Posted on by Matt Williams

Here’s Stephen Hawking’s Final Theory About the Big Bang

In honor of Dr. Stephen Hawking, the COSMOS center will be creating the most detailed 3D mapping effort of the Universe to date. Credit: BBC, Illus.: T.Reyes

Stephen Hawking is rightly seen as one of the most influential scientists of our time. In his time on this planet, the famed physicist, science communicator, author and luminary became a household name, synonymous with the likes of Einstein, Newton and Galileo. What is even more impressive is the fact that he managed to maintain his commitment to science, education and humanitarian efforts despite suffering from a slow, degenerative disease.

Even though Hawking recently passed away, his influence is still being felt. Shortly before his death, Hawking submitted a paper offering his final theory on the origins of the Universe. The paper, which was published earlier this week (on Wednesday, May 2nd), offers a new take on the Big Bang Theory that could revolutionize the way we think of the Universe, how it was created, and how it evolved.

The paper, titled “A smooth exit from eternal inflation?“, was published in the Journal of High Energy Physics. The theory was first announced at a conference at the University of Cambridge in July of last year, where Professor Thomas Hertog (a Belgian physicist at KU Leuven University) shared Hawking’s paper (which Hertog co-authored) on the occasion of his 75th birthday.

Stephen Hawking’s final theory on the Big Bang, submitted shortly before he passed away, was recently published. Credit: University of Cambridge

According to the current scientific consensus, all of the current and past matter in the Universe came into existence at the same time – roughly 13.8 billion years ago. At this time, all matter was compacted into a very small ball with infinite density and intense heat. Suddenly, this ball started to inflate at an exponential rate, and the Universe as we know it began.

However, it is widely believed that since this inflation started, quantum effects will keep it going forever in some regions of the Universe. This means that globally, the Universe’s inflation is eternal. In this respect, the observable part of our Universe (measuring 13.8 billion light-years in any direction) is just a region in which inflation has ended and stars and galaxies formed.

As Hawking explained in an interview with Cambridge University last autumn:

“The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean. The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse. But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory can’t be tested. ”

In their new paper, Hawking and Hertog offer a new theory that predicts that the Universe is not an infinite fractal-like multiverse, but is finite and reasonably smooth. In short, they theorize that the eternal inflation, as part of the theory of the Big Bang, is wrong. As Hertog explained:

“The problem with the usual account of eternal inflation is that it assumes an existing background universe that evolves according to Einstein’s theory of general relativity and treats the quantum effects as small fluctuations around this. However, the dynamics of eternal inflation wipes out the separation between classical and quantum physics. As a consequence, Einstein’s theory breaks down in eternal inflation.”

In contrast to this, Hawking and Hertog offer an explanation based on String Theory, a branch of theoretical physics that attempts to unify General Relativity with quantum physics. This theory was proposed to explain how gravity interacts with the three other fundamental forces of the Universe (weak and strong nuclear forces and electromagnetism), thus producing a Theory of Everything (ToE).

To put it simply, this theory describes the fundamental constituents of the Universe as tiny, one-dimensional vibrating strings. Hawking and Hertog’s approach uses the holography concept of string theory, which postulates that the Universe is a large and complex hologram. In this theory, physical reality in certain 3D spaces can be mathematically reduced to 2D projections on a surface.

 

This illustration shows the evolution of the Universe, from the Big Bang on the left, to modern times on the right. Image: NASA

Together, Hawking and Hertog developed a variation of this concept to project out the dimension of time in eternal inflation. This enabled them to describe eternal inflation without having to rely on General Relativity, thus reducing inflation to a timeless state defined on a spatial surface at the beginning of time. In this respect, the new theory represents a change from Hawking’s earlier work on “no boundary theory”.

Also known as the Hartle and Hawking No Bounary Proposal, this theory viewed the Universe like a quantum particle – assigning it a wave function that described all possible Universes. This theory also predicted that if you go back in time to the beginning of the Universe, it would shrink and close off like a sphere. Lastly, it predicted that the Universe would eventually stop expanding and collapse in on itself.

As Hertog explains, this new theory is a departure from that earlier work:

“When we trace the evolution of our universe backwards in time, at some point we arrive at the threshold of eternal inflation, where our familiar notion of time ceases to have any meaning. Now we’re saying that there is a boundary in our past.”

Using this theory, Hawking and Hertog were able to derive more reliable predictions about the global structure of the Universe. In addition, a Universe predicted to emerge from eternal inflation on the past boundary is also finite and much simpler. Last, but not least, the theory is more predictive and testable than the infinite Multiverse predicted by the old theory of eternal inflation.

 

In February 2016, LIGO detected gravity waves for the first time. As this artist's illustration depicts, the gravitational waves were created by merging black holes. The third detection just announced was also created when two black holes merged. Credit: LIGO/A. Simonnet.
Artist’s impression of merging binary black holes. Credit: LIGO/A. Simonnet.

“We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes,” said Hawking. In theory, a finite and smooth Universe is one we can observe (at least locally) and will be governed by physical laws that we are already familiar with. Compared to an infinite number of Universes governed by different physical laws, it certainly simplifies the math!

Looking ahead, Hertog plans to study the implications of this theory on smaller scales using data obtained by space telescopes about the local Universe. In addition, he hopes to take advantage of recent studies concerning gravitational waves (GWs) and the many events that have been detected. Essentially, Hertog believes that primordial GWs generated at the exit from eternal inflation are the most promising means to test the model.

