Small, cold stars known as red dwarfs are the most common type of star in the Universe, and the sheer number of planets that may exist around them potentially make them valuable places to hunt for signs of extraterrestrial life.
However, previous research into planets around red dwarfs suggested that while they may be warm enough to host life, they might also completely dry out, with any water they possess locked away permanently as ice. New research published on the topic finds that these planets may stay wet enough for life after all. The scientists detailed their findings online on November 12 in The Astrophysical Journal Letters.
Red dwarfs, also known as M stars, are roughly one-fifth as massive as the Sun and up to 50 times fainter. These stars comprise up to 70 percent of the stars in the cosmos, and NASA’s Kepler space observatory has discovered that at least half of these stars host rocky planets that are one-half to four times the mass of Earth.
Red dwarf planets are potentially key places to search for life as we know it, not just because there are so many of them, but also because of their incredible longevity. Unlike our Sun, which will die in a few billion years, red dwarfs will take trillions of years to burn through their fuel, significantly longer than the age of the Universe, which is less than 14 billion years old. This longevity potentially gives red dwarfs a great deal more time for life to evolve around them.
Research into whether a distant world might host life as we know it usually focuses on whether or not it has liquid water, since there is life virtually everywhere there is liquid water on Earth, even miles underground. Scientists typically concentrate on habitable zones, the area around a star where it is neither too hot for all its surface water to boil away, nor too cold enough for all its surface water to freeze.
Recent findings suggest that planets in the habitable zones of red dwarf stars could accumulate significant amounts of water. In fact, each planet could possess about 25 times more water than Earth.
The habitable zones of red dwarfs are close to these stars because of how dim they are, often closer than the distance Mercury orbits the Sun. This closeness makes them appealing to astrobiologists, since planets near their stars cross in front of them more often, making them easier to detect than planets that orbit farther away.
However, when a planet orbits very near a star, the star’s gravitational pull can force the world to become “tidally locked” to it. When a planet is tidally locked to its star, it will always show the same side to its star, just as the Moon always shows the same side to Earth. This causes the planet to have one permanent day side and one permanent night side.
The extremes of heat and cold that tidally locked planets experience could make them profoundly different from Earth. For example, prior research speculated the dark sides of tidally locked planets would become so cold that any water there would freeze. Sunlight would make water on the sunlit side evaporate, and this water vapor could get carried by air currents to the night sides, eventually leading to sheets of ice miles thick on the night sides and removing all water from the sunlit sides. Life as we know it probably could not develop on the day sides of such planets. Although they would have sunlight for photosynthesis, they would have no water to serve as the primordial soup for life to swim in.
To see how habitable tidally-locked planets really are, scientists devised a 3D global climate model of planets that simulated interactions between the atmosphere, ocean, sea ice, and land, as well as a 3-D model of ice sheets large enough to cover entire continents. They also simulated a red dwarf with a temperature of about 5,660 degrees Fahrenheit (3,125 degrees Celsius), and investigated whether all the water on these planets would indeed get trapped on their night sides. [The Strangest Alien Planets (Gallery)]
“I’ve been interested in trying to make calculations relevant for M-star planet habitability since being convinced by astronomers that these types of planets will likely be closest (in proximity) to Earth,” said study co-author Dorian Abbot, a geoscientistat the University of Chicago.
For instance, the nearest known star to the Sun, Proxima Centauri, is a red dwarf, and it remains uncertain whether or not it has a planet. The possibility that red dwarf planets might be relatively near to Earth “means that anything geoscientists can tell astronomers about habitability of these planets will be essential for planning future missions.”
The researchers simulated planets of Earth’s size and gravity that experienced between 63 percent and 77 percent as much sunlight as Earth. They also modeled a super-Earth planet 50 percent wider than Earth with 38 percent stronger gravity, because astronomers have discovered super-Earth worlds around red dwarfs. For instance, Gliese 667Cb, a super-Earth at least 4.5 times the mass of Earth, orbits Gliese 667C, a red dwarf about 22 light years from Earth. They set this super-Earth on an orbit where it received about two-thirds as much as sunlight as Earth.
The researchers modeled three different arrangements of continents for all these planets. One was a water world with no continents and global oceans of varying depths. Another involved a supercontinent covering the night side and an ocean covering the day side. The last mimicked Earth’s configuration of continents. The planets also had atmospheres similar to Earth’s, but the researchers also tested lower levels of the greenhouse gas, carbon dioxide, which traps heat and helps keep planets warm.
When it came to super-Earths covered entirely in water, and super-Earths with continental arrangements like Earth’s, the researchers found it was unlikely that all their water would get trapped on their night sides.
“This is because surface winds transport sea ice to the day side where it is melted easily,” said lead study author Jun Yang at the University of Chicago.
Moreover, ocean currents transport heat from the day side to the night side on these planets.
“Ocean heat transport strongly influences the climate and sea ice thickness on our Earth,” Yang said. “We found this may also work on exoplanets.”
