Institute of Astronomy

Feed aggregator

In pictures: Astro Photographer of the Year

Astronomy News - 19 September 2016 - 9:45am

Some of the winning images from this year's competition.

Kamikaze galaxy explodes after diving into the Milky Way 

Astronomy News - 16 September 2016 - 9:29am

Distant dwarf galaxy Hercules’s eccentric orbit of the Milky Way ripped it apart, scattering its stars across space

Gaia’s new star map will also reveal asteroids and dark matter

Astronomy News - 16 September 2016 - 9:28am

The Gaia satellite's main mission may be to map the stars in our home galaxy, but its extracurricular plans are just as thrilling

Hubble Takes Close-up Look at Disintegrating Comet

Astronomy News - 16 September 2016 - 9:25am

Get larger image formats

Comet 332P/Ikeya-Murakami survived for 4.5 billion years in the frigid Kuiper Belt, a vast reservoir of icy bodies on the outskirts of our solar system. The objects are the leftovers from our solar system's construction. But within the last few million years, the unlucky comet was gravitationally kicked to the inner solar system by the outer planets. The comet, dubbed 332P, found a new home, settling into an orbit just beyond Mars. But the new home, closer to the sun, has doomed the comet. Sunlight is heating up Comet 332P's surface, causing jets of gas and dust to erupt. The jets act like rocket engines, spinning up the comet's rotation. The faster spin rate loosened chunks of material, which are drifting off the surface and into space.

Starving Black Hole Returns Brilliant Galaxy to the Shadows

Astronomy News - 16 September 2016 - 9:23am
The mystery of a rare change in the behaviour of a supermassive black hole at the centre of a distant galaxy has been solved by an international team of astronomers using ESO’s Very Large Telescope along with the NASA/ESA Hubble Space Telescope and NASA’s Chandra X-ray Observatory. It seems that the black hole has fallen on hard times and is no longer being fed enough fuel to make its surroundings shine.

Western Isles rock offers potential clue to life on Mars

Astronomy News - 16 September 2016 - 9:22am

Analysis of rocks in the Western Isles has provided "a tantalising clue" that Mars may contain habitats which can potentially support life.

A radio-pulsing white dwarf binary star

Astronomy News - 15 September 2016 - 9:38am

A radio-pulsing white dwarf binary star

Nature 537, 7620 (2016). doi:10.1038/nature18620

Authors: T. R. Marsh, B. T. Gänsicke, S. Hümmerich, F.-J. Hambsch, K. Bernhard, C. Lloyd, E. Breedt, E. R. Stanway, D. T. Steeghs, S. G. Parsons, O. Toloza, M. R. Schreiber, P. G. Jonker, J. van Roestel, T. Kupfer, A. F. Pala, V. S. Dhillon, L. K. Hardy, S. P. Littlefair, A. Aungwerojwit, S. Arjyotha, D. Koester, J. J. Bochinski, C. A. Haswell, P. Frank & P. J. Wheatley

White dwarfs are compact stars, similar in size to Earth but approximately 200,000 times more massive. Isolated white dwarfs emit most of their power from ultraviolet to near-infrared wavelengths, but when in close orbits with less dense stars, white dwarfs can strip material from their companions and the resulting mass transfer can generate atomic line and X-ray emission, as well as near- and mid-infrared radiation if the white dwarf is magnetic. However, even in binaries, white dwarfs are rarely detected at far-infrared or radio frequencies. Here we report the discovery of a white dwarf/cool star binary that emits from X-ray to radio wavelengths. The star, AR Scorpii (henceforth AR Sco), was classified in the early 1970s as a δ-Scuti star, a common variety of periodic variable star. Our observations reveal instead a 3.56-hour period close binary, pulsing in brightness on a period of 1.97 minutes. The pulses are so intense that AR Sco’s optical flux can increase by a factor of four within 30 seconds, and they are also detectable at radio frequencies. They reflect the spin of a magnetic white dwarf, which we find to be slowing down on a 107-year timescale. The spin-down power is an order of magnitude larger than that seen in electromagnetic radiation, which, together with an absence of obvious signs of accretion, suggests that AR Sco is primarily spin-powered. Although the pulsations are driven by the white dwarf’s spin, they mainly originate from the cool star. AR Sco’s broadband spectrum is characteristic of synchrotron radiation, requiring relativistic electrons. These must either originate from near the white dwarf or be generated in situ at the M star through direct interaction with the white dwarf’s magnetosphere.

