Institute of Astronomy

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The Turbulent Birth of a Quasar

Astronomy News - 15 January 2016 - 4:26pm
The most luminous galaxy known in the Universe — the quasar W2246-0526, seen when the Universe was less than 10% of its current age — is so turbulent that it is in the process of ejecting its entire supply of star-forming gas, according to new observations with the Atacama Large Millimeter/submillimeter Array (ALMA).

We’ve found the brightest ever supernova but can’t explain it

Astronomy News - 15 January 2016 - 9:39am

Astronomers are now sure the incredibly violent stellar explosion spotted last June is the brightest ever seen. But they remain baffled about its source









ASTRO-H satellite ready for launch

Astronomy News - 15 January 2016 - 9:38am

On 12 January 2016, the Japan Aerospace Exploration Agency (JAXA) presented their ASTRO-H satellite to the media at the Tanegashima Space Center, situated on a small island in the south of Japan. The satellite, developed with institutions in Japan, the US, Canada and Europe, is now ready to be mounted on an H-IIA rocket for launch on 12 February.

A Milky Way twin swept by an ultra-fast X-ray wind

Astronomy News - 15 January 2016 - 9:36am

ESA's XMM-Newton has found a wind of high-speed gas streaming from the centre of a bright spiral galaxy like our own that may be reducing its ability to produce new stars.

Colossal star explosion detected

Astronomy News - 15 January 2016 - 9:35am

Astronomers have seen what could be the most powerful supernova yet detected - an event so big it shone with 570 billion times the brightness of our Sun.

Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars

Astronomy News - 14 January 2016 - 10:02am

Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars

Nature 529, 7585 (2016). doi:10.1038/nature16168

Authors: Jennifer L. van Saders, Tugdual Ceillier, Travis S. Metcalfe, Victor Silva Aguirre, Marc H. Pinsonneault, Rafael A. García, Savita Mathur & Guy R. Davies

A knowledge of stellar ages is crucial for our understanding of many astrophysical phenomena, and yet ages can be difficult to determine. As they become older, stars lose mass and angular momentum, resulting in an observed slowdown in surface rotation. The technique of ‘gyrochronology’ uses the rotation period of a star to calculate its age. However, stars of known age must be used for calibration, and, until recently, the approach was untested for old stars (older than 1 gigayear, Gyr). Rotation periods are now known for stars in an open cluster of intermediate age (NGC 6819; 2.5 Gyr old), and for old field stars whose ages have been determined with asteroseismology. The data for the cluster agree with previous period–age relations, but these relations fail to describe the asteroseismic sample. Here we report stellar evolutionary modelling, and confirm the presence of unexpectedly rapid rotation in stars that are more evolved than the Sun. We demonstrate that models that incorporate dramatically weakened magnetic braking for old stars can—unlike existing models—reproduce both the asteroseismic and the cluster data. Our findings might suggest a fundamental change in the nature of ageing stellar dynamos, with the Sun being close to the critical transition to much weaker magnetized winds. This weakened braking limits the diagnostic power of gyrochronology for those stars that are more than halfway through their main-sequence lifetimes.

Rebooted Kepler spacecraft hauls in the planets

Astronomy News - 14 January 2016 - 10:01am

Rebooted Kepler spacecraft hauls in the planets

Nature 529, 7585 (2016). http://www.nature.com/doifinder/10.1038/nature.2016.19126

Author: Alexandra Witze

Fresh worlds found by K2 mission push beyond original discoveries.

Eight per cent leakage of Lyman continuum photons from a compact, star-forming dwarf galaxy

Astronomy News - 14 January 2016 - 10:01am

Eight per cent leakage of Lyman continuum photons from a compact, star-forming dwarf galaxy

Nature 529, 7585 (2016). doi:10.1038/nature16456

Authors: Y. I. Izotov, I. Orlitová, D. Schaerer, T. X. Thuan, A. Verhamme, N. G. Guseva & G. Worseck

One of the key questions in observational cosmology is the identification of the sources responsible for ionization of the Universe after the cosmic ‘Dark Ages’, when the baryonic matter was neutral. The currently identified distant galaxies are insufficient to fully reionize the Universe by redshift z ≈ 6 (refs 1, 2, 3), but low-mass, star-forming galaxies are thought to be responsible for the bulk of the ionizing radiation. As direct observations at high redshift are difficult for a variety of reasons, one solution is to identify local proxies of this galaxy population. Starburst galaxies at low redshifts, however, generally are opaque to Lyman continuum photons. Small escape fractions of about 1 to 3 per cent, insufficient to ionize much surrounding gas, have been detected only in three low-redshift galaxies. Here we report far-ultraviolet observations of the nearby low-mass star-forming galaxy J0925+1403. The galaxy is leaking ionizing radiation with an escape fraction of about 8 per cent. The total number of photons emitted during the starburst phase is sufficient to ionize intergalactic medium material that is about 40 times as massive as the stellar mass of the galaxy.

