Institute of Astronomy

Astronomy News

VIDEO: 'We're going back to origins of life'

19 November 2014 - 3:05am
The Philae lander has detected organic molecules on the surface of its comet, scientists have confirmed.

Astronomy: Merged stars dodge black hole

19 November 2014 - 12:00am

Astronomy: Merged stars dodge black hole

Nature 515, 7527 (2014). doi:10.1038/515315c

A mysterious cloud-like object that survived a close encounter with a black hole might be a merged pair of stars.Andrea Ghez of the University of California in Los Angeles and her team used the Keck telescopes on Mauna Kea in Hawaii to observe the

The power of relativistic jets is larger than the luminosity of their accretion disks

19 November 2014 - 12:00am

The power of relativistic jets is larger than the luminosity of their accretion disks

Nature 515, 7527 (2014). doi:10.1038/nature13856

Authors: G. Ghisellini, F. Tavecchio, L. Maraschi, A. Celotti & T. Sbarrato

Theoretical models for the production of relativistic jets from active galactic nuclei predict that jet power arises from the spin and mass of the central supermassive black hole, as well as from the magnetic field near the event horizon. The physical mechanism underlying the contribution from the magnetic field is the torque exerted on the rotating black hole by the field amplified by the accreting material. If the squared magnetic field is proportional to the accretion rate, then there will be a correlation between jet power and accretion luminosity. There is evidence for such a correlation, but inadequate knowledge of the accretion luminosity of the limited and inhomogeneous samples used prevented a firm conclusion. Here we report an analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations. We find a clear correlation between jet power, as measured through the γ-ray luminosity, and accretion luminosity, as measured by the broad emission lines, with the jet power dominating the disk luminosity, in agreement with numerical simulations. This implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter.

Philae lander sleeps but Rosetta mission lives on

18 November 2014 - 6:30pm
The European Space Agency has announced that Philae has detected organic molecules on comet 67P – and there are many more scientific discoveries to come

Philae’s 64 hours of comet science yield rich data

18 November 2014 - 12:00am

Philae’s 64 hours of comet science yield rich data

Nature 515, 7527 (2014).

Author: Elizabeth Gibney

Comet lander is now hibernating, but has already altered our understanding of these objects.

New Geological Maps of Asteroid Vesta

17 November 2014 - 7:34pm
Images from NASA's Dawn Mission have been used to create a series of high-resolution geological maps of the large asteroid Vesta, revealing the variety of surface features in unprecedented detail. These maps are included with a series of 11 scientific papers published this week in a special issue of the journal Icarus.

OSIRIS spots Philae drifting across the comet

17 November 2014 - 7:29pm
These incredible images show the breathtaking journey of Rosetta's Philae lander as it approached and then rebounded from its first touchdown on Comet 67P/Churyumov-Gerasimenko on 12 November 2014.

Dark matter could be seen in GPS time glitches

17 November 2014 - 5:56pm
What if the unseen stuff making up 80 per cent of the universe's matter isn't a weird particle, but cosmic kinks? Then GPS satellites could reveal its effects

H2D+ observations give an age of at least one million years for a cloud core forming Sun-like stars

17 November 2014 - 12:00am

H2D+ observations give an age of at least one million years for a cloud core forming Sun-like stars

Nature 516, 7530 (2014). doi:10.1038/nature13924

Authors: Sandra Brünken, Olli Sipilä, Edward T. Chambers, Jorma Harju, Paola Caselli, Oskar Asvany, Cornelia E. Honingh, Tomasz Kamiński, Karl M. Menten, Jürgen Stutzki & Stephan Schlemmer

