What is life? This is a question that is often asked and typically confused.
The confusion starts from the several uses of the word “life” in English. There are at least three usages as exemplified by the following questions: 1) Is there life on Mars? 2) Is there life in this organism? 3) Is life worth living?
The definition of “life” in these three usages is quite different. In the first case, life refers to a collective phenomenon; in the second case it refers to the ability of an individual organism to metabolize and grow; and in the third case life refers to the history of activities that an organism undertakes. The first two usages are of direct relevance to astrobiology.
The usual definition of life, as used in the first case, is that it is a system of material entities that can undergo evolution, which implies reproduction, mutation and selection. This is what we are looking for on Mars and on other worlds. We would be most interested if it represented a second genesis — in other words, an independent origin of life. It is often pointed out that the definition of life as a system capable of evolution implies that single, isolated individuals not of child-bearing age are not “life.” This is nonsense and confuses the first and second cases of “life.”
Many commentators hold the view that an effective search for life on other worlds requires that we first have a concise, agreed-on definition of life. This is not the case. Along this line, it has been suggested that once we understand life we will be able to produce a completely mechanistic and predictive theory of life. The example of water is sometimes used. Water is simply defined as two hydrogens joined with one oxygen.
However, life is not a simple substance like water; rather, it is a process, more like fire than water. There is no simple definition of fire. If life is like fire, then even with a complete mechanistic and predictive theory of life, we may still not be able to define it in any simple, closed form. The search for life on other worlds can be based on what life does rather than its definition. One of the things that life does is build up large specialized molecules, such as DNA and proteins.
Viking, the only mission to search for life on another world (that being Mars), focused on the second case. The Viking biology experiments searched for something alive in the sample. The assumption was that if something was alive it would be able to consume organics and release gases; it would have a metabolism. Hence the operational definition of “life” in the Viking biology experiments was the ability to metabolize in the conditions of the experiment.
There are several problems with this operational definition. First, there are many non-biological processes the can consume organics and/or release gases. Second, experience on Earth shows that many micro-organisms are picky eaters and do not grow in laboratory conditions with nutrients added. Perhaps the most severe problem with the Viking approach is that it cannot detect organisms that are dead, which unfortunately is the most likely state of organisms on Mars (or on the surface of Europa, or in the plume of Enceladus). In fact, in the search for life in our solar system, what is needed more than a definition of life is a definition of death.
What does it mean to be dead? It means that the organism was once alive and is composed of organic molecules that are specific to life — molecules such as DNA, ATP, and proteins. These are biomarkers that would be compelling evidence that the organism was once alive and is the product of a system of life that has undergone evolution over time. The search for such biomarkers is the basis for life-search methods now being considered. The challenge is to design instruments that can search for biomarkers for Earth-like life and also can detect biomarkers of unknown alien life.
Alien life might flourish on an exotic kind of carbon dioxide, researchers say. This “supercritical” carbon dioxide, which has features of both liquids and gases, could be key to extraterrestrial organisms much as water is to biology on Earth.
Most familiar as a greenhouse gas that traps heat, helping warm the planet, carbon dioxide is exhaled by animals and used by plants in photosynthesis. While it can exist as a solid, liquid and gas, past a critical point of combined temperature and pressure, carbon dioxide can enter a “supercritical” state. Such a supercritical fluid has properties of both liquids and gases. For example, it can dissolve materials like a liquid, but flow like a gas.
The critical point for carbon dioxide is about 88 degrees Fahrenheit (31 degrees Celsius) and about 73 times Earth’s atmospheric pressure at sea level. This is about equal in pressure to that found nearly a half-mile (0.8 kilometers) under the ocean’s surface. Supercritical carbon dioxide is increasingly used in a variety of applications, such as decaffeinating coffee beans and dry cleaning.
Ordinarily, carbon dioxide is not considered a viable solvent to host the chemical reactions for life, but the properties of supercritical fluids can differ quite significantly from the regular versions of those fluids — for instance, while regular water is not acid, supercritical water is acidic. Given how substantially different supercritical carbon dioxide is from regular carbon dioxide in terms of physical and chemical properties, scientists explored whether it could be suitable for life.
“I always have been interested in possibly exotic life and creative adaptations of organisms to extreme environments,” said study co-author Dirk Schulze-Makuch, an astrobiologist at Washington State University in Pullman. “Supercritical CO2 is often overlooked, so I felt that someone had to put together something on its biological potential.”
The researchers noted that enzymes can be more stable in supercritical carbon dioxide than in water. In addition, supercritical carbon dioxide makes enzymes more specific about the molecules they bind to, leading to fewer unnecessary side reactions.
Surprisingly, a number of species of bacteria are tolerant of supercritical carbon dioxide. Prior research found that several different microbial species and their enzymes are active in the fluid.
In addition, exotic locales on Earth support the idea that life can survive in environments rich in carbon dioxide. Previous studies showed that microbes can live near pockets of liquid carbon dioxide trapped under Earth’s oceans.
This liquid carbon dioxide in the seafloor gets denser with greater depth, as the weight of the seas and rock above it increases. As that happens, the fluid could become supercritical, and microbes might use at least some of the biologically advantageous properties of this supercritical carbon dioxide to survive, Schulze-Makuch said. Indeed, there may be many reservoirs of supercritical carbon dioxide under the oceans, he added.