If a super-Earth has very large continents covering most of its night side, the scientists discovered ice sheets of at least 3,300 feet (1,000 meters) thick could grow on its night side. However, the day sides of these super-Earths would dry out completely only if they received less geothermal heat from volcanic activity than Earth, and had 10 percent of the amount of water on Earth’s surface or less. Similar results were seen with Earth-sized planets.
“The important implication is that it may be easier than previously thought to keep liquid water on the dayside of a tidally locked planet, where photosynthesis is possible,” Abbot said. “There are many issues that will affect the habitability of M-star planets, but our results suggest at least that water-trapping on the night side will only be a problem for relatively dry planets with large continents on their nightside and relatively low geothermal heat flux.”
Based on present and near-future technology, Yang said it would be very difficult for astronomers to gauge how thick the sea ice or the ice sheets are on the night sides of red dwarf planets and test whether their models are correct. Still, using current and upcoming technology “it may be possible to know whether the day sides are dry or not,” Yang said.
The new Milky Way galaxy maps are based on observations by the European Space Agency’s prolific Planck space observatory. They show the Milky Way in four distinct color signals that, when combined into a single mosaic, create a hypnotic view of our home galaxy.The Planck satellite observed the oldest light in the universe during its mission. In the new Milky Way maps, red colors indicate dust, yellow is gas, green is high energy particles, and blue is the magnetic field.
“Planck can see the old light from our universe’s birth, gas and dust in our own galaxy, and pretty much everything in between, either directly or by its effect on the old light,” Charles Lawrence, the U.S. project scientist for the mission at NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement.
The Planck satellite was built to detect microwave light, which made it sensitive to something called the cosmic microwave background, or light left over from the big bang. Planck’s study of the cosmic microwave background is helping scientists answer questions about the very early days of the universe, such as when the first stars were born.
With its microwave vision, Planck can detect more than just the cosmic microwave background.
One of the new Milky Way images released by the Planck collaboration is an overview that shows four separate galaxy views, as well as the final view of them combined. The red version (upper left) show the heat coming from dust throughout the Milky Way galaxy. Planck can capture this thermal light even though the dust is extremely cold — about minus 420 Fahrenheit (minus 251 Celsius).
The yellow version (upper right) shows carbon monoxide gas, which is concentrated in areas where new stars are being born. Meanwhile, the blue image (lower right) shows light created when charged particles get caught up in the Milky Way’s magnetic field, and are pulled along like a swimmer in a current. The particles accelerate to nearly the speed of light and begin to radiate. The green image (lower left) shows light that is created by free particles that zip past one another without quite colliding. This kind of light is often associated with hot, ionized gas near massive stars.
The $795 million Planck satellite launched in 2009 and collected data for just over four years before being decommissioned in 2013. Last week, the collaboration released the results of a much-anticipated joint study with the BICEP2 collaboration. In March 2014, BICEP2 announced what some scientists took as evidence of inflation in the early universe and evidence of gravitational waves. But the results of the join analysis showed that BICEP2′s measurements were contaminated by space dust.
The white spot on Ceres in a series of new photos taken on Jan. 13 by NASA’s Dawn spacecraft, which is rapidly approaching the round dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. But when the initial photo release on Monday (Jan. 19), the Dawn scientists gave no indication of what the white dot might be.
“Yes, we can confirm that it is something on Ceres that reflects more sunlight, but what that is remains a mystery,” Marc Rayman, mission director and chief engineer for the Dawn mission, told Space.com in an email.
The new images show areas of light and dark on the face of Ceres, which indicate surface features like craters. But at the moment, none of the specific features can be resolved, including the white spot.
“We do not know what the white spot is, but it’s certainly intriguing,” Rayman said. “In fact, it makes you want to send a spacecraft there to find out, and of course that is exactly what we are doing! So as Dawn brings Ceres into sharper focus, we will be able to see with exquisite detail what [the white spot] is.”
Ceres is a unique object in our solar system. It is the largest object in the asteroid belt and is classified as an asteroid. It is simultaneously classified as a dwarf planet, and at 590 miles across (950 kilometers, or about the size of Texas), Ceres is the smallest known dwarf planet in the solar system.
The $466 million Dawn spacecraft is set to enter into orbit around Ceres on March 6. Dawn left Earth in 2007 and in the summer of 2011, it made a year-long pit stop at the asteroid Vesta, the second largest object in the asteroid belt.
While Vesta shared many properties with our solar system’s inner planets, scientists with the Dawn mission suspect that Ceres has more in common with the outer most planets. 25 percent of Ceres’ mass is thought to be composed of water, which would mean the space rock contains even more fresh water than Earth. Scientists have observed water vapor plumes erupting off the surface of Ceres, which may erupt from volcano-like ice geysers.
The mysterious white spot captured by the Dawn probe is one more curious feature of this already intriguing object.
Scientists are finding more evidence of a galactic “skeleton” lurking inside the appendages of the Milky Way, and studying these massive “bones” could help researchers get a better idea of what our galaxy looks like from the outside.
