Violent Collision with Superluminous Supernovae

In a unique study, an international team of researchers including members from the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) simulated the violent collisions between supernovae and its surrounding gas – which is ejected before a supernova explosion, thereby giving off an extreme brightness.


Many supernovae have been discovered in the last decade with peak luminosity one-to-two orders of magnitude higher than for normal supernovae of known types. These stellar explosions are called Superluminous Supernovae (SLSNe).

Some of them have hydrogen in their spectra, while some others demonstrate a lack of hydrogen. The latter are called Type I, or hydrogen-poor, SLSNe-I. SLSNe-I challenge the theory of stellar evolution, since even normal supernovae are not yet completely understood from first principles.

Led by Sternberg Astronomical Institute researcher Elena Sorokina, who was a guest investigator at Kavli IPMU, and Kavli IPMU Principal Investigator Ken’ichi Nomoto, Scientific Associate Sergei Blinnikov, as well as Project Researcher Alexey Tolstov, the team developed a model that can explain a wide range of observed light curves of SLSNe-I in a scenario which requires much less energy than other proposed models.

The models demonstrating the events with the minimum energy budget involve multiple ejections of mass in presupernova stars. Mass loss and buildup of envelopes around massive stars are generic features of stellar evolution. Normally, those envelopes are rather diluted, and they do not change significantly the light produced in the majority of supernovae.

In some cases, large amount of mass are expelled just a few years before the final explosion. Then, the “clouds” around supernovae may be quite dense. The shockwaves produced in collisions of supernova ejecta and those dense shells may provide the required power of light to make the supernova much brighter than a “naked” supernova without pre-ejected surrounding material.

This class of the models is referred to as “interacting” supernovae. The authors show that the interacting scenario is able to explain both fast and slowly fading SLSNe-I, so the large range of these intriguingly bright objects can in reality be almost ordinary supernovae placed into extraordinary surroundings.

Another extraordinarity is the chemical composition expected for the circumstellar “clouds.” Normally, stellar wind consists of mostly hydrogen, because all thermonuclear reactions happen in the center of a star, while outer layers are hydrogenous.

In the case of SLSNe-I, the situation must be different. The progenitor star must lose its hydrogen and a large part of helium well before the explosion, so that a few months to a few years before the explosion, it ejects mostly carbon and oxygen, and then explode inside that dense CO cloud. Only this composition can explain the spectral and photometric features of observed hydrogen-poor SLSNe in the interacting scenario.

It is a challenge for the stellar evolution theory to explain the origin of such hydrogen- and helium-poor progenitors and the very intensive mass loss of CO material just before the final explosion of the star. These results have been published in a paper accepted by The Astrophysical Journal.

New Family of Stars Discovered in Milky Way

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


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

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

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

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

Ricardo Schiavon, lead researcher on the project said:

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

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

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

Powerful Punch of Gamma Rays Found in Mysterious Fast Radio Bursts

Penn State University astronomers have discovered that the mysterious “cosmic whistles” known as fast radio bursts can pack a serious punch, in some cases releasing a billion times more energy in gamma-rays than they do in radio waves and rivaling the stellar cataclysms known as supernovae in their explosive power. The discovery, the first-ever finding of non-radio emission from any fast radio burst, drastically raises the stakes for models of fast radio bursts and is expected to further energize efforts by astronomers to chase down and identify long-lived counterparts to fast radio bursts using X-ray, optical, and radio telescopes.


Fast radio bursts, which astronomers refer to as FRBs, were first discovered in 2007, and in the years since radio astronomers have detected a few dozen of these events. Although they last mere milliseconds at any single frequency, their great distances from Earth — and large quantities of intervening plasma — delay their arrival at lower frequencies, spreading the signal out over a second or more and yielding a distinctive downward-swooping “whistle” across the typical radio receiver band.

“This discovery revolutionizes our picture of FRBs, some of which apparently manifest as both a whistle and a bang,” said coauthor Derek Fox, a Penn State professor of astronomy and astrophysics. The radio whistle can be detected by ground-based radio telescopes, while the gamma-ray bang can be picked up by high-energy satellites like NASA’s Swift mission. “Rate and distance estimates for FRBs suggest that, whatever they are, they are a relatively common phenomenon, occurring somewhere in the universe more than 2,000 times a day.”