“It would be great to drill into areas with supercritical carbon dioxide on Earth and investigate those environments in detail, but this is obviously difficult because of practical limitations and huge expenses,” Schulze-Makuch said.
Was Venus a supercritical haven?
Since carbon dioxide is a very common molecule in planetary atmospheres, the researchers suggest that supercritical carbon dioxide may be present on many worlds. This is especially true for Venus, whose atmosphere is mostly carbon dioxide.
In its early history, Venus was located in the sun’s habitable zone, the area where liquid water can form on a planet’s surface. Life as it is currently known could have developed there before Venus heated up enough to lose all its water. Although Schulze-Makuch said it was unlikely that any such life could have switched from water to supercritical carbon dioxide, perhaps some organic remnants of such life, if it existed, could have been preserved in that fluid.
Beyond the solar system, Schulze-Makuch noted that many newfound planets orbiting distant stars are so-called super-Earths, worlds up to 10 or more times the mass of Earth. Under the stronger gravitational pulls and correspondingly higher atmospheric pressures of those planets, supercritical carbon dioxide might be common, he said.
Although Schulze-Makuch noted there is no proof that life that does not depend on water is possible, “there are good reasons to hypothesize that this is so,” he told Space.com.
The reports, issued by the International Energy Agency (IEA), stated that by 2050, PV panels could produce 16% of the world’s electricity, while solar thermal electricity (STE) is on track to produce 11%. Solar thermal electricity is created by concentrating the sun’s rays to produce steam, which then turns a turbine.
Photovoltaic panels capable of producing 137 billion watts (gigawatts) of power have been installed worldwide since the end of 2013, according to the IEA, a Paris-based agency that advises on global energy consumption.
Perhaps just as important, solar power could reduce carbon dioxide emissions by more than 6 billion tons over the next four decades, the reports state.
Rooftop solar panels will account for half of the world’s solar PV installations because as a distributed energy source, the technology is “unbeatable,” the report said.
In the U.S., solar power capacity for producing electricity has grown six-fold since 2010, according to the Energy Information Administration (EIA), a federal agency that provides information about the nation’s energy production across all markets.
Meanwhile, the IEA’s report indicates the cost of solar power worldwide is expected to drop to four cents per kilowatt hour (kWh) by 2050. In the U.S.,electricity costs about 13 cents per kilowatt hour for residential power and seven cents for industrial power.
IEA Executive Director Maria van der Hoeven stressed in a statement that her agency’s two reports do not represent a forecast. As with other IEA technology roadmaps, they detail the expected technology improvement targets and the policy actions required to achieve those goals by 2050.
However, van der Hoeven noted that the cost of solar system hardware is rapidly declining.
Researchers at the University of the West of England, Bristol and the University of Bristol collaborated to build a system that will enable robots to function without batteries or being plugged into an electrical outlet.
Based on the functioning of the human heart, the system is designed to pump urine into the robot’s “engine room,” converting the waste into electricity and enabling the robot to function completely on its own.
Scientists are hoping the system, which can hold 24.5 ml of urine, could be used to power future generations of robots, or what they’re calling EcoBots.
“In the city environment, they could re-charge using urine from urinals in public lavatories,” said Peter Walters, a researcher with the University of the West of England. “In rural environments, liquid waste effluent could be collected from farms.”
In the past 10 years, researchers have built four generations of EcoBots, each able to use microorganisms to digest the waste material and generate electricity from it, the university said.
Along with using human and animal urine, the robotic system also can create power by using rotten fruit and vegetables, dead flies, waste water and sludge.
Ioannis Ieropoulos, a scientist with the Bristol Robotics Laboratory, explained that the microorganisms work inside microbial fuel cells where they metabolize the organics, converting them into carbon dioxide and electricity.
Like the human heart, the robotic system works by using artificial muscles that compress a soft area in the center of the device, forcing fluid to be expelled through an outlet and delivered to the fuel cells. The artificial muscles then relax and go through the process again for the next cycle.
“The artificial heartbeat is mechanically simpler than a conventional electric motor-driven pump by virtue of the fact that it employs artificial muscle fibers to create the pumping action, rather than an electric motor, which is by comparison a more complex mechanical assembly,” Walter said.
A new simulation of Pluto’s upper atmosphere shows that it extends so far from the planet that stray molecules may be deposited on its largest moon, Charon.
“That is amazing, from my perspective,” said Justin Erwin, the lead author of the paper and a Ph.D. student at the University of Virginia.
Researchers combined two previously known models of Pluto‘s atmosphere to better estimate the escape rate of molecules into space. Their refinement made a big difference.
“Our [calculated escape rate] is a little bit smaller, but the small change in the escape rate causes a large change in the structure of the atmosphere,” Erwin added.
Erwin’s supervisor at the University of Virginia, Robert Johnson, was a co-author of the paper reporting the findings, which was published on the preprint site Arxiv and has been submitted to the journal Icarus for publication.
