Yesterday, we reported that an international team of astronomers detected signals coming from almost 100 light years away, that appeared to be a strong candidate for extraterrestrial contact, according to a document circulated by Alexander Panov, a theorectical physicist at Lomonosov Moscow State University --"a strong signal in the direction of HD164595, a planet system in the constellation Hercules was detected on May 15, using the RATAN-600 radio telescope (below) in the Russian Republic of Karachay-Cherkessia."

Today, Eric Korpela, an astronomer with Berkeley SETI, downplayed the hype over this latest signal in a note reported by VOX on the Berkeley SETI website.  "All in all, it's relatively uninteresting from a SETI standpoint." Korpela continued:

"I looked over the presentation. I was unimpressed. In one out of 39 scans that passed over star showed a signal at about 4.5 times the mean noise power with a profile somewhat like the beam profile. Of course SETI@home has seen millions of potential signals with similar characteristics, but it takes more than that to make a good candidate. Multiple detections are a minimum criterion.

"Because the receivers used were making broad band measurements, there's really nothing about this "signal" that would distinguish it from a natural radio transient (stellar flare, active galactic nucleus, microlensing of a background source, etc.) There's also nothing that could distinguish it from a satellite passing through the telescope field of view. All in all, it's relatively uninteresting from a SETI standpoint."

"If the transient claimed originates from beyond the Earth, then, given what we currently know of the parameters of the RATAN search, such events ought to be common. The fact that they are not frequently seen in continuum imaging surveys suggests that the RATAN transient is likely due to instrumental interference or to some other artifact of human technology. While absence of evidence for extraterrestrial intelligence is by no means evidence of absence, our GBT observations did not detect ongoing emission from the direction of HD 164595 between9.1 and 11.6 GHz to a sensitivity of ∼ 10 mJy (10σ).

"Single-epoch transients are by their nature hard to confirm ordeny, illustrating the need for confirming followup, either at a later time, or as part of the observing strategy (whether triggered follow-up of interesting sources, or some form of onoff observing). We intend to re-observe HD 164595 as part of the Breakthrough Listen target list, along with ongoing observations of targets selected using a range of criteria."

The Berkeley SETI team concluded that they "welcome opportunities for partnership in order to quickly validate and analyze candidate signals, to continue to develop tools and techniques, and to share our excitement with those who, like us, seek to answer the question, “Are we alone?”.

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The world's attention is now on Proxima Centauri b, a possibly Earth-like planet orbiting the closest star, 4.22 light-years away. The planet's orbit is just right to allow liquid water on its surface, needed for life. But could it in fact be habitable? If life is possible there, the planet evolved very differently than Earth, say researchers at the University of Washington-based Virtual Planetary Laboratory, where astronomers, geophysicists, climatologists, evolutionary biologists and others team to study how distant planets might host life.

“If Proxima b is habitable, then it might be an ideal place to move. Perhaps we have just discovered a future home for humanity. But in order to know for sure, we must make more observations, run many more computer simulations and, hopefully, send probes to perform the first direct reconnaissance of an exoplanet,” says Rory Barnes, University of Washington research assistant professor of astronomy. “The challenges are huge, but Proxima b offers a bounty of possibilities that fills me with wonder.”

Proxima Centauri b may be the first exoplanet to be directly characterized by powerful ground- and space-based telescopes planned, and its atmosphere spectroscopically probed for active biology.

Astronomers at Queen Mary University in London have announced discovery of Proxima Centauri b, a planet orbiting close to a star 4.22 light years away. The find has been called “the biggest exoplanet discovery since the discovery of exoplanets.”

Rory Barnes, UW research assistant professor of astronomy, published a blog post about the discovery at palereddot.org, a website dedicated to the search for life around Proxima Centauri. His essay describes research underway through the UW planetary lab — part of the NASA Astrobiology Institute — to answer the question, is life possible on this world?

