The newfound world — nicknamed “Einstein’s planet” by the astronomers who discovered it — is the latest of more than 800 planets known to exist beyond our solar system, and the first to be found through this method.
The planet, officially known as Kepler-76b, is 25 percent larger than Jupiter and weighs about twice as much, putting it in a class known as “hot Jupiters.” The world orbits a star located about 2,000 light-years from Earth in the constellation Cygnus. [7 Ways to Discover Alien Planets]
The researchers capitalized on subtle effects predicted by Albert Einstein’s special theory of relativity to find the planet. The first is called the “beaming” effect, and occurs when light from the parent star brightens as its planet tugs it a nudge closer to Earth, and dims as the planet pulls it away. Relativistic effects cause light particles, called photons, to pile up and become focused in the direction of the star’s motion.
“This is the first time that this aspect of Einstein’s theory of relativity has been used to discover a planet,” research team member Tsevi Mazeh of Tel Aviv University in Israel said in a statement.
Additionally, gravitational tides from the orbiting planet caused its star to stretch slightly into a football shape, causing it to appear brighter when its wider side faces us, revealing more surface area. Finally, the planet itself reflects a small amount of starlight, which also contributed to its discovery.
“We are looking for very subtle effects,” said team member David Latham of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “We needed high quality measurements of stellar brightnesses, accurate to a few parts per million.”
The researchers used data from NASA’s Kepler spacecraft, which provided the extremely detailed observations necessary. While Kepler was designed to hunt for alien planets, it normally does so using the transit method, which looks for stars that dim periodically as planets pass in front of them.
“This was only possible because of the exquisite data NASA is collecting with the Kepler spacecraft,” said study leader Simchon Faigler of Tel Aviv University.
The other most popular planet-hunting tactic is called the wobble method, and searches for slight signs of movement in stars’ radial velocities caused by tugging planets.
The new Einstein-based method is best for larger worlds, and is currently incapable of finding Earth-sized planets, the scientists said. Still, it offers some benefits, as it does not require high-precision measurements of a star’s velocity, or for a star and its planet to align perfectly as viewed from Earth — the two main drawbacks of the most common methods.
“Each planet-hunting technique has its strengths and weaknesses. And each novel technique we add to the arsenal allows us to probe planets in new regimes,” said Avi Loeb, also from the Center for Astrophysics.
A paper detailing the planet discovery will be published in an upcoming issue of The Astrophysical Journal.
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 photo, taken by a telescope at the European Southern Observatory’s La Silla Observatory, shows the head portion of the Seagull Nebula. The cloud of gas spotlighted in the image glows intensely due to radiation blasted out by a hot young star at its heart, scientists said.
Like other nebulas, the Seagull is a stellar nursery — an enormous cloud of dust, hydrogen, helium and other ionized gases where stars are being born. Nebulas come in a variety of sizes and shapes, some of which spur astronomers’ imaginations and evoke comparisons to animals or familiar objects.
The Seagull Nebula is so named because it resembles a gull in flight. The nebula, which is formally known as IC 2177, spans about 100 light-years from wingtip to wingtip. It’s found about 3,700 light-years from Earth, on the border between the constellations Monoceros (The Unicorn) and Canis Major (The Great Dog).
The nebula appears to be close to Sirius, the brightest star in the sky. But IC 2177 actually lies more than 400 times farther away from us than Sirius, researchers said.
The bright star lighting up the Seagull’s head is known as HD 53367. This star, which is visible in the center of the image and could be taken to be the bird’s eye, is about 20 times more massive than our own sun, researchers said.
Radiation streaming from the nebula’s young stars causes surrounding hydrogen gas to glow a rich red color. Light from these hot bluish-white stars also scatters off tiny dust particles, creating the blue haze seen in parts of the picture.
Parts of the Seagull Nebula complex were first observed in 1785 by the famed German-British astronomer Sir William Herschel, but the region imaged in the new picture weren’t photographed until a century later, researchers said.
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.
It is science fiction made fact: Astronomers have discovered two alien planets around the same star whose orbits come so close together that each rises in the night sky of its sister world like an exotic full moon.
The newfound planets are 1,200 light-years from Earth and an unprecedented find, researchers said. They differ greatly in size and composition but come within just 1.2 million miles (1.9 million kilometers) of each other, closer than any other pair of planets known, according to a new study.
One of the newly discovered alien planets, called Kepler-36b, appears to be a rocky “super-Earth” 4.5 times as massive as our planet. The other, Kepler-36c, is a gaseous, Neptune-size world about eight times as massive as Earth. The two planets meet up every 97 days in a conjunction that would make each dramatically visible in the other’s sky.
