Category: Science &Technology

  • New stars discovery shed new light on Galaxy’s formation

    {An astronomer from LJMU’s Astrophysics Research Institute has discovered a new family of stars in the core of the Milky Way Galaxy which provides new insights into the early stages of the Galaxy’s formation.}

    The discovery has shed new light on the origins of globular clusters — which are concentrations of typically a million stars, formed at the beginning of the Milky Way’s history.

    LJMU is a member of Sloan Digital Sky Survey — an international collaboration of scientists at numerous institutions. One of the projects of this collaboration is APOGEE (the Apache Point Observatory Galactic Evolution Experiment) which collects infrared data for hundreds of thousands of stars in the Milky Way.

    It was through observing stars in the infrared towards the Galactic centre that led to the discovery of a new population of stars, the likes of which had only been seen before inside globular clusters.

    This intriguing new family of stars could have possibly belonged to globular clusters that were destroyed during the violent initial formation of the Galactic centre, in which case there would have been about 10 times more globular clusters in the Milky Way in early life than today. This means that a substantial fraction of the old stars inhabiting the inner parts of the Galaxy today may have been initially formed in globular clusters that were later destroyed.

    Ricardo Schiavon, lead researcher on the project said: “This is a very exciting finding that helps us address fascinating questions such as what is the nature of the stars in the inner regions of the Milky Way, how globular clusters formed and what role they played in the formation of the early Milky Way — and by extension the formation of other galaxies.”

    “The center of the Milky Way is poorly understood, because it is blocked from view by intervening dust. Observing in the infrared, which is less absorbed by dust than visible light, APOGEE can see the center of the Galaxy better than other teams

    “From our observations we could determine the chemical compositions of thousands of stars, among which we spotted a considerable number of stars that differed from the bulk of the stars in the inner regions of the Galaxy, due to their very high abundance of nitrogen. While not certain, we suspect that these stars resulted from globular cluster destruction. They could also be the byproducts of the first episodes of star formation taking place at the beginning of the Galaxy’s history. We are conducting further observations to test these hypotheses.”

    Artist's concept of the Milky Way Galaxy. GLAST will provide detailed information on where stars are forming.
  • Mars ice deposit holds as much water as Lake Superior

    {Frozen beneath a region of cracked and pitted plains on Mars lies about as much water as what’s in Lake Superior, largest of the Great Lakes, researchers using NASA’s Mars Reconnaissance Orbiter have determined.}

    Scientists examined part of Mars’ Utopia Planitia region, in the mid-northern latitudes, with the orbiter’s ground-penetrating Shallow Radar (SHARAD) instrument. Analyses of data from more than 600 overhead passes with the onboard radar instrument reveal a deposit more extensive in area than the state of New Mexico. The deposit ranges in thickness from about 260 feet (80 meters) to about 560 feet (170 meters), with a composition that’s 50 to 85 percent water ice, mixed with dust or larger rocky particles.

    At the latitude of this deposit — about halfway from the equator to the pole — water ice cannot persist on the surface of Mars today. It sublimes into water vapor in the planet’s thin, dry atmosphere. The Utopia deposit is shielded from the atmosphere by a soil covering estimated to be about 3 to 33 feet (1 to 10 meters) thick.

    “This deposit probably formed as snowfall accumulating into an ice sheet mixed with dust during a period in Mars history when the planet’s axis was more tilted than it is today,” said Cassie Stuurman of the Institute for Geophysics at the University of Texas, Austin. She is the lead author of a report in the journal Geophysical Research Letters.

    Mars today, with an axial tilt of 25 degrees, accumulates large amounts of water ice at the poles. In cycles lasting about 120,000 years, the tilt varies to nearly twice that much, heating the poles and driving ice to middle latitudes. Climate modeling and previous findings of buried, mid-latitude ice indicate that frozen water accumulates away from the poles during high-tilt periods.

    Martian Water as a Future Resource

    The name Utopia Planitia translates loosely as the “plains of paradise.” The newly surveyed ice deposit spans latitudes from 39 to 49 degrees within the plains. It represents less than one percent of all known water ice on Mars, but it more than doubles the volume of thick, buried ice sheets known in the northern plains. Ice deposits close to the surface are being considered as a resource for astronauts.

    “This deposit is probably more accessible than most water ice on Mars, because it is at a relatively low latitude and it lies in a flat, smooth area where landing a spacecraft would be easier than at some of the other areas with buried ice,” said Jack Holt of the University of Texas, a co-author of the Utopia paper who is a SHARAD co-investigator and has previously used radar to study Martian ice in buried glaciers and the polar caps.