“The short answer is, ‘It's complicated,' Barnes writes. “Our observations are few, and what we do know allows for a dizzying array of possibilities” — and almost as many questions.

Using computer models, the Virtual Planetary Laboratoryresearchers studied clues from the orbits of the planet, its system, its host star and apparent companion stars Alpha Centauri A and B — plus what is known of stellar evolution to begin evaluating Proxima b's chances.

It's at least as massive as Earth and may be several times more massive, and its “year” — the time it takes to orbit its star — is only 11 days. Its star is only 12 percent as massive as our sun and much dimmer (so its habitable zone, allowing liquid water on the surface, is much closer in) and the planet is 25 times closer in than Earth is to our Sun.

The star may form a third part of the Alpha Centauri binary star system, separated by a distance of 15,000 “astronomical units,” which could affect the planet's orbit and history. The new data hint at the existence of a second planet in the system with an orbital period near 200 days, but this has not been proven

Perhaps the biggest obstacle to life on the planet, Barnes writes, is the brightness of its host star. Proxima Centauri, a red dwarf star, is comparatively dim, but wasn't always so.

“Proxima's brightness evolution has been slow and complicated,” Barnes writes. “Stellar evolution models all predict that for the first one billion years Proxima slowly dimmed to its current brightness, which implies that for about the first quarter of a billion years, planet b's surface would have been too hot for Earth-like conditions.”

Barnes notes that he and UW graduate student Rodrigo Luger recently showed that had modern Earth been in such a situation, “it would have become a Venus-like world, in a runaway greenhouse state that can destroy all of the planet's primordial water,” thus extinguishing any chance for life.

Next come a host of questions about the planet's makeup, location and history, and the team's work toward discerning answers.

Is the planet “rocky” like Earth? Most orbits simulated by the planetary lab suggest it could be — and thus can host water in liquid form, a prerequisite for life.

Where did it form, and was there water? Whether it formed in place or further from its star, where ice is more likely, planetary lab researchers believe it “entirely possible” Proxima b could be water-rich, though they are not certain.

Did it start out as a hydrogen-enveloped Neptune-like planet and then lose its hydrogen to become Earth-like? Planetary laboratory research shows this is indeed possible, and could be a viable pathway to habitability.

Proxima Centauri flares more often than our sun; might such flares have long-since burned away atmospheric ozone that might protect the surface and any life? This is possible, though a strong magnetic field, as Earth has, could protect the surface. Also, any life under even a few meters of liquid water would be protected from radiation.

Another concern is that the planet might be tidally locked, meaning one side permanently faces its star, as the moon does Earth. Astronomers long thought this to mean a world could not support life, but now believe planetwide atmospheric winds would transport heat around the planet.

“These questions are central to unlocking Proxima's potential habitability and determining if our nearest galactic neighbor is an inhospitable wasteland, an inhabited planet, or a future home for humanity,” Barnes writes.

Planetary lab researchers also are developing techniques to determine whether Proxima b's atmosphere is amenable to life.
“Nearly all the components of an atmosphere imprint their presence in a spectrum (of light),” Barnes writes. “So with our knowledge of the possible histories of this planet, we can begin to develop instruments and plan observations that pinpoint the critical differences.”

At high enough pressures, he notes, oxygen molecules can momentarily bind to each other to produce an observable feature in the light spectrum. “Crucially, the pressures required to be detectable are large enough to discriminate between a planet with too much oxygen, and one with just the right amount for life. As we learn more about the planet and the system, we can build a library of possible spectra from which to quantitatively determine how likely it is that life exists on planet b.”

Our own Sun is expected to burn out in about 4 billion years, but Proxima Centauri has a much better forecast, perhaps burning for 4 trillion years longer.

“Whether habitable or not,” Barnes concluded, “Proxima Centauri b offers a new glimpse into how the planets and life fit into our universe.”