“These two worlds are having close encounters,” said co-lead author Josh Carter, of the Harvard-Smithsonian Center for Astrophysics, in a statement.
At their closest approach, the two planets are separated by five times the distance between the Earth and the moon. How such different bodies ended up in such similar orbits may be tough for current theories of planet formation and migration to explain, researchers said.
“This is unprecedented,” co-lead author Eric Agol, of the University of Washington, told SPACE.com via email. “They are as different in density as Earth and Saturn (the highest and lowest density planets in our solar system), yet they are 30 times closer than any pair of planets in our solar system.” (Agol later clarified to SPACE.com that Kepler-36b and c are actually more like 20 times closer together than any two planets in our neck of the woods.) [Gallery: The Strangest Alien Planets]
The two known planets in the Kepler-36 system — which is located in the constellation Cygnus (The Swan) — were detected by NASA’s Kepler Space Telescope.
Kepler is staring continuously at more than 150,000 stars, watching for telltale brightness dips caused when planets cross in front of the stars from the telescope’s perspective. Since its March 2009 launch, Kepler has flagged more than 2,300 potential alien planets; while only a small fraction have been confirmed to date, mission scientists think more than 80 percent of them will end up being the real deal.
Kepler-36c, which is about 3.7 times wider than Earth, likely has a rocky core surrounded by a substantial atmosphere filled with lots of hydrogen and helium, researchers said.
Kepler-36b, on the other hand, is a super-Earth just 1.5 times wider than our planet. Iron likely constitutes about 30 percent of its mass, water around 15 percent and atmospheric hydrogen and helium less than 1 percent, researchers said.
Though they’re very different in size and makeup, the two planets travel on surprisingly similar paths around their host star. Kepler-36c orbits once every 16 days, at an average distance of 12 million miles (19 million km). Kepler-36b orbits each 14 days and sits about 11 million miles (18 million km) from the star.
Kepler-36b probably formed relatively close to the star, while Kepler-36c likely took shape farther out. Astronomers model large-scale migrations that can bring initially far-flung planets much closer together, but the peculiar Kepler-36 system may force some refinements, researchers said.
“These models rely on assumptions that will likely have to be ‘tweaked’ or refined to account for both b and c’s proximity and compositional differences,” Carter told SPACE.com via email. “The existence of Kepler-36 may help clarify or invalidate these assumptions.”
Both planets are likely too hot to support life as we know it, with Kepler-36b probably sporting lava flows on its surface. They orbit roughly three times closer to their host star, known as Kepler-36a, than the hellishly hot planet Mercury does to our sun. And Kepler-36a is likely a bit hotter than our star, researchers said.
The researchers publish their results Thursday (June 21) in the journal Science.
An impressive sky scene
Every 97 days, Kepler-36b and c experience a conjunction that brings them within just 1.2 million miles (1.9 million km) of each other — roughly five times the Earth-moon distance. This would be quite a sight for an observer on the surface of either planet.
“Planet c would appear roughly 2.5 times the size of the full moon when viewed from the surface of planet b. Conversely, planet b would appear about the size of the full moon on planet c,” Carter said.
“We can speculate on the appearance of planet c: It may appear slightly more purple that Neptune,” he added. “The purple hue owes to absorption of red and yellow by sodium and potassium. There could also be a slight brown tint owing to hazes of photo-disassociated methane.”
Such dramatic vistas could well be around for many years to come, researchers said, for the orbits of Kepler-36b and c appear unlikely to change anytime soon.
“We are addressing this in a follow-up paper, but the short answer is that yes, these do appear to be stable on a long timescale,” Agol said.
Think of it as a win for the little guys. Astronomers using a small ground-based telescope have discovered two unusual alien planets around extremely bright, distant stars.
The two extrasolar planets are gas giant worlds detected using the Kilodegree Extremely Little Telescope (KELT) in southern Arizona, which has a lens that is roughly as powerful as a high-end digital camera, the researchers said.
“KELT is slightly more diminutive than Kepler, but we like to think it’s small but fierce,” said Thomas Beatty, a doctoral student at Ohio State University in Columbus. NASA’s Kepler space telescope is an orbiting observatory specially built to seek out distant planets.
Beatty presented the findings on June 13 at the 220th meeting of the American Astronomical Society in Anchorage, Alaska.