Efforts to identify FRB counterparts began soon after their discovery but have all come up empty until now. In a paper recently published in Astrophysical Journal Letters the Penn State team, led by physics graduate student James DeLaunay, reports bright gamma-ray emission from the fast radio burst FRB 131104, named after the date it occurred, 4 November 2013. “I started this search for FRB counterparts without expecting to find anything,” said DeLaunay. “This burst was the first that even had useful data to analyse. When I saw that it showed a possible gamma-ray counterpart, I couldn’t believe my luck!”


Discovery of the gamma-ray “bang” from FRB 131104, the first non-radio counterpart to any FRB, was made possible by NASA’s Earth-orbiting Swift satellite, which was observing the exact part of the sky where FRB 131104 occurred as the burst was detected by the Parkes Observatory radio telescope in Parkes, Australia. “Swift is always watching the sky for bursts of X-rays and gamma-rays,” said Neil Gehrels, the mission’s principal investigator and chief of the Astroparticle Physics Laboratory at NASA’s Goddard Space Flight Center. “What a delight it was to catch this flash from one of the mysterious fast radio bursts.”

“Although theorists had anticipated that FRBs might be accompanied by gamma rays, the gamma-ray emission we see from FRB 131104 is surprisingly long-lasting and bright,” Fox said. The duration of the gamma-ray emission, at two to six minutes, is many times the millisecond duration of the radio emission. And the gamma-ray emission from FRB 131104 outshines its radio emissions by more than a billion times, dramatically raising estimates of the burst’s energy requirements and suggesting severe consequences for the burst’s surroundings and host galaxy.

Two common models for gamma-ray emission from FRBs exist: one invoking magnetic flare events from magnetars — highly magnetized neutron stars that are the dense remnants of collapsed stars — and another invoking the catastrophic merger of two neutron stars, colliding to form a black hole. According to coauthor Kohta Murase, a Penn State professor and theorist, “The energy release we see is challenging for the magnetar model unless the burst is relatively nearby. The long timescale of the gamma-ray emission, while unexpected in both models, might be possible in a merger event if we observe the merger from the side, in an off-axis scenario.”

“In fact, the energy and timescale of the gamma-ray emission is a better match to some types of supernovae, or to some of the supermassive black hole accretion events that Swift has seen,” Fox said. “The problem is that no existing models predict that we would see an FRB in these cases.”

The bright gamma-ray emission from FRB 131104 suggests that the burst, and others like it, might be accompanied by long-lived X-ray, optical, or radio emissions. Such counterparts are dependably seen in the wake of comparably energetic cosmic explosions, including both stellar-scale cataclysms — supernovae, magnetar flares, and gamma-ray bursts — and episodic or continuous accretion activity of the supermassive black holes that commonly lurk in the centers of galaxies.

In fact, Swift X-ray and optical observations were carried out two days after FRB 131104, thanks to prompt analysis by radio astronomers (who were not aware of the gamma-ray counterpart) and a nimble response from the Swift mission operations team, headquartered at Penn State. In spite of this relatively well-coordinated response, no long-lived X-ray, ultraviolet, or optical counterpart was seen.

The authors hope to participate in future campaigns aimed at discovering more FRB counterparts, and in this way, finally revealing the sources responsible for these ubiquitous and mysterious events. “Ideally, these campaigns would begin soon after the burst and would continue for several weeks afterward to make sure nothing gets missed. Maybe we’ll get even luckier next time,” DeLaunay said.

Close Galactic Encounter Leaves ‘Nearly Naked’ Supermassive Black Hole

Astronomers using the super-sharp radio vision of the National Science Foundation’s Very Long Baseline Array (VLBA) have found the shredded remains of a galaxy that passed through a larger galaxy, leaving only the smaller galaxy’s nearly-naked supermassive black hole to emerge and speed away at more than 2,000 miles per second.


