Institute of Astronomy

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Hubble Sees 'Ghost Light' From Dead Galaxies

Astronomy News - 30 October 2014 - 5:00pm

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The universe is an infinite sea of galaxies, which are majestic star-cities. When galaxies group together in massive clusters, some of them can be ripped apart by the gravitational tug of other galaxies. It's a giant cosmic mosh pit. Astronomers using the Hubble Space Telescope to probe the massive galaxy cluster Abell 2744 nicknamed Pandora's Cluster have found forensic evidence of galaxies torn apart long ago. It's in the form of a phantom-like faint glow filling the space between the galaxies. This glow comes from stars scattered into intergalactic space as a result of a galaxy's disintegration.

Planet-forming Lifeline Discovered in a Binary Star System

Astronomy News - 29 October 2014 - 6:00pm
For the first time, researchers using ALMA have detected a streamer of gas flowing from a massive outer disc toward the inner reaches of a binary star system. This never-before-seen feature may be responsible for sustaining a second, smaller disc of planet-forming material that otherwise would have disappeared long ago. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets. The results are published in the journal Nature on 30 October 2014.

Planetary science: Mercury's ice is a recent arrival

Astronomy News - 29 October 2014 - 12:00am

Planetary science: Mercury's ice is a recent arrival

Nature 514, 7524 (2014). doi:10.1038/514538b

Ice at Mercury's poles is a relatively new arrival — a finding that could help to resolve a debate about whether ice may have survived for billions of years on the planet closest to the Sun.Using data from NASA's MESSENGER spacecraft, Nancy Chabot of

Astronomy: Mysterious signals may be from Earth

Astronomy News - 29 October 2014 - 12:00am

Astronomy: Mysterious signals may be from Earth

Nature 514, 7524 (2014). doi:10.1038/514538d

Radio pulses that look like they came from deep space could actually have earthly origins.A team led by Pascal Saint-Hilaire at the University of California, Berkeley, detected five short but intense radio bursts at the Bleien Radio Observatory in Switzerland. This is only the

Possible planet formation in the young, low-mass, multiple stellar system GG Tau A

Astronomy News - 29 October 2014 - 12:00am

Possible planet formation in the young, low-mass, multiple stellar system GG Tau A

Nature 514, 7524 (2014). doi:10.1038/nature13822

Authors: Anne Dutrey, Emmanuel Di Folco, Stéphane Guilloteau, Yann Boehler, Jeff Bary, Tracy Beck, Hervé Beust, Edwige Chapillon, Fredéric Gueth, Jean-Marc Huré, Arnaud Pierens, Vincent Piétu, Michal Simon & Ya-Wen Tang

The formation of planets around binary stars may be more difficult than around single stars. In a close binary star (with a separation of less than a hundred astronomical units), theory predicts the presence of circumstellar disks around each star, and an outer circumbinary disk surrounding a gravitationally cleared inner cavity around the stars. Given that the inner disks are depleted by accretion onto the stars on timescales of a few thousand years, any replenishing material must be transferred from the outer reservoir to fuel planet formation (which occurs on timescales of about one million years). Gas flowing through disk cavities has been detected in single star systems. A circumbinary disk was discovered around the young low-mass binary system GG Tau A (ref. 7), which has recently been shown to be a hierarchical triple system. It has one large inner disk around the single star, GG Tau Aa, and shows small amounts of shocked hydrogen gas residing within the central cavity, but other than a single weak detection, the distribution of cold gas in this cavity or in any other binary or multiple star system has not hitherto been determined. Here we report imaging of gas fragments emitting radiation characteristic of carbon monoxide within the GG Tau A cavity. From the kinematics we conclude that the flow appears capable of sustaining the inner disk (around GG Tau Aa) beyond the accretion lifetime, leaving time for planet formation to occur there. These results show the complexity of planet formation around multiple stars and confirm the general picture predicted by numerical simulations.

Cold moon Enceladus has heart of warm fluff

Astronomy News - 28 October 2014 - 6:04pm
Known for shooting spectacular plumes of water into space, Saturn's tiny moon keeps warm thanks to a core that is slushy and soft rather than rock solid






Poland to Join the European Southern Observatory

Astronomy News - 28 October 2014 - 4:00pm
Today Professor Lena Kolarska-Bobińska, the Polish Minister of Science and Higher Education, signed an agreement that will lead to the country joining the European Southern Observatory (ESO) — the world’s most productive ground-based observatory. ESO is looking forward to welcoming Poland as a Member State, following subsequent ratification of the accession agreement.

Here's Looking At You: Spooky Shadow Play Gives Jupiter a Giant Eye

Astronomy News - 28 October 2014 - 2:00pm

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The Hubble Space Telescope treats astronomers to gorgeous close-up views of the eerie outer planets. But it's a bit of a trick when it seems like the planet's looking back at you! In this view, the shadow of the Jovian moon Ganymede swept across the center of the Great Red Spot a giant storm on the planet. This gave Jupiter the uncanny appearance of having a pupil in the center of a 10,000-mile-diameter "eye." Now if it blinks, we may really have to worry!