In 2013, researchers first suggested that long, thin, dense clouds of gas may form inside the spiral arms of the Milky Way, creating a sort of galactic skeleton that traces the shape of these massive structures. At the time, only one such “bone” — known as Nessie — had been identified.
Now, new research presented at the 225th meeting of the American Astronomical Society shows that Nessie is not alone. Catherine Zucker, an undergraduate physics student at the University of Virginia, has dug up six strong candidates for additional galactic bones.
Living inside the Milky Way comes with a disadvantage: Astronomers cannot see what this galactic house looks like from the outside. The Milky Way is a spiral galaxy, meaning multiple “arms” sprout from a central region and then swirl around it, like streams of water spiraling down a drain. These arms coil around each other in a flat plane, so the galaxy is like a pancake: When it’s viewed face-on, it is circular, but when it’s viewed edge-on, it’s a straight line. The Earth is nestled inside this pancake, toward the outside of the disc. As a result, the Milky Way appears as a ribbon running down the middle of the night sky.
The sun and the Earth are elevated just slightly above the galactic plane, giving scientists a small boost when they’re trying to look at the larger galactic structure (like a kid on an adult’s shoulders, trying to see over a crowd). Scientists have identified the large spiral arms that make up the galaxy, but there is still debate about the exact location of those arms, as well as the location of smaller spirals that branch off of the larger ones.
But the “bones” that scientists have now identified — long, thin, highly dense clouds of gas that can also be identified by the light they absorb — would be significantly easier to spot, and could help scientists create a more precise sketch of what the Milky Way looks like from the outside.
“It’s a really new field of study,” Zucker told Space.com at the AAS meeting in Seattle, where she presented a poster featuring her work on the galactic skeleton. When Zucker started her work, the gas cloud known as “Nessie” was the only object of its kind that had been identified, and the only candidate for a bone. “What I was trying to do was basically prove that the Nessie filament wasn’t some curiosity, wasn’t a fluke — that there are other filaments out there similar to Nessie that can trace galactic structure.”
Zucker started looking through images of the galaxy taken by various telescopes, including the Spitzer Space Telescope. She found 15 long, thin gas clouds that looked like they could be galactic bones.
There were six initial criteria for a galactic bone. For example, it must lie mostly parallel to the plane of the galaxy and be associated with a known spiral arm — Nessie appears to trace the spine of the Scutum-Centaurus Arm, one of the largest arms in the Milky Way. A bone must also be more than 50 times longer than it is wide — Nessie is more than 300 times longer. Zucker also had to make sure she was seeing a single cloud and not multiple clouds in the same line of sight.
With her list of criteria, Zucker identified 10 candidate bones, six of which met the entire list of requirements. She spelled out her conclusion on her poster: “Nessie is not a ‘curiosity’ – other bones exist.”
Zucker is focusing on something called “Filament 5,” which could be a bone that lies in the Scutum-Centaurus Arm, just like Nessie, but on the opposite side of the galaxy. There is still some debate about the exact location of the Scutum-Centaurus arm. Different measurements put it within a few degrees of the center of the galactic plane. Zucker said bones like Nessie could “potentially resolve a lot of those issues.”
Ultimately, these bones could serve as a guide for creating a sketch of the Milky Way’ major structural elements, and give scientists an outside view of our galaxy, without requiring them to leave home.
The giant black hole at the center of the Milky Way galaxy recently spit out the largest X-ray flare ever seen in that region, astronomers say.
The enormous eruption from the Milky Way’s core was detected on Sept. 14, 2013, very close to the supermassive black hole known as Sagittarius A*. Pronounced “Sagittarius A star” and abbreviated as Sgr A*, the Milky Way’s monster black hole has a mass that is about 4.5 million times that of the sun. Scientists unveiled the discovery of the record-breaking flare this month at the 225th meeting of the American Astronomical Society.
The so-called “megaflare” flare was spotted by NASA’s Chandra X-ray Observatory, which can peer through dust and starlight to the center of the Milky Way. The event was 400 times brighter than the normal level of radiation from this region and nearly three times brighter than the previous record-holding flare, recorded in 2012. A second X-ray flare, with a flash 200 times brighter than normal levels, was then seen on Oct. 22, 2014.
Daryl Haggard, of Amherst College in Massachusetts, presented the findings at a news conference here at the AAS meeting on Jan. 5. Haggard and her colleagues have two possible explanations for what might have caused the flare. First, the black hole may be behaving like our own sun, which also emits bright X-ray flares. In the sun, these flares occur when magnetic-field lines become very tightly packed together or twisted, and the researchers said it’s possible something similar took place near the black hole.
It’s also plausible that the flare was the product of Sgr A* having a snack. An asteroid or other object may have come too close to the black hole, ripping it apart. The debris would have accelerated rapidly and potentially radiated a bright burst of X-rays.
“If an asteroid was torn apart, it would go around the black hole for a couple of hours — like water circling an open drain — before falling in,” Fred Baganoff, of the Massachusetts Institute of Technology and a member of the research team, said in a statement. “That’s just how long we saw the brightest X-ray flare last, so that is an intriguing clue for us to consider.”