    The Utopian water is all frozen now. If there were a melted layer — which would be significant for the possibility of life on Mars — it would have been evident in the radar scans. However, some melting can’t be ruled out during different climate conditions when the planet’s axis was more tilted. “Where water ice has been around for a long time, we just don’t know whether there could have been enough liquid water at some point for supporting microbial life,” Holt said.

    Utopia Planitia is a basin with a diameter of about 2,050 miles (3,300 kilometers), resulting from a major impact early in Mars’ history and subsequently filled. NASA sent the Viking 2 Lander to a site near the center of Utopia in 1976. The portion examined by Stuurman and colleagues lies southwest of that long-silent lander.

    Use of the Italian-built SHARAD instrument for examining part of Utopia Planitia was prompted by Gordon Osinski at Western University in Ontario, Canada, a co-author of the study. For many years, he and other researchers have been intrigued by ground-surface patterns there such as polygonal cracking and rimless pits called scalloped depressions — “like someone took an ice-cream scoop to the ground,” said Stuurman, who started this project while a student at Western.

    Clue from Canada

    In the Canadian Arctic, similar landforms are indicative of ground ice, Osinski noted, “but there was an outstanding question as to whether any ice was still present at the Martian Utopia or whether it had been lost over the millions of years since the formation of these polygons and depressions.”

    The large volume of ice detected with SHARAD advances understanding about Mars’ history and identifies a possible resource for future use.

    “It’s important to expand what we know about the distribution and quantity of Martian water,” said Mars Reconnaissance Orbiter Deputy Project Scientist Leslie Tamppari, of NASA’s Jet Propulsion Laboratory, Pasadena, California. “We know early Mars had enough liquid water on the surface for rivers and lakes. Where did it go? Much of it left the planet from the top of the atmosphere. Other missions have been examining that process. But there’s also a large quantity that is now underground ice, and we want to keep learning more about that.”

    Joe Levy of the University of Texas, a co-author of the new study, said, “The ice deposits in Utopia Planitia aren’t just an exploration resource, they’re also one of the most accessible climate change records on Mars. We don’t understand fully why ice has built up in some areas of the Martian surface and not in others. Sampling and using this ice with a future mission could help keep astronauts alive, while also helping them unlock the secrets of Martian ice ages.”

    SHARAD is one of six science instruments on the Mars Reconnaissance Orbiter, which began its prime science phase 10 years ago this month. The mission’s longevity is enabling studies of features and active processes all around Mars, from subsurface to upper atmosphere. The Italian Space Agency provided the SHARAD instrument and Sapienza University of Rome leads its operations. The Planetary Science Institute, based in Tucson, Arizona, leads U.S. involvement in SHARAD. JPL, a division of Caltech in Pasadena, manages the orbiter mission for NASA’s Science Mission Directorate in Washington. Lockheed Martin Space Systems of Denver built the spacecraft and supports its operations.

    This vertically exaggerated view shows scalloped depressions in a part of Mars where such textures prompted researchers to check for buried ice, using ground-penetrating radar aboard NASA's Mars Reconnaissance Orbiter.
  • ‘False’ biosignatures may complicate search for ancient life on Earth, other planets

    {Self-assembling carbon microstructures created in a lab by University of Colorado Boulder researchers could provide new clues — and new cautions — in efforts to identify microbial life preserved in the fossil record, both on Earth and elsewhere in the solar system.}

    The geological search for ancient life frequently zeroes in on fossilized organic structures or biominerals that can serve as “biosignatures,” that survive in the rock record over extremely long time scales. Mineral elements such as sulfur are often formed through biological activity. Microbes can also produce a variety of telltale extracellular structures that resemble sheaths and stalks.

    However, according to new findings published in the journal Nature Communications, carbon-sulfur microstructures that would be recognized today by some experts as biomaterials are capable of self-assembling under certain conditions, even without direct biological activity. These “false” biosignatures could potentially be misinterpreted as signs of biological activity due to their strong resemblance to microbial structures.

    “Surprisingly, we found that we could create all sorts of biogenic-like materials that have the right shape, structure and chemistry to match natural materials we assume are produced biologically,” said Associate Professor Alexis Templeton of CU Boulder’s Department of Geological Sciences and senior author of the new study.

    The study arose from field research in the Canadian High Arctic, where a team of scientists working with Templeton had identified sulfur-metabolizing organisms that live in shopping mall-sized mineral deposits that form on ice surfaces. Some of these sulfur deposits were returned to CU Boulder to determine whether they contained “biosignatures” that could be relevant to the search for life on Mars or Europa, one of Jupiter’s moons.