The galaxies are part of a cluster of galaxies more than 2 billion light-years from Earth. The close encounter, millions of years ago, stripped the smaller galaxy of nearly all its stars and gas. What remains is its black hole and a small galactic remnant only about 3,000 light-years across. For comparison, our Milky Way Galaxy is approximately 100,000 light-years across.

The discovery was made as part of a program to detect supermassive black holes, millions or billions of times more massive than the Sun, that are not at the centers of galaxies. Supermassive black holes reside at the centers of most galaxies. Large galaxies are thought to grow by devouring smaller companions. In such cases, the black holes of both are expected to orbit each other, eventually merging.

“We were looking for orbiting pairs of supermassive black holes, with one offset from the center of a galaxy, as telltale evidence of a previous galaxy merger,” said James Condon, of the National Radio Astronomy Observatory. “Instead, we found this black hole fleeing from the larger galaxy and leaving a trail of debris behind it,” he added.

“We’ve not seen anything like this before,” Condon said.

The astronomers began their quest by using the VLBA to make very high resolution images of more than 1,200 galaxies, previously identified by large-scale sky surveys done with infrared and radio telescopes. Their VLBA observations showed that the supermassive black holes of nearly all these galaxies were at the centers of the galaxies.

However, one object, in a cluster of galaxies called ZwCl 8193, did not fit that pattern. Further studies showed that this object, called B3 1715+425, is a supermassive black hole surrounded by a galaxy much smaller and fainter than would be expected. In addition, this object is speeding away from the core of a much larger galaxy, leaving a wake of ionized gas behind it.

The scientists concluded that B3 1715+425 is what has remained of a galaxy that passed through the larger galaxy and had most of its stars and gas stripped away by the encounter — a “nearly naked” supermassive black hole.

The speeding remnant, the scientists said, probably will lose more mass and cease forming new stars.

“In a billion years or so, it probably will be invisible,” Condon said. That means, he pointed out, that there could be many more such objects left over from earlier galactic encounters that astronomers can’t detect.

The scientists will keep looking, however. They’re observing more objects, in a long-term project with the VLBA. Since their project is not time-critical, Condon explained, they use “filler time” when the telescope is not in use for other observations.

“The data we get from the VLBA is very high quality. We get the positions of the supermassive black holes to extremely good precision. Our limiting factor is the precision of the galaxy positions seen at other wavelengths that we use for comparison,” Condon said. With new optical telescopes that will come on line in future years, such as the Large Synoptic Survey Telescope (LSST), he said, they will then have improved images that can be compared with the VLBA images. They hope that this will allow them to discover more objects like B3 1714+425.

“And also maybe some of the binary supermassive black holes we originally sought,” he said.

Galactic Fireworks Illuminate Monster Hydrogen Blob In Space

An international team of researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) and other telescopes has discovered the power source illuminating a so-called Lyman-alpha Blob — a rare, brightly glowing, and enormous concentration of gas in the distant universe.


Until now, astronomers wondered why these huge clouds of gas shined so brightly. The answer, in this example at least, appears to be two galaxies at the heart of the blob undergoing furious star formation and lighting up their surroundings. These large galaxies, which are destined to eventually merge into a single elliptical galaxy, are in the midst of a swarm of smaller galaxies. This appears to be an early phase in the formation of a massive cluster of galaxies.

Lyman-alpha Blobs (LABs) are gigantic clouds of hydrogen gas that can span hundreds of thousands of light-years and are found at very large cosmic distances. The name reflects the characteristic wavelength of ultraviolet light that they emit, known as Lyman-alpha radiation. Since their discovery, the processes that give rise to LABs have been an astronomical puzzle. New observations with ALMA have now cleared up the mystery.

One of the largest Lyman-alpha Blobs known, and the most thoroughly studied, is SSA22-Lyman-alpha blob 1, or LAB-1. Embedded in the core of a huge cluster of galaxies in the early stages of formation, it was the very first such object to be discovered — in 2000 — and is located so far away that its light has taken about 11.5 billion years to reach us.

A team of astronomers, led by Jim Geach, from the Center for Astrophysics Research of the University of Hertfordshire, UK, has now used ALMA’s unparalleled ability to observe light from cool dust clouds in distant galaxies to peer deeply into LAB-1. This allowed them to pinpoint and resolve several sources of submillimeter emission.