Due to the expansion of our Universe since the Big Bang, these GWs would have very long wavelengths,  ones which are outside the normal range of the Laser Interferometry Gravitational-Wave Observatory‘s (LIGO) or Virgo‘s detectors. However, the Laser Interferometry Space Antenna (LISA) – an ESA-led plan for a space-based gravitational wave observatory – and other future experiments may be capable of measuring them.

Even though he is longer with us, Hawking’s final theory could be his profound contribution to science. If future research should prove him correct, then Hawking will have resolved one of the most daunting problems in modern astrophysics and cosmology. Just one more achievement from a man who spent his life changing how people think about the Universe!

Further Reading: University of Cambridge

Posted on by Matt Williams

NASA Has Tested a New Fission Space Reactor that Could be Used in Future Missions

Artist's concept of new fission power system on the lunar surface. Credits: NASA

Looking to the future of crewed space exploration, it is clear to NASA and other space agencies that certain technological requirements need to be met. Not only are a new generation of launch vehicles and space capsules needed (like the SLS and Orion spacecraft), but new forms of energy production are needed to ensure that long-duration missions to the Moon, Mars, and other locations in the Solar System can take place.

One possibility that addresses these concerns is Kilopower, a lightweight fission power system that could power robotic missions, bases and exploration missions. In collaboration with the Department of Energy’s National Nuclear Security Administration (NNSA), NASA recently conducted a successful demonstration of a new nuclear reactor power system that could enable long-duration crewed missions to the Moon, Mars, and beyond.

Known as the Kilopower Reactor Using Stirling Technology (KRUSTY) experiment, the technology was unveiled at a recent news conference on Wednesday, May 2nd, at NASA’s Glenn Research Center. According to NASA, this power system is capable of generating up to 10 kilowatts of electrical power – enough power several households continuously for ten years, or an outpost on the Moon or Mars.

NASA and NNSA engineers lower the wall of the vacuum chamber around the Kilowatt Reactor Using Stirling TechnologY (KRUSTY system). Credits: Los Alamos National Laboratory

As Jim Reuter, NASA’s acting associate administrator for the Space Technology Mission Directorate (STMD), explained in a recent NASA press release:

“Safe, efficient and plentiful energy will be the key to future robotic and human exploration. I expect the Kilopower project to be an essential part of lunar and Mars power architectures as they evolve.”

The prototype power system employs a small solid uranium-235 reactor core and passive sodium heat pipes to transfer reactor heat to high-efficiency Stirling engines, which convert the heat to electricity. This power system is ideally suited to locations like the Moon, where power generation using solar arrays is difficult because lunar nights are equivalent to 14 days on Earth.

In addition, many plans for lunar exploration involve building outposts in the permanently-shaded polar regions or in stable underground lava tubes. On Mars, sunshine is more plentiful, but subject to the planet’s diurnal cycle and weather (such as dust storms). This technology could therefore ensure a steady supply of power that is not dependent on intermittent sources like sunlight. As Marc Gibson, the lead Kilopower engineer at Glenn, said:

“Kilopower gives us the ability to do much higher power missions, and to explore the shadowed craters of the Moon. When we start sending astronauts for long stays on the Moon and to other planets, that’s going to require a new class of power that we’ve never needed before.”

Artist’s impression of four KRUSTY generators providing power to an outpost on the surface of Mars. Credit: NASA/STMD

The Kilopower experiment was conducted at the NNSA’s Nevada National Security Site (NNSS) between November and March of 2017. In addition to demonstrating that the system could produce electricity through fission, the purpose of the experiment was also to show that it is stable and safe in any environment. For this reason, the Kilopower team conduct in the experiment in four phases.

The first two phases, which were conducted without power, confirmed that each component in the system functioned properly. For the third phase, the team increased power to heat the core slowly before moving on to phase four, which consisted of a 28-hour, full-power test run. This phase simulated all stages of a mission, which included a reactor startup, ramp up to full power, steady operation and shutdown.

Throughout the experiment, the team simulated various system failures to ensure that the system would keep working – which included power reductions, failed engines and failed heat pipe. Throughout, the KRUSTY generator kept on providing electricity, proving that it can endure whatever space exploration throws at it. As Gibson indicated:

“We put the system through its paces. We understand the reactor very well, and this test proved that the system works the way we designed it to work. No matter what environment we expose it to, the reactor performs very well.”

A Kilopower reactor could allow for permanent bases on the Moon and Mars and allow for the local production of fuel and other materials. Credit: ESA/Foster + Partners

Looking ahead, the Kilopower project will remain a part of NASA’s Game Changing Development (GCD) program. As part of NASA’s Space Technology Mission Directorate (STMD), this program’s goal is to advance space technologies that may lead to entirely new approaches for the Agency’s future space missions. Eventually, the team hopes to make the transition to the Technology Demonstration Mission (TDM) program by 2020.

If all goes well, the KRUSTY reactor could allow for permanent human outposts on the Moon and Mars. It could also offer support to missions that rely on In-situ Resource Utilization (ISRU) to produce hydrazine fuel from local sources of water ice, and building materials from local regolith.

Basically, when robotic missions are mounted to the Moon to 3D print bases out of local regolith, and astronauts begin making regular trips to the Moon to conduct research and experiments (like they do today to the International Space Station), it could be KRUSTY reactors that provide them will all their power needs. In a few decades, the same could be true for Mars and even locations in the outer Solar System.

This reactor system could also pave the way for rockets that rely on nuclear-thermal or nuclear-electric propulsion, enabling missions beyond Earth that are both faster and more cost-effective!