    Templeton and CU-Boulder Research Associate Julie Cosmidis then set out to study the underlying mechanisms of biological sulfur mineral formation before realizing that some of the “extracellular structures” and associated sulfur minerals could be reproduced in the lab without any organisms present.

    “It was very disconcerting- at first to see that the carbon-sulfur structures appear in our tests without biological activity, as they looked very microbial,” said Cosmidis, the lead study author.

    “But the fact that these structures self-assemble makes their discovery even more exciting. They challenge our conception of what a biosignature is, and they can teach us about unexpected interactions between carbon and sulfur,” said Cosmidis.

    The findings indicate that carbon-sulfur microstructures may no longer be surefire microbial indicators, but they are still useful for reconstructing environmental processes anywhere there is active sulfur cycling.

    “We’re interested to learn how organisms mediate mineralization and commonly it is challenging to demonstrate that a mineral was produced by living organism,” said Templeton. “This research is another step forward in understanding fundamental self-assembly processes that are important to materials scientists, biologists and chemists alike.”

    But while carbon-sulfur microstructures could confound efforts to identify ancient life, they may provide a roadmap to an entirely different innovation: Next-generation lithium-sulfur (Li-S) batteries.

    Rechargeable Li-S batteries are considered to be a promising successor to the lithium-ion batteries that power most of today’s consumer electronics. Li-S batteries can contain up to five times the energy of lithium-ion batteries, but present a number of manufacturing hurdles that have yet to be overcome on a commercial scale.

    The carbon-sulfur microstructures created in the new study, however, may solve one of the key challenges by encasing the sulfur in conductive carbon, potentially creating more electrically efficient Li-S batteries.

    “We’re making materials that have the desired properties and we’re doing it by mimicking a natural environmental process,” said Templeton. “It’s a promising new pathway to battery design.”

    Associate Professor Alexis Templeton and Dr. Stephen Grasby prospecting for sulfur biominerals in a yellow sulfur deposit forming on a glacier surface in the High Arctic.
  • Mystery solved behind birth of Saturn’s rings

    {A team of researchers has presented a new model for the origin of Saturn’s rings based on results of computer simulations. The results of the simulations are also applicable to rings of other giant planets and explain the compositional differences between the rings of Saturn and Uranus. The findings were published on October 6 in the online version of Icarus.}

    The lead author of the paper is HYODO Ryuki (Kobe University, Graduate School of Science), and co-authors are Professor Sébastien Charnoz (Institute de Physique du Globe/Université Paris Diderot), Professor OHTSUKI Keiji (Kobe University, Graduate School of Science), and Project Associate Professor GENDA Hidenori (Earth-Life Science Institute, Tokyo Institute of Technology).

    The giant planets in our solar system have very diverse rings. Observations show that Saturn’s rings are made of more than 95% icy particles, while the rings of Uranus and Neptune are darker and may have higher rock content. Since the rings of Saturn were first observed in the 17th century, investigation of the rings has expanded from earth-based telescopes to spacecraft such as Voyagers and Cassini. However, the origin of the rings was still unclear and the mechanisms that lead to the diverse ring systems were unknown.

    The present study focused on the period called the Late Heavy Bombardment that is believed to have occurred 4 billion years ago in our solar system, when the giant planets underwent orbital migration. It is thought that several thousand Pluto-sized (one fifth of Earth’s size) objects from the Kuiper belt existed in the outer solar system beyond Neptune. First the researchers calculated the probability that these large objects passed close enough to the giant planets to be destroyed by their tidal force during the Late Heavy Bombardment. Results showed that Saturn, Uranus and Neptune experienced close encounters with these large celestial objects multiple times.

    Next the group used computer simulations to investigate disruption of these Kuiper belt objects by tidal force when they passed the vicinity of the giant planets. The results of the simulations varied depending on the initial conditions, such as the rotation of the passing objects and their minimum approach distance to the planet. However they discovered that in many cases fragments comprising 0.1-10% of the initial mass of the passing objects were captured into orbits around the planet. The combined mass of these captured fragments was found to be sufficient to explain the mass of the current rings around Saturn and Uranus. In other words, these planetary rings were formed when sufficiently large objects passed very close to giants and were destroyed.

    The researchers also simulated the long-term evolution of the captured fragments using supercomputers at the National Astronomical Observatory of Japan. From these simulations they found that captured fragments with an initial size of several kilometers are expected to undergo high-speed collisions repeatedly and are gradually shattered into small pieces. Such collisions between fragments are also expected to circularize their orbits and lead to the formation of the rings observed today.