Researchers saw the flare by chance while watching Sgr A* in anticipation of a different event: A gas cloud called G2 was set to make a close pass by Sgr A*, and some scientists hypothesized that material from G2 would fall into the black hole, generating a bright display of X-rays, NASA officials said in a statement. But no X-ray signal was detected as G2 made its closest approach to Sgr A*. The new flares do not appear to be part of the missing light show, according to Haggard.
We do not think flares are connected to the G2 object,” Haggard said. “And the reason for that is that the time scales don’t quite match. The time scale for these flares is fairly rapid — thousands of seconds,” or an hour or two, she said.
This time scale is characteristic of an object roughly one astronomical unit (the distance from the Earth to the sun) from Sgr A*, Haggard added. G2′s closest approach to Sgr A* was 150 astronomical units, “so the time scale doesn’t quite match up,” she added.
Haggard and her colleagues are hoping for flares from Sgr A*. With more detailed observations, she said, it might be possible to discern whether Sgr A* is rotating or stationary — a feature that can change aspects of a black hole’s physiology.
A “dark nebula” of thick space dust blots out the light from a teeming star nursery in a striking new imag from an observatory in Chile.
The new view of the Lynds Dark Nebula 483, or LDN 483, shows off a region of starbirth that includes wide swaths that are obscured in visible light. It was obtained using the MPG/ESO 2.2-metre telescope at La Silla Observatory, which is overseen by the European Southern Observatory.
In the new image, the molecular dust clouds inside LDN 483 are so thick that they obscure light from the stars behind the clouds. While the disappearing act makes it appear at first glance that stars cannot be born here, the thick ooze of materials indicates quite the opposite.
“Astronomers studying star formation in LDN 483 have discovered some of the youngest observable kinds of baby stars buried in LDN 483′s shrouded interior,” ESO officials wrote in a statement. “These gestating stars can be thought of as still being in the womb, having not yet been born as complete, albeit immature, stars.”
LDN 483 is located about 700 light-years from Earth in the constellation Serpens, the Serpent.
As a star evolves, the force of gravity slowly contracts a ball of dust and gas that is pulled from the surroundings. The stellar youngster isn’t producing much heat yet — its temperature is only at about minus 418 degrees Fahrenheit (minus 250 degrees Celsius).
Eventually, as the baby star’s core contracts, pressure and temperature will increase and fusion will ignite. But before it reaches that point, the protostar will spend a blink of astronomical time — about a few thousand years — in the earliest stage, and then a few more million years getting warmer, denser and putting out increased-energy light emissions. As time goes on, it will shine in visible light rather than just in infrared.
“As more and more stars emerge from the inky depths of LDN 483, the dark nebula will disperse further and lose its opacity,” ESO officials wrote. “The missing background stars that are currently hidden will then come into view — but only after the passage of millions of years, and they will be outshone by the bright young-born stars in the cloud.”
The term Lynds Dark Nebula is rooted in the American astronomer Beverly Turner Lynds, who compiled and published a survey of dark nebulas— the Lynds Dark Nebula catalogue — in 1960. At that time, Lynds discovered dark nebulas through the painstaking visual inspection of photographic plates of observations made by the Palomar Sky Survey.
In the new photo, captured by NASA’s Spitzer Space Telescope, the shadowy Horsehead nebula loses its distinctive shape because of the infrared light wavelength used to make the image penetrates cosmic dust.
It is that dust that gives the Horsehead nebula its “horse’s head” shape. Without that telltale dust, only a “wispy arc” remains of the iconic space feature, according to NASA
The main view in the new Spitzer image is the Orion Molecular Cloud Complex, the larger home of the Horsehead nebula. At the center of the image is the Flame nebula (NGC 2024) and to the right, just beside the Horsehead, is a smaller nebula called NGC 2023. Collectively, all of these areas are about 1,200 light-years from Earth.
“The two carved-out cavities of the Flame nebula and NGC 2023 were created by the destructive glare of recently formed massive stars within their confines,” NASA officials wrote in a statement. “They can be seen tracing a spine of glowing dust that runs through the image.”
Hotter wavelengths in the image are represented by blue and cyan (blue-green) light, which show wavelengths of 3.6 microns and 4.5 microns respectively. At the other end of the scale, cooler green and red colors show the nebulae’s dust.
Part of the image includes data from NASA’s Wide-field Infrared Survey Explorer (WISE), which observed in infrared wavelengths over the entire sky.
The Horsehead’s official name is Barnard 33, or B33. It was first discovered in photographic plates in 1888 at the Harvard College Observatory.
The discoverer was Williamina Fleming, a maid of astronomy professor Edward Pickering. Pickering hired Fleming and several other women, who were known as “computers,” to catalog images taken at the observatory. Fleming had a productive career, discovering 58 other nebulae, 10 novae and more than 300 variable stars.