Fire and ice
Pluto’s tenuous atmosphere is mainly composed of methane, nitrogen and poisonous carbon monoxide that likely comes from ice on the dwarf planet’s surface. The size of the atmosphere changes as Pluto moves closer and farther from the sun in its elliptical orbit.
When Pluto swings near the sun, the sun’s heat evaporates the ice and gases slowly escape into space. This process continues until Pluto moves away and the sun’s heat fades. Then, the ice builds up until Pluto approaches the sun again.
Pluto’s last close approach to the sun was in 1989. That is considered a fairly recent event, because it takes 248 years for the dwarf planet to orbit the sun once.
Researchers are trying to refine the escape rate of the gases ahead of the arrival of NASA’s New Horizons probe at Pluto in 2015, so that the spacecraft knows what to look for. For the new calculations, Erwin’s team used previously published research from themselves and other scientists. [Destination Pluto: NASA's New Horizons Mission in Pictures]
Uncertain atmospheric model
It’s difficult to figure out the size of Pluto’s atmosphere because of a debate over how best to measure it.
Pluto’s atmosphere is heated by infrared and ultraviolet light from the sun. Closer to the planet, ultraviolet light is absorbed in the atmosphere and only infrared heating takes place.
But farther away from the planet, the atmosphere is thin enough that the ultraviolet light affects the molecules. This is why researchers use ultraviolet heating models for the upper reaches of the atmosphere.
Molecules that are escaping from Pluto’s atmosphere move through a region called the thermosphere. The thermosphere is where much of the ultraviolet light is absorbed in the atmosphere; this heating drives the escape process.
In the exosphere, at the top of Pluto’s atmosphere, the atmosphere is so tenuous that collisions between particles do not happen as frequently.
The boundary between the thermosphere and the exosphere is called the exobase. Researchers aren’t sure where the “boundary” is. Because the mathematical model for each section of the atmosphere is different, this leads to vast uncertainties in calculating the size of Pluto’s atmosphere.
Last year, Erwin participated in an Icarus paper that demonstrated a new model to estimate the upper atmosphere’s extent during the solar minimum (when Pluto receives the least heat from the sun).
This time around, Erwin and his co-authors extended that model to include solar maximum — when Pluto is warmest — and solar medium, or average heating.
Pluto is so far from Earth, and so small, that its size isn’t precisely known. When forming their model, the researchers assumed that the diameter of Pluto is roughly 1,429 miles (2,300 kilometers). However, the accepted range for the diameter differs by as much as 62 miles (100 km).
The New Horizons team plans to better measure the size of Pluto and its atmosphere when the spacecraft swings by Pluto in 2015.
The more stars a system of alien worlds starts with, the more likely those planets will orbit those stars at odd tilts, scientists say.
The discovery, based on a study unveiled today (Nov. 14), suggests that even Earth’s own sun may have had a companion star early in its development.
In recent years, astronomers have detected hundreds of exoplanets — worlds circling distant stars. Many of these are “hot Jupiters” — gas giants like Jupiter or Saturn that are closer to their stars than Mercury is to the sun.
Researchers had thought hot Jupiters arose when giant planets were dragged inward by protoplanetary disks of gas and dust falling toward stars. However, this idea was recently cast into doubt by the surprising discovery that a major fraction of hot Jupiters have orbits that are tilted in respect to their stars’ rotation.
Stars all spin, just as Earth’s does, and their worlds often line up with this spin — they orbit around the equators of their stars and revolve in the same direction. However, sometimes alien planets have misaligned orbits instead, ones that are at slight or even sharp angles around their stars. The orbits of some exoplanets are so far tilted that they are actually backwards — they move in retrogradeorbits in exactly the opposite direction of their stars’ spin.
Scientists had thought if hot Jupiters were dragged toward their stars by protoplanetary disks, they would all end up in relatively normal orbits around the equators of their stars. However, astronomers recently discovered that a whopping 25 to 50 percent of these planets actually may have misaligned orbits.
“The misalignments seemed to point towards a much more volatile, violent evolutionary path for hot Jupiters,” said study author Konstantin Batygin, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics.
For instance, perhaps it was a gravitational tug of war between exoplanets that hurled some inward at their stars. Still, it seemed unlikely such processes were responsible for all these misaligned planets.
“A crude and oversimplified analogy is taking a machine gun, shooting in every direction possible, and hitting the correct target about 1 percent of the time,” Batygin said. “Surely not impossible, but it seems unlikely.”
Now Batygin has discovered protoplanetary disks can indeed produce such tilted orbits if these systems each harbored multiple stars. [Photos: Alien Planet With Twin Suns Found]
Although the solar system has only one sun, most stars like Earth’s sun are binaries— two stars orbiting each other as a pair. Increasingly, astronomers are discovering planetary systems with twin suns (like Luke Skywalker’s fictional home planet Tatooine in “Star Wars”). There are also many three-star triples in the universe, at least one of which is known to host planets, and the number of stars a system has can even climb as high as seven.
Through computer modeling, Batygin found that the complex system of gravitational pulls that binary stars exert on protoplanetary disks would disrupt them enough to misalign the disks. He added that the more stars a system has, the more likely its planets orbits would be tilted.
This idea does not require that a system have multiple stars for billions of years, Batygin added.