The astronomers then combined the ALMA images with observations from the Multi Unit Spectroscopic Explorer (M– — USE) instrument mounted on ESO’s Very Large Telescope (VLT), which map the Lyman-alpha light. This showed that the ALMA sources are located in the very heart of the Lyman-alpha Blob, where they are forming stars at a rate over 100 times that of the Milky Way.

Deep imaging with the NASA/ESA Hubble Space Telescope and spectroscopy at the W. M. Keck Observatory also revealed that the ALMA sources are surrounded by numerous faint companion galaxies that could be bombarding the central ALMA sources with material, helping to drive their high star formation rates.

The team then turned to a sophisticated simulation of galaxy formation, known as the Feedback in Realistic Environments (FIRE), to demonstrate that the giant glowing cloud of Lyman-alpha emission can be explained if ultraviolet light produced by star formation in the ALMA sources scatters off the surrounding hydrogen gas. This would give rise to the Lyman-alpha Blob we see.

Jim Geach, lead author of the new study accepted for publication in the Astrophysical Journal, explains: “Think of a streetlight on a foggy night — you see the diffuse glow because light is scattering off the tiny water droplets. A similar thing is happening here, except the streetlight is an intensely star-forming galaxy and the fog is a huge cloud of intergalactic gas. The galaxies are illuminating their surroundings.”

Understanding how galaxies form and evolve is a massive challenge. Astronomers think Lyman-alpha Blobs are important because they seem to be the places where the most massive galaxies in the universe form. In particular, the extended Lyman-alpha glow provides information on what is happening in the primordial gas clouds surrounding young galaxies, a region that is very difficult to study, but critical to understand.

“Unveiling the galaxies shrouded in LAB-1 did more than just put to bed the longstanding issue of the gas cloud’s glow,” said Desika Narayanan of Haverford College in Pennsylvania and coauthor of the paper. “It provided a rare opportunity to see how young, growing galaxies behaved when the universe was quite young.”

Jim Geach concludes, “What’s exciting about these blobs is that we are getting a rare glimpse of what’s happening around these young, growing galaxies. For a long time, the origin of the extended Lyman-alpha light has been controversial. But with the combination of new observations and cutting-edge simulations, we think we have solved a 15-year-old mystery: Lyman-alpha Blob-1 is the site of formation of a massive elliptical galaxy that will one day be the heart of a giant cluster. We are seeing a snapshot of the assembly of that galaxy 11.5 billion years ago.”

Twin Jets Pinpoint The Heart Of An Active Galaxy

Two particle jets shoot out from the heart of active galaxy NGC 1052 at the speed of light, apparently originating in the vicinity of a massive black hole. A team of researchers headed by Anne-Kathrin Baczko from the Max Planck Institute for Radio Astronomy Bonn have now measured the magnetic fields in this area. They observed the bright, very compact structure of just two light days in size using a global ensemble of millimetre-wavelength telescopes. The magnetic field value recorded at the event horizon of the black hole was between 0.02 and 8.3 tesla. The team concludes that the magnetic fields provide enough magnetic energy to power the twin jets.


The technique used to investigate details at the centre of galaxy NGC 1052 is known as very-long-baseline interferometry (VLBI), and has the potential to locate the bases of jets at tiny length scales. In fact, these latest observations extend right up close to the event horizon of the central power source — a supermassive black hole. The event horizon marks the boundary between free space and the gravitational pull of the black hole, beyond which no radiation can escape.

The black hole itself remains invisible, however, so its exact position can only be inferred indirectly by tracking the jet positions depending on their wavelengths. The unknown offset distance of the jet base from the black hole makes it difficult to determine fundamental physical properties such as magnetic field values and particle density.

However, the striking symmetry in these latest observations of the twin jets in NGC 1052 allows astronomers to pinpoint the true centre of activity inside the central structure. Only one jet is observed in most other galaxies, but the symmetrical jets of NGC 1052 allow great precision in determining the “centre” and thus also the location of the power source.

