Salts left over from ancient seawater reveal new information about the oxygenation of the Earth’s atmosphere more than 2 billion years ago. Shown here is a sample of 2-billion-year-old salt (pink-white recrystallized halite) with embedded fragments of calcium sulfate from a geological drill core in Russian Karelia. Credit: Aivo Lepland, Geological Survey of Norway; courtesy of Science/AAAS
Billions of years ago, Earth’s environment was very different from the one we know today. Basically, our planet’s primordial atmosphere was toxic to life as we know it, consisting of carbon dioxide, nitrogen and other gases. However, by the Paleoproterozoic Era (2.5–1.6 billion years ago), a dramatic change occurred where oxygen began to be introduced to the atmosphere – known as the Great Oxidation Event (GOE).
Until recently, scientists were not sure if this event – which was the result of photosynthetic bacteria altering the atmosphere – occurred rapidly or not. However, according to a recent study by a team of international scientists, this event was much more rapid than previously thought. Based on newly-discovered geological evidence, the team concluded that the introduction of oxygen to our atmosphere was “more like a fire hose” than a trickle.
NASA’s Parker Solar Probe will launch this summer and study both the solar wind and unanswered questions about the Sun’s sizzling corona. Credit: NASA
How would you like to take an all-expenses-paid trip to the Sun? NASA is inviting people around the world to submit their names to be placed on a microchip aboard the Parker Solar Probe mission that will launch this summer. As the spacecraft dips into the blazing hot solar corona your name will go along for the ride. To sign up, submit your name and e-mail. After a confirming e-mail, your digital “seat” will be booked. You can even print off a spiffy ticket. Submissions will be accepted until April 27, so come on down!
Step right up! Head over before April 27 to put a little (intense) sunshine in your life. Click the image to go there. Credit: NASA
The Parker Solar Probe is the size of a small car and named for Prof. Eugene Parker, a 90-year-old American astrophysicist who in 1958 discovered the solar wind. It’s the first time that NASA has named a spacecraft after a living person. The Parker probe will launch between July 31 and August 19 but not immediately head for the Sun. Instead it will make a beeline for Venus for the first of seven flybys. Each gravity assist will slow the craft down and reshape its orbit (see below), so it later can pass extremely close to the Sun. The first flyby is slated for late September.
When heading to faraway places, NASA typically will fly by a planet to increase the spacecraft’s speed by robbing energy from its orbital motion. But a probe can also approach a planet on a different trajectory to slow itself down or reconfigure its orbit.
The spacecraft will swing well within the orbit of Mercury and more than seven times closer than any spacecraft has come to the Sun before. When closest at just 3.9 million miles (6.3 million km), it will pass through the Sun’s outer atmosphere called the corona and be subjected to temperatures around 2,500°F (1,377°C). The primary science goals for the mission are to trace how energy and heat move through the solar corona and to explore what accelerates the solar wind as well as solar energetic particles.
The Parker Solar Probe will use seven Venus flybys over nearly seven years to gradually shrink its orbit around the Sun, coming as close as 3.7 million miles (5.9 million km), well within the orbit of Mercury. Closest approaches (called perihelia) will happen in late December 2024 and the first half of 2025 before the mission ends. Credit: NASA
The vagaries of the solar wind, a steady flow of particles that “blows” from the Sun’s corona at more than million miles an hour, can touch Earth in beautiful ways as when it energizes the aurora borealis. But it can also damage spacecraft electronics and poorly protected power grids on the ground. That’s why scientists want to know more about how the corona works, in particular why it’s so much hotter than the surface of the Sun — temperatures there are several million degrees.
During the probe’s closest approach, the Sun’s apparent diameter will span 14° of sky. Compare that to the ½° Sun we see from Earth. Can you imagine how hot the Sun’s rays would be if it were this large from Earth? Life as we know it would be over. Wikipedia / CC BY-SA 3.0
As you can imagine, it gets really, really hot near the Sun, so you’ve got to take special precautions. To perform its mission, the spacecraft and instruments will be protected from the Sun’s heat by a 4.5-inch-thick carbon-composite shield, which will keep the four instrument suites designed to study magnetic fields, plasma and energetic particles, and take pictures of the solar wind, all at room temperature.