And be sure to enjoy this video of the GCD program, courtesy of NASA 360:

Further Reading: NASA

Posted on by Matt Williams

One of the TRAPPIST-1 Planets Has an Iron Core

Artist's impression of TRAPPIST-1e, which has a large iron core, according to a recent study. Credit: NASA/JPL-Caltech

In February of 2017, a team of European astronomers announced the discovery of a seven-planet system orbiting the nearby star TRAPPIST-1. Aside from the fact that all seven planets were rocky, there was the added bonus of three of them orbiting within TRAPPIST-1’s habitable zone. Since that time, multiple studies have been conducted to determine whether or not any of these planets could be habitable.

In accordance with this goal, these studies have focused on whether or not these planets have atmospheres, their compositions and their interiors. One of the latest studies was conducted by two researchers from Columbia University’s Cool Worlds Laboratory, who determined that one of the TRAPPIST-1 planets (TRAPPIST-1e) has a large iron core – a finding which could have implications for this planet’s habitability.

Continue reading “One of the TRAPPIST-1 Planets Has an Iron Core”

Posted on by Matt Williams

NASA is Investigating a Self-Assembling Space Telescope

Graphic depiction of Modular Active Self-Assembling Space Telescope Swarms Credit: D. Savransky

NASA has some pretty advanced concepts in mind when it comes to the next generation of space telescopes. These include the Transiting Exoplanet Survey Satellite (TESS), which recently took to space, as well as the James Webb Space Telescope (JWST) (scheduled to launch in 2020) and the Wide-Field Infrared Survey Telescope (WFIRST), which is still in development.

Beyond these, NASA has also identified several promising proposals as part of its 2020 Decadal Survey for Astrophysics. But perhaps the most ambitious concept is one that calls for a space telescope made up of modules that would assemble themselves. This concept was recently selected for Phase I development as part of the 2018 NASA Innovative Advanced Concepts (NIAC) program.

The team behind this concept is led by Dmitri Savransky, an assistant professor of mechanical and aerospace engineering at Cornell University. Along with 15 colleagues from across the US, Savransky has produced a concept for a ~30 meter (100 foot) modular space telescope with adaptive optics. But the real kicker is the fact that it would be made up of a swarm of modules that would assemble themselves autonomously.

On March. 23rd, 16 concepts received a Phase I award as part of the NASA Innovative Advanced Concepts (NIAC) program. Credit: NASA

Prof. Savransky is well-versed in space telescopes and exoplanet hunting, having assisted in the integration and testing of the Gemini Planet Imager – an instrument on the Gemini South Telescope in Chile. He also participated in the planning of the Gemini Planet Imager Exoplanet Survey, which discovered a Jupiter-like planet orbiting 51 Eridani (51 Eridani b) in 2015.

But looking to the future, Prof. Savransky believes that self-assembly is the way to go to create a super telescope. As he and his team described the telescope in their proposal:

“The entire structure of the telescope, including the primary and secondary mirrors, secondary support structure and planar sunshield will be constructed from a single, mass-produced spacecraft module. Each module will be composed of a hexagonal ~1 m diameter spacecraft topped with an edge-to-edge, active mirror assembly.”

These modules would be launched independently and then navigate to the Sun-Earth L2 point using deployable solar sails. These sails will then become the planar telescope sunshield once the modules come together and assemble themselves, without the need for human or robotic assistance. While this may sound radically advanced, it is certainly in keeping with what the NIAC looks for.

“That’s what the NIAC program is,” said Dr. Savransky in recent interview with the Cornell Chronicle. “You pitch these somewhat crazy-sounding ideas, but then try to back them up with a few initial calculations, and then it’s a nine-month project where you’re trying to answer feasibility questions.”

Artist’s concept of the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) space telescope. Credits: NASA/GSFC

As part of the 2018 NAIC’s Phase I awards, which were announced on March 30th, the team was awarded $125,000 over a nine month period to conduct these studies. If these are successful, the team will be able to apply for a Phase II award. As Mason Peck, an associate professor of mechanical and aerospace engineering at Cornell and the former chief technology officer at NASA, indicated, Savransky is on the right track with his NIAC proposal:

“As autonomous spacecraft become more common, and as we continue to improve how we build very small spacecraft, it makes a lot of sense to ask Savransky’s question: Is it possible to build a space telescope that can see farther, and better, using only inexpensive small components that self-assemble in orbit?”

The target mission for this concept is the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR), a proposal that is currently being explored as part of NASA’s 2020 Decadal Survey. As one of two concepts being investigated by NASA’s Goddard Space Flight Center, this mission concept calls for a space telescope with a massive segmented primary mirror that measures about 15 meters (49 feet) in diameter.

Much like the JWST, LUVOIR’s mirror would be made up of adjustable segments that would unfold once it deployed to space. Actuators and motors would actively adjust and align these segments in order to achieve the perfect focus and capture light from faint and distant objects. The primary aim of this mission would be to discover new exoplanets as well as analyze light from those that have already been discovered to asses their atmospheres.

The Hubble Space Telescope on the left has a 2.4 meter mirror and the James Webb Space Telescope has a 6.5 meter mirror. LUVOIR, not shown, will dwarf them both with a massive 15 meter mirror. Image: NASA
The Hubble Space Telescope on the left has a 2.4 meter mirror and the James Webb Space Telescope has a 6.5 meter mirror. LUVOIR, not shown, will dwarf them both with a massive 15 meter mirror. Image: NASA

As Savransky and his colleagues indicated in their proposal, their concept is directly in line with the priorities of the NASA Technology Roadmaps in Science Instruments, Observatories, and Sensor Systems and Robotics and Autonomous Systems. They also state that the architecture is a credible means to construct a giant space telescope, which would not be possible for previous generations of telescopes like Hubble and the JWST.