The official name of the nebula comes from Edward Barnard, an American astronomer who photographed it from Lick Observatory in California. No one is sure when the name “Horsehead nebula” was first used, NASA officials said.
A NASA probe is about to get the first up-close look at a potentially habitable alien world.
In March 2015, NASA’s Dawn spacecraft will arrive in orbit around the dwarf planet Ceres, the largest object in the main asteroid belt between Mars and Jupiter. Ceres is a relatively warm and wet body that deserves to be mentioned in the same breath as the Jovian moon Europa and the Saturn satellite Enceladus, both of which may be capable of supporting life as we know it, some researchers say.
“I don’t think Ceres is less interesting in terms of astrobiology than other potentially habitable worlds,” Jian-Yang Li, of the Planetary Science Institute in Tucson, Arizona, said Thursday (Dec. 18) during a talk here at the annual fall meeting of the American Geophysical Union.
Life as we know it requires three main ingredients, Li said: liquid water, an energy source and certain chemical building blocks (namely, carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur).
The dwarf planet Ceres — which is about 590 miles (950 kilometers) wide — is thought to have a lot of water, based on its low overall density (2.09 grams per cubic centimeter; compared to 5.5 g/cubic cm for Earth). Ceres is likely a differentiated body with a rocky core and a mantle comprised of water ice, researchers say, and water-bearing minerals have been detected on its surface.
Indeed, water appears to make up about 40 percent of Ceres’ volume, Li said.
“Ceres is actually the largest water reservoir in the inner solar system other than the Earth,” he said. However, it’s unclear at the moment how much, if any, of this water is liquid, he added.
As far as energy goes, Ceres has access to a decent amount via solar heating, since the dwarf planet lies just 2.8 astronomical units (AU) from the sun, Li said. (One AU is the distance between Earth and the sun — about 93 million miles, or 150 million km). Europa and Enceladus are much farther away from our star — 5.2 and 9 AU, respectively.
Both Europa and Enceladus possess stores of internal heat, which is generated by tidal forces. This heat keeps the ice-covered moons’ subsurface oceans of liquid water from freezing up, and also drives the eruption of water-vapor plumes on Enceladus (and probably Europa as well; researchers announced last year that NASA’s Hubble Space Telescope spotted water vapor erupting from the Jupiter moon in December 2012).
Intriguingly, scientists announced the discovery of water-vapor emission from Ceres — which may also possess a subsurface ocean — earlier this year.
Ceres’ plumes may or may not be evidence of internal heat, Li said. For example, they may result when water ice near Ceres’ surface is heated by sunlight and warms enough to sublimate into space.
“Right now, we just don’t know much about the outgassing on Ceres,” Li said.
Dawn should help bring Ceres into much clearer focus when it reaches the dwarf planet this spring. The spacecraft, which orbited the huge asteroid Vesta from July 2011 through September 2012, will map Ceres’ surface in detail and beam home a great deal of information about the body’s geology and thermal conditions before the scheduled end of its prime mission in July 2015.
Ground-based instruments should also play a role in unveiling Ceres. For example, the Atacama Large Millimeter/submillimeter Array, or ALMA — a huge system of radio dishes in Chile — has the ability to probe deeper than Dawn, going into Ceres’ subsurface and shedding more light on the dwarf planet’s composition and thermal properties, Li said.
“This is highly complementary to the Dawn mission,” he said.
Ceres’ relative proximity to Earth also makes it an attractive target for future space missions, Li added.
Kip Thorne, the physicist who brought real science to the movie “Interstellar,” has a history of coming up with ideas that sound like they are straight out of science fiction. We’ve rounded up three of Thorne’s most mind-bending theories — at least one of which may have recently been confirmed.
Looking to travel from one star to another, but don’t want the trip to take tens of thousands of years? How about using a wormhole?
Wormholes were first theorized in 1916 (although they weren’t called that at the time), derived from Einstein’s equations for relativity. A wormhole connects two points in space via a sort of tunnel through a higher dimension. An object entering one end of a wormhole would emerge almost instantly on the other end, even if the openings were separated by trillions of miles.
In the 1980′s, Thorne, who is the Feynman Professor of Theoretical Physics, Emeritus, at the California institute of Technology, kicked off a serious discussion among physicists about whether or not an object (like a spaceship) could physically travel through a wormhole. In other words, do the laws of physics forbid it? Or, with unlimited resources and knowledge, could a civilization build a wormhole and use it as a cosmic highway?
Physicists, including Thorne, have made some progress on this question. Scientists knew prior to the 1980s that if wormholes existed, they would evaporate before anything (even light) could pass from one opening to another. So sending something through a wormhole would require a kind of scaffolding made from “exotic matter” to hold the wormhole open.
In addition, wormholes for travel would likely need to be artificially constructed, because there is no solid evidence that they exist naturally.
“We see no objects in our universe that could become wormholes as they age,” Thorne writes in his new book “The Science of Interstellar” (W.W. Norton & Co. 2014). By contrast, scientists see huge numbers of stars that will eventually collapse to form black holes. There is a possibility that very, very small wormholes exist in the universe in something called “quantum foam,” which may or may not exist in the universe.