Milky Way mapper: 6 ways the Gaia spacecraft will change astronomy

Astronomy News - 15 September 2016 - 9:34am

Milky Way mapper: 6 ways the Gaia spacecraft will change astronomy

Nature 537, 7620 (2016). http://www.nature.com/doifinder/10.1038/nature.2016.20569

Author: Davide Castelvecchi

European mission will shed light on hidden asteroids, the Universe’s expansion and exoplanets.

Astronomy: Galaxy collisions make waves fast

Astronomy News - 15 September 2016 - 9:34am

Astronomy: Galaxy collisions make waves fast

Nature 537, 7620 (2016). doi:10.1038/537283b

When galaxies with supermassive black holes at their centres collide, they could produce a burst of gravitational waves within just 10 million years.Gravitational waves were first detected earlier this year, sparking great interest in finding more. Some scientists have predicted that wave production happens

Gaia's billion-star map hints at treasures to come

Astronomy News - 15 September 2016 - 9:33am

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.

Asteroid assault on early planets was more like a gentle massage

Astronomy News - 15 September 2016 - 9:33am

Most models of the early solar system say it endured a period of intense asteroid strikes dubbed the Late Heavy Bombardment - but new isotope data paints a calmer picture

Gaia’s map of 1 billion stars is the clearest view of our galaxy

Astronomy News - 15 September 2016 - 9:32am

The first data released from the European Space Agency’s star mapping space telescope will transform astronomy forever, expanding our view 1000-fold

New Horizons discovery raises solar wind riddle around Pluto

Astronomy News - 15 September 2016 - 9:32am

The spacecraft’s observations of the dwarf planet’s atmosphere have raised questions over existing models of the solar wind

Gaia results revealed – first data release from the most detailed map ever made of the sky

Astronomy News - 15 September 2016 - 9:29am

Detailed information about more than a billion stars in the Milky Way has been published in the first data release from the Gaia satellite, which is conducting the first-ever ‘galactic census.’ The release marks the first chance astronomers and the public have had to get their hands on the most detailed map ever made of the sky.

Gaia, which orbits the sun at a distance of 1.5 million kilometres from the earth, was launched by the European Space Agency in December 2013 with the aim of observing a billion stars and revolutionising our understanding of the Milky Way. During its expected five-year lifespan, Gaia will observe each of a billion stars about 70 times.

The 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.

“Gaia’s first major data release is both a wonderful achievement in its own right, and a taster of the truly dramatic advances to come in future years,” said Professor Gerry Gilmore from the Institute of Astronomy, who is also the UK Principal Investigator for Gaia. “Several UK teams have leading roles in Gaia’s Data Processing and Analysis efforts, which convert the huge raw data streams from the satellite into the beautiful science-ready information now made available for the global scientific and public communities. UK industry made critical contributions to the Gaia spacecraft. The UK public, including school students, as well as scientists, are sharing the excitement of this first ever galactic census.”

In addition to the work taking place at Cambridge, teams from Edinburgh, the Mullard Space Science Laboratory (MSSL) at UCL London, Leicester, Bristol and the Science and Technology Facilities Council’s Rutherford Appleton Lab are all contributing to the processing of the vast amounts of data from Gaia, in collaboration with industrial and academic partners from across Europe.

The team in Cambridge, led by Dr Floor van Leeuwen, Dr Dafydd Wyn Evans and Dr Francesca De Angeli, processed the flux information – the amount of energy that crosses a unit area per unit time – providing the calibrated magnitudes of around 1.6 billion stars, 1.1 billion of which are now published as part of the first data release.

The Cambridge team also check the daily photometric data for unexpected large outliers, which led to the regular publication of photometric science alerts that were ready for immediate follow-up observations from the ground.

“The sheer volume of data processed for this first release is beyond imagination: around 120 billion images were analysed, and most of these more than once, as all the processing is iterative,” said van Leeuwen, who is Gaia photometric data processing lead. “Many problems had to be overcome, and a few small ones still remain. Calibrations have not yet reached their full potential. Nevertheless, we are already reaching accuracies that are significantly better than expected before the mission, and which can challenge most ground-based photometric data in accuracy.”

“This first Gaia data release has been an important exercise for the Gaia data reduction teams, getting them to focus on deliverable products and their description,” said Evans. “But it is only the first small step towards much more substantial results.”

While today marks the first major data release from Gaia, in the two years since its launch, the satellite has been producing scientific results in the form of Gaia Alerts.

Dr Simon Hodgkin, lead of the Cambridge Alerts team said, “The Gaia Alerts project takes advantage of the fact that the Gaia satellite scans each part of the sky repeatedly throughout the mission. By comparing successive observations of the same patch of sky, scientists can search for transients – astronomical objects which brighten, fade, change or move. These transients are then announced to the world each day as Gaia Alerts for both professional and amateur astronomers to observe with telescopes from the ground.”