“James Webb is going to be the largest astrophysical observatory we’ve ever put in space, and it’s incredibly difficult,” he said. “So going up in scale, to 10 meters or 12 meters or potentially even 30 meters, it seems almost impossible to conceive how you would build those telescopes the same way we’ve been building them.”

Having been granted a Phase I award, the team is planning to conduct detailed simulations of how the modules would fly through space and rendezvous with each other to determine how large the solar sails need to be. They also plan to conduct an analysis of the mirror assembly to validate that the modules could achieve the required surface figure once assembled.

As Peck indicated, if successful, Dr. Savransky’s proposal could be a game changer:

“If Professor Savransky proves the feasibility of creating a large space telescope from tiny pieces, he’ll change how we explore space. We’ll be able to afford to see farther, and better than ever – maybe even to the surface of an extrasolar planet.”

On June 5th and 6th, NASA will also be conducting an NIAC Orientation Meeting in Washington D.C., where all the Phase I winners will have a chance to meet and discuss their ideas. Other proposals that received a Phase I award include shape-shifting robots for exploring Titan, lightweight aerial sensors to explore Venus’ atmosphere, flapping-wing swarm robots to explore Mars, a new form of beam propulsion for interstellar missions (similar to Breakthrough Starshot),  a steam-powered robot for ocean worlds, and a self-replicating habitat made from fungus.

You can read more about these concepts, as well as those that were given Phase II award, here.

Further Reading: Cornell Chronicle, NASA

Posted on by Matt Williams

One Bonus From the Gaia Data Release: the Rotation of the Large Magellanic Cloud

Rotation of the Large Magellanic Cloud, as revealed by the ESA's Gaia spacecraft. Copyright: ESA/Gaia/DPAC

On December 19th, 2013, the European Space Agency’s (ESA) Gaia spacecraft took to space with for a very ambitious mission. Over the course of its planned 5-year mission (which was recently extended), this space observatory would map over a billion stars, planets, comets, asteroids and quasars in order to create the largest and most precise 3D catalog of the Milky Way ever created.

Since that time, the ESA has made two data releases that cover the first three years of the Gaia mission. The second data release, which took on April 25th, 2018, has already proven to be a treasure trove for astronomers. In addition to the positions, distance indicators and motions of over a billion stars and celestial objects in the Milky Way Galaxy, it also contained a hidden gem – the proper motions of stars within the Large Magellanic Cloud (LMC).

Located about 200,000 light-years from Earth, the LMC has dense clouds of dust that results in it experiencing high rates of star formation. In addition, it’s central bar is warped (where the east and west ends are nearer to the Milky Way), suggesting that it was once a barred dwarf spiral galaxy who’s spiral arms were disrupted by interaction with the Small Magellanic Cloud (SMC) and the Milky Way.

The proper motions of the stars in the LMC, as captured by the Gaia spacecraft (without color). Copyright: ESA/Gaia/DPAC

For these reasons, astronomers have been hoping to derive the orbits of dwarf galaxies (and globular clusters) that revolve around the Milky Way. In so doing, they hope to learn more about how our galaxy evolved due to mergers with clusters and other galaxies. By determining the proper motions of the LMC’s stars, the Gaia mission has provided clues as to how the Milky Way and its largest satellite galaxy have interacted over time.

As you can see from the image (at top), the bar of the LMC is outlined in great detail, along with individual star-forming regions like the Tarantula Nebula (aka. 30 Doradus, which is visible just above the center of the galaxy). The image combines the total amount of radiation detected by the observatory in each pixel. The radiation measurements were then taken through different filters on the spacecraft to generate color information.

This allowed Gaia to obtain information about the total density of stars within the LMC as well as their proper motions. As you can see, the image is dominated by the brightest, most massive stars, which greatly outshine their fainter, lower-mass counterparts. The proper motions of the stars observed is represented as the texture of the image – which looks a lot like a fingerprint.

The Large Magellanic Cloud (LMC), one of the nearest galaxies to our Milky Way, as viewed by ESA’s Gaia satellite using information from the mission’s second data release. Copyright ESA/Gaia/DPAC

From this, scientists were able to see an imprint of the stars rotating clockwise around the center of the galaxy. Using this information, astronomers will be able to create new models on how the LMC, SMC, and Milky Way evolved together over time. This, in turn, could shed light on how galaxies like our own, formed and evolved over the course of billions of years.

As with other information contained in the first and second data releases, this latest discovery demonstrates that the Gaia mission is fulfilling its intended purpose. The third release of Gaia data is scheduled to take place in late 2020, with the final catalog being published in the 2020s. Meanwhile, an extension has already been approved for the Gaia mission, which will now remain in operation until the end of 2020 (to be confirmed at the end of this year).

And be sure to enjoy this animated view of the LMC’s rotation, courtesy of the ESA:

Further Reading: ESA

Posted on by Matt Williams

ExoMars Has Sent Back its First Images From Mars

ExoMars images Korolev Crater. Copyright: ESA/Roscosmos/CaSSIS

On October 19th, 2016, the European Space Agency’s Exobiology on Mars (ExoMars) mission established orbit around Mars. Consisting of the ExoMars Trace Gas Orbiter (TGO) and the Schiaparelli lander, the purpose of this mission is to investigate Mars for past signs of life. And whereas the Schiaparelli unfortunately crashed during deployment, the TGO has managed to begin its mission ahead of schedule.

A few weeks ago, the satellite achieved a near circular orbit around Mars after performing a series of braking maneuvers. Since that time, the orbiter’s Color and Stereo Surface Imaging System (CaSSIS) took a stunning image of the surface. This picture was not only the TGO’s first image of Mars, it was also a test to see if the orbiter is ready to being its main mission on April 28th.