Thorne’s question on the possibility of interstellar travel through wormholes remains unanswered. But at the moment, he told Space.com, wormhole travel will likely only ever exist in science fiction. [Star Trek's Warp Drive: Are We There Yet? | Video]
Wormholes for time travel
When Thorne began to consider the likelihood that wormholes could be used for space travel, he realized that they could also be used for time travel.
In his 1994 book “Black Holes and Time Warps” (W.W. Norton & Co. 1994), Thorne proposes a thought experiment: Say he obtains a small wormhole, which connects two points in space as if they were not separated by any distance at all. [What's New in Black Holes? A conversation with Kip Thorne]
Thorne takes his wormhole and puts one end in his living room, and the other aboard a spaceship parked in his front yard. Thorne’s wife, Carolee, hops aboard the spaceship to prepare for a trip. The two don’t have to say goodbye, though, because no matter how far away Coralee travels, they can see each other through the wormhole. They can even hold hands, as if through an open doorway.
Carolee starts up the spaceship, heads into space and travels for six hours at the speed of light. She then turns around and comes back home traveling at the same speed — a round trip of 12 hours. Thorne watches through the wormhole and sees this trip occur. He sees Coralee return from her trip, land on the front lawn, get out of the spaceship and head into the house.
But when Thorne looks out the window in his own world, his front lawn is empty. Coralee has not returned. Because she traveled at the speed of light, time slowed down for her: What was 12 hours for her was 10 years for Thorne back on Earth.
Now, as Thorne and Coralee hold hands through the wormhole, they are each traveling in time. Coralee has landed on Earth 10 years after she left, and there she will meet Thorne, 10 years older. But she can still reach through the wormhole and find Thorne, who is only 12 hours older. Thorne can step through the wormhole and find himself 10 years in the future, or his future self can step back 10 years into the past.
Thorne’s idea is a thought experiment, intended to answer a larger question: Is time travel forbidden by the laws of the universe? Scientists know that time moves more slowly at high speeds (although traveling at the speed of light would actually kill a person) or in areas with very high gravity. (This was portrayed in the movie “Interstellar,” when time moves more slowly on a planet orbiting a black hole.) Hence, traveling “into the future” is not forbidden.
But backward time travel is still unresolved. Stephen Hawking has stated adamantly that the laws of physics will prevent backward time travel. Thorne writes in “The Science of Interstellar” that the answer lies with more advanced physics than scientists currently understand.
Scientists may prove at least one of Thorne’s wild theories in the near future: that one star can take up residence inside another star.
In 1975, Thorne and his colleague Anna Zytkow proposed that a very small, dense star could fall into a very large, diffuse star and go on living (rather than ending in the destruction or merger of the two). In October, other researchers announced that they had found what they believe to be the first Thorne-Zytkow Object (ZTO) ever detected.
The large, diffuse star would be a red giant: a star nearing the end of its fuel supply, which, as a result, has begun to inflate. (A red giant large enough to form a TZO would have a diameter the size of Saturn’s orbit, according to scientists.)
A TZO would look very much like a normal red giant, but at its core would be a neutron star: an incredibly dense object (a teaspoon of neutron star material would weigh 1 billion tons) created when a massive star stops burning and explodes, and the remaining material collapses. A neutron star cannot form inside a red giant, so it would have to form outside and then fall in.
Thorne and Zytkow showed that if this odd merger actually occurred, it would create a unique kind of stellar oven.
“It would have a shell of burning material around the neutron core, a shell that would generate new elements as it burned,” Thorne said in an interview. “Convection, the circulation of hot gas inside the star, would reach right into the burning shell and carry the products of burning all the way to the surface of the star long before the burning was complete.”
Subsequent work by Thorne’s graduate student Garrett Biehle showed that ZTOs produce high levels of the elements rubidium, molybdenum and lithium. This activity differs from that of normal red giants, giving astronomers a way of identifying a ZTO based on its chemical profile.
In June, researchers from the University of Colorado Boulder and colleagues announced that they’d identified a red giant that fit the profile of a TZO. The star, HV 2112, is located in the Small Magellanic Cloud, a dwarf galaxy about 20,000 light-years away from Earth.
“The evidence is compelling but by no means ironclad,” Thorne told Space.com. “We need to get additional observational data before victory can really be declared. So I think it’s premature to say that a Thorne-Zytkow Object has been discovered.”
Wormholes are theoretical tunnels through the fabric of space-time that could potentially allow rapid travel between widely separated points — from one galaxy to another, for example, as depicted in Christopher Nolan’s “Interstellar,” which opened in theaters around the world earlier this month.
While wormholes are possible according to Einstein’s theory of general relativity, such exotic voyages will likely remain in the realm of science fiction, said renowned astrophysicist Kip Thorne of the California Institute of Technology in Pasadena, who served as an adviser and executive producer on “Interstellar.”
