Institute of Astronomy

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Probe refines Pluto flyby path

Astronomy News - 2 July 2015 - 9:33am

The American New Horizons spacecraft makes its last planned targeting manoeuvre as it bears down on Pluto.

Rosetta spies cometary sinkholes

Astronomy News - 2 July 2015 - 9:33am

The comet being studied by Europe’s Rosetta probe is riddled with pits that formed much like sinkholes here on Earth, say scientists.

VIDEO: Leap second: What does it mean?

Astronomy News - 1 July 2015 - 9:21am

Midnight will come later tonight, as for the first time in three years, an extra second is added to the official time set by atomic clocks.

Misbehaving pulsar's sudden slow-down may teach us how they tick

Astronomy News - 30 June 2015 - 9:45am

A bright young pulsar that seemed to be stable has slammed on its brakes. Understanding this shift in behaviour could help astronomers calibrate cosmic clocks









'Leap second' delays midnight

Astronomy News - 30 June 2015 - 9:33am

Midnight came later on Tuesday as for the first time in three years an extra second was added to the official time set by atomic clocks.

Handprints on Hubble

Astronomy News - 29 June 2015 - 10:28am
As the Hubble Space Telescope celebrates its 25th anniversary, scientists are reflecting on the key role astronauts played in allowing the telescope to continue making great discoveries.

Rainbow X-ray echoes pinpoint faraway neutron star

Astronomy News - 29 June 2015 - 10:27am

By observing ripples of X-rays bouncing off dust around a remote binary star, astronomers have solved a puzzle over its distance









Galaxy's supermassive black hole is a cool neighbourhood for ice

Astronomy News - 29 June 2015 - 10:26am

Despite searing radiation at the Milky Way's core, water and hydrocarbon ice are clinging on – probably thanks to sheltering dust grains









Monster black hole wakes up after 26 years

Astronomy News - 26 June 2015 - 9:33am

Over the past week, ESA's INTEGRAL satellite has been observing an exceptional outburst of high-energy light produced by a black hole that is devouring material from its stellar companion.

Giant Galaxy is Still Growing

Astronomy News - 26 June 2015 - 9:30am
New observations with ESO’s Very Large Telescope have revealed that the giant elliptical galaxy Messier 87 has swallowed an entire medium-sized galaxy over the last billion years. For the first time a team of astronomers has been able to track the motions of 300 glowing planetary nebulae to find clear evidence of this event and also found evidence of excess light coming from the remains of the totally disrupted victim.

Exposed water ice detected on comet's surface

Astronomy News - 25 June 2015 - 9:38am

Using the high-resolution science camera on board ESA's Rosetta spacecraft, scientists have identified more than a hundred patches of water ice a few metres in size on the surface of Comet 67P/Churyumov-Gerasimenko.

Hubble sees atmosphere being stripped from Neptune-sized exoplanet [heic1515]

Astronomy News - 25 June 2015 - 9:38am

Astronomers using the NASA/ESA Hubble Space Telescope have discovered an immense cloud of hydrogen dispersing from a warm, Neptune-sized planet orbiting a nearby star. The enormous gaseous tail of the planet is about 50 times the size of the parent star. The findings will be published in the 25 June issue of the journal Nature.

Hubble Sees a 'Behemoth' Bleeding Atmosphere Around a Warm Neptune-Sized Exoplanet

Astronomy News - 25 June 2015 - 9:33am

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Astronomers using NASA's Hubble Space Telescope have discovered an immense cloud of hydrogen dubbed "The Behemoth" bleeding off a planet orbiting a nearby star. The enormous, comet-like feature is about 50 times the size of the parent star. The hydrogen is evaporating from a warm, Neptune-sized planet, due to extreme radiation from the star. A phenomenon this large has never before been seen around any exoplanet. It may offer clues to how Super-Earths massive, rocky, versions of Earth are born around other stars through the evaporation of their outer layers of hydrogen. Finding "The Behemoth" could be a game-changer for characterizing atmospheres of the whole population of Neptune-sized planets and Super-Earths in ultraviolet observations.