The image captured a 40 km- (25 mi) long segment of the Korolev Crater, which is located high in Mars’ northern hemisphere. The image was a composite of three images in different colors that were taken simultaneously on April 15th, 2018, which were then assembled to produce this color image. The bright material that appears at the edge of the crater is water ice.

The ExoMars Colour and Stereo Surface Imaging System, CaSSIS, captured this view of the rim of Korolev crater (73.3ºN/165.9ºE). Copyright ESA/Roscosmos/CaSSIS

As Antoine Pommerol, a member of the CaSSIS science team working on the calibration of the data, explained in a recent ESA press release:

“We were really pleased to see how good this picture was given the lighting conditions. It shows that CaSSIS can make a major contribution to studies of the carbon dioxide and water cycles on Mars.”

Prior to the test phase, the camera team transmitted new software to the TGO, and after a few minor issues, they determined that the instrument was ready to work. The camera is one of four instruments on the TGO, which also carries two spectrometer suites and a neutron detector. The spectrometers began their science mission on April 21st by taking the first sample of the atmosphere to see how its molecules absorb sunlight.

By doing this, the TGO hopes to determine the chemical composition of Mars atmosphere and find evidence of methane and other trace atmospheric gases that could be signatures of active biological or geological processes. Eventually, the camera will help characterize features on the surface that could be related to trace gas sources. Hence the importance of this recent test.

ExoMars’ Trace Gas Orbiter (TGO) and Schiaparelli lander seperating in orbit of Mars. Credit: ESA/ATG medialab

“We aim to fully automate the image production process,” said Nicolas Thomas, the camera’s principal investigator from the University of Bern. “Once we achieve this, we can distribute the data quickly to the science community for analysis.”

A lot of challenges lie ahead, which includes a long period of data collection to bring out the details of rare (or yet to be discovered) trace gases in Mars’ atmosphere. This is necessary since trace gases (as the name would suggest) are present in only very small amounts – i.e. less than 1% of the volume of the planet’s atmosphere. But as Håkan Svedhem – the ESA’s TGO project scientist – indicated, the test image was a good start.

“We are excited to finally be starting collecting data at Mars with this phenomenal spacecraft,” he said. “The test images we have seen so far certainly set the bar high.”

By 2020, the second part of the ExoMars mission is scheduled to launch. This will consist of a Russian surface platform and a European rover landing on the surface in support of a science mission that is expected to last into 2022 or longer. Alongside NASA’s proposed Mars 2020 rover, the Red Planet is due to have several more visitors in the coming years!

Further Reading: ESA

Posted on by Matt Williams

For the First Time, Astronomers Have Found a Star That Survived its Companion Exploding as Supernova

Hubble image of the supernova SN 2001ig, which indicated the presence of a companion. Credits: NASA, ESA, S. Ryder (Australian Astronomical Observatory), and O. Fox (STScI)

A Type II supernova is a truly amazing astronomical event. As with all supernovae, a Type II consists of a star experiencing core collapse at the end of its life cycle and exploding, causing it to shed its outer layers. A subclass of this type is known as Type IIb, which are stars that have been stripped of their hydrogen fuel and undergo collapse because they are no longer able to maintain fusion in their core.

Seventeen years ago, astronomers were fortunate enough to witness a Type IIb supernova in the galaxy NGC 7424, located 40 million light-years away in the southern constellation Grus. Now that this supernova has faded, the Hubble Space Telescope recently captured the first image of a surviving companion, thus demonstrating that supernovae do indeed happen in double-star systems.

The study, titled “Ultraviolet Detection of the Binary Companion to the Type IIb SN 2001ig“, was recently published in the Astrophysical Journal. The study was led by Stuart Ryder of the Australian Astronomical Observatory and included members from California Institute of Technology (Caltech), the Space Telescope Science Institute (STSI), the University of Amsterdam, the University of Arizona, the University of York, and the University of California.

This discovery is the most compelling evidence to date that some supernovae originate as a result of siphoning between binary pairs. As Stuart Ryder indicated in a recent NASA press release:

“We know that the majority of massive stars are in binary pairs. Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together.”

The supernova, called SN 2001ig, was pinpointed by astronomers in 2002 using the European Southern Observatory’s Very Large Telescope (VLT). In 2004, these observations were followed-up with the Gemini South Observatory, which first hinted at the presence of a surviving binary companion. Knowing the exact coordinates, Ryder and his team were able to focus Hubble on that location as the supernova’s glow faded.

The find was especially fortuitous because it might also shed light on a astronomical mystery, which is how stripped-envelop supernovae lose their outer envelopes. Originally, scientists believed they were the result of stars with very fast winds that pushed off their outer envelopes. However, when astronomers began looking for the primary stars which spawned these supernovae, they could not find them.

Artist’s impression of a pulsar siphoning material from a companion star. Credit: NASA

As Ori Fox, a member of the Space Telescope Science Institute and a co-author on the paper, explained:

“That was especially bizarre, because astronomers expected that they would be the most massive and the brightest progenitor stars. Also, the sheer number of stripped-envelope supernovas is greater than predicted.”

This led scientists to theorize that many of the stripped-envelop stars were the primary in lower-mass binary star systems. All that remained was to find a supernova that was part of a binary system, which Ryder and his colleagues set out to do. This was no easy task, seeing as how the companion was rather faint and at the very limits of what Hubble could see.

In addition, not many supernovae are known to go off within this distance range. Last, but not least, they had to know the exact position through very precise measurements. Thanks to Hubble’s exquisite resolution and ultraviolet capability, they were able to find and photograph the surviving companion.