Hot Jupiters revealed
One of the newly found planets, called KELT-1b, is a massive world that is both incredibly hot and dense. The alien planet, which is mostly metallic hydrogen, is slightly larger than Jupiter, but contains a whopping 27 times the mass. [Gallery: The Strangest Alien Planets]
These types of alien worlds are known as “hot Jupiters” because they are gas giant planets that orbit extremely close to their parent stars.
KELT-1b is so close to its host star that it completes one orbit in a mere 29 hours. Being this close to its star, the planet’s surface temperature is likely above 4,000 degrees Fahrenheit (roughly 2,200 degrees Celsius), in the process receiving 6,000 times the amount of radiation that Earth receives from the sun, Beatty explained.
“[It] resets the bar for weird,” he said. “It’s the sort of object that we would not have expected to find this close to its parent star.”
KELT-1b is located approximately 825 light-years away in the constellation of Andromeda. The massive planet stood out to astronomers not only because of its close proximity to its parent star, but because of its unusual orbital dynamics.
“It’s massive enough that KELT-1 has raised tides on its parent star and actually spun it up,” Beatty said. “KELT-1 grabbed the star it’s around, pulled it so it’s spinning at the same rate, so now both KELT-1 and its parent star are locked in each other’s gaze as they go around.”
Auriga’s alien world
The other newly identified planet is called KELT-2Ab, and is located about 360 light-years away in the constellation of Auriga. The alien world is 30 percent larger than Jupiter with 50 percent more mass.
This discovery more closely resembles other exoplanets found to date, except KELT-2Ab’s parent star is so bright it can be seen from Earth through binoculars. In fact, the star is so luminous that researchers will be able to make direct observations of the planet’s atmosphere by examining light that shines through it when the star passes within KELT North’s field of view again in November.
Follow-up observations are also being planned using other ground-based instruments, as well as several space observatories, including the Hubble Space Telescope and the infrared Spitzer Space Telescope.
“We want to look at what’s going on in its atmosphere and its interior,” Beatty said. “The reason why individual hot Jupiters like these are still interesting is because we still fundamentally do not understand what goes on inside them.”
KELT-2Ab orbits a star that is slightly bigger than the sun, within a binary system called HD 42176.
It resides in a binary system called HD 42176, with one star that is slightly bigger than our sun, and another star that is slightly smaller. KELT-2Ab orbits the bigger star, which is bright enough to be seen from Earth with binoculars.
How they were found
Astronomers use KELT to find large planets orbiting very bright stars using the so-called transit method, which involves watching for tiny dips in the star’s light that could indicate a planet is crossing, or transiting, in front.
Rather than staring at a small group of stars at high resolution, the twin KELT North and KELT South telescopes observe millions of very bright stars at low resolution, the researchers said. KELT North scans the northern sky from Arizona, while KELT South covers the southern sky from Cape Town, South Africa.
While NASA’s prolific Kepler Space Telescope has identified roughly 2,300 alien planet candidates, the small ground-based KELT telescopes provide a low-cost alternative for exoplanet hunters by primarily using off-the-shelf technology. The hardware for a KELT telescope costs less than $75,000, the researchers said.
NASA’s Voyager 1 spacecraft has encountered a new environment more than 11 billion miles from Earth, suggesting that the venerable probe is on the cusp of leaving the solar system.
The Voyager 1 probe has entered a region of space with a markedly higher flow of charged particles from beyond our solar system, researchers said. Mission scientists suspect this increased flow indicates that the spacecraft — currently 11.1 billion miles (17.8 billion kilometers) from its home planet — may be poised to cross the boundary into interstellar space.
“The laws of physics say that someday Voyager will become the first human-made object to enter interstellar space, but we still do not know exactly when that someday will be,” said Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena, in a statement.
“The latest data indicate that we are clearly in a new region where things are changing more quickly,” Stone added. “It is very exciting. We are approaching the solar system’s frontier.” [Photos From NASA's Voyager 1 and 2 Probes]
Voyager 1 and its twin, Voyager 2, launched in 1977, tasked chiefly with studying Saturn, Jupiter and the gas giants’ moons. The two spacecraft made many interesting discoveries about these far-flung bodies, and then they just kept going, checking out Uranus and Neptune on their way toward interstellar space.
They’re not quite out of the solar system yet, however. Both are still within a huge bubble called the heliosphere, which is made of solar plasma and solar magnetic fields. This gigantic structure is about three times wider than the orbit of Pluto, researchers have said.
Specifically, the Voyagers are plying the heliosphere’s outer shell, a turbulent region called the heliosheath. But Voyager 1′s new measurements — of fast-moving galactic cosmic rays hurled our way by star explosions — suggest the probe may be nearing the heliosphere’s edge.
