Institute of Astronomy

Astronomy News

Measuring the Milky Way’s mind-boggling mass

30 April 2018 - 9:06am

Measuring the Milky Way’s mind-boggling mass

Measuring the Milky Way’s mind-boggling mass, Published online: 27 April 2018; doi:10.1038/d41586-018-04970-z

A combination of telescope data and 87,000 simulated galaxies helps scientists to size up the Galaxy.

Stellar Thief Is the Surviving Companion to a Supernova

30 April 2018 - 9:06am

Seventeen years ago, astronomers witnessed a supernova go off 40 million light-years away in the galaxy called NGC 7424, located in the southern constellation Grus, the Crane. Now, in the fading afterglow of that explosion, NASA's Hubble Space Telescope has captured the first image of a surviving companion to a supernova. This picture is the most compelling evidence that some supernovas originate in double-star systems.

News Article Type: Homepage ArticlesPublished: Friday, April 27, 2018 - 10:26

Genesis of magnetic fields in isolated white dwarfs. (arXiv:1804.09910v1 [astro-ph.SR])

27 April 2018 - 9:24am

A dynamo mechanism driven by differential rotation when stars merge has been proposed to explain the presence of strong fields in certain classes of magnetic stars. In the case of the high field magnetic white dwarfs (HFMWDs), the site of the differential rotation has been variously thought to be the common envelope, the hot outer regions of a merged degenerate core or an accretion disc formed by a tidally disrupted companion that is subsequently accreted by a degenerate core. We have shown previously that the observed incidence of magnetism and the mass distribution in HFMWDs are consistent with the hypothesis that they are the result of merging binaries during common envelope evolution. Here we calculate the magnetic field strengths generated by common envelope interactions for synthetic populations using a simple prescription for the generation of fields and find that the observed magnetic field distribution is also consistent with the stellar merging hypothesis. We use the Kolmogorov-Smirnov test to study the correlation between the calculated and the observed field strengths and find that it is consistent for low envelope ejection efficiency. We also suggest that field generation by the plunging of a giant gaseous planet on to a white dwarf may explain why magnetism among cool white dwarfs (including DZ white dwarfs) is higher than among hot white dwarfs. In this picture a super Jupiter residing in the outer regions of the planetary system of the white dwarf is perturbed into a highly eccentric orbit by a close stellar encounter and is later accreted by the white dwarf.

Mars quakes set to reveal tantalizing clues to planet's early years

26 April 2018 - 2:36pm

Mars quakes set to reveal tantalizing clues to planet's early years

Mars quakes set to reveal tantalizing clues to planet's early years , Published online: 26 April 2018; doi:10.1038/d41586-018-04964-x

NASA’s Mars InSight spacecraft will listen for seismic activity to understand the planet’s core.

Space agencies intent on mission to return Mars rocks to Earth

26 April 2018 - 2:35pm

Nasa and Esa sign a letter of intent that could lead to the first "round trip" to the Red Planet.

Multiple Stellar Fly-Bys Sculpting the Circumstellar Architecture in RW Aurigae. (arXiv:1804.09190v1 [astro-ph.SR])

26 April 2018 - 9:48am

We present high-resolution ALMA Band 6 and 7 observations of the tidally disrupted protoplanetary disks of the RW Aurigae binary. Our observations reveal the presence of additional tidal streams to the previously observed tidal arm around RW Aur A. The observed configuration of tidal streams surrounding RW Aur A and B is incompatible with a single star-disk tidal encounter, suggesting that the RW Aurigae system has undergone multiple fly-by interactions. We also resolve the circumstellar disks around RW Aur A and B, with CO radii of 68 au and 38 au consistent with tidal truncation, and 2.5 times smaller dust emission radii. The disks appear misaligned by 12$^{\circ}$ or 57$^{\circ}$. Using new photometric observations from the American Association of Variable Star Observers (AAVSO) and All Sky Automated Survey for SuperNovae (ASAS-SN) archives, we have also identified an additional dimming event of the primary that began in late 2017 and is currently ongoing. With over a century of photometric observations, we are beginning to explore the same spatial scales as ALMA.

Gaia telescope's 'book of the heavens' takes shape

26 April 2018 - 9:38am

A European space telescope measures the precise positions and distances to over one billion stars.

Gaia creates richest star map of our Galaxy – and beyond

26 April 2018 - 9:35am

ESA's Gaia mission has produced the richest star catalogue to date, including high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home Galaxy.

Ancient Galaxy Megamergers

26 April 2018 - 9:33am
The ALMA and APEX telescopes have peered deep into space — back to the time when the Universe was one tenth of its current age — and witnessed the beginnings of gargantuan cosmic pileups: the impending collisions of young, starburst galaxies. Astronomers thought that these events occurred around three billion years after the Big Bang, so they were surprised when the new observations revealed them happening when the Universe was only half that age! These ancient systems of galaxies are thought to be building the most massive structures in the known Universe: galaxy clusters.