Massive flares erupt from largest sunspot in 25 years

Astronomy News - 28 October 2014 - 1:45pm
A solar eruption on 26 October was the sixth large flare in a week, all emanating from a gigantic sunspot 10 times the diameter of Earth






NASA’S Chandra Observatory Identifies Impact of Cosmic Chaos on Star Birth

Astronomy News - 27 October 2014 - 4:00pm
The same phenomenon that causes a bumpy airplane ride, turbulence, may be the solution to a long-standing mystery about stars’ birth, or the absence of it, according to a new study using data from NASA’s Chandra X-ray Observatory.

Fresh hints of dark matter at Milky Way's core

Astronomy News - 27 October 2014 - 4:00pm
The discovery of a third type of light associated with dark matter could strengthen the case that we are seeing a signal of the mysterious stuff






Scifi short promotes comet mission

Astronomy News - 24 October 2014 - 3:15pm
The European Space Agency releases a short scifi movie to promote its audacious bid to land on a comet next month.

Comet stinks of rotten eggs and cat wee, finds Rosetta

Astronomy News - 24 October 2014 - 1:00pm
Data from the European Space Agency's Rosetta probe reveals that eau de comet 67P/Churyumov-Gerasimenko smells awful – but that's good news






Close Encounters: Comet Siding Spring Seen Next to Mars

Astronomy News - 23 October 2014 - 4:00pm

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This is a photo composite of the encounter of Comet Siding Spring with Mars on October 19, 2014. Separate Hubble Space Telescope images of Mars and the comet have been combined together into a single picture. This is a composite image because a single exposure of the stellar background, Comet Siding Spring, and Mars would be problematic because the objects are all moving with respect to each other and the background stars. Hubble can only track one planetary target at a time. Also, Mars is actually 10,000 times brighter than the comet, and the exposure here has been adjusted so that details on the Red Planet can be seen.

Close Encounters: Comet Siding Spring Seen Next to Mars

Astronomy News - 23 October 2014 - 4:00pm
This composite NASA Hubble Space Telescope Image captures the positions of comet Siding Spring and Mars in a never-before-seen close passage of a comet by the Red Planet.

Churning galaxy boasts a fiery halo of baby stars

Astronomy News - 23 October 2014 - 2:51pm
The suburbs are where it's at – a baby boom on the outskirts of a distant galaxy is setting its swirly arms aflame






Two Families of Comets Found Around Nearby Star

Astronomy News - 22 October 2014 - 5:00pm
The HARPS instrument at ESO’s La Silla Observatory in Chile has been used to make the most complete census of comets around another star ever created. A French team of astronomers has studied nearly 500 individual comets orbiting the star Beta Pictoris and has discovered that they belong to two distinct families of exocomets: old exocomets that have made multiple passages near the star, and younger exocomets that probably came from the recent breakup of one or more larger objects. The new results will appear in the journal Nature on 23 October 2014.

Dark matter signal points to exotic black-hole origins

Astronomy News - 22 October 2014 - 3:30pm
If our best sign yet of dark matter is what it seems, then the supermassive black hole at the centre of our galaxy is a complex beast






Astrophysics: Secret ingredient exposed

Astronomy News - 22 October 2014 - 12:00am

Astrophysics: Secret ingredient exposed

Nature 514, 7524 (2014). doi:10.1038/nature13932

Authors: Christopher M. Johns-Krull

Astronomers have suspected for some time that magnetic fields are a key ingredient in the accretion of material that surrounds young stars. New observations have just begun to reveal these fields in action. See Letter p.597

Spatially resolved magnetic field structure in the disk of a T Tauri star

Astronomy News - 22 October 2014 - 12:00am

Spatially resolved magnetic field structure in the disk of a T Tauri star

Nature 514, 7524 (2014). doi:10.1038/nature13850

Authors: Ian W. Stephens, Leslie W. Looney, Woojin Kwon, Manuel Fernández-López, A. Meredith Hughes, Lee G. Mundy, Richard M. Crutcher, Zhi-Yun Li & Ramprasad Rao

Magnetic fields in accretion disks play a dominant part during the star formation process but have hitherto been observationally poorly constrained. Field strengths have been inferred on T Tauri stars and possibly in the innermost part of their accretion disks, but the strength and morphology of the field in the bulk of a disk have not been observed. Spatially unresolved measurements of polarized emission (arising from elongated dust grains aligned perpendicularly to the field) imply average fields aligned with the disks. Theoretically, the fields are expected to be largely toroidal, poloidal or a mixture of the two, which imply different mechanisms for transporting angular momentum in the disks of actively accreting young stars such as HL Tau (ref. 11). Here we report resolved measurements of the polarized 1.25-millimetre continuum emission from the disk of HL Tau. The magnetic field on a scale of 80 astronomical units is coincident with the major axis (about 210 astronomical units long) of the disk. From this we conclude that the magnetic field inside the disk at this scale cannot be dominated by a vertical component, though a purely toroidal field also does not fit the data well. The unexpected morphology suggests that the role of the magnetic field in the accretion of a T Tauri star is more complex than our current theoretical understanding.