    This model can also explain the compositional difference between the rings of Saturn and Uranus. Compared to Saturn, Uranus (and also Neptune) has higher density (the mean density of Uranus is 1.27g cm-3, and 1.64g cm-3 for Neptune, while that of Saturn is 0.69g cm-3). This means that in the cases of Uranus (and Neptune), objects can pass within close vicinity of the planet, where they experience extremely strong tidal forces. (Saturn has a lower density and a large diameter-to-mass ratio, so if objects pass very close they will collide with the planet itself). As a result, if Kuiper belt objects have layered structures such as a rocky core with an icy mantle and pass within close vicinity of Uranus or Neptune, in addition to the icy mantle, even the rocky core will be destroyed and captured, forming rings that include rocky composition. However if they pass by Saturn, only the icy mantle will be destroyed, forming icy rings. This explains the different ring compositions.

    These findings illustrate that the rings of giant planets are natural by-products of the formation process of the planets in our solar system. This implies that giant planets discovered around other stars likely have rings formed by a similar process. Discovery of a ring system around an exoplanet has been recently reported, and further discoveries of rings and satellites around exoplanets will advance our understanding of their origin.

    {{Notes}}

    (1) Late Heavy Bombardment: a period of orbital instability that occurred in our solar system approximately 4 billion years ago. It is thought that during this period there were many small bodies that did not ultimately become planets that existed in orbit beyond Neptune. As a result of gravitational interactions with the giant planets, the orbits of these small bodies became unstable, and many of them entered the solar system and collided with planets that had already formed. It is thought that most of the craters on the surface of the moon were formed during this period.

    (2) Kuiper belt objects: A large number of small bodies made of ice and rock that exist beyond the orbit of Neptune.

    Left: Image of Saturn's rings taken by the Cassini spacecraft. Right: Image of Uranus' rings taken by the Hubble Space Telescope.
  • Drones launch off-grid healthcare in rural Madagascar

    {New project aims to enable villagers to diagnose and treat conditions via drone-delivered test samples and vaccines.}

    Drones, initially developed for warfare, are being co-opted to provide revolutionary off-grid healthcare to those who live in the most remote parts of the world.

    A fully autonomous drone recently flew blood samples from rural Madagascar to a central lab.

    The drone was developed by Vayu , a company founded by Daniel Pepper, which aims to bridge the gap between far-flung villages and healthcare that is so often centrally available, but out of reach for local inhabitants.

    Pepper discovered a chasm between medicinal availability and supply while working as a journalist in India.

    He recognised it was a major challenge for patients to travel to hospitals because of weather conditions, transport and family traditions there, and so he created Vayu with funds from governments, healthcare organisations and NGOs.

    Vayu’s drones, which took two years to develop, are used to serve and connect rural villages to central hospitals.

    The company hopes to enable the off-grid villages to diagnose and treat the conditions via drone-delivered test samples and vaccines, preventing unnecessary deaths and illnesses.

    “The biggest hurdle has been regulatory rather than technical,” said Pepper. “Currently, no countries provide blanket permission for beyond line of sight autonomous flight.”

    This means that Vayu and its partners work individually with national governments to overcome bans. Though regulation was not the only issue that Vayu encountered.

    {{Years in development}}

    The team spent years developing a drone that would be able to fly far enough to make the technology worthwhile.

    In the areas that Vayu targets, “there is not enough space for a runway or resting net, this lack of infrastructure means the drone has to take off and land vertically”, said Pepper.

    The drone must therefore rise and touch down in helicopter fashion, though this hover method during flight would prevent the drone from making the 60km journey, Pepper said.

    “Drones are 10 times more efficient in forward flight than during hovering,” he said.

    The result is a model with helicopter-style propellers attached to static plane-like wings. This wing and propeller combination allows Vayu’s drone to land precisely while still flying long distances economically.

    Vayu are not the only ones who have identified this possibility – similar projects are being launched by Zipline, which hopes to launch publicly this month.

    The company aims to provide each of Rwanda’s 11 million citizens with guaranteed 15-35 minute delivery of any essential medical product they need by releasing drones that drop medical supplies with a parachute.

    “The Zipline base is centrally located and contain 15-20 drones. Each drone can fly a 150km round trip and carry 1.5kg of blood – enough to save a person’s life,” said Justin Hamilton, spokesman from Zipline.

    While such technology from Vayu and Zipline is revolutionary in providing marginalised communities with access to healthcare, its success will be hindered without a holistic approach.