Construction resumes on Hawaii's Thirty Meter Telescope

Astronomy News - 25 June 2015 - 9:31am

After a two-month pause and potential game over, construction on the biggest telescope on Mauna Kea will resume – but protests continue







A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b

Astronomy News - 25 June 2015 - 9:29am

A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b

Nature 522, 7557 (2015). doi:10.1038/nature14501

Authors: David Ehrenreich, Vincent Bourrier, Peter J. Wheatley, Alain Lecavelier des Etangs, Guillaume Hébrard, Stéphane Udry, Xavier Bonfils, Xavier Delfosse, Jean-Michel Désert, David K. Sing & Alfred Vidal-Madjar

Exoplanets orbiting close to their parent stars may lose some fraction of their atmospheres because of the extreme irradiation. Atmospheric mass loss primarily affects low-mass exoplanets, leading to the suggestion that hot rocky planets might have begun as Neptune-like, but subsequently lost all of their atmospheres; however, no confident measurements have hitherto been available. The signature of this loss could be observed in the ultraviolet spectrum, when the planet and its escaping atmosphere transit the star, giving rise to deeper and longer transit signatures than in the optical spectrum. Here we report that in the ultraviolet the Neptune-mass exoplanet GJ 436b (also known as Gliese 436b) has transit depths of 56.3 ± 3.5% (1σ), far beyond the 0.69% optical transit depth. The ultraviolet transits repeatedly start about two hours before, and end more than three hours after the approximately one hour optical transit, which is substantially different from one previous claim (based on an inaccurate ephemeris). We infer from this that the planet is surrounded and trailed by a large exospheric cloud composed mainly of hydrogen atoms. We estimate a mass-loss rate in the range of about 108–109 grams per second, which is far too small to deplete the atmosphere of a Neptune-like planet in the lifetime of the parent star, but would have been much greater in the past.

Galaxies at redshifts 5 to 6 with systematically low dust content and high [C ii] emission

Astronomy News - 25 June 2015 - 9:29am

Galaxies at redshifts 5 to 6 with systematically low dust content and high [C ii] emission

Nature 522, 7557 (2015). doi:10.1038/nature14500

Authors: P. L. Capak, C. Carilli, G. Jones, C. M. Casey, D. Riechers, K. Sheth, C. M. Carollo, O. Ilbert, A. Karim, O. LeFevre, S. Lilly, N. Scoville, V. Smolcic & L. Yan

The rest-frame ultraviolet properties of galaxies during the first three billion years of cosmic time (redshift z > 4) indicate a rapid evolution in the dust obscuration of such galaxies. This evolution implies a change in the average properties of the interstellar medium, but the measurements are systematically uncertain owing to untested assumptions and the inability to detect heavily obscured regions of the galaxies. Previous attempts to measure the interstellar medium directly in normal galaxies at these redshifts have failed for a number of reasons, with two notable exceptions. Here we report measurements of the forbidden C ii emission (that is, [C ii]) from gas, and the far-infrared emission from dust, in nine typical star-forming galaxies about one billion years after the Big Bang (z ≈ 5–6). We find that these galaxies have thermal emission that is less than 1/12 that of similar systems about two billion years later, and enhanced [C ii] emission relative to the far-infrared continuum, confirming a strong evolution in the properties of the interstellar medium in the early Universe. The gas is distributed over scales of one to eight kiloparsecs, and shows diverse dynamics within the sample. These results are consistent with early galaxies having significantly less dust than typical galaxies seen at z < 3 and being comparable in dust content to local low-metallicity systems.

Astrophysics: Dust-poor galaxies at early times

Astronomy News - 25 June 2015 - 9:29am

Astrophysics: Dust-poor galaxies at early times

Nature 522, 7557 (2015). doi:10.1038/522422a

Authors: Veronique Buat

Observations of galaxies that formed early in the Universe's history reveal much lower dust levels than are found in sources from a slightly later era. It seems that galaxies underwent rapid change during a relatively short period. See Letter p.455

Planetary science: Space-rock alert

Astronomy News - 25 June 2015 - 9:28am

Planetary science: Space-rock alert

Nature 522, 7557 (2015). doi:10.1038/522418a

Author: Alexandra Witze

Alexandra Witze watches a pair of films on asteroids — according to many, a vast accident waiting to happen.

Private asteroid hunt lacks cash to spy threats in orbit

Astronomy News - 25 June 2015 - 9:27am

Private asteroid hunt lacks cash to spy threats in orbit

Nature 522, 7557 (2015). http://www.nature.com/doifinder/10.1038/522402a

Author: Traci Watson

Foundation fails to raise funds it needs for a space telescope to catalogue near-Earth objects.

Astronomers claim first glimpse of primordial stars

Astronomy News - 25 June 2015 - 9:27am

Astronomers claim first glimpse of primordial stars

Nature 522, 7557 (2015). http://www.nature.com/doifinder/10.1038/nature.2015.17802

Author: Elizabeth Gibney

Bright galaxy thought to hold stars from generation that seeded rest of Universe.