Prior to the supernova, the stars orbited each other with a period of about one year. When the primary star exploded, it had an impact on the companion, but it remained intact. Because of this, SN 2001ig is the first surviving companion to ever be photographed.

Artist’s rendering of SN 1993J, where a red supergiant supernova progenitor star (left) is exploding after having transferred about 10 solar masses of hydrogen gas to the blue companion star (right). Credit: ESA

Looking ahead, Ryder and his team hope to precisely determine how many supernovae with stripped envelopes have companions. At present, it is estimated that at least half of them do, while the other half lose their outer enveloped due to stellar winds. Their next goal is to examine completely stripped-envelope supernovae, as opposed to SN 2001ig and SN 1993J, which were only about 90% stripped.

Luckily, they won’t have to wait as long to examine these completely stripped-envelope supernovae, since they don’t have as much shock interaction with gas in their surrounding environment. In short, since they lost their outer envelopes long before they exploded, they fade much faster. This means that the team will only have to wait two to three years before looking for the surviving companions.

Their efforts are also likely to be helped by the deployment of the James Webb Space Telescope (JWST), which is scheduled to launch in 2020. Depending on what they find, astronomers may be ready to resolve the mystery of what causes the different types of supernovae, which could also reveal more about the life cycles of stars and the birth of black holes.

Further Reading: NASA, The Astrophysical Journal

Posted on by Matt Williams

Astronomers See a Pileup of 14 Separate Galaxies in the Early Universe

Artist impression of 14 galaxies detected by ALMA as they appear in the very early, very distant universe. These galaxies are in the process of merging and will eventually form the core of a massive galaxy cluster. Credit: NRAO/AUI/NSF; S. Dagnello

Looking deep into the observable Universe – and hence, back to the earliest periods of time – is an immensely fascinating thing. In so doing, astronomers are able to see the earliest galaxies in the Universe and learn more about how they evolved over time. From this, they are not only able to see how large-scale structures (like galaxies and galaxy clusters) formed, but also the role played by dark matter.

Most recently, an international team of scientists used the Atacama Large Millimeter-submillimeter Array (ALMA) to observe the Universe when it was just 1.4 billion years old. What they observed was a “protocluster”, a series of 14 galaxies located 12.4 billion light-years away that were about to merge. This would result in the formation of a massive galaxy cluster, one of the largest objects in the known Universe.

The study which described their findings, titled “A massive core for a cluster of galaxies at a redshift of 4.3“, recently appeared in the journal Nature. The study was led by Tim Miller – an astronomer from Dalhousie University, Halifax, and Yale University – and included members from NASA’s Jet Propulsion Laboratory, the European Southern Observatory (ESO), Canada’s National Research Council, the Harvard-Smithsonian Center for Astrophysics, the National Radio Astronomy Observatory, and multiple universities and research institutions.

ALMA image of 14 galaxies forming a protocluster known as SPT2349-56. These galaxies are in the process of merging and will eventually form the core of a truly massive galaxy cluster. Credit: ALMA (ESO/NAOJ/NRAO); B. Saxton (NRAO/AUI/NSF)

As they indicate in their study, this protocluster (designated SPT2349-56) was first observed by the National Science Foundation’s South Pole Telescope. Using the Atacama Pathfinder Experiment (APEX), the team conducted follow-up observations that confirmed that it was an extremely distant galactic source, which was then observed with ALMA. Using ALMA’s superior resolution and sensitivity, they were able to distinguish the individual galaxies.

What they found was that these galaxies were forming stars at rate 1,000 times faster than our galaxy, and were crammed inside a region of space that was about three times the size of the Milky Way. Using the ALMA data, the team was also able to create sophisticated computer simulations that demonstrated how this current collection of galaxies will likely grow and evolve over billion of years.

These simulations indicated that once these galaxies merge, the resulting galaxy cluster will rival some of the most massive clusters we see in the Universe today. As Scott Chapman, and astrophysicist at Dalhousie University and a co-author on the study, explained:

“Having caught a massive galaxy cluster in throes of formation is spectacular in and of itself. But, the fact that this is happening so early in the history of the universe poses a formidable challenge to our present-day understanding of the way structures form in the universe.”

Zooming in to the galaxies discovered by ALMA that are evolving into a galaxy cluster. Credit: ALMA (ESO/NAOJ/NRAO), T. Miller & S. Chapman et al.; Herschel; South Pole Telescope; (NRAO/AUI/NSF) B. Saxton

The current scientific consensus among astrophysicists states that a few million years after the Big Bang, normal matter and dark matter began to form larger concentrations, eventually giving rise to galaxy clusters. These objects are the largest structures in the Universe, containing trillions of stars, thousands of galaxies, immense amounts of dark matter and massive black holes.

However, current theories and computer models have suggested that protoclusters – like the one observed by ALMA – should have taken much longer to evolve. Finding one that dates to just 1.4 billion years after the Big Bang was therefore quite the surprise. As Tim Miller, who is currently a doctoral candidate at Yale University, indicated:

“How this assembly of galaxies got so big so fast is a bit of a mystery, it wasn’t built up gradually over billions of years, as astronomers might expect. This discovery provides an incredible opportunity to study how galaxy clusters and their massive galaxies came together in these extreme environments.”

Looking to the future, Chapman and his colleagues hope to conduct further studies of SPT2349-56 to see how this protoclusters eventually became a galaxy cluster. “ALMA gave us, for the first time, a clear starting point to predict the evolution of a galaxy cluster,” he said. “Over time, the 14 galaxies we observed will stop forming stars and will collide and coalesce into a single gigantic galaxy.”