    Vaccines are only useful if village health workers are able administer them, and diagnoses can only be made if samples are taken in sterile conditions and packaged correctly.

    Peter Small, founding director of Stony Brook University Global Health Institute , who has worked alongside Pepper in launching the Vayu project in Madagascar, said he was currently working on a full-circle project.

    “The project trains village health workers to identify prolonged coughs and send for drones to deliver tuberculosis testing kits,” he said.

    Upon return to the lab, the drone will fly back out with suitable medication should the samples test positive for TB. This delivery will also include a tablet containing video instructions to enable untrained individuals to administer the treatment.

    “This kind of approach empowers small communities” said Small.

    {{User-friendly }}

    While Vayu is developed with the best intentions, the most important thing is the integration of these drones into local communities.

    Dean Irvine, communications director at Doctors Without Borders (MSF), explained the most important aspect of Vayu was user friendliness.

    “This is especially important if it needs to be operated by those in communities that have limited expertise and education of tech,” he said.

    “But they also need to be accepted in areas where that kind of technology might not be common, so working with communities to explain what all these things zooming overhead are actually doing. In that regard, we also really need to demilitarise UAVs in people’s minds.”

    Following the current innovation, Vayu plans to launch pilot projects in Papua New Guinea, Peru and Nepal among others.

    The drone must rise and touch down in helicopter fashion
  • Uranus may have two undiscovered moons

    {NASA’s Voyager 2 spacecraft flew by Uranus 30 years ago, but researchers are still making discoveries from the data it gathered then. A new study led by University of Idaho researchers suggests there could be two tiny, previously undiscovered moonlets orbiting near two of the planet’s rings.}

    Rob Chancia, a University of Idaho doctoral student, spotted key patterns in the rings while examining decades-old images of Uranus’ icy rings taken by Voyager 2 in 1986. He noticed the amount of ring material on the edge of the alpha ring — one of the brightest of Uranus’ multiple rings — varied periodically. A similar, even more promising pattern occurred in the same part of the neighboring beta ring.

    “When you look at this pattern in different places around the ring, the wavelength is different — that points to something changing as you go around the ring. There’s something breaking the symmetry,” said Matt Hedman, an assistant professor of physics at the University of Idaho, who worked with Chancia to investigate the finding. Their results will be published in The Astronomical Journal and have been posted to the pre-press site arXiv.

    Chancia and Hedman are well-versed in the physics of planetary rings: both study Saturn’s rings using data from NASA’s Cassini spacecraft, which is currently orbiting Saturn. Data from Cassini have yielded new ideas about how rings behave, and a grant from NASA allowed Chancia and Hedman to examine Uranus data gathered by Voyager 2 in a new light. Specifically, they analyzed radio occultations — made when Voyager 2 sent radio waves through the rings to be detected back on Earth — and stellar occultations, made when the spacecraft measured the light of background stars shining through the rings, which helps reveal how much material they contain.

    They found the pattern in Uranus’ rings was similar to moon-related structures in Saturn’s rings called moonlet wakes.

    The researchers estimate the hypothesized moonlets in Uranus’ rings would be 2 to 9 miles (4 to 14 kilometers) in diameter — as small as some identified moons of Saturn, but smaller than any of Uranus’ known moons. Uranian moons are especially hard to spot because their surfaces are covered in dark material.

    “We haven’t seen the moons yet, but the idea is the size of the moons needed to make these features is quite small, and they could have easily been missed,” Hedman said. “The Voyager images weren’t sensitive enough to easily see these moons.”

    Hedman said their findings could help explain some characteristics of Uranus’ rings, which are strangely narrow compared to Saturn’s. The moonlets, if they exist, may be acting as “shepherd” moons, helping to keep the rings from spreading out. Two of Uranus’ 27 known moons, Ophelia and Cordelia, act as shepherds to Uranus’ epsilon ring.

    “The problem of keeping rings narrow has been around since the discovery of the Uranian ring system in 1977 and has been worked on by many dynamicists over the years,” Chancia said. “I would be very pleased if these proposed moonlets turn out to be real and we can use them to approach a solution.”

    Confirming whether or not the moonlets actually exist using telescope or spacecraft images will be left to other researchers, Chancia and Hedman said. They will continue examining patterns and structures in Uranus’ rings, helping uncover more of the planet’s many secrets.

    “It’s exciting to see Voyager 2’s historic Uranus exploration still contributing new knowledge about the planets,” said Ed Stone, project scientist for Voyager, based at Caltech, Pasadena, California.