“It is generally believed that 85 to 100 percent of stars form as multiples,” he said. Many times, stars then get stripped from these systems during the first 1 million to 10 million years of their lifetimes.
Batygin noted the orbital plane of the solar system’s planets is misaligned from the sun’s equatorial plane by 7 degrees. Given this skew, “I think it is safe to say that the solar system falls into the misaligned category.” In other words, the sun once may have had a companion star very early in its history.
Future research can analyze other details about the interactions between planets, their stars and protoplanetary disks. “For instance, the magnetic coupling between the disk and the host star should be looked at more carefully,” Batygin said.
Batygindetails his findings in the Nov. 15 issue of the journal Nature.
Amateur astronomers have helped discover an alien planet with two suns and a twinkling twist: The entire twin-sun setup, a real-life version of Tatooine from “Star Wars,” is orbited by two more stars — a solar system that is the first of its kind known.
The alien planet, called PH1, is a gas giant planet slightly bigger than Neptune. Its discovery in the midst of a strange, four-star planetary system is the first confirmed world discovered as part of the Yale University-led Planet Hunters project, in which armchair astronomers work with professional scientists to find evidence of new worlds in the bountiful data collected by NASA’s Kepler space telescope.
“Planet Hunters is a symbiotic project, pairing the discovery power of the people with follow-up by a team of astronomers,” said Debra Fischer, a professor of astronomy at Yale and planet expert who helped launch Planet Hunters in 2010, in a statement. “This unique system might have been entirely missed if not for the sharp eyes of the public.”
Since its March 2009 launch, Kepler has found evidence of more than 2,300 candidate alien worlds. [Gallery: More Alien Planets with Twin Suns]
Finding a strange, new world
Since its initial discovery via Planet Hunters, the existence of PH1 has been confirmed by a team of professional astronomers, who will present their work today (Oct. 15) at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society in Reno, Nev.
With a radius about 6.2 times that of Earth’s, PH1 is a smidge bigger than Neptune. The gassy planet spends 138 days completing a single orbit around its two parent stars, which have masses about 1.5 and 0.41 times that of the sun. The stars circle each other once every 20 days.
The two other stars orbiting the PH1′s twin suns are about 1,000 astronomical units (AU) from the parent stars. (One AU is about the distance between the Earth and sun, about 93 million miles or 150 million kilometers.)
If you’re hoping to catch the quadruple sunset, this may not be your best bet. The researchers estimate PH1′s temperature would range from a minimum of about 484 degrees Fahrenheit (524 Kelvin, or 251 degrees Celsius) and a maximum of 644 degrees F (613 Kelvin, or 340 degrees C), too hot to be in the habitable zone.
“Although PH1 is a gas giant planet, even if there is a possibility of rocky moons orbiting the body, their surfaces would be too hot for liquid water to exist,” researcher Meg Schwamb of Yale University and colleagues write in a draft of their research article.
Alien Planet Quiz: Are You an Exoplanet Expert?
Astronomers have confirmed more than 700 planets beyond our own solar system, and the discoveries keep rolling in. How much do you know about these exotic worlds?
A planet with two suns
Until now, scientists had identified just six planets orbiting two parent stars, called circumbinary planets, and none of these have stellar companions orbiting them. Until their discovery, circumbinary planets were once the realm of science fiction with Tatooine, the fictional homeworld of Luke Skywalker in “Star Wars,” among the most famous.
“Circumbinary planets are the extremes of planet formation,” Schwamb said in a statement. “The discovery of these systems is forcing us to go back to the drawing board to understand how such planets can assemble and evolve in these dynamically challenging environments.”
The Planet Hunter volunteers, Kian Jek of San Francisco, Calif., and Robert Gagliano of Cottonwood, Ariz., spotted PH1 using the transit method, noticing faint dips in light as the plant passed in front of, or transited, its parent stars.
Gagliano said he was “absolutely ecstatic” about the finding. “It’s a great honor to be a Planet Hunter, citizen scientist, and work hand in hand with professional astronomers, making a real contribution to science,” he said.
Jek, too, expressed his amazement.
“It still continues to astonish me how we can detect, let alone glean so much information, about another planet thousands of light-years away just by studying the light from its parent star,” he said in a statement.
Schwamb led the team of professional astronomers who confirmed the discovery and characterized the planet, following observations from the Keck telescopes on Mauna Kea, Hawaii.
The research was supported by NASA and the National Science Foundation Astronomy and Astrophysics Postdoctoral Fellowship.
The discovery of the first alien planet with two suns — like the “Star Wars” world Tatooine — residing in its parent star’s habitable zone is good news for the search for life beyond Earth, scientists say.
The planet, known as Kepler-47c, is a gas giant and therefore probably not suitable for life as we know it. But its existence hints that smaller, rockier worlds may inhabit other two-star systems’ habitable zones —that just-right range of distances where liquid water can exist.
And that’s important, because there are a lot of binary systems out there, scientists say.