Similar to how the Juno probe makes close passes over Jupiter’s radiation-fraught polar regions and then loops back out to safer ground, the Parker probe will make 24 orbits around the Sun, spending a relatively short amount of face to face time with our star. At closest approach, the spacecraft will be tearing along at about 430,000 mph, fast enough to get from Washington, D.C., to Tokyo in under a minute, and will temporarily become the fastest manmade object. The current speed record is held by Helios-B when it swung around the Sun at 156,600 mph (70 km/sec) on April 17, 1976.
A composite of the August 21, 2017 total solar eclipse showing the Sun’s spectacular corona. Astronomers still are sure why it’s so much hotter than the 10,000°F solar surface (photosphere). Theories include a microflares or magnetic waves that travel up from deep inside the Sun. Credit and copyright: Alan Dyer / amazingsky.com
Many of you saw last August’s total solar eclipse and marveled at the beauty of the corona, that luminous spider web of light around Moon’s blackened disk. When closest to the Sun at perihelion the Parker probe will fly to within 9 solar radii (4.5 solar diameters) of its surface. That’s just about where the edge of the furthest visual extent of the corona merged with the blue sky that fine day, and that’s where Parker will be!
Artist’s impression of the first interstellar asteroid/comet, "Oumuamua". This unique object was discovered on 19 October 2017 by the Pan-STARRS 1 telescope in Hawaii. Credit: ESO/M. Kornmesser
On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) telescope in Hawaii announced the first-ever detection of an interstellar asteroid – I/2017 U1 (aka. ‘Oumuamua). Since that time, no effort has been spared to study this object before it leaves our Solar System. These include listening to it for signs of communications, determining its true nature and shape, and determining where it came from.
In fact, the question of this interstellar object’s origins has been mystery since it was first discovered. While astronomers are sure that it came from the direction of Vega and some details have been learned about its past, where it originated from remains unknown. But according to a new study by a team of astronomers from the University of Toronto, Scarborough, ‘Oumuamua may have originally come from a binary star system.
Oumuamua as it appeared using the William Herschel Telescope on the night of October 29. Credit: Queen’s University Belfast/William Herschel Telescope
For the sake of their study, Jackson and his co-authors considered how in single star systems (like our own), asteroids do not get ejected very often. For the most part, it is comets that become interstellar objects, mainly because they orbit the Sun at a greater distance and are less tightly bound by its gravity. And while ‘Oumuamua was initially mistaken for a comet, follow-up observations by the European Southern Observatory (ESO) indicated that it is likely an asteroid.
With the help of other astronomers, it soon became apparent that ‘Oumuamua was likely an oddly-shaped rocky object that measured about 400 meters (1312 ft) long and was tube-shaped. These findings were rather surprising to astronomers. As Jackson explained in a recent Royal Astronomical Society press release:
“It’s really odd that the first object we would see from outside our system would be an asteroid, because a comet would be a lot easier to spot and the Solar System ejects many more comets than asteroids.”
As such, Jackson and his team hypothesized that interstellar objects like ‘Oumuamau are more likely to be ejected from a binary system. To test this theory, they constructed a population synthesis model that considered just how common binary star systems are in the Galaxy. They also conducted 2000 N-body simulations to see just how efficient such systems would be at ejecting objects like ‘Oumuamua.
Diagram showing the orbit of the interstellar asteroid ‘Oumuamua as it passes through the Solar System. Credit: ESO/K. Meech et al.
What they found was that binary stars are produced at a rate of about 30% by number and 41% by mass, and that rocky objects like ‘Oumuamua are far more likely to be ejected from binary than single star systems. Based on ‘Oumuamua’s rocky composition, they also determined that the asteroid was likely ejected from the inner part of its solar system (i.e. inside the “Ice Line”) while the system was still in the process of formation.
Lastly, they determined that rocky objects are ejected from binary systems in comparable numbers to icy objects. This is based on the fact that the presence of a companion star would mean that more material would become unstable due to stellar encounters. In the end, this material would be more likely to be ejected rather than accreted to form planets, or take up residence in the outer reaches of the star system.
While there are still many unanswered questions about ‘Oumuamua, it remains the first interstellar asteroid that scientists have ever known. As such, its continued study can tell us a great deal about what lies beyond our Solar System. As Jackson put it:
“The same way we use comets to better understand planet formation in our own Solar System, maybe this curious object can tell us more about how planets form in other systems.”
The first Long March 5 rocket being rolled out for launch at Wenchang in late October 2016. Credit: Su Dong/China Daily
In the past decade, China’s space program has advanced by leaps and bounds. In recent years, the Chinese National Space Agency (CNSA) has overseen the development of a modern rocket family (the Long March series), the deployment of a space station (Tiangong-1) and the development of the Chinese Lunar Exploration Program (CLEP) – otherwise known as the Chang’e Program.