“From January 2009 to January 2012, there had been a gradual increase of about 25 percent in the amount of galactic cosmic rays Voyager was encountering,” Stone said. “More recently, we have seen very rapid escalation in that part of the energy spectrum. Beginning on May 7, the cosmic ray hits have increased five percent in a week and nine percent in a month.”
More measurements needed
While it may be tough to identify the moment when Voyager 1 finally pops free into interstellar space, scientists are keeping an eye on the cosmic ray measurements and a few other possible indicators.
One is the intensity of energetic particles generated inside the heliosphere. Voyager 1 has recorded a gradual decline in these particles as it flies farther and farther away from Earth, but it hasn’t seen the dramatic dropoff that scientists expect would accompany an exit from the solar system.
The Voyager team also thinks the magnetic fields surrounding the spacecraft should change when it crosses the solar boundary. Those field lines run roughly east-west within the heliosphere, and researchers predict they’ll shift to a more north-south orientation in interstellar space. They’re currently looking at Voyager 1 data for any signs of such a transition.
In the meantime, both Voyagers just keep on flying and exploring. Voyager 2 trails its twin a little bit; it’s currently 9.1 billion miles (14.7 billion km) from home.
“When the Voyagers launched in 1977, the space age was all of 20 years old,” Stone said. “Many of us on the team dreamed of reaching interstellar space, but we really had no way of knowing how long a journey it would be — or if these two vehicles that we invested so much time and energy in would operate long enough to reach it.”
Microbes living at the edges of Arctic ice sheets could help researchers pinpoint evidence for similar microorganisms that may have evolved on Mars, Jupiter’s moon Europa or Saturn’s moon Enceladus, researchers say.
Scientists are investigating the receding edge of ice sheets on Earth to study the release of methane there.
Methane is a colorless, odorless, flammable gas. On Earth, some methane is produced abiotically — not by life — through reactions between water and rock, as well as through the breakdown of hydrocarbons by geological processes.
On the other hand, some methane comes directly or indirectly from methanogenic microbes, as a byproduct of fermentation of acetate — a derivative of vinegar — into methane and carbon dioxide.
“It is increasingly clear that on Earth, there are cold-adapted methanogenic microbes in Arctic, Antarctic and sea-bottom settings,” said Jeffrey White, an environmental biogeochemist at Indiana University. “Acetate fermentation is the principal pathway accounting for as much as 95 percent of methane production in these cold environments.” [Extremophiles: World's Weirdest Life]
Similar ice sheets exist elsewhere in the solar system, such as the buried water ice glaciers in the Hellas Basin region on Mars. The plan is to see what methods can best determine whether the sources of any such methane are biological or not.
Studying Arctic microbes
Methanogenic microbes rely on a community of microorganisms that provide the acetate and other simple molecules they consume. If such communities evolved in the cold corners of Earth, “it seems reasonable to search for evidence of similar biological processes on other icy bodies in our solar system,” White said.
Such objects include Enceladus and Europa — moons of Saturn and Jupiter, respectively — both of which are thought to harbor oceans of liquid water beneath their icy shells.
To analyze these microbes and their methane emissions, White and his colleagues recently went to Greenland as part of a $2.6 million NASA ASTEP (Astrobiology Science and Technology for Exploring Planets) grant.
The researchers investigated the western edge of the Greenland ice sheet, “one of the most readily accessible margins of a large ice sheet on Earth,” White said. “The relatively manageable logistics and climate in Greenland compared to Antarctica made this area an excellent choice.”
Careful analysis of the isotopes making up methane can shed light on its origins. Isotopes are variants of elements. All isotopes of an element have the same number of protons in their atomic nuclei, but each has a different number of neutrons. For instance, atoms of carbon-12 each have six neutrons while atoms of carbon-13 have seven.
The available data suggest that methane from microbial reactions is substantially richer in lighter isotopes at 20 to 40 parts per thousand than abiotic methane, explained researcher Lisa Pratt, an astrobiologist and geomicrobiologist at Indiana University.
Small dissolved molecules or ions containing a lighter isotope move more rapidly at a given temperature than ones containing a heavy isotope. Consequently, those containing a light isotope interact more often with a bacterium’s enzymes, and so get incorporated more often into what it makes metabolically, such as methane.
In 2011, the researchers used an infrared laser to look for methane at multiple sites across a valley that extends for tens of miles near the margin of the Greenland ice sheet. Measurements were taken about 6 feet (2 meters) above the soil surface for 1 to 4.5 hours each time.