    Voyager 2 and its twin, Voyager 1, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn, and Voyager 2 also flew by Uranus and Neptune. Voyager 2 is the longest continuously operated spacecraft. It is expected to enter interstellar space in a few years, joining Voyager 1, which crossed over in 2012. Though far past the planets, the mission continues to send back unprecedented observations of the space environment in the solar system, providing crucial information on the environment our spacecraft travel through as we explore farther and farther from home.

    NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, built the twin Voyager spacecraft and operates them for the Heliophysics Division within NASA’s Science Mission Directorate in Washington.

    Uranus is seen in this false-color view from NASA's Hubble Space Telescope from August 2003. The brightness of the planet's faint rings and dark moons has been enhanced for visibility.
  • Fully charged battery poses danger to users

    {Smartphones and other electronic gadgets that use lithium-ion (Li-ion) batteries — used in billions of mobile devices — and charged to 100 per cent are more likely to release toxic gases and explode than a half-charged battery when the batteries overheat or explode, new research suggests.}

    These findings, including that the gases can cause serious sickness and even death, are crucial in the wake of exploding phones.

    The Galaxy Note 7 smartphone, made by Samsung Electronics, and its replacement were banned on aeroplanes as they were prone to exploding. They were recalled because they overheat and pose a safety risk.

    A week ago, the top floor of a residential house in the upmarket Kileleshwa suburb of Nairobi was reduced to ashes when a power bank that was being charged exploded and set fire to the house.

    Power banks — for energy-hungry smartphones with larger screens — also use lithium-ion batteries.

    EMIT HARMFUL GASES

    The gases from these batteries cause irritations to the skin, eyes and nasal passages and are fatal. The gases are also harmful to the environment. One of them, carbon monoxide, is colourless, odourless and tasteless and is poisonous and potentially fatal.

    If leaked inside a small, sealed environment, such as the interior of a car or an aeroplane, carbon monoxide can cause serious harm within a short period of time, according to Dr Jie Sun from the Institute of NBC Defence and Tsinghua University in China, who conducted the research.

    The report of the study — Toxicity, a Serious Concern of Thermal Runaway from Commercial Li-ion Battery — was published in the Nano Energy Journal, which publishes articles on science and engineering.

    The study further notes consumers are unaware of the risks related to overheating and using low quality or damaged chargers for smartphones.

    Dr Jie says it is imperative that the general public understands the risks behind the lithium-ion battery used by millions of families.

    The batteries are preferred as they can hold twice as much energy as a nickel-based one and four times that of a lead acid battery and are easy to use, says the study.

    A trader holds mobile phone batteries at her shop in Nairobi. New research suggests that batteries charged to 100 per cent are more likely to release toxic gases and explode than a half-charged ones.
  • More evidence for ninth planet roming Solar System’s outer fringes

    {As the search for a hypothetical, unseen planet far, far beyond Neptune’s orbit continues, research by a team of the University of Arizona provides additional support for the possible existence of such a world and narrows the range of its parameters and location.}

    Led by Renu Malhotra, a Regents’ Professor of Planetary Sciences in the UA’s Lunar and Planetary Lab, the team found that the four Kuiper Belt Objects with the longest known orbital periods revolve around the Sun in patterns most readily explained by the presence of a hypothetical “Planet Nine” approximately ten times the mass of Earth. Malhotra is presenting the results at the joint 48th meeting of the Division for Planetary Sciences of the American Astronomical Society and 11th European Planetary Science Congress in Pasadena, California.

    According to the researchers’ calculations, such a hypothetical planet would complete one orbit around the Sun roughly every 17,000 years and, at its farthest point from our central star, it would swing out more than 660 astronomical units, with one AU being the average distance between Earth and the Sun.

    Scientists think that objects in the Kuiper Belt, a vast region of dwarf planets and icy rocks populating the fringes of our solar system beyond the orbit of Neptune, dance mostly to the tune of the giant planets, Saturn, Jupiter, Uranus and Neptune, influenced by their gravity either directly or indirectly.

    However, there are a few known Kuiper Belt objects (KBOs) that are unlikely to be significantly perturbed by the known giant planets in their current orbits. Referred to as “extreme KBOs” (eKBOs) by the authors, all of these have extremely large orbital eccentricities, in other words, they get very close to the Sun at one point on their orbital journey, only to swing far out into space once they pass the Sun, on long elliptical orbits that take these strange mini worlds hundreds of AUs away from the Sun.

    “We analyzed the data of these most distant Kuiper Belt objects,” Malhotra said, “and noticed something peculiar, suggesting they were in some kind of resonances with an unseen planet.”