Looking to the future, China plans to create new classes of heavy rockets in order to conduct more ambitious missions. These include the Long March 9 rocket (aka. the Changzheng 9), a three-stage, super-heavy rocket that would allow for crewed missions to the Moon. According to a recent story from Aviation Weekly, China hopes to conduct an engine demonstration of this rocket, and could do so as early as later this year.
This demonstration is part of a research effort intended to create engines for the first stage of the Long March 9. According to statements made by the Academy of Aerospace Propulsion Technology (AAPT) – part of the China Aerospace and Technology Corporation (CASC) and the one’s responsible for developing the hardware – these engines would be capable of delivering 3,500 to 4,000 metric tons (3,858 to 4,409 US tons) of thrust.
Launch of the modified Saturn V rocket carrying the Skylab space station. Credit: NASA
AAPT also indicated that work on a second-stage and third-stage engine – which would be capable of generating about 200 metric tons (440,000 lbs) and 25 metric tons (55,000 lbs) thrust, respectively – is also in progress. All told, this is roughly six times the thrust that China’s heaviest rocket (the Long March 5) can generate and would make it comparable to theSaturn V – the Apollo-era rocket that took the NASA astronauts to the Moon.
For starters, the Saturn V‘s engines delivered roughly 3,400 metric tons of thrust, and the rocket was capable of delivering 140 metric tons (310,000 lbs) to Low Earth Orbit (LEO) and about 48 metric tons (107,100 lbs) to a Lunar Transfer Orbit (LTO). By comparison, the Long March 9 will reportedly have the ability to 140 metric tons to LEO and at least 50 metric tons (110,000 lbs) to LTO.
According to Li Hong, the head of the China Academy of Launch Vehicle Technology (the CASC unit responsible for overall development and production of most Chinese space launchers), a massive turbopump has also been built for the main engine. A pump of this size is necessary, since the engine will generate four time the thrust of the largest Chinese rocket engine to date – AAPT’s YF-100, which generates 120 metric tons (265,000 lbs) of thrust.
While the full specifications of the rocket are not yet available, the China News Service has indicated that the rocket will measure 10 meters (33 ft.) in diameter. According to statements made by both Li and Lui, the first-stage engine will burn kerosene and achieve a thrust of 480 metric tons (529 US tons) – comparable to the Saturn V F-1 engine’s 680 metric tons (750 US tons) of thrust – while the second and third stage engines will likely burn hydrogen fuel.
At their current rate of progress, an engine demonstration could be taking place later this year. As AAPT President Liu Zhirang stated in an interview with Science and Technology Daily (part of the state-owned China News Service):
“A complete prototype for the engine in the 500-metric-ton class can be built and assembled this year… Because of the great parameter changes that come with rises in thrust, the current test and verification equipment cannot satisfy requirements [of the Moon rocket propulsion program]. We cannot always do 1:1 scale tests. As a result, only simulations and scaled-down tests can be done for some technology and hardware. This increases the degree of difficulty for the program.”
If successful, the Long March 9 will join the ranks of super heavy-lift launch vehicles, such as the SpaceX Falcon Heavy, the KRK rocket (currently under development in Russia), and the Space Launch System being developed by NASA. These and other rockets are being built for the purpose of bringing astronauts to the Moon, Mars, and even beyond in the coming decades.
Beyond a possible demonstration of the Long March 9′s engine technology, the CNSA has many other ambitious plans for 2018. These include a planned 35 launches involving the Long March series, fourteen of which will be carried out by the Long March-3A and six by the Long March-3C rockets. Most of these missions will involve the deployment of Beidou satellites, but will also include the launch of the Chang’e-4 lunar probe later this year.
Buzz Aldrin salutes the first American flag erected on the Moon, July 21, 1969. Credit: NASA/Neil A. Armstrong
This year is also when China hopes to conduct mission using its newest rocket – the Long March 5 – in preparation for China’s lunar probe and Mars probe missions. This year is also expected to see a lot of developments in the Long March 7 series, which is likely to become the main carrier when China begins construction of its new space station (Tiangong-2, which is scheduled for completion in 2022).
Between all of these developments, it is clear that the age of renewed space exploration is upon us. Whereas the Space Race was characterized by two superpowers competing for dominance and “getting their first”, the current one is defined by both competition and cooperation between multiple space agencies and lucrative partnerships between the public sector and private industry.