The range of Gaia’s discoveries from Science Alerts is large – supernovae of various types, cataclysmic variable stars, novae, flaring stars, gravitational microlensing events, active galactic nuclei and quasars, and many sources whose nature remains a mystery.

Gaia has discovered many supernovae, the brilliant explosions of stars at the end of their lives. Many of these have been ‘Type Ia’ supernovae, which can be used to measure the accelerating expansion of the Universe. But among these apparently typical supernovae there have been some rarer events. Gaia16ada was spotted by Gaia in the nearby galaxy NGC4559, and appears to be an eruption of a very massive, unstable star. The Hubble Space Telescope observed this galaxy some years ago, allowing astronomers to pinpoint the precise star which erupted.

Another lucky catch for Gaia was the discovery of Gaia16apd – a supernova which is nearly a hundred times brighter than normal. Astronomers still don't know what the missing ingredient in these ultra-bright supernovae is, and candidates include exotic rapidly spinning neutron stars, or jets from a black hole. Cambridge astronomer Dr Morgan Fraser is trying to understand these events, saying, “We have only found a handful of these exceptionally bright supernovae, compared to thousands of normal supernovae. For Gaia to spot one so nearby is a fantastic result.”

Many of the Gaia Alerts found so far are bright enough to be observable with a small telescope. Amateur astronomers have taken images of supernovae found by Gaia, while schoolchildren have used robotic telescopes including the Faulkes Telescopes in Australia and Hawaii to do real science with transients.

Dr Hodgkin said: “Since the announcement of the first transients discovered with Gaia in September 2014, over one thousand alerts have been released. With Gaia continually relaying new observations to ground, and our team working on finding transients continually improving their software, the discoveries look set to continue well into the future!”

For the UK teams the future means providing improvements in the pre-processing of the data and extending the processing to cover the photometric Blue and Red prism data. Also data from the Radial Velocity Spectrometer, with major involvement from MSSL, will be included in future releases. The photometric science alerts will continue to operate throughout the mission, and summaries of the results will be included in future releases. “Despite the considerable amount of data, the first Gaia data release provides just a taste of the accuracy and completeness of the final catalogue,” said De Angeli.

The Cambridge Gaia team has also released a dedicated smartphone app, which will allow anyone worldwide to follow the Gaia Alerts discoveries as they happen. Real spacecraft data will be available to the world as soon as it is processed, with users able to follow the discoveries and see what they are. Information to access the app is available at https://gaia.ac.uk.

The Gaia data processing teams in the UK have been and are being supported by the UK Space Agency and the STFC. STFC helped the set-up of the data applications centre and STFC’s current support involves the UK exploitation of the scientific data to be yielded from the mission. Industrial partners include Airbus, MSSL and e2v Technologies.

The first results from the Gaia satellite, which is completing an unprecedented census of more than one billion stars in the Milky Way, are being released today to astronomers and the public.

Gaia’s first major data release is both a wonderful achievement in its own right, and a taster of the truly dramatic advances to come in future years.Gerry GilmoreESA/Gaia/DPACGaia’s first sky map


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

Yes

A new map of the Milky Way

Astronomy News - 15 September 2016 - 9:27am

The European Space Agency has released details of the position and brightness of more than a billion stars.

What does space sound like?

Astronomy News - 15 September 2016 - 9:27am

An astrophysics professor and contemporary music producers have teamed up to create a special remix of some of the observatory's historic archive recordings.

Star's dust cloud gives birth to giant planet

Astronomy News - 15 September 2016 - 9:26am

Astronomers have discovered signs of a baby planet developing around another star.

Gaia space telescope plots a billion stars

Astronomy News - 14 September 2016 - 11:51am

Europe's Gaia space telescope releases its first batch of data as it builds the most precise map ever made of the night sky.

Astronomers observe star reborn in a flash [heic1618]

Astronomy News - 14 September 2016 - 9:25am

An international team of astronomers using Hubble have been able to study stellar evolution in real time. Over a period of 30 years dramatic increases in the temperature of the star SAO 244567 have been observed. Now the star is cooling again, having been reborn into an earlier phase of stellar evolution. This makes it the first reborn star to have been observed during both the heating and cooling stages of rebirth.

Rosetta set for a grand finale by diving into cometary cave

Astronomy News - 14 September 2016 - 9:24am

ESA’s Rosetta spacecraft will end its two-year mission orbiting comet 67P/Churyumov-Gerasimenko by crashing into a once-active pit named Deir el-Medina