    In their paper, “Corralling a Distant Planet with Extreme Resonant Kuiper Belt Objects,” Malhotra and her co-authors, Kathryn Volk and Xianyu Wang, point out peculiarities of the orbits of the extreme KBOs that went unnoticed until now: they found that the orbital period ratios of these objects are close to ratios of small whole numbers. An example of this would be one KBO traveling around the Sun once while another takes twice as long, or three times as long, or four times as long etc., but not, say, 2.7 times as long.

    According to the authors, such ratios could arise most naturally if the extreme KBOs’ orbital periods are in small whole number ratios with a massive planet, which would help to stabilize the highly elliptical orbits of eKBOs.

    The findings bolster previous work by other scientists that showed that six of those bodies travel on highly eccentric orbits whose long axes all point in the same direction. This clustering of orbital parameters of the most distant KBOs suggested a large, planetary size body shepherding their orbits.

    Another paper published earlier this year presented the results of numerical simulations providing a range of possibilities for the mass and orbit for such a hypothetical planet, that could account for the observed clustering of eKBO orbits.

    “Our paper provides more specific estimates for the mass and orbit that this planet would have, and, more importantly, constraints on its current position within its orbit,” Malhotra said.

    The team’s calculations also suggest two likely orbital planes for the planet: one moderately close to the mean plane of the solar system and near the mean plane of the four eKBOs at about 18 degrees, and one steeper plane, inclined at about 48 degrees.

    While the results provide additional support for the idea of a potential “Planet Nine” and lay out possible scenarios, the authors stress that their paper should not be considered definitive proof of the planet’s existence.

    For one, the very far and faint KBOs haven’t been observed for very long, and given their minuscule apparent motion along their immensely long journeys around the Sun, the estimates for their closeness to whole number ratios of orbital periods come with uncertainties that can be narrowed down only through more observations.

    The authors also note that the long orbital timescales in this region of the outer solar system may allow formally unstable orbits to persist for very long times, possibly even to the age of the solar system, without the help of orbital resonances. In this scenario, orbits whose orderly parameters appear as testimony to the stabilizing influence of an unseen planet may in fact be in the process of deterioration but haven’t been observed long enough for it to show.

    Future observations and studies into the dynamical lifetimes of non-resonant planet-crossing orbits in the far regions of the outer solar system could help to further test the case for the existence and whereabouts of a ninth planet, Malhotra and her co-authors write.

    Note: The above press release was issued by University of Arizona to coincide with a presentation at the joint 48th annual meeting of the Division for Planetary Sciences (DPS) of the American Astronomical Society (AAS) and 11th annual European Planetary Science Congress (EPSC).

    An artist's illustration of Planet Nine, a hypothesized Neptune-size planet orbiting in the distant reaches of our solar system.
  • Oldest known planet-forming disk discovered

    {A group of citizen scientists and professional astronomers, including Carnegie’s Jonathan Gagné, joined forces to discover an unusual hunting ground for exoplanets. They found a star surrounded by the oldest known circumstellar disk — a primordial ring of gas and dust that orbits around a young star and from which planets can form as the material collides and aggregates.}

    Led by Steven Silverberg of University of Oklahoma, the team described a newly identified red dwarf star with a warm circumstellar disk, of the kind associated with young planetary systems. Circumstellar disks around red dwarfs like this one are rare to begin with, but this star, called AWI0005x3s, appears to have sustained its disk for an exceptionally long time. The findings are published by The Astrophysical Journal Letters.

    “Most disks of this kind fade away in less than 30 million years,” said Silverberg. “This particular red dwarf is a candidate member of the Carina stellar association, which would make it around 45 million years old [like the rest of the stars in that group]. It’s the oldest red dwarf system with a disk we’ve seen in one of these associations.”

    The discovery relied on citizen scientists from Disk Detective, a project led by NASA/GSFC’s Dr. Marc Kuchner that’s designed to find new circumstellar disks. At the project’s website, DiskDetective.org, users make classifications by viewing ten-second videos of data from NASA surveys, including the Wide-field Infrared Survey Explorer mission (WISE) and Two-Micron All Sky Survey (2MASS) projects. Since the launch of the website in January 2014, roughly 30,000 citizen scientists have participated in this process, performing roughly 2 million classifications of celestial objects.

    “Without the help of the citizen scientists examining these objects and finding the good ones, we might never have spotted this object,” Kuchner said. “The WISE mission alone found 747 million [warm infrared] objects, of which we expect a few thousand to be circumstellar disks.”