And while the specter of renewed competition by space powers has a tendency to make many people nervous (especially those who are concerned about military applications), it is a testament to how humanity is growing as a space-faring species. By the time 2050 rolls around, we may just see many flags being planted on the Moon and Mars, and not just Old Glory.
Image of the Tharsis region of Mars taken by Mars Express featuring several prominent shield volcanoes includes the massive Olympus Mons (at left). Credit: ESA
Thanks to the many missions that have been studying Mars in recent years, scientists are aware that roughly 4 billion years ago, the planet was a much different place. In addition to having a denser atmosphere, Mars was also a warmer and wetter place, with liquid water covering much of the planet’s surface. Unfortunately, as Mars lost its atmosphere over the course of hundreds of millions of years, these oceans gradually disappeared.
When and where these oceans formed has been the subject of much scientific inquiry and debate. According to a new study by a team of researchers from UC Berkeley, the existence of these oceans was linked to the rise of the Tharis volcanic system. They further theorize that these oceans formed several hundred millions years earlier than expected and were not as deep as previously thought.
The early ocean known as Arabia (left, blue) would have looked like this when it formed 4 billion years ago on Mars, while the Deuteronilus ocean (right), about 3.6 billion years old, had a smaller shoreline. Credit: Robert Citron/UC Berkeley
As Michael Manga explained in a recent Berkeley News press release:
“The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later. We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.”
The debate over the size and extent of Mars’ past oceans is due to some inconsistencies that have been observed. Essentially, when Mars lost its atmosphere, its surface water would have frozen to become underground permafrost or escaped into space. Those scientists who don’t believe Mars once had oceans point to the fact that the estimates of how much water could have been hidden away or lost is not consistent with estimates on the oceans’ sizes.
What’s more, the ice that is now concentrated in the polar caps is not enough to create an ocean. This means that either less water was present on Mars than previous estimates indicate, or that some other process was responsible for water loss. To resolve this, Citron and his colleagues created a new model of Mars where the oceans formed before or at the same time as Mars’ largest volcanic feature – Tharsis Montes, roughly 3.7 billion years ago.
A colorized image of the surface of Mars taken by the Mars Reconnaissance Orbiter. The line of three volcanoes is the Tharsis Montes, with Olympus Mons to the northwest. Valles Marineris is to the east. Image: NASA/JPL-Caltech/ Arizona State University
Since Tharsis was smaller at the time, it did not cause the same level of crustal deformation that it did later. This would have been especially true of the plains that cover most the northern hemisphere and are believed to have been an ancient seabed. Given that this region was not subject to the same geological change that would have come later, it would have been shallower and held about half the water.
“The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later,” said Manga. “We’re saying that the oceans predate and accompany the lava outpourings that made Tharsis.”
In addition, the team also theorized that the volcanic activity that created Tharsis may have been responsible for the formation of Mars’ early oceans. Basically, the volcanoes would have spewed gases and volcanic ash into the atmosphere that would have led to a greenhouse effect. This would have warmed the surface to the point that liquid water could form, and also created underground channels that allowed water to reach the northern plains.
Their model also counters other previous assumptions about Mars, which are that its proposed shorelines are very irregular. Essentially, what is assumed to have been “water front” property on ancient Mars varies in height by as much as a kilometer; whereas on Earth, shorelines are level. This too can be explained by the growth of the Tharsis volcanic region, roughly 3.7 billion years ago.
A map of Mars today shows where scientists have identified possible ancient shoreline that may have been etched by intermittent oceans billions of years ago. Credit: Robert Citron/UC Berkeley.
Using current geological data of Mars, the team was able to trace how the irregularities we see today could have formed over time. This would have began when Mars first ocean (Arabia) started forming 4 billion years ago and was around to witness the first 20% of Tharsis Montes growth. As the volcanoes grew, the land became depressed and the shoreline shifted over time.
Similarly, the irregular shorelines of a subsequent ocean (Deuteronilus) can be explained by this model by indicating that it formed during the last 17% of Tharsis’ growth – roughly 3.6 billion years ago. The Isidis feature, which appears to be an ancient lakebed slightly removed from the Utopia shoreline, could also be explained this way. As the ground deformed, Isidis ceased being part of the northern ocean and became a connected lakebed.