The study of this and other protoclusters will be made possible thanks to instruments like ALMA, but also next-generation observatories like the Square Kilometer Array (SKA). Equipped with more sensitive arrays and more advanced computer models, astronomers may be able to create a truly accurate timeline of how our Universe became what it is today.

Further Reading: NRAO, Nature

Posted on by Matt Williams

Jeff Bezos Says The New Shepard Will Soar Next on Sunday. Here’s How to Watch It Live.

The New Shepard launching from its facility in West Texas. Image: Blue Origin
The New Shepard rocket launching from its facility in West Texas. Image: Blue Origin

One of the greatest challenges of modern spaceflight is finding a way to make launching rockets into space commercially viable. Reduced costs will not only mean more launches, but the ability to conduct more ambitious programs in Low Earth Orbit (LEO) and beyond. To this end, many private aerospace companies are investing in reusability, where the first-stages of a rocket and even entire vehicles are retrieved after launch and reused.

In recent years, Elon Musk has become famous for his development of reusable first-stage boosters and fairings. But Blue Origin’s Jeff Bezos has also been no slouch when it comes to making the company’s fleet of rockets reusable. On Sunday, April 29th, the company is passing another milestone with the 8th test flight of the New Shephard rocket, an event which is being live-streamed.

As a fully reusable vertical takeoff, vertical landing (VTVL) space vehicle, the New Shephard is crucial to Blue Origins’ vision of commercial spaceflight and space tourism. Consisting of a pressurized capsule aboard a booster, the combined vehicle launches vertically and accelerates for two and a half minutes before the engine cuts off. The capsule then separates and floats into suborbit while the booster returns to Earth under its own power and with the help of parachutes.

Named in honor of famed astronaut Alan Shepard, the rocket’s crew capsule has room for six people. These will consist of customers looking to take a flight to suborbital altitudes and experience the sensation of weightlessness. As they state on their website:

“The New Shepard capsule’s interior is an ample 530 cubic feet – offering over 10 times the room Alan Shepard had on his Mercury flight. It seats six astronauts and is large enough for you to float freely and turn weightless somersaults.”

The announcement for the 8th test launch came on Friday, April. 27th, when Bezos tweeted that “launch preparations are underway for New Shepard’s 8th test flight, as we continue our progress toward human spaceflight. Currently targeting Sunday 4/29 with launch window opening up at 830am CDT.” The launch would take place at the company’s suborbital launch and engine test site near the town of Van Horn in West Texas.

As with the previous New Shepard test launch, which took place on Dec. 12th, 2017, the crew for this mission would be the mannequin known as “Mannequin Skywalker” (check out the video of this flight below). As with the previous uncrewed flight, Mannequin Skywalker will be testing the capsule’s safety restrains in advance of a crewed test flight.

At 0526 (0826 PST), Bezos tweeted that the flight window – which was originally set for 0845 CDT (0630 PDT) – had been delayed due to thunderstorm over West Texas.  At 0950 CDT (0750 PDT), Bezos issued a follow-up tweet that the liftoff target was now 1113 CDT (0913 PST). Live streaming will begin 15 minutes before the launch, which you can watch by going to Blue Origin’s website.

If successful, this launch test will place Blue Origin one step closer to conducting space tourism. As Bob Smith, the CEO of Blue Origin, recently indicated in an interview with CNBC, he hopes the company will begin these launches by the end of this year. In addition, he said that the company continues to pursue the development of engine technology, which it hopes United Launch Alliance will use on its Vulcan rockets as well.

Be sure to check out the live-steam of the launch, and feel free to enjoy this video of the New Shepard conducting a space tourism flight while you’re waiting:

Further Reading: Blue Origin

Posted on by Matt Williams

Dream About the Future of Big Telescopes; Monster Space Telescopes That Could Fly by the 2030s

Image: James Webb Space Telescope
NASA's James Webb Telescope, shown in this artist's conception, will provide more information about previously detected exoplanets. Beyond 2020, many more next-generation space telescopes are expected to build on what it discovers. Credit: NASA

With the recent launch of the Transiting Exoplanet Survey Satellite (TESS) – which took place on Wednesday, April 18th, 2018 – a lot of attention has been focused on the next-generation space telescopes that will be taking to space in the coming years. These include not only the James Webb Space Telescope, which is currently scheduled for launch in 2020, but some other advanced spacecraft that will be deployed by the 2030s.

Such was the subject of the recent 2020 Decadal Survey for Astrophysics, which included four flagship mission concepts that are currently being studied. When these missions take to space, they will pick up where missions like Hubble, Kepler, Spitzer and Chandra left off, but will have greater sensitivity and capability. As such, they are expected to reveal a great deal more about our Universe and the secrets it holds.

As expected, the mission concepts submitted to the 2020 Decadal Survey cover a wide range of scientific goals – from observing distant black holes and the early Universe to investigating exoplanets around nearby stars and studying the bodies of the Solar System. These ideas were thoroughly vetted by the scientific community, and four have been selected as being worthy of pursuit.

Artist’s concept of the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) space telescope. Credits: NASA/GSFC

As Susan Neff, the chief scientist of NASA’s Cosmic Origins Program, explained in a recent NASA press release:

“This is game time for astrophysics. We want to build all these concepts, but we don’t have the budget to do all four at the same time. The point of these decadal studies is to give members of the astrophysics community the best possible information as they decide which science to do first.”