“Roughly half of the stars in the galaxy are in binary systems,” study lead author Jerome Orosz, of San Diego State University, told SPACE.com. “I thought it would only be a matter of time before we found a system like Kepler-47 where a planet is in the habitable zone.” [Gallery: The Tatooine-Like Kepler-47 System]
The Kepler-47 system, whose discovery was announced Tuesday (Aug. 28), dwells about 5,000 light-years away, in the constellation Cygnus (The Swan). It is a close binary system, with two stars orbiting near each other at its center. Around these stars whirl two planets known as Kepler-47b and Kepler-47c.
They make Kepler-47 the first system seen with multiple worlds circling a pair of stars.
“If single stars and close binary stars can host planetary systems with an equal probability — that is not at all clear at the moment — then it would follow that life could be just as common on circumbinary planets as on planets with single stars,” Orosz said.
Kepler-47c, which appears to be slightly larger than Uranus, is the outer world. It takes the planet 303 days to complete an orbit, placing it squarely in the system’s habitable zone. (Kepler-47b is a bit smaller than its planetary sibling but much closer-in, making it likely too hot to host life.)
Kepler-47c itself is likely not a good bet to support life. But any large moons of the planet — if they exist — would be very intriguing to astrobiologists, said study co-author William Welsh at San Diego State University.
Scientists have already found several exoplanets that are Earth-size or smaller, and they hope to discover many more. NASA’s prolific Kepler space telescope, which discovered Kepler-47b and c, is a key tool in this search.
Indeed, Kepler’s main mission is to determine just how commonly Earth-size planets occur in their stars’ habitable zones throughout the galaxy. The telescope detects alien planets by flagging the telltale brightness dips caused when they cross in front of, or transit, their stars’ faces from the instrument’s perspective..
“I expect that the transits of an Earth-sized planet will be very hard to spot by eye, so we will need to refine our automated search programs to work for binary systems,” Orosz said. “As Kepler gets more and more data, the chances go up that we can identify the smaller transits due to terrestrial planets.”
The scientists published their findings online Aug. 28 in the journal Science. They also detailed their results Aug. 29 at the General Assembly of the International Astronomical Union in Beijing.
Fleeing from the scene of a violent supernova explosion, a compact runaway star may be the fastest traveling pulsar yet discovered, scientists say. The small but powerful star is rushing away from the source of the blast almost 25 times faster than most similar objects move.
When the dust clears from a supernova, the outer layers of the dying star blow into space, leaving behind a neutron star, which is a city-sized object with a mass comparable to the sun.
“In a lot of cases, when the neutron star is not moving fast, you’ll find it right in the middle of the supernova remnant,” John Tomsick of the University of California, Berkeley, told SPACE.com.
Not so for IGR J11014-6103, a special type of rotating neutron star known as a pulsar. The explosion that created this object came with a kick that sent it flying away from its birth location at blistering speeds of between 5.4 and 6.5 million miles per hour.
According to Tomsick, most neutron stars travel anywhere between 225,000 to a mph (100 to 600 kilometers per second), with only a few exceeding 2.2 million mph (1,000 km/s). [Supernova Photos: Great Images of Star Explosions
An uneven explosion
In order for a neutron star to travel after a supernova, there must be some kind of push created by the stellar death, the researchers said. In a symmetrical explosion, the forces pressing on the new neutron star cancel each other out, and the star remains in the center, where the initial explosion occurred.
But if there is any type of asymmetry in the explosion, the stronger force imparts a kick to the compact star, sending it flying through space.
Scientists are still uncertain what causes these asymmetric explosions. Tomsick explained that there could be a correlation between the magnetic field of the neutron star and its strong kick, but nothing conclusive has been demonstrated yet.
Tomsick hopes that a closer look at the atypical IGR J10014-6103 pulsar could shed some light on the mystery.
“If we found that this neutron star had a high magnetic field, it would provide some evidence that it’s related to the velocity,” he said.
Lying in a bed of dust and gas about 30,000 light-years away from Earth, the energetic source first turned up in a survey of hard X-ray objects by the European Space Agency’s Integral satellite. Tomsick and his team have performed follow-up studies of several of Integrals’ new objects.
Initially, nothing about IGR J10014-6103 stood out. But, after examining the object using NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton satellite, as well as the Parkes radio telescope in Australia, they realized a tail 3 light-years long trailed behind the source.
“When (the neutron star) plows through, it accelerates the particles that are in the interstellar medium,” Tomsick said.
This creates a bow shock effect, much like a boat breaking through water. A slow-moving star forms a wider shock, while a fast-moving star produces a narrow one, such as the one formed by IGR J10014-6103.
A curious pulsar
Knowing that the supernova is 15,000 years old, and logging the distance the neutron star had traveled in that time, Tomsick and his team were able to calculate its speed.
Pulsars are a special type of neutron star that rotates rapidly, emitting a beam of high-energy that spins much like the bulb in a lighthouse. But astronomers have not yet been able to actually detect this signature beam from IGR J10014-6103.
According to Tomsick, the radio emission from the gas and dust surrounding the star make those pulses more difficult to read. In fact, the only way the pulses could have been seen with the current observations would be if the flashing neutron star was excessively bright.
“It could be a typical pulsar, and we still wouldn’t be able to detect it,” Tomsick said.