“These shorelines could have been emplaced by a large body of liquid water that existed before and during the emplacement of Tharsis, instead of afterwards,” said Citron. This is certainly consistent with the observable effect that Tharsis Mons has had on the topography of Mars. It’s bulk not only creates a bulge on the opposite side of the planet (the Elysium volcanic complex), but a massive canyon system in between (Valles Marineris).
This new theory not only explains why previous estimates about the volume of water in the northern plains were inaccurate, it can also account for the valley networks (cut by flowing water) that appeared around the same time. And in the coming years, this theory can be tested by the robotic missions NASA and other space agencies are sending to Mars.
This artist’s concept from August 2015 depicts NASA’s InSight Mars lander fully deployed for studying the deep interior of Mars. Credit: NASA/JPL-Caltech
Consider NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission, which is scheduled for launch in May, 2018. Once it reaches Mars, this lander will use a suite of advanced instruments – which includes a seismometer, temperature probe and radio science instrument – to measure Mars interior and learn more about its geological activity and history.
Among other things, NASA anticipates that InSight might detect the remains of Mars’ ancient ocean frozen in the interior, and possibly even liquid water. Alongside the Mars 2020 rover, the ExoMars 2020, and eventual crewed missions, these efforts are expected to provide a more complete picture of Mars past, which will include when major geological events took place and how this could have affected the planet’s ocean and shorelines.
The more we learn about what happened on Mars over the past 4 billion years, the more we learn about the forces that shaped our Solar System. These studies also go a long way towards helping scientists determine how and where life-bearing conditions can form. This (we hope) will help us locate life it in another star system someday!
70,000 years ago, Scholz's star, a red dwarf, came as close as 1 light year to our Solar System. At that time, neanderthals were still around. Image: Credit: José A. Peñas/SINC
70,000 years ago, our keen-eyed ancestors may have noticed something in the sky: a red dwarf star that came as close as 1 light year to our Sun. They would’ve missed the red dwarf’s small, dim companion—a brown dwarf—and in any case they would’ve quickly returned to their hunting and gathering. But that star’s visit to our Solar System had an impact astronomers can still see today.
The star in question is called Scholz’s star, after astronomer Ralf-Dieter Scholz, the man who discovered it in 2013. A new study published in the Monthly Notices of the Royal Astronomical Society by astronomers at the Complutense University of Madrid, and at the University of Cambridge, shows the impact Scholz’s star had. Though the star is now almost 20 light years away, its close approach to our Sun changed the orbits of some comets and asteroids in our Solar System.
When it came to our Solar System 70,000 years ago, Scholz’s star entered the Oort Cloud. The Oort Cloud is a reservoir of mostly-icy objects that spans the range from about 0.8 to 3.2 light years from the Sun. Its visit to the Oort Cloud was first explained in a paper in 2015. This new paper follows up on that work, and shows what impact the visit had.
“Using numerical simulations, we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come.” – Carlos de la Fuente Marcos, Complutense University of Madrid.
In this new paper, the astronomers studied almost 340 objects in our Solar System with hyperbolic orbits, which are V-shaped rather than elliptical. Their conclusion is that a significant number of these objects had their trajectories shaped by the visit from Scholz’s star. “Using numerical simulations, we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come,” explains Carlos de la Fuente Marcos, a co-author of the study now published in Monthly Notices of the Royal Astronomical Society. They found that there’s a cluster of these objects in the direction of the Gemini Constellation.
A comparison of the Solar System and its Oort Cloud. 70,000 years ago, Scholz’s Star and companion passed along the outer boundaries of our Solar System (Credit: NASA, Michael Osadciw/University of Rochester)
“In principle,” he adds, “one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort cloud. However, what we find is very different—a statistically significant accumulation of radiants. The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz’s star.”
There are four ways that objects like those in the study can gain hyperbolic orbits. They might be interstellar, like the asteroid Oumuamua, meaning they gained those orbits from some cause outside our Solar System. Or, they could be natives of our Solar System, originally bound to an elliptical orbit, but cast into a hyperbolic orbit by a close encounter with one of the planets, or the Sun. For objects originally from the Oort Cloud, they could start on a hyperbolic orbit because of interactions with the galactic disc. Finally, again for objects from the Oort Cloud, they could be cast into a hyperbolic orbit by interactions with a passing star. In this study, the passing star is Scholz’s star.