“The jury is not in, so we just don’t know,” Thorne, one of the world’s leading authorities on relativity, black holes and wormholes, told Space.com. “But there are very strong indications that wormholes that a human could travel through are forbidden by the laws of physics. That’s sad, that’s unfortunate, but that’s the direction in which things are pointing.”
The major barrier has to do with a wormhole’s instability, he said.
“Wormholes — if you don’t have something threading through them to hold them open — the walls will basically collapse so fast that nothing can go through them,” Thorne said.
Holding wormholes open would require the insertion of something that anti-gravitates — namely, negative energy. Negative energy has been created in the lab via quantum effects, Thorne said: One region of space borrows energy from another region that didn’t have any to begin with, creating a deficit.
“So it does happen in physics,” he said. “But we have very strong, but not firm, indications that you can never get enough negative energy that repels and keeps the wormhole’s walls open; you can never get enough to do that.”
Furthermore, traversable wormholes — if they can exist at all — almost certainly cannot occur naturally, Thorne added. That is, they must be created by an advanced civilization.
And that’s exactly what happens in “Interstellar”: Mysterious beings construct a wormhole near Saturn, allowing a small band of pioneers, led by a former farmer named Cooper (played by Matthew McConaughey) to journey far afield in search of a new home for humanity, whose existence on Earth is threatened by global crop failures.
Anyone interested in learning more about the science of “Interstellar” — which also features gravitational time dilation and depictions of several alien planets orbiting close to a supermassive black hole — can check out Thorne’s new book, which is called, appropriately enough, “The Science of ‘Interstellar.’”
Wormholes have been a staple of science fiction for decades. Interestingly, Thorne said that one of the genre’s most famous titles helped inspire scientists to try to better understand the hypothetical structures.
“The modern research on the physics of wormholes largely stems from the movie ‘Contact,’ from conversations I had with [renowned late scientist] Carl Sagan — actually, when he was writing his novel ‘Contact,’” Thorne said.
“Contact” features traversable wormholes. The novel came out in 1985, while the movie (which also stars Matthew McConaughey, apparently a wormhole connoisseur) was released in 1997.
Astronomers using a NASA space telescope are in the midst of a survey designed to figure out how galaxies in the young universe grew so quickly.
The first results from the project, which used the Spitzer Space Telescope, show hundreds of huge galaxies (100 times the mass of the Milky Way) that were around when the 13.8-billion-year-old universe was in its cosmic infancy.
This presents a dilemma for astronomers, who are hard-pressed to explain how such behemoths came to be so early in the universe’s history. Spitzer is about to embark on a three-month examination to hunt dim galaxies that are billions of light-years from Earth. [Read the latest news about galaxies and stars]
“If you think of our survey as fishing for galaxies in the cosmic sea, then we are finding many more big fish in deep waters than previously expected,” lead author Charles Steinhardt, of NASA’s Infrared Processing and Analysis Center (IPAC) at the California Institute of Technology in Pasadena, said in a statement.
The project is dubbed SPLASH (short for Spitzer Large Area Survey with Hyper-Suprime-Cam). Researchers aim to use the telescope for 2,475 hours to look at two dark areas of the sky, far away from the Milky Way’s field of stars.
The fields, which have been examined before, are called the Cosmic Evolution Survey (COSMOS) and Subaru/XMM-Newton deep field (SXDS). Each sky area is about the size of eight full moons. Spitzer’s examination in infrared wavelengths will help astronomers see the masses of these galaxies.
Star formation models now postulate that the earliest galaxies crashed into each other and as they came together, grew larger and encouraged starbirth. However, this process would not work fast enough (as far as astronomers understand) to create the huge galaxies Spitzer is seeing between 800 million and 1.6 billion years after the universe was formed.
Perhaps the first galaxies came into existence than scientists thought. While many astronomers believe galaxies began growing about 500 million years after the Big Bang that formed the universe, the growth rate works if this process started at 400 million years. But there are other theories as well.
“It’s really hard to form something so massive so quickly,” Josh Speagle, co-author of the study from Harvard University in Massachusetts, said in the same statement. “So it’s entirely possible that these galaxies have been forming stars continuously since the moment they were born.”
Scientists will take a closer look at these galaxies using the Subaru telescope in Hawaii, which will do several years of observations to follow up on what Spitzer found.
The large project is possible with Spitzer because it is past its prime mission; its coolant ran out in 2009, meaning some of its instruments don’t work. The telescope, however, is still able to work in two infrared channels despite being warmer, and now looks at bigger areas of the sky for longer.
The photo, taken by Spitzer observatory in infrared light, shows a burst of starbirth in the galaxy NGC 1291, which lies 33 million light-years from Earth and is about 12 billion years old. Older stars are colored blue in the photo and cluster mostly in the central region of the galaxy; younger, red stars appear around the fringes.
“The rest of the galaxy is done maturing,” said lead researcher Kartik Sheth, of the National Radio Astronomy Observatory of Virginia, in a statement. “But the outer ring is just now starting to light up with stars.”