The Daily Galaxy via University of Washington and PaleRedDot.org

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The solar system could be thrown into disaster when the sun dies if the mysterious ‘Planet Nine' exists, according to research from the University of Warwick. Physicist Dimitri Veras at the University of Warwick has discovered that the presence of Planet Nine could cause the elimination of at least one of the giant planets after the sun dies, hurling them out into interstellar space through a sort of ‘pinball' effect.

When the sun starts to die in around seven billion years, it will blow away half of its own mass and inflate itself — swallowing the Earth — before fading into an ember known as a white dwarf. This mass ejection will push Jupiter, Saturn, Uranus and Neptune out to what was assumed a safe distance.

However, Veras has discovered that the existence of Planet Nine could rewrite this happy ending. He found that Planet Nine might not be pushed out in the same way, and in fact might instead be thrust inward into a death dance with the solar system's four known giant planets — most notably Uranus and Neptune. The most likely result is ejection from the solar system, forever.

Using a unique code that can simulate the death of planetary systems, Dr. Veras has mapped numerous different positions where a ‘Planet Nine' could change the fate of the solar system. The further away and the more massive the planet is, the higher the chance that the solar system will experience a violent future.

This discovery could shed light on planetary architectures in different solar systems. Almost half of existing white dwarfs contain rock, a potential signature of the debris generated from a similarly calamitous fate in other systems with distant “Planet Nines” of their own.

In effect, the future death of our sun could explain the evolution of other planetary systems. Veras explains the danger that Planet Nine could create: "The existence of a distant massive planet could fundamentally change the fate of the solar system. Uranus and Neptune in particular may no longer be safe from the death throes of the Sun. The fate of the solar system would depend on the mass and orbital properties of Planet Nine, if it exists."

"The future of the Sun may be foreshadowed by white dwarfs that are 'polluted' by rocky debris. Planet Nine could act as a catalyst for the pollution. The Sun's future identity as a white dwarf that could be 'polluted' by rocky debris may reflect current observations of other white dwarfs throughout the Milky Way," Dr Veras adds.

The paper ‘The fates of solar system analogues with one additional distant planet' will be published in the Monthly Notices of the Royal Astronomical Society.

The Daily Galaxy via University of Warwick

Image credit: wikimedia.org

Where terrestrial life on Earth got its phosphorus has been a mystery. University of Arizona scientists have discovered that meteorites, particularly iron meteorites, may have been critical to the evolution of life on Earth. Their research shows that meteorites easily could have provided more phosphorus than naturally occurs on Earth — enough phosphorus to give rise to biomolecules which eventually assembled into living, replicating organisms.

Phosphorus is central to life. It forms the backbone of DNA and RNA because it connects these molecules' genetic bases into long chains. It is vital to metabolism because it is linked with life's fundamental fuel, adenosine triphosphate (ATP), the energy that powers growth and movement. And phosphorus is part of living architecture it is in the phospholipids that make up cell walls and in the bones of vertebrates.

"In terms of mass, phosphorus is the fifth most important biologic element, after carbon, hydrogen, oxygen, and nitrogen," said Matthew A. Pasek, at the University of Arizona's planetary sciences department and Lunar and Planetary Laboratory. "But where terrestrial life got its phosphorus has been a mystery," he added.

Phosphorus is much rarer in nature than are hydrogen, oxygen, carbon, and nitrogen. Pasek cites recent studies that show there's approximately one phosphorus atom for every 2.8 million hydrogen atoms in the cosmos, every 49 million hydrogen atoms in the oceans, and every 203 hydrogen atoms in bacteria. Similarly, there's a single phosphorus atom for every 1,400 oxygen atoms in the cosmos, every 25 million oxygen atoms in the oceans, and 72 oxygen atoms in bacteria. The numbers for carbon atoms and nitrogen atoms, respectively, per single phosphorus atom are 680 and 230 in the cosmos, 974 and 633 in the oceans, and 116 and 15 in bacteria.