In this image the blue is a hyperbolic orbit while the green is a parabolic orbit. Image: By ScottAlanHill [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia CommonsThe timing of Scholz’s star’s visit to the Oort Cloud and our Solar System strongly coincides with the data in this study. It’s very unlikely to be coincidental. “It could be a coincidence, but it is unlikely that both location and time are compatible,” says De la Fuente Marcos. In fact, De la Fuente Marcos points out that their simulations suggest that Scholz’s star approached even closer than the 0.6 light-years pointed out in the 2015 study.
The one potentially weak area of this study is pointed out by the authors themselves. As they say in their summary, “…due to their unique nature, the orbital solutions of hyperbolic minor bodies are based on relatively brief arcs of observation and this fact has an impact on their reliability. Out of 339 objects in the sample, 232 have reported uncertainties and 212 have eccentricity with statistical significance.” Translated, it means that some of the computed orbits of individual objects may have errors. But the team expects the overall conclusions of their study to be correct.
The study of minor objects with hyperbolic orbits has heated up since the interstellar asteroid Oumuamua made its visit. This new study successfully connects one population of hyperbolic objects with a pre-historic visit to our Solar System by another star. The team behind the study expects that follow up studies will confirm their results.
Composite which combines gas temperature (as the color) and shock mach number (as the brightness). Red indicates 10 million Kelvin gas at the centers of massive galaxy clusters, while bright structures show diffuse gas from the intergalactic medium shock heating at the boundary between cosmic voids and filaments. Credit: Illustris Team
Since time immemorial, philosophers and scholars have sought to determine how existence began. With the birth of modern astronomy, this tradition has continued and given rise to the field known as cosmology. And with the help of supercomputing, scientists are able to conduct simulations that show how the first stars and galaxies formed in our Universe and evolved over the course of billions of years.
Until recently, the most extensive and complete study was the “Illustrus” simulation, which looked at the process of galaxy formation over the course of the past 13 billion years. Seeking to break their own record, the same team recently began conducting a simulation known as “Illustris, The Next Generation,” or “IllustrisTNG”. The first round of these findings were recently released, and several more are expected to follow.
This illustration shows the evolution of the Universe, from the Big Bang on the left, to modern times on the right. Image: NASA
Using the Hazel Hen supercomputer at the High-Performance Computing Center Stuttgart (HLRS) – one of the three world-class German supercomputing facilities that comprise the Gauss Centre for Supercomputing (GCS) – the team conducted a simulation that will help to verify and expand on existing experimental knowledge about the earliest stages of the Universe – i.e. what happened from 300,000 years after the Big Bang to the present day.
To create this simulation, the team combined equations (such as the Theory of General Relativity) and data from modern observations into a massive computational cube that represented a large cross-section of the Universe. For some processes, such as star formation and the growth of black holes, the researchers were forced to rely on assumptions based on observations. They then employed numerical models to set this simulated Universe in motion.
Compared to their previous simulation, IllustrisTNG consisted of 3 different universes at three different resolutions – the largest of which measured 1 billion light years (300 megaparsecs) across. In addition, the research team included more precise accounting for magnetic fields, thus improving accuracy. In total, the simulation used 24,000 cores on the Hazel Hen supercomputer for a total of 35 million core hours.
As Prof. Dr. Volker Springel, professor and researcher at the Heidelberg Institute for Theoretical Studies and principal investigator on the project, explained in a Gauss Center press release:
“Magnetic fields are interesting for a variety of reasons. The magnetic pressure exerted on cosmic gas can occasionally be equal to thermal (temperature) pressure, meaning that if you neglect this, you will miss these effects and ultimately compromise your results.”
Illustris simulation overview poster. Shows the large scale dark matter and gas density fields in projection (top/bottom). Credit: Illustris Project
Another major difference was the inclusion of updated black hole physics based on recent observation campaigns. This includes evidence that demonstrates a correlation between supermassive black holes (SMBHs) and galactic evolution. In essence, SMBHs are known to send out a tremendous amount of energy in the form of radiation and particle jets, which can have an arresting effect on star formation in a galaxy.
While the researchers were certainly aware of this process during the first simulation, they did not factor in how it can arrest star formation completely. By including updated data on both magnetic fields and black hole physics in the simulation, the team saw a greater correlation between the data and observations. They are therefore more confident with the results and believe it represents the most accurate simulation to date.