But the scientists are confident the object is a pulsar, rather than a regular neutron star, because of its high-energy emission and the fact that it doesn’t show up in optical wavelengths. They intend to do more in-depth observations of the object in the near future, searching for details about its pulsation and its magnetic field.
“If we do a study in X-rays and still don’t see pulsation, then we’ll be pretty surprised.”
Detailed results of the study were published in the May edition of the Astrophysical Journal Letters.
Panasonic said on Monday it has created a new system for artificial photosynthesis that can remove carbon dioxide from the air almost as well as plants do, as part of the company’s entry into an industry-wide trend toward greener tech.
The company said its system uses nitride semiconductors, which are widely used in LEDs (light-emitting diodes) to convert light to energy, and a metal catalyst to convert carbon dioxide and water to formic acid, which is widely used in dyes, leather production and as a preservative.
Carbon dioxide is a major pollutant and considered to be a main cause of the “greenhouse effect,” which most climate scientists believe causes global warming.
Panasonic has struggled with its traditional electronics business and has made eco-friendly products and practices the key element in its turnaround plan. The company is hoping to leverage its large rechargeable battery and solar businesses, while joining the industry in embracing technologies that are friendlier to the environment. The issue is an important one with customers, as demonstrated by the the outcry earlier this month when Apple was forced to rejoin a green standards program when clients complained about its earlier withdrawal.
Panasonic said the system can convert carbon dioxide and water to formic acid with an efficiency of 0.2 percent in laboratory conditions, which is similar to the conversion rate for green plants. The efficiency refers to the portion of the incoming light energy stored in materials produced during the process.
The company aims to eventually employ the system in industrial applications that produce high quantities of carbon dioxide, such as power plants and incinerators.
A surprising number of massive stars in our Milky Way galaxy are part of close stellar duos, a new study finds, but most of these companion stars have turbulent relationships — with one “vampire star” sucking gas from the other, or the two stars violently merging to form a single star.
Astronomers using the European Southern Observatory’s Very Large Telescope in Chile studied massive O-type stars, which are very hot and incredibly bright. These stars, which have surface temperatures of more than 54,000 degrees Fahrenheit (30,000 degrees Celsius) live short, violent lives, but they play key roles in the evolution of galaxies.
The researchers discovered that more than 70 percent of these massive stars have close companions, making up so-called binary systems in which two stars orbit each other.
While this percentage is far more than was previously expected, the astronomers were more surprised to find that majority of these stellar pairs have tumultuous relationships with one another, said study co-author Selma de Mink, of the Space Telescope Science Institute in Baltimore.
“We already knew that massive stars are very often in binaries,” de Mink told SPACE.com. “What is very surprising to us is that they’re so close, and such a large fraction is interacting. If a star has a companion so close next to it, it will have a very different evolutionary path. Before, this was very complicated for us to model, so we were hoping it was a minority of stars. But, if 70 percent of massive stars are behaving like this, we really need to change how we view these stars.” [Top 10 Star Mysteries]
Studying stellar behemoths
Type O stars drive galaxy evolution, but these stellar giants can also exhibit extreme behavior, garnering the nickname “vampire stars” for the way they suck matter from neighboring companions.
“These stars are absolute behemoths,” study lead author Hugues Sana, of the University of Amsterdam in the Netherlands, said in a statement. “They have 15 or more times the mass of our sun and can be up to a million times brighter.”
These massive stars typically end their lives in violent explosions, such as core-collapse supernovas or gamma-ray bursts, which are so luminous they can be observed throughout most of the universe.
For the new study, the astronomers analyzed the light coming from 71 O-type stars — a mix of single and binary stars — in six different star clusters, all located roughly 6,000 light-years away.
The researchers found that almost three-quarters of these stars have close companions. Most of these pairs are also close enough to interact with one another, with mass being transferred from one star to the other in a sort of stellar vampirism. About one-third of these binary systems are even expected to eventually merge to form a single star, the researchers said.
The results of the study indicate that massive stars with companions are more common than was once thought, and that these heavyweights in binary systems evolve differently than single stars — a fact that has implications for how scientists understand galaxy evolution.
“It makes a big difference for understanding the life of massive stars and how they impact the whole universe,” said de Mink.
Big stars with a big impact
Type O stars make up less than 1 percent of the stars in the universe, but they have powerful effects on their surroundings. The winds and shocks from these stars can both trigger and halt star formation processes, the researchers said.
Over the course of their lives, culminating in the supernova explosions that signal their death, these massive stars also produce all the heavy elements in the universe. These elements enrich galaxies and are crucial for life.
But for massive stars in close binary systems, the interactions between the pair impact the evolution of both stars.
With vampire stars, the lower-mass star sucks fresh hydrogen from its companion, substantially increasing its mass and enabling it to live much longer than a single star of the same mass would, the researchers explained. The victim star, on the other hand, is left with an exposed core that mimics the appearance of a much younger star.
These factors could combine to give researchers misleading information about galaxies and the stars within them.
“The only information astronomers have on distant galaxies is from the light that reaches our telescopes,” said Sana. “Without making assumptions about what is responsible for this light, we cannot draw conclusions about the galaxy, such as how massive or young it is. This study shows that the frequent assumption that most stars are single can lead to wrong conclusions.”