The four selected concepts include the Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR), a giant space observatory developed in the tradition of the Hubble Space Telescope. As one of two concepts being investigated by NASA’s Goddard Space Flight Center, this mission concept calls for a space telescope with a massive segmented primary mirror that measures about 15 meters (49 feet) in diameter.

In comparison, the JWST‘s (currently the most advanced space telescope) primary mirror measures 6.5 m (21 ft 4 in) in diameter. Much like the JWST, LUVOIR’s mirror would be made up of adjustable segments that would unfold once it deployed to space. Actuators and motors would actively adjust and align these segments in order to achieve the perfect focus and capture light from faint and distant objects.

With these advanced tools, LUVOIR would be able to directly image Earth-sized planets and assess their atmospheres. As Study Scientist Aki Roberge explained:

“This mission is ambitious, but finding out if there is life outside the solar system is the prize. All the technology tall poles are driven by this goal… Physical stability, plus active control on the primary mirror and an internal coronagraph (a device for blocking starlight) will result in picometer accuracy. It’s all about control.”

There’ also the Origins Space Telescope (OST), another concept being pursued by the Goddard Space Flight Center. Much like the Spitzer Space Telescope and the Herschel Space Observatory, this far-infrared observatory would offer 10,000 times more sensitivity than any preceding far-infrared telescope. Its goals include observing the farthest reaches of the universe, tracing the path of water through star and planet formation, and searching for signs of life in the atmospheres of exoplanets.

Its primary mirror, which would measure about 9 m (30 ft) in diameter, would be the first actively cooled telescope, keeping its mirror at a temperature of about 4 K (-269 °C; -452 °F) and its detectors at a temperature of 0.05 K. To achieve this, the OST team will rely on flying layers of sunshields, four cryocoolers, and a multi-stage continuous adiabatic demagnetization refrigerator (CADR).

Artist’s concept of the the Origins Space Telescope (OST). Credits: NASA/GSFC

According to Dave Leisawitz, a Goddard scientist and OST study scientist, the OST is especially reliant on large arrays of superconducting detectors that measure in the millions of pixels. “When people ask about technology gaps in developing the Origins Space Telescope, I tell them the top three challenges are detectors, detectors, detectors,” he said. “It’s all about the detectors.”

Specifically, the OST would rely on two emerging types of detectors: Transition Edge Sensors (TESs) or Kinetic Inductance Detectors (KIDs). While still relatively new, TES detectors are quickly maturing and are currently being used in the HAWC+ instrument aboard NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA).

Then there’s the Habitable Exoplanet Imager (HabEx) which is being developed by NASA’s Jet Propulsion Laboratory. Like LUVOIR, this telescope would also directly image planetary systems to analyze the composition of planets’ atmospheres with a large segmented mirror. In addition, it would study the earliest epochs in the history of the Universe and the life cycle of the most massive stars, thus shedding light on how the elements that are necessary for life are formed.

Also like LUVOIR, HabEx would be able to conduct studies in the ultraviolet, optical and near-infrared wavelengths, and be able to block out a parent star’s brightness so that it could see light being reflected off of any planets orbiting it. As Neil Zimmerman, a NASA expert in the field of coronagraphy, explained:

“To directly image a planet orbiting a nearby star, we must overcome a tremendous barrier in dynamic range: the overwhelming brightness of the star against the dim reflection of starlight off the planet, with only a tiny angle separating the two. There is no off-the-shelf solution to this problem because it is so unlike any other challenge in observational astronomy.”

Artist’s rendition of the Habitable Exoplanet Imager (HabEx) space telescope. Credits: NASA/JPL

To address this challenge, the HabEx team is considering two approaches, which include external petal-shaped star shades that block light and internal coronagraphs that prevent starlight from reaching the detectors. Another possibility being investigated is to apply carbon nanotubes onto the coronagraphic masks to modify the patterns of any diffracted light that still gets through.

Last, but not least, is the X-ray Surveyor known as Lynx being developed by the Marshall Space Flight Center. Of the four space telescopes, Lynx is the only concept which will examine the Universe in X-rays. Using an X-ray microcalorimeter imaging spectrometer, this space telescope will detect X-rays coming from Supermassive Black Holes (SMBHs) at the center of the earliest galaxies in the Universe.

This technique consists of X-ray photos hitting a detector’s absorders and converting their energy to heat, which is measured by a thermometer. In this way, Lynx will help astronomers unlock how the earliest SMBHs formed. As Rob Petre, a Lynx study member at Goddard, described the mission:

“Supermassive black holes have been observed to exist much earlier in the universe than our current theories predict. We don’t understand how such massive objects formed so soon after the time when the first stars could have formed. We need an X-ray telescope to see the very first supermassive black holes, in order to provide the input for theories about how they might have formed.”

Artist’s impression of the X-ray Surveyor (Lynx) space telescope. Credits: NASA/MSFC

Regardless of which mission NASA ultimately selects, the agency and individual centers have begun investing in advanced tools to pursue such concepts in the future. The four teams submitted their interim reports back in March. By next year, they are expected to finish final reports for the National Research Council (NRC), which will be used to inform its recommendations to NASA in the coming years.

As Thai Pham, the technology development manager for NASA’s Astrophysics Program Office, indicated:

“I’m not saying it will be easy. It won’t be. These are ambitious missions, with significant technical challenges, many of which overlap and apply to all. The good news is that the groundwork is being laid now.”

With TESS now deployed and the JWST scheduled to launch by 2020, the lessons learned in the next few years will certainly be incorporated into these missions. At present, it is not clear which of the following concepts will be going to space by the 2030s. However, between their advanced instruments and the lessons learned from past missions, we can expect that they will make some profound discoveries about the Universe.

Further Reading: NASA, NASA (2)