But as Dr. Dylan Nelson – a physicist with the Max Planck Institute of Astronomy and an llustricTNG member – explained, future simulations are likely to be even more accurate, assuming advances in supercomputers continue:
“Increased memory and processing resources in next-generation systems will allow us to simulate large volumes of the universe with higher resolution. Large volumes are important for cosmology, understanding the large-scale structure of the universe, and making firm predictions for the next generation of large observational projects. High resolution is important for improving our physical models of the processes going on inside of individual galaxies in our simulation.”
Gas density (left) and magnetic field strength (right) centered on the most massive galaxy cluster. Credit: Illustris Team
This latest simulation was also made possible thanks to extensive support provided by the GCS staff, who assisted the research team with matters related to their coding. It was also the result of a massive collaborative effort that brought together researchers from around the world and paired them with the resources they needed. Last, but not least, it shows how increased collaboration between applied research and theoretical research lead to better results.
Looking ahead, the team hopes that the results of this latest simulation proves to be even more useful than the last. The original Illustris data release gained over 2,000 registered users and resulted in the publication of 130 scientific studies. Given that this one is more accurate and up-to-date, the team expects that it will find more users and result in even more groundbreaking research.
Who knows? Perhaps someday, we may create a simulation that captures the formation and evolution of our Universe with complete accuracy. In the meantime, be sure to enjoy this video of the first Illustris Simulation, courtesy of team member and MIT physicist Mark Vogelsberger:
Artist's impression of rocky exoplanets orbiting Gliese 832, a red dwarf star just 16 light-years from Earth. Credit: ESO/M. Kornmesser/N. Risinger (skysurvey.org).
In February of 2017, the world was astounded to learn that astronomers – using data from the TRAPPIST telescope in Chile and the Spitzer Space Telescope – had identified a system of seven rocky exoplanets in the TRAPPIST-1 system. As if this wasn’t encouraging enough for exoplanet-enthusiasts, it was also indicated that three of the seven planets orbited within the stars’ circumstellar habitable zone (aka. “Goldilocks Zone”).
Since that time, this system has been the focus of considerable research and follow-up surveys to determine whether or not any of its planets could be habitable. Intrinsic to these studies has been the question whether or not the planets have liquid water on their surfaces. But according to a new study by a team of American astronomers, the TRAPPIST planets may actually have too much water to support life.
The technique of gravitational lensing relies on the presence of a large cluster of matter between the observer and the object to magnify light coming from that object. Credit: NASA
For the sake of studying the most distant objects in the Universe, astronomers often rely on a technique known as Gravitational Lensing. Based on the principles of Einstein’s Theory of General Relativity, this technique involves relying on a large distribution of matter (such as a galaxy cluster or star) to magnify the light coming from a distant object, thereby making it appear brighter and larger.
However, in recent years, astronomers have found other uses for this technique as well. For instance, a team of scientists from the Harvard-Smithsonian Center for Astrophysics (CfA) recently determined that Gravitational Lensing could also be used to determine the mass of white dwarf stars. This discovery could lead to a new era in astronomy where the mass of fainter objects can be determined.
The study which details their findings, titled “Predicting gravitational lensing by stellar remnants” appeared in the Monthly Noticed of the Royal Astronomical Society. The study was led by Alexander J. Harding of the CfA and included Rosanne Di Stefano, and Claire Baker (also from the CfA), as well as members from the University of Southampton, Georgia State University, the University of Nigeria, and Cornell University.
A Hubble image of the white dwarf star PM I12506+4110E (the bright object, seen in black in this negative print) and its field which includes two distant stars PM12-MLC1&2. Credit: Harding et al./NASA/HST
To put it simply, determining the mass of an astronomical object is one the greatest challenges for astronomers. Until now, the most successful method relied on binary systems because the orbital parameters of these systems depend on the masses of the two objects. Unfortunately, objects that are at the end states of stellar evolution – like black holes, neutron stars or white dwarfs – are often too faint or isolated to be detectable.
This is unfortunate, since these objects are responsible for a lot of dramatic astronomical events. These include the accretion of material, the emission of energetic radiation, gravitational waves, gamma-ray bursts, or supernovae. Many of these events are still a mystery to astronomers or the study of them is still in its infancy – i.e. gravitational waves. As they state in their study:
“Gravitational lensing provides an alternative approach to mass measurement. It has the advantage of only relying on the light from a background source, and can therefore be employed even for dark lenses. In fact, since light from the lens can interfere with the detection of lensing effects, compact objects are ideal lenses.”