The most common terrestrial form of the element is a mineral called apatite. When mixed with water, apatite releases only very small amounts of phosphate. Scientists have tried heating apatite to high temperatures, combining it with various strange, super-energetic compounds, even experimenting with phosphorous compounds unknown on Earth. This research hasn't explained where life's phosphorus comes from, Pasek noted.

Pasek began working with Dante Lauretta, UA assistant professor of planetary sciences, on the idea that meteorites are the source of living Earth's phosphorus. The work was inspired by Lauretta's earlier experiments that showed that phosphorus became concentrated at metal surfaces that corroded in the early solar system.

"This natural mechanism of phosphorus concentration in the presence of a known organic catalyst (such as iron-based metal) made me think that aqueous corrosion of meteoritic minerals could lead to the formation of important phosphorus-bearing biomolecules," Lauretta said.

"Meteorites have several different minerals that contain phosphorus," Pasek said. "The most important one, which we've worked with most recently, is iron-nickel phosphide, known as schreibersite."

Schreibersite is a metallic compound that is extremely rare on Earth. But it is ubiquitous in meteorites, especially iron meteorites, which are peppered with schreibersite grains or slivered with pinkish-colored schreibersite veins.

"We saw a whole slew of different phosphorus compounds being formed," Pasek said. "One of the most interesting ones we found was P2-O7 (two phorphorus atoms with seven oxygen atoms), one of the more biochemically useful forms of phosphate, similar to what's found in ATP."

Previous experiments have formed P2-07, but at high temperature or under other extreme conditions, not by simply dissolving a mineral in room-temperature water, Pasek said.

"This allows us to somewhat constrain where the origins of life may have occurred," he said. "If you are going to have phosphate-based life, it likely would have had to occur near a freshwater region where a meteorite had recently fallen. We can go so far, maybe, as to say it was an iron meteorite. Iron meteorites have from about 10 to 100 times as much schreibersite as do other meteorites.

"I think meteorites were critical for the evolution of life because of some of the minerals, especially the P2-07 compound, which is used in ATP, in photosynthesis, in forming new phosphate bonds with organics (carbon-containing compounds), and in a variety of other biochemical processes," Pasek said.

"I think one of the most exciting aspects of this discovery is the fact that iron meteorites form by the process of planetesimal differentiation," Lauretta said. That is, the building-blocks of planets, called planestesmals, form both a metallic core and a silicate mantle. Iron meteorites represent the metallic core, and other types of meteorites, called achondrites, represent the mantle.

"No one ever realized that such a critical stage in planetary evolution could be coupled to the origin of life," he added. "This result constrains where, in our solar system and others, life could originate. It requires an asteroid belt where planetesimals can grow to a critical size around 500 kilometers in diameter and a mechanism to disrupt these bodies and deliver them to the inner solar system."

Jupiter drives the delivery of planetesimals to our inner solar system, Lauretta said, thereby limiting the chances that outer solar system planets and moons will be supplied with the reactive forms of phosphorus used by biomolecules essential to terrestrial life.

Solar systems that lack a Jupiter-sized object that can perturb mineral-rich asteroids inward toward terrestrial planets also have dim prospects for developing life, Lauretta added.

The Daily Galaxy via University of Arizona and astrobio.net

Image credit: Tohoku University

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For years, astronomers have puzzled over a massive star lodged deep in the Milky Way that shows conflicting signs of being extremely old and extremely young. Researchers initially classified the star as elderly, perhaps a red supergiant. But a new study by a NASA-led team of researchers suggests that the object, labeled IRAS 19312+1950, might be something quite different - a protostar, a star still in the making.

"Astronomers recognized this object as noteworthy around the year 2000 and have been trying ever since to decide how far along its development is," said Martin Cordiner, an astrochemist working at NASA's Goddard Space Flight Center in Greenbelt, Maryland. He is the lead author of a paper in the Astrophysical Journal describing the team's findings, from observations made using NASA's Spitzer Space Telescope and ESA's Herschel Space Observatory.