The image was captured as part of a study on structural features in barred galaxies, so called because they have a long central bar of stars within them. The Milky Way is an example of a barred spiral galaxy.
Astronomers believe NGC 1291′s bar was created when the galaxy was young. The bar moves material through the galaxy, shifting stars and gas into noncircular orbits. In some places, galactic gas is pushed together, where it collapses to form stars, researchers said.
Scientists believe that early in a galaxy’s history, the bars push gas into the center and spark starbirth there. As the galaxy ages, the fuel depletes and stars are born farther and farther from the core.
Spitzer survey aims to discover more about how barred galaxies form and evolve, which could shed light on the conditions that created the Milky Way, among other things.
“Now, with Spitzer we can measure the precise shape and distribution of matter within the bar structures,” Sheth said. “The bars are a natural product of cosmic evolution, and they are part of the galaxies’ endoskeleton. Examining this endoskeleton for the fossilized clues to their past gives us a unique view of their evolution.”
That question will took center stage during a debate on Oct. 16 at 7:30 p.m. EDT (2330 GMT) organized by the Harvard-Smithsonian Center for Astrophysics (CfA). You can watch the event live here on Space.com, courtesy of the CfA, or on the CfA’s “Observatory Nights” YouTube channel: http://www.youtube.com/user/ObsNights
Two CfA researchers will participate in tonight’s debate, CfA representatives wrote in a media advisory:
“Ofer Cohen will discuss the latest research suggesting that harsh winds and stellar radiation would scour any planets in the habitable zone. Elisabeth Newton will argue that red dwarf worlds could be more resilient than we think.”
Astronomers have discovered nearly 2,000 alien planets to date, and they’ve only scratched the surface: Each one of the Milky Way’s 100 billion or so stars is believed to host more than one planet on average.
The new image of the Spiderweb Galaxy (also known as MRC 1138-262) shows blobs of dust that are actually galaxies, captured by a European Southern Observatory telescope in Chile. The entire galaxy cluster surrounds a radio galaxy that has a supermassive black hole at its center.
Here’s where the surprise came: Scientists discovered that 10 billion years ago, star formation was happening mostly in one spot that wasn’t at the center of the galaxy complex. Astronomers instead thought star formation would happen in the filaments of the cluster. Why is unclear.
“We aimed to find the hidden star formation in the Spiderweb cluster — and succeeded — but we unearthed a new mystery in the process; it was not where we expected,” lead researcher Helmut Dannerbauer, a post-doctoral galaxy researcher at the University of Vienna, Austria, said in a statement. “The mega city is developing asymmetrically.”
Galaxy clusters are the largest structures in the universe, but their formation and evolution is poorly understood.
The image was captured using the ESO’s Atacama Pathfinder Experiment telescope (APEX) telescope in Chile.
APEX examined the galaxy cluster in submillimeter wavelengths designed to penetrate dust. Across 40 hours of observations, the researchers found four times as many sources of star formation than previously known.
This is one of the deepest observations ever made with APEX and pushes the technology to its limits – as well as the endurance of the staff working at the high-altitude APEX site,” Carlos De Breuck, a co-author on the study who is the APEX project scientist at ESO said in the same statement.
These starbirth hubs are happening at the same distance as the cluster itself, according to observations using other wavelengths of light, which shows the star-formation regions must be part of the cluster.
For years, mysterious dark matter has eluded scientists, and now, a new study shows there may be less of it to find.
Using a century-old equation, scientists have found that the Milky Way galaxy holds half as much dark matter — the invisible stuff believed to make up a sizable chunk of the universe — as scientists had previously thought.
By calculating the speed of stars throughout the galaxy and conducting a detailed study of the Milky Way’s outer edges, a team of astronomers in Australia determined that the amount of the unseen dark matter in the galaxy is just 80 billion times the mass of the sun — half the mass of recent estimates.
In the 1950s, scientists determined that galaxies contain more matter than the human eye can see. The everyday material humans can see is made of baryonic matter, and it contains protons, neutrons and electrons. Scientists think dark matter may be composed of baryonic matter, nonbaryonic matter or a mixture of the two. Several possibilities for the material have been raised in recent years.
“Stars, dust, you and me — all the things that we see — only make up about 4 percent of the entire universe,” study lead author Prajwal Kafle, from the University of Western Australia, said in a statement. “About 25 percent is dark matter, and the rest is dark energy.”
Kafle and his team utilized the most up-to-date measurements of the galaxy. The measurements of the outer edges of the galaxy included more detailed studies than previous observations had. Then, the team used a technique developed by British astronomer James Jeans in 1915, long before researchers had envisioned dark matter.
In determining that the Milky Way contains less dark matter than previously thought, Kafle and his fellow researchers gained insight into a problem that theorists have been struggling with for almost 20 years.
“The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter Theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don’t see that,” Kafle said. “When you use our measurement of the mass of the dark matter, the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see — the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf [Spheroidal] galaxy.”