NASA's NEOWISE Asteroid-Hunter Spacecraft -- Four Years of Data

26 April 2018 - 9:31am

NASA's Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission has released its fourth year of survey data. Since the mission was restarted in December 2013, after a period of hibernation, the asteroid- and comet-hunter has completely scanned the skies nearly eight times and has observed and characterized 29,375 objects in four years of operations. This total includes 788 near-Earth objects and 136 comets since the mission restart.

News Article Type: Homepage ArticlesPublished: Wednesday, April 25, 2018 - 15:40

Gaia creates richest star map of our Galaxy – and beyond

26 April 2018 - 9:26am

A multitude of discoveries are on the horizon after today’s much-awaited release, which is based on 22 months of charting the sky, as part of Gaia’s mission to produce the largest, most precise three-dimensional map of our Galaxy ever created. The new data includes positions, distance indicators and motions of more than one billion stars, along with high-precision measurements of asteroids within our Solar System and stars beyond our own Milky Way Galaxy.

Preliminary analysis of this phenomenal data reveals fine details about the makeup of the Milky Way’s stellar population and about how stars move, essential information for investigating the formation and evolution of our home Galaxy.

“The observations collected by Gaia are redefining the foundations of astronomy,” said Günther Hasinger, ESA Director of Science. “Gaia is an ambitious mission that relies on a huge human collaboration to make sense of a large volume of highly complex data. It demonstrates the need for long-term projects to guarantee progress in space science and technology and to implement even more daring scientific missions of the coming decades.”

This unique mission is reliant on the work of Cambridge researchers who collect the vast quantities of data transmitted by Gaia to a data processing centre at the University, overseen by a team at the Institute of Astronomy.

“There is hardly a branch of astrophysics which will not be revolutionised by Gaia data,” said Cambridge’s Professor Gerry Gilmore, Principal Investigator for the UK participation in the Gaia Data Processing and Analysis Consortium, and one of the original proposers of the mission to ESA. “The global community will advance our understanding of what we see, where it came from, what it is made from, how it is changing. All this is made freely available to everyone, based on the dedicated efforts of hundreds of people.”

Gaia was launched in December 2013 and started science operations the following year. The first data release, based on just over one year of observations, was published in 2016; it contained distances and motions of two million stars. The new data release, which covers the period between 25 July 2014 and 23 May 2016, pins down the positions of nearly 1.7 billion stars, and with a much greater precision. For some of the brightest stars in the survey, the level of precision equates to Earth-bound observers being able to spot a Euro coin lying on the surface of the Moon.

With these accurate measurements it is possible to separate the parallax of stars – an apparent shift on the sky caused by Earth’s yearly orbit around the Sun – from their true movements through the Galaxy. The new catalogue lists the parallax and velocity across the sky, or proper motion, for more than 1.3 billion stars. From the most accurate parallax measurements, about ten percent of the total, astronomers can directly estimate distances to individual stars.

The comprehensive dataset provides a wide range of topics for the astronomy community. As well as positions, the data include brightness information of all surveyed stars and colour measurements of nearly all, plus information on how the brightness and colour of half a million variable stars change over time. It also contains the velocities along the line of sight of a subset of seven million stars, the surface temperatures of about a hundred million and the effect of interstellar dust on 87 million.

Gaia also observes objects in our Solar System: the second data release comprises the positions of more than 14,000 known asteroids, which allows precise determination of their orbits. A much larger asteroid sample will be compiled in Gaia’s future releases.

Further afield, Gaia closed in on the positions of half a million distant quasars, bright galaxies powered by the activity of the supermassive black holes at their cores. These sources are used to define a reference frame for the celestial coordinates of all objects in the Gaia catalogue, something that is routinely done in radio waves but now for the first time is also available at optical wavelengths.

Major discoveries are expected to come once scientists start exploring Gaia’s new release. An initial examination performed by the data consortium to validate the quality of the catalogue has already unveiled some promising surprises – including new insights on the evolution of stars.

The team in Cambridge is led by Dr Floor van Leeuwen, Dr Dafydd Wyn Evans, Dr Francesca De Angeli and Dr Nicholas Walton.

“This data release has proven an exciting challenge to process from spacecraft camera images to science-ready catalogues,” said De Angeli, head of the Cambridge processing centre. “More sophisticated strategies and updated models will be applied to the Gaia data to achieve even more precise and accurate photometric and spectrophotometric information, which will enable even more exciting scientific investigations and results.”

