruction. Previous research suggests that the energy of the AGN will ultimately jettison much, if not all of the galaxy’s star-forming fuel.

An earlier work led by co-author Chao-Wei Tsai of UCLA estimates that the black hole at the center of W2246-0526 is about 4 billion times the mass of the Sun. The mass of the black hole directly influences how bright the AGN can become, but — according to this earlier research — W2246-0526 is about 3 times more luminous than what should be possible. Solving this apparent contradiction will require additional observations.