    “Unraveling the mysteries of our universe, while contributing to the advancement of astronomy, is without a doubt a dream come true,” says Hugo Durantini Luca from Argentina, one of eight citizen scientist co-authors.

    Determining the age of a star can be tricky or impossible. But the Carina association, where this red dwarf was found, is a group of stars whose motions through the Galaxy indicate that they were all born at roughly the same time in the same stellar nursery.

    Carnegie’s Gagné devised a test that showed this newly found red dwarf and its disk are likely part of the Carina association, which was key to revealing its surprising age.

    “It is surprising to see a circumstellar disk around a star that may be 45 million years old, because we normally expect these disks to dissipate within a few million years,” Gagné explained. “More observations will be needed to determine whether the star is really as old as we suspect, and if it turns out to be, it will certainly become a benchmark system to understand the lifetime of disks.”

    Knowing that this star and its disk are so old may help scientists understand why M dwarf disks appear to be so rare.

    This star and its disk are interesting for another reason: the possibility that it could host extrasolar planets. Most of the extrasolar planets that have been found by telescopes have been located in disks similar to the one around this unusual red dwarf. Moreover, this particular star is the same spectral type as Proxima Centauri, the Sun’s nearest neighbor, which was shown to host at least one exoplanet, the famous Proxima b, in research published earlier this year.

    An artist's conception of this unusual system.
  • Curious tilt of the Sun traced to undiscovered planet

    {Planet Nine the undiscovered planet at the edge of the solar system that was predicted by the work of Caltech’s Konstantin Batygin and Mike Brown in January 2016 appears to be responsible for the unusual tilt of the Sun, according to a new study.}

    The large and distant planet may be adding a wobble to the solar system, giving the appearance that the Sun is tilted slightly.

    “Because Planet Nine is so massive and has an orbit tilted compared to the other planets, the solar system has no choice but to slowly twist out of alignment,” says Elizabeth Bailey, a graduate student at Caltech and lead author of a study announcing the discovery.

    All of the planets orbit in a flat plane with respect to the Sun, roughly within a couple degrees of each other. That plane, however, rotates at a six-degree tilt with respect to the Sun giving the appearance that the Sun itself is cocked off at an angle. Until now, no one had found a compelling explanation to produce such an effect. “It’s such a deep-rooted mystery and so difficult to explain that people just don’t talk about it,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy.

    Brown and Batygin’s discovery of evidence that the Sun is orbited by an as-yet-unseen planet that is about 10 times the size of Earth with an orbit that is about 20 times farther from the Sun on average than Neptune’s changes the physics. Planet Nine, based on their calculations, appears to orbit at about 30 degrees off from the other planets’ orbital plane in the process, influencing the orbit of a large population of objects in the Kuiper Belt, which is how Brown and Batygin came to suspect a planet existed there in the first place.

    “It continues to amaze us; every time we look carefully we continue to find that Planet Nine explains something about the solar system that had long been a mystery,” says Batygin, an assistant professor of planetary science.

    Their findings have been accepted for publication in an upcoming issue of the Astrophysical Journal, and will be presented this week at the American Astronomical Society’s Division for Planetary Sciences 48th annual meeting, held jointly in Pasadena, California, with the 11th European Planetary Science Congress.

    The tilt of the solar system’s orbital plane has long befuddled astronomers because of the way the planets formed: as a spinning cloud slowly collapsing first into a disk and then into objects orbiting a central star.

    Planet Nine’s angular momentum is having an outsized impact on the solar system based on its location and size. A planet’s angular momentum equals the mass of an object multiplied by its distance from the Sun, and corresponds with the force that the planet exerts on the overall system’s spin. Because the other planets in the solar system all exist along a flat plane, their angular momentum works to keep the whole disk spinning smoothly.

    Planet Nine’s unusual orbit, however, adds a multi-billion-year wobble to that system. Mathematically, given the hypothesized size and distance of Planet Nine, a six-degree tilt fits perfectly, Brown says.

    The next question, then, is how did Planet Nine achieve its unusual orbit? Though that remains to be determined, Batygin suggests that the planet may have been ejected from the neighborhood of the gas giants by Jupiter, or perhaps may have been influenced by the gravitational pull of other stellar bodies in the solar system’s extreme past.

    For now, Brown and Batygin continue to work with colleagues throughout the world to search the night sky for signs of Planet Nine along the path they predicted in January. That search, Brown says, may take three years or more.

    Artist’s illustration of a possible ninth planet in our solar system. A recent study has revealed that the unexpected behavior of some Kuiper belt objects could be explained by the presence of a distant, planet-sized object yet undetected in our solar system.