“Gaia has so far observed each of its more than 1.7 billion sources on average about 200 times,” said Evans. “This very large data set has to have all the changing satellite and sky responses removed, and everything converted on to a well-defined scale of brightness and colour. While a huge challenge, it is worth it.”

“Groups of dwarf galaxies, including the Magellanic Clouds, can now be observed to be moving around in very similar orbits, hinting at a shared formation history,” said van Leeuwen, Project Manager for the UK and European photometric processing work. “Similarly, a pair of globular clusters has been observed with very similar orbital characteristics and chemical composition, again pointing towards a shared history of formation. The accurate observed motions and positions of the globular clusters and dwarf galaxies provide tracers of the overall mass distribution of our galaxy in a way that has not been possible with this level of accuracy before.”

“The Gaia data will be a globally accessible resource for astronomical research for decades to come, enabling the future research of today's young astronomers in the UK, Europe and the World,” said Walton, a member of the ESA Gaia Science Team. “Gaia is raising excitement and opportunity, bringing the next generation of researchers together to tackle many key questions in our understanding of the Milky Way.”

More data releases will be issued in future years, with the final Gaia catalogue to be published in the 2020s. This will be the definitive stellar catalogue for the foreseeable future, playing a central role in a wide range of fields in astronomy.

“This vast step into a new window on the Universe is a revolution in our knowledge of the contents, motions and properties of our local Universe,” said Gilmore. “We look forward to the international astronomical community building on this European project, with its major UK contributions, to interpret these Gaia data to revolutionise our understanding of our Universe. This is a magnificent harvest, but cornucopia awaits. We are all proud to be part of this magnificent project.”

Adapted from an ESA press release.

The European Space Agency’s Gaia mission has produced the richest star catalogue to date, including high-precision measurements of nearly 1.7 billion stars and revealing previously unseen details of our home Galaxy. 

There is hardly a branch of astrophysics which will not be revolutionised by Gaia data.Gerry Gilmore ESA/Gaia/DPAC Gaia’s sky in colour – equirectangular projection

The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.


Jupiter’s Great Red Spot, Spotted

25 April 2018 - 9:14am

This image of Jupiter’s iconic Great Red Spot and surrounding turbulent zones was captured by NASA’s Juno spacecraft.

News Article Type: Homepage ArticlesPublished: Tuesday, April 24, 2018 - 10:47

Lagoon Nebula (Visible-light View)

25 April 2018 - 9:14am

This colorful image, taken by NASA’s Hubble Space Telescope, celebrates the Earth-orbiting observatory’s 28th anniversary of viewing the heavens, giving us a window seat to the universe’s extraordinary tapestry of stellar birth and destruction.

News Article Type: Homepage ArticlesPublished: Tuesday, April 24, 2018 - 10:42

Rotten egg gas found on planet Uranus

24 April 2018 - 9:25am

The planet Uranus has clouds made up of hydrogen sulphide, the gas that gives rotten eggs their unpleasant smell.

Call for media: Second data release from ESA's Gaia mission

20 April 2018 - 9:19am
Media representatives are invited to a briefing on the second data release of ESA's Gaia mission, an astrometry mission to map more than one billion stars in our Galaxy, the Milky Way. The media briefing is being organised by ESA at the ILA Berlin Air and Space Show in Germany, on Wednesday 25 April 2018, 11:00–12:15 CEST. The show opens at 10:00 CEST.

Hubble celebrates 28th anniversary with a trip through the Lagoon Nebula [heic1808]

20 April 2018 - 9:18am

This colourful cloud of glowing interstellar gas is just a tiny part of the Lagoon Nebula, a vast stellar nursery. This nebula is a region full of intense activity, with fierce winds from hot stars, swirling chimneys of gas, and energetic star formation all embedded within a hazy labyrinth of gas and dust. Hubble used both its optical and infrared instruments to study the nebula, which was observed to celebrate Hubble's 28th anniversary.

SKA prototype dish unveiled

20 April 2018 - 9:16am
The first prototype dish for what will be the world's largest radio telescope array was unveiled last month at a ceremony in Shijiazhuang, China.

Boost for chance of exoplanet life

20 April 2018 - 9:15am
The possibility that some of the exoplanets in the TRAPPIST-1 system could harbour life has been boosted by new measurements.

Two Hubble Views of the Same Stellar Nursery

20 April 2018 - 9:15am

These NASA Hubble Space Telescope images compare two diverse views of the roiling heart of a vast stellar nursery, known as the Lagoon Nebula. The images, one taken in visible and the other in infrared light, celebrate Hubble’s 28th anniversary in space.

News Article Type: Homepage ArticlesPublished: Thursday, April 19, 2018 - 13:22

Nasa's Tess: Planet-hunting satellite lifts off

19 April 2018 - 9:52am

Nasa's Transiting Exoplanet Survey Satellite (Tess) searches for new planets.