Striking views of our Solar System

Astronomy News - 14 January 2016 - 9:43am

Fog on Mars, storms on Jupiter and fiery flares on the Sun

Exposed ice on Rosetta's comet confirmed as water

Astronomy News - 14 January 2016 - 9:42am

Observations made shortly after Rosetta's arrival at its target comet in 2014 have provided definitive confirmation of the presence of water ice.

First Light For Future Black Hole Probe

Astronomy News - 14 January 2016 - 9:39am
Zooming in on black holes is the main mission for the newly installed instrument GRAVITY at ESO’s Very Large Telescope in Chile. During its first observations, GRAVITY successfully combined starlight using all four Auxiliary Telescopes. The large team of European astronomers and engineers, led by the Max Planck Institute for Extraterrestrial Physics in Garching, who designed and built GRAVITY, are thrilled with the performance. During these initial tests, the instrument has already achieved a number of notable firsts. This is the most powerful VLT Interferometer instrument yet installed.

Lights on for LISA Pathfinder

Astronomy News - 13 January 2016 - 9:25am

While LISA Pathfinder is en route to its operational orbit, the science and engineering teams are testing the systems on the spacecraft. This week, they will begin to switch on elements of the science payload, including the laser that will be used to monitor the most precise free-fall motion ever obtained in space.

Famous Wow! signal might have been from comets, not aliens

Astronomy News - 12 January 2016 - 9:40am

A powerful radio signal from space has puzzled astronomers for decades and led to talk of alien signals, but now there might be a more mundane explanation









Philae lander fails to respond to last-ditch efforts to wake it

Astronomy News - 12 January 2016 - 9:40am

A signal sent to comet 67P/Churyumov-Gerasimenko last night received no response, suggesting the famous space lander has reached the end of its life









AUDIO: How to take a picture of a black hole

Astronomy News - 11 January 2016 - 9:31am

Astronomer Feryal Ozel speaks to the BBC's Jonathan Webb about the Event Horizon Telescope.

'Age map' traces galactic history

Astronomy News - 11 January 2016 - 9:30am
By measuring the age of 70,000 stars across the Milky Way, astronomers make a "growth chart" for our galaxy.

Comet dust 'ballistics' probed in 3D

Astronomy News - 11 January 2016 - 9:29am
Scientists make microscopic 3D maps of the tracks carved by comet dust when a Nasa spacecraft collected samples in blocks of gel.

NASA's Great Observatories Weigh Massive Young Galaxy Cluster

Astronomy News - 8 January 2016 - 9:15am

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Astronomers have made the most detailed study yet of an extremely massive young galaxy cluster using three of NASA's Great Observatories. This multiwavelength image shows this galaxy cluster, called IDCS J1426.5+3508 (IDCS 1426 for short), in X-rays recorded by the Chandra X-ray Observatory in blue, visible light observed by the Hubble Space Telescope in green, and infrared light from the Spitzer Space Telescope in red.

Event horizon snapshot due in 2017

Astronomy News - 8 January 2016 - 9:13am

A global network of nine radio telescopes is set to take the first ever picture of a black hole's event horizon in 2017.

NASA's Spitzer, Hubble Find 'Twins' of Superstar Eta Carinae in Other Galaxies

Astronomy News - 7 January 2016 - 4:49pm

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Eta Carinae, the most luminous and massive stellar system located within 10,000 light-years of Earth, is best known for an enormous eruption seen in the mid-19th century that hurled an amount of material at least 10 times the sun's mass into space. Still shrouded by this expanding veil of gas and dust, Eta Carinae is the only object of its kind known in our galaxy. Now a study using archival data from NASA's Spitzer and Hubble space telescopes has found five similar objects in other galaxies for the first time.