Located more than 12,000 light-years from Earth, the object first stood out as peculiar when it was observed at particular radio frequencies. Several teams of astronomers studied it using ground-based telescopes and concluded that it is an oxygen-rich star about 10 times as massive as the sun. The question was: What kind of star?

Some researchers favor the idea that the star is evolved - past the peak of its life cycle and on the decline. For most of their lives, stars obtain their energy by fusing hydrogen in their cores, as the sun does now. But older stars have used up most of their hydrogen and must rely on heavier fuels that don't last as long, leading to rapid deterioration.

Two early clues - intense radio sources called masers - suggested the star was old. In astronomy, masers occur when the molecules in certain kinds of gases get revved up and emit a lot of radiation over a very limited range of frequencies. The result is a powerful radio beacon - the microwave equivalent of a laser.

One maser observed with IRAS 19312+1950 is almost exclusively associated with late-stage stars. This is the silicon oxide maser, produced by molecules made of one silicon atom and one oxygen atom. Researchers don't know why this maser is nearly always restricted to elderly stars, but of thousands of known silicon oxide masers, only a few exceptions to this rule have been noted.

Also spotted with the star was a hydroxyl maser, produced by molecules comprised of one oxygen atom and one hydrogen atom. Hydroxyl masers can occur in various kinds of astronomical objects, but when one occurs with an elderly star, the radio signal has a distinctive pattern - it's especially strong at a frequency of 1612 megahertz. That's the pattern researchers found in this case.

Even so, the object didn't entirely fit with evolved stars. Especially puzzling was the smorgasbord of chemicals found in the large cloud of material surrounding the star. A chemical-rich cloud like this is typical of the regions where new stars are born, but no such stellar nursery had been identified near this star.

Scientists initially proposed that the object was an old star surrounded by a surprising cloud typical of the kind that usually accompanies young stars. Another idea was that the observations might somehow be capturing two objects: a very old star and an embryonic cloud of star-making material in the same field.

Cordiner and his colleagues began to reconsider the object, conducting observations using ESA's Herschel Space Observatory and analyzing data gathered earlier with NASA's Spitzer Space Telescope. Both telescopes operate at infrared wavelengths, which gave the team new insight into the gases, dust and ices in the cloud surrounding the star.

The additional information leads Cordiner and colleagues to think the star is in a very early stage of formation. The object is much brighter than it first appeared, they say, emitting about 20,000 times the energy of our sun. The team found large quantities of ices made from water and carbon dioxide in the cloud around the object. These ices are located on dust grains relatively close to the star, and all this dust and ice blocks out starlight making the star seem dimmer than it really is.

In addition, the dense cloud around the object appears to be collapsing, which happens when a growing star pulls in material. In contrast, the material around an evolved star is expanding and is in the process of escaping to the interstellar medium. The entire envelope of material has an estimated mass of 500 to 700 suns, which is much more than could have been produced by an elderly or dying star.

"We think the star is probably in an embryonic stage, getting near the end of its accretion stage - the period when it pulls in new material to fuel its growth," said Cordiner.

Also supporting the idea of a young star are the very fast wind speeds measured in two jets of gas streaming away from opposite poles of the star. Such jets of material, known as a bipolar outflow, can be seen emanating from young or old stars. However, fast, narrowly focused jets are rarely observed in evolved stars. In this case, the team measured winds at the breakneck speed of at least 200,000 miles per hour (90 kilometers per second) - a common characteristic of a protostar.

Still, the researchers acknowledge that the object is not a typical protostar. For reasons they can't explain yet, the star has spectacular features of both a very young and a very old star.

"No matter how one looks at this object, it's fascinating, and it has something new to tell us about the life cycles of stars," said Steven Charnley, a Goddard astrochemist and co-author of the paper.

The Daily Galaxy via NASA/Jet Propulsion Laboratory

Image Credit: NASA/JPL-Caltech

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