With the exception of our own Milky Way, this is the most precisely known location of a supermassive black hole in the universe. “NGC 1052 is truly a key source, since it pinpoints directly and unambiguously the position of a black hole,” says Anne-Kathrin Baczko, who carried out this research at the Universities of Erlangen-Nuremberg and Wurzburg, and at the Max Planck Institute for Radio Astronomy.

NGC 1052 is an elliptical galaxy at a distance of about 60 million light years in the direction of the constellation Cetus (the Whale). The magnetic field at the supermassive black hole was determined by measuring the compactness and brightness of the central region of NGC 1052, yielding values between 0.02 and 8.3 tesla. (By way of comparison, Earth’s magnetic field is only about 50 microtesla.) The central region appears as a strong radio source with a diameter of just 57 microarcseconds: equivalent in size to a DVD on the surface of the moon.

This astonishing resolution was obtained by the Global mm VLBI Array, a network of radio telescopes in Europe, the USA and East Asia, managed by the Max Planck Institute for Radio Astronomy in Bonn. “It yields unprecedented image sharpness and is soon to be applied to reach event-horizon scales in nearby objects,” says Eduardo Ros, a Max Planck researcher who collaborated in the project.

How are powerful relativistic jets formed in the centres of numerous active galaxies? The telescope array observations may help solve this long-standing mystery, as they show that it is possible for jets to be driven by the magnetic energy released by a very rapidly rotating supermassive black hole.

Gaia’s Billion Star Maps Hints At Treasures To Come

The first catalogue of more than a billion stars from ESA’s Gaia satellite was published today — the largest all-sky survey of celestial objects to date.


On its way to assembling the most detailed 3D map ever made of our Milky Way galaxy, Gaia has pinned down the precise position on the sky and the brightness of 1142 million stars.

As a taster of the richer catalogue to come in the near future, today’s release also features the distances and the motions across the sky for more than two million stars.

“Gaia is at the forefront of astrometry, charting the sky at precisions that have never been achieved before,” says Alvaro Giménez, ESA’s Director of Science.

“Today’s release gives us a first impression of the extraordinary data that await us and that will revolutionise our understanding of how stars are distributed and move across our Galaxy.”

Launched 1000 days ago, Gaia started its scientific work in July 2014. This first release is based on data collected during its first 14 months of scanning the sky, up to September 2015.

“The beautiful map we are publishing today shows the density of stars measured by Gaia across the entire sky, and confirms that it collected superb data during its first year of operations,” says Timo Prusti, Gaia project scientist at ESA.

The stripes and other artefacts in the image reflect how Gaia scans the sky, and will gradually fade as more scans are made during the five-year mission.

“The satellite is working well and we have demonstrated that it is possible to handle the analysis of a billion stars. Although the current data are preliminary, we wanted to make them available for the astronomical community to use as soon as possible,” adds Dr Prusti.

Transforming the raw information into useful and reliable stellar positions to a level of accuracy never possible before is an extremely complex procedure, entrusted to a pan-European collaboration of about 450 scientists and software engineers: the Gaia Data Processing and Analysis Consortium, or DPAC.

In addition to processing the full billion-star catalogue, the scientists looked in detail at the roughly two million stars in common between Gaia’s first year and the earlier Hipparcos and Tycho-2 Catalogues, both derived from ESA’s Hipparcos mission, which charted the sky more than two decades ago.

By combining Gaia data with information from these less precise catalogues, it was possible to start disentangling the effects of ‘parallax’ and ‘proper motion’ even from the first year of observations only. Parallax is a small motion in the apparent position of a star caused by Earth’s yearly revolution around the Sun and depends on a star’s distance from us, while proper motion is due to the physical movement of stars through the Galaxy.

In this way, the scientists were able to estimate distances and motions for the two million stars spread across the sky in the combined Tycho-Gaia Astrometric Solution, or TGAS.

This new catalogue is twice as precise and contains almost 20 times as many stars as the previous definitive reference for astrometry, the Hipparcos Catalogue.

As part of their work in validating the catalogue, DPAC scientists have conducted a study of open stellar clusters — groups of relatively young stars that were born together — that clearly demonstrates the improvement enabled by the new data.

