Institute of Astronomy

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#Rosettawatch: homing in on Philae's resting spot

Astronomy News - 25 November 2014 - 5:39pm
Its on-going mission, to explore the strange new comet, to seek out new plumes of dust and gas, spewing from the warming surface of 67P/Churyumov-Gerasimenko

Dark sky status bid for South Downs

Astronomy News - 24 November 2014 - 12:01pm
A campaign begins to reduce light pollution in South Downs National Park and give it dark skies special status.

Saturn's calming nature keeps Earth friendly to life

Astronomy News - 21 November 2014 - 4:56pm
Even slight tweaks to Saturn's orbital plane and distance could have put Earth on a comet-like path around the sun – and ejected Mars from the solar system

NASA Announces New Opportunities for Public Participation in Asteroid Grand Challenge

Astronomy News - 21 November 2014 - 4:00pm
Ten new projects are providing opportunities for the public to participate in NASA's Asteroid Grand Challenge, which accelerates the agency's asteroid initiative work through innovative partnerships and collaborations.

Galaxies in filaments spaced like pearls on a necklace

Astronomy News - 21 November 2014 - 10:59am
What began as a project looking at the statistics of galaxy distributions found an underlying pattern that could help astronomers learn how the universe evolved

The riddle of the missing stars - Hubble observations cast further doubt on how globular clusters formed [heic1425]

Astronomy News - 20 November 2014 - 3:00pm
Thanks to the NASA/ESA Hubble Space Telescope, some of the most mysterious cosmic residents have just become even more puzzling. New observations of globular clusters in a small galaxy show they are very similar to those found in the Milky Way, and so must have formed in a similar way. One of the leading theories on how these clusters form predicts that globular clusters should only be found nestled in among large quantities of old stars. But these old stars, though rife in the Milky Way, are not present in this small galaxy, and so, the mystery deepens.

Rosetta continues into its full science phase

Astronomy News - 20 November 2014 - 9:01am
With the Philae lander's mission complete, Rosetta will now continue its own extraordinary exploration, orbiting Comet 67P/Churyumov-Gerasimenko during the coming year as the enigmatic body arcs ever closer to our Sun.

Us vs the universe: 8 ways we bend the laws of physics

Astronomy News - 19 November 2014 - 12:12pm
Whether it's squeezing the uncertainty out of Heisenberg or busting the cosmic speed limit, we're outsmarting the universe to learn its secrets

Spooky Alignment of Quasars Across Billions of Light-years

Astronomy News - 19 November 2014 - 11:00am
New observations with ESO’s Very Large Telescope (VLT) in Chile have revealed alignments over the largest structures ever discovered in the Universe. A European research team has found that the rotation axes of the central supermassive black holes in a sample of quasars are parallel to each other over distances of billions of light-years. The team has also found that the rotation axes of these quasars tend to be aligned with the vast structures in the cosmic web in which they reside.

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

Astronomy News - 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

Astronomy News - 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

Astronomy News - 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

Astronomy News - 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

Astronomy News - 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

Astronomy News - 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

Astronomy News - 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

Astronomy News - 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

Astronomy News - 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'

Astronomy News - 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

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