Methane was spotted at several lakes and wetland areas. However, the methane levels seen were very close to what would be detected from normal atmospheric levels at ice margins in Greenland. Their next measurements will be taken at heights just above the soil surface to better distinguish local sources of emission.
So far, the researchers have been surprised by how much biology and biogeochemistry can vary across several small lakes arrayed along a single valley near the ice margin.
“If life was widespread during an early period on Mars when small lakes were common, we need to approach sampling with the expectation that pronounced variation in biological markers could occur even over distances as small as 100 meters (330 feet),” Pratt said.
In the coming summer, the researchers intend to look for potential subsurface gaseous signs of life with an innovative drill they have developed. The device allows rapid transfer of unaltered gas samples from drilled boreholes directly into analytical instruments.
A similar instrument could one day find use in planetary exploration, Pratt said.
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.
Astronomers have caught four dying stars in the act of chowing down on rocky alien planets similar to Earth, a destructive cosmic process that may one day play out in our very own solar system, a new study reveals.
Evidence of the distant celestial meals was found around four white dwarfs — stars that are in the final stages of their lives. The stars are surrounded by dust and rocky debris from shattered alien planets that appear to have once shared very similar compositions to Earth, according to astrophysicists at the University of Warwick in the U.K.
“What we are seeing today in these white dwarfs several hundred light-years away could well be a snapshot of the very distant future of the Earth,” said study leader Boris Gänsicke, a professor in the department of physics at the University of Warwick, in a statement.
The researchers used the Hubble Space Telescope to examine the atmospheres of more than 80 white dwarf stars within a few hundred light-years of the sun. They found that the most common chemical elements in the dust around four of the white dwarfs were oxygen, magnesium, iron and silicon — the four elements that make up roughly 93 percent of the Earth, the astronomers said. [Gallery: Dying Stars Consume Rocky Alien Planets]
The dusty veils of material also contained an extremely low proportion of carbon, which is similar to what is found with Earth and the other rocky planets that orbit closest to the sun. According to the researchers, this is the first time that such low proportions of carbon have been measured in the atmospheres of white dwarf stars surrounded by cosmic debris.
These observations indicate that the stars once hosted at least one rocky planet that has since been destroyed. The astrophysicists also determined that they are witnessing the final phase in the deaths of these alien worlds.
Last gasps of dying stars
White dwarfs are the compact stellar remains of relatively small stars, like our sun, that have exhausted their fuel, leaving behind dim, fading cores of material. The sun, and more than 90 percent of the stars in the Milky Way galaxy, will one day end up as white dwarfs, astronomers have said.
The atmospheres of white dwarfs are typically made up of hydrogen and helium, so heavier elements that are incorporated into their atmospheres are dragged downward to the stellar core by its intense gravity, and are usually out of sight within a matter of days, the researchers explained.
Since the astronomers were able to detect oxygen, magnesium, iron and silicon in the atmospheres of four of the white dwarfs, they must have been observing the final phase of the planets’ death, as shattered material rained down on the stars at staggering rates of up to 2.2 million pounds (1 million kilograms) per second.
One white dwarf in particular, called PG0843+516, stood out from the rest because of its seemingly overabundant stores of iron, nickel and sulfur in the dust in its atmosphere. Iron and nickel are elements typically found in the cores of terrestrial planets, as gravity pulls them into the center during the formation of planets.
This suggests that PG0843+516 is in the midst of swallowing up the remains of a rocky planet that had a similar composition to Earth, the researchers said.
“It is entirely feasible that in PG0843+516 we see the accretion of such fragments made from the core material of what was once a terrestrial exoplanet,” Gänsicke said.
Preview of Earth’s fate?
But while this process is occurring hundreds of light-years away, the cannibalistic scene could be a harbinger for the eventual fate of our planet.
“As stars like our sun reach the end of their life, they expand to become red giants when the nuclear fuel in their cores is depleted,” Gänsicke said. “When this happens in our own solar system, billions of years from now, the sun will engulf the inner planets Mercury and Venus. It’s unclear whether the Earth will also be swallowed up by the sun in its red giant phase — but even if it survives, its surface will be roasted.”
As the sun sheds large amounts of its mass, the planets will migrate further out, he said, which will wreak havoc in the solar system.
“This may destabilize the orbits and lead to collisions between planetary bodies as happened in the unstable early days of our solar system,” Gänsicke said. “This may even shatter entire terrestrial planets, forming large amounts of asteroids, some of which will have chemical compositions similar to those of the planetary core. In our solar system, Jupiter will survive the late evolution of the sun unscathed, and scatter asteroids, new or old, towards the white dwarf.”