As they go on to state, of the 18,000 lensing events that have been detected to date, roughly 10 to 15% are believed to have been caused by compact objects. However, scientists are unable to tell which of the detected events were due to compact lenses. For the sake of their study then, the team sought to circumvent this problem by identifying local compact objects and predicting when they might produce a lensing event so they could be studied.
Animation showing the white dwarf star Stein 2051B as it passes in front of a distant background star. Credit: NASA
“By focusing on pre-selected compact objects in the near vicinity of the Sun, we ensure that the lensing event will be caused by a white dwarf, neutron star, or black hole,” they state. “Furthermore, the distance and proper motion of the lens can be accurately measured prior to the event, or else afterwards. Armed with this information, the lensing light curve allows one to accurately measure the mass of the lens.”
In the end, the team determined that lensing events could be predicted from thousands of local objects. These include 250 neutron stars, 5 black holes, and roughly 35,000 white dwarfs. Neutron stars and black holes present a challenge since the known populations are too small and their proper motions and/or distances are not generally known.
But in the case of white dwarfs, the authors anticipate that they will provide for many lensing opportunities in the future. Based on the general motions of the white dwarfs across the sky, they obtained a statistical estimate that about 30-50 lensing events will take place per decade that could be spotted by the Hubble Space Telescope, the ESA’s Gaia mission, or NASA’s James Webb Space Telescope (JWST). As they state in their conclusions:
“We find that the detection of lensing events due to white dwarfs can certainly be observed during the next decade by both Gaia and HST. Photometric events will occur, but to detect them will require observations of the positions of hundreds to thousands of far-flung white dwarfs. As we learn the positions, distances to, and proper motions of larger numbers of white dwarfs through the completion of surveys such as Gaia and through ongoing and new wide-field surveys, the situation will continue to improve.”
The future of astronomy does indeed seem bright. Between improvements in technology, methodology, and the deployment of next-generation space and ground-based telescopes, there is no shortage of opportunities to see and learn more.
The Parkes Telescope in New South Wales, Australia. Credit: Roger Ressmeyer/Corbis
Fast Radio Bursts (FRBs) have been one of the more puzzling and fascinating areas of astronomical study ever since the first was detected in 2007 (known as the Lorimer Burst). Much like gravitational waves, the study of these short-lived radio pulses (which last only a few milliseconds) is still in its infancy, and only a 33 events have been detected. What’s more, scientists are still not sure what accounts for them.
While some believe that they are entirely natural in origin, others have speculated that they could be evidence of extra-terrestrial activity. Regardless of their cause, according to a recent study, three FRBs were detected this month in Australia by the Parkes Observatory radio telescope in remote Australia. Of these three, one happened to be the most powerful FRB recorded to date.
The signals were detected on March 1st, March 9th, and March 11th, and were designated as FRB 180301, FRB 180309 and FRB 180311. Of these, the one recorded on March 9th (FRB 180309) was the brightest ever recorded, having a signal-to-noise ratio that was four times higher than the previous brightest FRB. This event, known as FRB 170827, was detected on August 27th, 2017, by the UTMOST array in Australia.
The Parkes radio telescope, one of the telescopes comprising CSIRO’s Australia Telescope National Facility. Credit: CSIRO
All three of these events were detected by the Parkes radio telescope, which is located in New South Wales about 380 kilometers (236 mi) from Sydney. As one of three telescopes that makes up the Australia Telescope National Facility, this telescope has been studying pulsars, rapidly spinning neutron stars, and conducting large-scale surveys of the sky since 1961. In recent years, it has been dedicated to the detection of FRBs in our Universe.
Considering how rare and short-lived FRBs are, recording three in the space of one month is quite the achievement. What’s more, the fact that the detections happened in real-time, rather than being discovered in archival data, is also impressive. Shortly after the event, Stefan Oslowski (of the Swinburne University of Technology) tweeted about this rather fortunate discovery (see below).
At present, none of the three events are believed to be “repeaters” – aka. Repeating Fast Radio Bursts. So far, only one FRB has been found to be repeating. This was none other than FRB 121102, which was first detected by the Arecibo radio telescope in Puerto Rico on November 2nd, 2012. In 2015, several more bursts were detected from this some source which had properties that were consistent with the original signal.
As noted, and in spite of all the events that have been detected, scientists are still not sure what causes these strange bursts. But with three more events detected, and the possibility that they could repeat in the near-future, scientists now have more events to pore over and base their theories on. And with next-generation arrays being constructed, a great many more events (and repeaters) are likely to be detected in the coming years.