A new method used to scan the atmosphere of a distant “hot Jupiter” world could eventually reveal insights about many distant alien planets — including, perhaps, whether or not they support life, the researchers added.
“If we could detect gases like oxygen, these could point to biological activity,” study co-author Ignas Snellen, an astronomer at Leiden University in the Netherlands, told SPACE.com.
A new look at exoplanet atmospheres
Scientists have analyzed the atmospheres of exoplanets before, but only when those worlds passed in front of their parent stars, much like Venus did during its recent transit of the sun.
The change in the light of a star as it streams through an exoplanet’s atmosphere can reveal details about the air’s composition. Different molecules absorb light in distinct ways, resulting in patterns known as spectra that allow scientists to identify what they are. [Gallery: The Strangest Alien Planets]
Now scientists have for the first time analyzed the atmosphere of an exoplanet that, like most such alien worlds, does not pass between its star and Earth.
The planet in question is Tau Boötis b, one of the first exoplanets to be discovered back in 1996 and one of the nearest exoplanets to Earth known, at about 51 light-years away. The world is a “hot Jupiter” — a gas giant orbiting very close to its parent star.
The exoplanet’s parent star, Tau Boötis, is easily visible with the naked eye, but the planet is not. Up to now, Tau Boötis b was only detectable through its gravitational pull on the star.
An international team caught the faint infrared glow from Tau Boötis b using the European Southern Observatory‘s Very Large Telescope (VLT).
“We were able to study the spectrum of the system in much more detail than has been possible before,” study lead author Matteo Brogi, of Leiden Observatory in the Netherlands, said in a statement. “Only about 0.01 percent of the light we see comes from the planet, and the rest from the star, so this was not easy.”
A wealth of information
Seeing the planet’s light directly also enabled the astronomers to measure the angle of the planet’s orbit, helping them deduce its mass — six times that of Jupiter’s — accurately for the first time.
“The new VLT observations solve the 15-year-old problem of the mass of Tau Boötis b. And the new technique also means that we can now study the atmospheres of exoplanets that don’t transit their stars, as well as measuring their masses accurately, which was impossible before,” Snellen said. “This is a big step forward.”
The spectra also yielded details about the temperature of the exoplanet’s atmosphere at different altitudes. Surprisingly, they found the planet’s atmosphere seems to be cooler higher up, the opposite of what is seen with other hot Jupiters.
Earth’s atmosphere is cooler at higher altitudes, the closer air gets to the frigid depths of space. Hot Jupiters, on the other hand, typically have atmospheres that are warmer farther up, perhaps due to gases present in their higher layers, such as titanium oxide.
Tau Boötis is a star very high in ultraviolet activity, radiation that may destroy these heat-absorbing gases and give Tau Boötis b an atmosphere with temperature features more like Earth’s, researchers said.
The researchers focused on the spectrum of carbon monoxide, which is expected to be the second-most common gas in the atmospheres of hot Jupiters, after hydrogen. Unlike hydrogen, carbon monoxide has very strong and observable infrared spectral features. Future research can concentrate on other common gases in hot Jupiter atmospheres, such as water vapor and methane.
“Our method shows that exoplanet atmospheres can be very well studied using ground-based telescopes,” Snellen said. Although Tau Boötis b is much too hot for any life, “possibly in the future we can extend this method to study much cooler planets like the Earth.”
The scientists detailed their findings in the June 28 issue of the journal Nature.
Big, bad Jupiter likely squashed any chance the giant asteroid Vesta may have had of growing into a full-fledged planet long ago, researchers say.
Scientists analyzing observations from NASA’s Dawn spacecraft announced on (May 10) that the enormous asteroid Vesta is actually an ancient protoplanet, a planetary building block left over from the solar system’s earliest days.
Many other Vesta-like objects were incorporated into rocky worlds such as Earth, but Vesta’s development along this path was halted.
Vesta’s stunted growth is chiefly a product of its location, researchers said. The protoplanets that glommed together to form Mercury, Earth, Mars and Venus did so in the inner solar system, relatively far from the disruptive gravitational influence of a giant planet.
The 330-mile-wide (530-kilometer) Vesta, on the other hand, grew up in the main asteroid belt between Mars and Jupiter. And the solar system’s largest planet made it tough for Vesta to hook up with others of its kind.
“In the asteroid belt, Jupiter basically stirred things up so much that they weren’t able to easily accrete with one another,” Dawn scientist David O’Brien, of the Planetary Science Institute in Tucson, Ariz., told reporters today.
“The velocities in the asteroid belt were really high, and the higher the velocity is, the harder it is for things to merge together under their own gravity,” O’Brien added.
Those high velocities also set the stage for some incredibly violent collisions, which probably destroyed a fair number of Vesta-like bodies. Vesta itself was battered and bloodied by some huge impacts; one crater near its south pole is 314 miles (505 km) wide, and another underneath that one measures 250 miles (400 km) across.
So while Vesta — the second-largest denizen of the asteroid belt — was doomed to a life of solitude, it has had the toughness and luck to stick around for the last 4.5 billion years. And scientists are thankful that it did.