The detailed results of the study will be published in the journal Monthly Notices of the Royal Astronomical Society.
The planet’s two remaining pieces, which researchers tentatively identified as planet-size objects just slightly smaller than Earth, were possibly created when their parent body spiraled inward too close to the bloated red giant star KIC 05807616. Extreme tidal forces then tore the parent planet into pieces, some of which seem to have stabilized in orbit around the star, revealing that a planet’s life doesn’t always start and end neatly, researchers said.
“Planets can still evolve, by disintegrating to several small bodies, or by being completely destroyed,” authors Ealeal Bear and Noam Soker, of the Israel Institute of Technology, told SPACE.com by email.
A dance of death
Once a common star like the sun, KIC 05807616 swelled into a red giant as it reached the end of its life. The gas surrounding it ballooned outward, engulfing any alien planets that lay too close.
But one gas giant may have escaped complete destruction. By spiraling in through the star’s shell, the planet’s massive girth would have allowed it to function the same way a companion star might, stripping off the excess gas and allowing the star to contract to a more manageable size.
At the same time, tidal forces would have ripped the giant planet to shreds, creating at least two rocks only a little smaller than Earth. Known as KOI 55.01 and KOI 55.02, the two planets orbit the sun between 550,000 and 700,000 miles (900,000 to 1,100,000 km), far closer than Mercury, and too hot to hold water on their surface.
While much of the giant planet flew into space — or into the star — other pieces may also have been caught in orbit. When KOI 55.01 and KOI 55.02 were first identified, the presence of a third was also tentatively noted. If other pieces are found, it would strengthen the idea that the two rocky planets formed from a single object.
Like KIC 05807616, our sun will one day balloon outward, engulfing the rocky bodies in the inner solar system. But Mercury, Venus, and Earth are too small to have an effect on the sun’s outer atmosphere, while the larger gas planets will be too far away. [Video: How the Sun Will Swallow Earth]
But other planets throughout the galaxy may play a role in their stars’ evolution. The authors emphasized that there are more indications for planets existing around dying stars, calling the pairing “a general process that we expect to take place in other circumstances,” Bear and Soker said. They intend to continue monitoring new discoveries of planets around evolved stars, analyzing possible evolution routes to explain their existence.
The researchers’ findings are detailed in the April edition of the Astrophysical Journal Letters.
Into the fire
When the extrasolar planets around KIC 05807616 were initially discovered in December, their location near the star surprised astronomers.
“Before this discovery, the consensus was that planets simply cannot influence the evolution of their parent star, and cannot survive being swallowed by a red giant star,” Stephane Charpinet, of the University of Toulouse in France, told SPACE.com in an email.
Charpinet was the lead author on the paper that first identified the potential planets.
Using NASA’s planet-hunting Kepler spacecraft, Charpinet and his team noticed periodic dimming around the dying star. After analyzing the data, they concluded that the changes were caused by two planets zipping around the star.
They initially suggested that the rocky bodies could have started as two gas planets whose atmospheres were torn away as they demolished the outer layers of the star.
“We were hoping that other groups would jump on this discovery and propose their own ideas, or refine our interpretations on the subject,” Charpinet said. “We are glad that this happened quite rapidly, as Ealeal Bear and Noam Soker proposed this truly interesting alternative to our scenario.”
The pesky reality that the universe’s expansion is accelerating — an observation that prompted astronomers to invoke an unknown entity called dark energy to explain it — has been further confirmed by new measurements.
Scientists have used cosmic magnifying glasses called gravitational lenses to observe super-bright distant galaxies, giving a measure of how quickly the universe is blowing up like a giant balloon. They found, in agreement with previous measurements, that the universe’s expansion is indeed speeding up over time.
The first measurement of this phenomenon, based on exploding stars called supernovae, was made in the 1990s.
“The accelerated cosmic expansion is one of the central problems in modern cosmology,” Masamune Oguri, of the University of Tokyo’s Kavli Institute for the Physics and Mathematics of the Universe, said in a statement. “In 2011 the Nobel Prize in Physics was awarded to the discovery of the accelerated expansion of the universe using observations of distant supernovae. A caution is that this method using supernovae is built on several assumptions, and therefore independent checks of the result are important in order to draw any robust conclusion.”
Scientists still don’t have much of an idea why the universe is not only expanding doing so ever-faster. The gravity of all the mass in the universe would be expected to pull everything back inward, so scientists call whatever force is counteracting gravity “dark energy.”