The age of dense interstellar cloud cores, where stars and planets form, is a crucial parameter in star formation and difficult to measure. Some models predict rapid collapse, whereas others predict timescales of more than one million years (ref. 3). One possible approach to determining the age is through chemical changes as cloud contraction occurs, in particular through indirect measurements of the ratio of the two spin isomers (ortho/para) of molecular hydrogen, H2, which decreases monotonically with age. This has been done for the dense cloud core L183, for which the deuterium fractionation of diazenylium (N2H+) was used as a chemical clock to infer that the core has contracted rapidly (on a timescale of less than 700,000 years). Among astronomically observable molecules, the spin isomers of the deuterated trihydrogen cation, ortho-H2D+ and para-H2D+, have the most direct chemical connections to H2 (refs 8, 9, 10, 11, 12) and their abundance ratio provides a chemical clock that is sensitive to greater cloud core ages. So far this ratio has not been determined because para-H2D+ is very difficult to observe. The detection of its rotational ground-state line has only now become possible thanks to accurate measurements of its transition frequency in the laboratory, and recent progress in instrumentation technology. Here we report observations of ortho- and para-H2D+ emission and absorption, respectively, from the dense cloud core hosting IRAS 16293-2422 A/B, a group of nascent solar-type stars (with ages of less than 100,000 years). Using the ortho/para ratio in conjunction with chemical models, we find that the dense core has been chemically processed for at least one million years. The apparent discrepancy with the earlier N2H+ work arises because that chemical clock turns off sooner than the H2D+ clock, but both results imply that star-forming dense cores have ages of about one million years, rather than 100,000 years.

Pictures show comet probe 'bounce'

16 November 2014 - 6:30pm
Images of the Philae probe moments after its initial touchdown on comet 67P have been published by the European Space Agency.

Pioneering Philae completes main mission before hibernation

15 November 2014 - 8:49am
Rosetta's lander has completed its primary science mission after nearly 57 hours on Comet 67P/Churyumov–Gerasimenko.

Habitable exomoons born in cosmic collisions

14 November 2014 - 6:00pm
Simulations suggest that moons that can hang on to an atmosphere only form in certain types of cosmic collisions

Three touchdowns for Rosetta's lander

14 November 2014 - 3:13pm
After achieving touchdown on a comet for the first time in history, scientists and engineers are busy analysing this new world and the nature of the landing.

The Party's Over for These Youthful Compact Galaxies

13 November 2014 - 6:00pm

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Hubble has uncovered young, massive, compact galaxies whose raucous star-making parties are ending early. The firestorm of star birth has blasted out most of the remaining gaseous fuel needed to make future generations of stars. Now the party's over for these gas-starved galaxies, and they are on track to possibly becoming so-called "red and dead galaxies," composed only of aging stars. An analysis of 12 merging galaxies is suggesting that energy from the star-birthing frenzy created powerful winds that are blowing out the gas, squelching future generations of stars. This activity occurred when the universe was half its current age of 13.7 billion years.

RAS statement on the abolition of Europe's Chief Scientific Advisor. Our presi...

13 November 2014 - 5:26pm
RAS statement on the abolition of Europe's Chief Scientific Advisor.

Our president calls for the position to be re-instated.

RAS statement on the abolition of Europe's Chief Scientific Advisor
The new European Commission has abolished the position of its main scientific advisor, according to recent media reports. The RAS wishes to express its disappointment at this decision, which is likely to weaken the role of scientific evidence in EU g

Race to get comet data before Philae dies

13 November 2014 - 4:30pm
The first spacecraft to land on a comet bounced twice before it settled, but its batteries are running out, leaving scientists in a race against time

Comet probe Philae 'has stabilised'

13 November 2014 - 9:22am
The robot probe Philae that made a historic landing on a comet is now stable after initially failing to attach to the surface, scientists say.

Touchdown! Rosetta's Philae probe lands on comet

12 November 2014 - 6:32pm
ESA's Rosetta mission has soft-landed its Philae probe on a comet, the first time in history that such an extraordinary feat has been achieved.

MUSE Reveals True Story Behind Galactic Crash

10 November 2014 - 12:01am
The new MUSE instrument on ESO’s Very Large Telescope (VLT) has provided researchers with the best view yet of a spectacular cosmic crash. The new observations reveal for the first time the motion of gas as it is ripped out of the galaxy ESO 137-001 as it ploughs at high speed into a vast galaxy cluster. The results are the key to the solution of a long-standing mystery — why star formation switches off in galaxy clusters.