“Vesta is special, because it survived the intense collisional environment of the main asteroid belt for billions of years, allowing us to interrogate a key witness to the events at the very beginning of the solar system,” said Dawn deputy principal investigator Carol Raymond, of NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“We believe Vesta is the only intact member of a family of similar bodies that have since perished,” she added.
These bubbles are blown by young, hot stars into the surrounding gas and dust, and indicate areas of brand-new star formation, scientists say.
“These findings make us suspect that the Milky Way is a much more active star-forming galaxy than previously thought,” Eli Bressert, an astrophysics doctoral student at the European Southern Observatory, said in a statement. “The Milky Way’s disk is like champagne with bubbles all over the place.”
About 35,000 volunteers sifted through data from NASA’s Spitzer Space Telescope on the online Milky Way Project to make the discoveries. These citizen scientists have found about 10 times more bubbles than previous surveys. [See the space bubbles]
In this case, human eyes are very good at spotting what computer programs often miss. The volunteers were able to identify partially broken rings and overlapping bubbles that would have confused algorithms. To make sure the volunteers identify likely bubbles, the program requires each candidate bubble to be flagged by five participants before it’s added to the catalog.
“The Milky Way Project is an attempt to take the vast and beautiful data from Spitzer and make extracting the information a fun, online, public endeavor,” said principal investigator of the Milky Way Project Robert Simpson, a postdoctoral researcher in astronomy at Oxford University in England.
Astronomers hope to use this collection of cosmic bubbles to study star formation in the galaxy. The results are already turning up some surprises, such as the fact that bubbles seem to be less common on either side of the galactic center.
“We would expect star formation to be peaking in the galactic center because that’s where most of the dense gas is,” Bressert said. “This project is bringing us way more questions than answers.”
Our Milky Way galaxy may be teeming with rogue planets that ramble through space instead of being locked in orbit around a star, a new study suggests.
These “nomad planets” could be surprisingly common in our bustling galaxy, according to researchers at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of Stanford University and the SLAC National Accelerator Laboratory. The study predicts that there may be 100,000 times more of these wandering, homeless planets than stars in the Milky Way.
If this is the case, these intriguing cosmic bodies would belong to a whole new class of alien worlds, shaking up existing theories of planet formation. These free-flying planets may also raise new and tantalizing questions in the search for life beyond Earth.
“If any of these nomad planets are big enough to have a thick atmosphere, they could have trapped enough heat for bacterial life to exist,” study leader Louis Strigari said in a statement.
And while nomad planets cannot benefit from the heat given off from their parent stars, these worlds could generate heat from tectonic activity or internal radioactive decay, the researchers said.
For now, characteristics of these foreign objects are still unknown; they could be icy bodies, similar to other objects found in the outer solar system, rocky like asteroids, or gas giants similar to the most massive planets in our solar system. [Gallery: First Earth-Size Alien Planets Found]
Over the past several decades, astronomers have keenly hunted for planets outside our solar system. So far, the search has turned up more than 700 of these exoplanets. Almost all of these newfound worlds orbit stars, but last year, scientists found about a dozen planets with no discernible host star.
The researchers used a technique called gravitational microlensing to detect these homeless planets. This method examines the effects of a massive object passing in front of a star.
From Earth, the nearby object bends and magnifies the light from the distant star like a lens, making the faraway star’s light appear to brighten and fade over time. The resulting “light curve” helps astronomers distinguish characteristics of the foreground object.
Based on initial estimates, approximately two free-flying planets exist for every “normal” star in our galaxy, but the results of the new study produced even more staggering findings: nomad planets may be up to 50,000 times more common than that.
“To paraphrase Dorothy from ‘The Wizard of Oz,’ if correct, this extrapolation implies that we are not in Kansas anymore, and in fact we never were in Kansas,” Alan Boss, of the Carnegie Institution for Science in Washington, D.C., said in a statement. “The universe is riddled with unseen planetary-mass objects that we are just now able to detect.”
The KIPAC researchers made their prediction by calculating the known gravitational pull of the Milky Way, the amount of matter available in the galaxy to make such celestial objects, and how that matter might be distributed to make up objects that range from as small as Pluto to as large as Jupiter.
These measurements were challenging since astronomers are unsure where these wandering planets came from, the researchers said. Some of these rogue worlds were likely ejected from other star systems, but there is evidence that not all of them could have been formed this way, Strigari said.
The researchers are hopeful that follow-up observations using next generation telescopes, particularly of the smaller objects, will yield more detailed results. The planned space-based Wide Field Infrared Survey Telescope, and the Large Synoptic Survey Telescope on the ground, are both set to begin operations in the early 2020s.
If the estimated number of these nomad planets is correct, the results could lead to exciting prospects about the origin and abundance of life in our Milky Way galaxy. For instance, as these homeless planets mosey through space, collisions could break apart pieces of these rogue worlds and fling bacterial life onto other celestial bodies, the researchers said.
“Few areas of science have excited as much popular and professional interest in recent times as the prevalence of life in the universe,” study co-author Roger Blandford, director of KIPAC, said in a statement. “What is wonderful is that we can now start to address this question quantitatively by seeking more of these erstwhile planets and asteroids wandering through interstellar space, and then speculate about hitchhiking bugs.”