“Our new result using gravitational lensing not only provides additional strong evidence for the accelerated cosmic expansion, but also is useful for accurate measurements of the expansion speed, which is essential for investigating the nature of dark energy,” Oguri said.
Ogiri led the new study of quasars with Naohisa Inada at Japan’s Nara National College of Technology.
Quasars are objects bright enough to be spotted halfway across the universe. They are thought to be powered by hungry black holes that gobble up copious amounts of matter in the centers of galaxies, releasing radiant jets of light that shoot out into space.
The light from quasars sometimes passes by massive objects on its way to telescopes on Earth, and the gravity from these objects bends space-time, causing the light to travel along a curved path. This can produce warped and distorted double images of a single distant quasar. [Video: Quasar Details Seen With Gravitational Lenses]
As the universe expands, the distance to quasars increases, and so do the chances that a quasar’s light will pass by a massive object and be gravitationally lensed.
Thus the frequency of gravitationally lensed quasars can indicate the expansion speed of the universe.
Ogiri, Inada and their colleagues searched for such quasars in the catalog of the Sloan Digital Sky Survey (SDSS), which took detailed observations of giant swaths of the night sky. In a collection of about 100,000 quasars, the researchers identified 50 that were being gravitationally lensed, significantly increasing the known total sample of these objects.
The researchers used their calculation of the frequency of gravitationally lensed quasars to deduce that the universe’s expansion is indeed accelerating.
The new results will be reported in an upcoming paper published in the Astronomical Journal.
The first true “alien Earth” will likely be discovered in the next two years, a NASA scientist says.
Astronomers have found more than 750 alien planets to date, and NASA’s Kepler Space Telescope has flagged 2,300 additional “candidates” awaiting confirmation by follow-up studies. This haul has not yet included an Earth-like exoplanet — one that’s the size of our planet and orbits at the right distance from its star to support liquid water and, possibly, life as we know it.
But that could change soon, according to Shawn Domagal-Goldman, a researcher at NASA Headquarters in Washington, D.C. who specializes in exoplanet biology.
“I believe Kepler will find a ‘Goldilocks planet’ within the next two years,” Domagal-Goldman said in a statement. “We’ll be able to point at a specific star in the night sky and say ‘There it is — a planet that could support life!’” [Video: How to Find Earth's Alien Twin]
Studying a ‘Goldilocks planet’
Some NASA officials appear to share Domagal-Goldman’s optimism, for the agency is already looking into ways to study alien Earths once they’re found.
It’s difficult to investigate such worlds directly, since faraway Earth-size planets are small and faint, their dim light almost completely drowned out by the bright glare of their parent stars. But researchers are confident that an indirect approach, called transit spectroscopy, can reveal a lot about Goldilocks worlds.
This technique scrutinizes starlight that bounces off the atmosphere of an alien Earth on its way to our cosmic neighborhood. Such starlight carries a sort of fingerprint of the atmosphere, which astronomers can study to learn about the atmosphere’s composition.
“The reflected light of an exoplanet tells its story,” said Doug Hudgins, Kepler program scientist at NASA Headquarters.
New missions coming?
One new mission under consideration, called Finesse, uses the transit spectroscopy method. Finesse, which is short for “Fast INfrared Exoplanet Spectroscopy Survey Explorer,” would measure the spectra of stars and their planets in two situations — once when the planet is in view, and again when it’s hidden behind its star.
The mission would be able to separate the planet’s dim light from the star’s blazing glare, revealing the composition of the planet’s atmosphere in the process, researchers said.
NASA is also considering an observatory named Tess (Transiting Exoplanet Survey Satellite). Supported in part by Google, this mission is designed to find alien planets in our local galactic neighborhood. Tess would study hundreds of stars within 50 light-years of Earth, close enough to study in some detail.
“With better detectors and instruments designed to block the glare of the parent stars, these next-generation telescopes could not only find a Goldilocks planet, but also tell us what its atmosphere is made of, what sort of cloud cover graces its skies, and maybe even what the surface is like — whether oceans cover part of the globe, how much land there is, and so on,” Hudgins said.
Domagal-Goldman expects big finds, and big surprises.
“We’ve found so many unexpected things about planets that now I expect to be amazed,” he said. “When we can study a Goldilocks planet, I believe we’ll discover something revolutionary about how life interacts with a planetary environment. Nature is so much more diverse than we anticipated.”
The lively cosmic scene was captured by the European Southern Observatory’s VLT Survey Telescope at the Paranal Observatory in Chile. The dynamic interactions taking place in the Hercules cluster make these galaxies look like the young galaxies of the more distant universe, according to ESO officials.