“With Hipparcos, we could only analyse the 3D structure and dynamics of stars in the Hyades, the nearest open cluster to the Sun, and measure distances for about 80 clusters up to 1600 light-years from us,” says Antonella Vallenari from the Istituto Nazionale di Astrofisica (INAF) and the Astronomical Observatory of Padua, Italy.

“But with Gaia’s first data, it is now possible to measure the distances and motions of stars in about 400 clusters up to 4800 light-years away.

For the closest 14 open clusters, the new data reveal many stars surprisingly far from the centre of the parent cluster, likely escaping to populate other regions of the Galaxy.”

Many more stellar clusters will be discovered and analysed in even greater detail with the extraordinary data that Gaia continues to collect and that will be released in the coming years.

The new stellar census also contains 3194 variable stars, stars that rhythmically swell and shrink in size, leading to periodic brightness changes.

Many of the variables seen by Gaia are in the Large Magellanic Cloud, one of our galactic neighbours, a region that was scanned repeatedly during the first month of observations, allowing accurate measurement of their changing brightness.

Details about the brightness variations of these stars, 386 of which are new discoveries, are published as part of today’s release, along with a first study to test the potential of the data.

“Variable stars like Cepheids and RR Lyraes are valuable indicators of cosmic distances,” explains Gisella Clementini from INAF and the Astronomical Observatory of Bologna, Italy.

“While parallax is used to measure distances to large samples of stars in the Milky Way directly, variable stars provide an indirect, but crucial step on our ‘cosmic distance ladder’, allowing us to extend it to faraway galaxies.”

This is possible because some kinds of variable stars are special. For example, in the case of Cepheid stars, the brighter they are intrinsically, the slower their brightness variations. The same is true for RR Lyraes when observed in infrared light. The variability pattern is easy to measure and can be combined with the apparent brightness of a star to infer its true brightness.

This is where Gaia steps in: in the future, scientists will be able to determine very accurate distances to a large sample of variable stars via Gaia’s measurements of parallaxes. With those, they will calibrate and improve the relation between the period and brightness of these stars, and apply it to measure distances beyond our Galaxy. A preliminary application of data from the TGAS looks very promising.

“This is only the beginning: we measured the distance to the Large Magellanic Cloud to test the quality of the data, and we got a sneak preview of the dramatic improvements that Gaia will soon bring to our understanding of cosmic distances,” adds Dr Clementini.

Knowing the positions and motions of stars in the sky to astonishing precision is a fundamental part of studying the properties and past history of the Milky Way and to measure distances to stars and galaxies, but also has a variety of applications closer to home — for example, in the Solar System.

In July, Pluto passed in front of a distant, faint star, offering a rare chance to study the atmosphere of the dwarf planet as the star gradually disappeared and then reappeared behind Pluto.

This stellar occultation was visible only from a narrow strip stretching across Europe, similar to the totality path that a solar eclipse lays down on our planet’s surface. Precise knowledge of the star’s position was crucial to point telescopes on Earth, so the exceptional early release of the Gaia position for this star, which was 10 times more precise than previously available, was instrumental to the successful monitoring of this rare event.

Early results hint at a pause in the puzzling pressure rise of Pluto’s tenuous atmosphere, something that has been recorded since 1988 in spite of the dwarf planet moving away from the Sun, which would suggest a drop in pressure due to cooling of the atmosphere.

“These three examples demonstrate how Gaia’s present and future data will revolutionise all areas of astronomy, allowing us to investigate our place in the Universe, from our local neighbourhood, the Solar System, to Galactic and even grander, cosmological scales,” explains Dr Brown.

This first data release shows that the mission is on track to achieve its ultimate goal: charting the positions, distances, and motions of one billion stars — about 1% of the Milky Way’s stellar content — in three dimensions to unprecedented accuracy.

“The road to today has not been without obstacles: Gaia encountered a number of technical challenges and it has taken an extensive collaborative effort to learn how to deal with them,” says Fred Jansen, Gaia mission manager at ESA.

“But now, 1000 days after launch and thanks to the great work of everyone involved, we are thrilled to present this first dataset and are looking forward to the next release, which will unleash Gaia’s potential to explore our Galaxy as we’ve never seen it before.”