The Hercules cluster, which is also known as Abell 2151, is located about 500 million light-years from Earth in the constellation of Hercules. While there are no giant elliptical galaxies nearby, the irregularly shaped Hercules cluster contains a wide variety of galaxy types, including many young, star-forming spiral galaxies.
Pairs of galaxies can be seen throughout the image, bumping up against one another as they prepare to merge into single, larger galaxies, ESO officials said. These collisions, plus the numerous gas-rich spiral galaxies in the cluster, are reminiscent of young galaxies in the distant universe, leading astronomers to estimate that the Hercules cluster is relatively young.
This swarm of galaxies will one day mature and more closely resemble the older galaxy clusters that are more commonly found nearby, ESO officials said. [New Hercules galaxy cluster photos]
Gaggle of galaxies
Galaxy clusters form when smaller groups of galaxies are pulled together by their own gravity. As these groups approach one another, the cluster becomes more spherical and compact. Meanwhile, as the galaxies come closer together, they begin to collide.
In clusters dominated by spiral galaxies, these collisions have the power to distort the spiral structures and strip off their gas and dust — the raw materials from which new stars are born. This is why most off the galaxies in a mature cluster are elliptical or irregular in shape, the astronomers said.
Typically, one or two large elliptical galaxies, formed by merging smaller galaxies, can be found at the center of these adult clusters.
Breaking down Hercules
The Hercules cluster is thought to be made up of three small clusters and groups of galaxies that are currently merging into a larger structure. The entire cluster itself is also fusing itself with other large clusters to form a galaxy supercluster, ESO scientists explained. These giant assemblies are some of the largest structures in the universe.
In this new image, the galaxies of the Hercules cluster can be seen, in addition to many fainter background objects that represent galaxies that are much further away.
In the foreground, several bright Milky Way stars are visible and interestingly enough, the short trails of asteroids as they flew across the image during exposures can also be seen.
The new picture of the Hercules cluster was taken with the VLT Survey Telescope’s huge 268-megapixel OmegaCAM, which is capable of producing images across large areas of the sky.
The distribution of matter across the cosmos is most easily explained by inflation, a theory that suggests our universe inflated rapidly — just like a balloon — shortly after its birth, according to new research.
A new study found that cosmic inflation, which was first proposed in 1980, is the simplest explanation that fits the measurements of the distribution of matter throughout the universe made by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), a spacecraft that scans radiation left over from the Big Bang.
According to inflation, the universe expanded by a factor of at least 1078 (that’s 10 with 78 zeroes after it), all in less than a second. This stage could have formed the basis for the large-scale structure we can detect in the distribution of galaxies around us now.
This theory can explain why the universe appears to be about 13.7 billion years old, and why it seems to be nearly flat, say University at Buffalo physicists Ghazal Geshnizjani, Will Kinney and Azadeh Moradinezhad Dizgah. The researchers recently analyzed the latest measurements offering a hint at what went on in the early universe, and found that only three kinds of theories can account for WMAP’s observations.
Aside from inflation, the other two possible theory categories require more significant leaps of logic and physics, they said. [Images: The Big Bang & Early Universe]
“The takeaway result here is that this idea of inflation turns out to be the only way to do it within the context of standard physics,” Kinney said in a statement. “I think in many ways it puts the idea of inflation on a much stronger footing, because the available alternatives have problems, or weirdnesses, with them.”
For example, alternative explanations must invoke either a speed of sound faster than the speed of light, or energies so high that exotic quantum gravity theories such as string theory would be needed to describe them.
“It may well be that you can come up with a speed of sound faster than the speed of light, but I think people, as a general rule, would be more comfortable with something that doesn’t involve super-luminal propagation,” Kinney said. “Inflation doesn’t require any exotic physics. It’s just standard particle physics.”
Inflation theory still involves a few mind-bending ideas of its own, though. For instance, inflation suggests that during the first 10 to the minus 34 seconds (that’s 0.0000000000000000000000000000000001 seconds), the universe doubled its size at least 90 times.
This would have allowed pairs of matter and antimatter particles to appear out of nothingness, but then move apart from each other so quickly that they wouldn’t have had time to meet and annihilate, as matter and antimatter usually do.
Tiny irregularities in the spread of energy throughout the early universe would have magnified to eventually produce the denser pockets of mass in some areas that allowed gas to condense into stars, forming the galaxies and galaxy clusters that we see today.
The research was first detailed in the November 2011 edition of the Journal of Cosmology and Astroparticle Physics in November 2011 and announced in a public release today (Feb. 27).