Institute of Astronomy

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A Colourful Gathering of Middle-aged Stars

Astronomy News - 26 November 2014 - 11:00am
The MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile has captured a richly colourful view of the bright star cluster NGC 3532. Some of the stars still shine with a hot bluish colour, but many of the more massive ones have become red giants and glow with a rich orange hue.

Astronomy: Cosmic triangles and black-hole masses

Astronomy News - 26 November 2014 - 12:00am

Astronomy: Cosmic triangles and black-hole masses

Nature 515, 7528 (2014). doi:10.1038/515498a

Authors: Martin Elvis

A geometric measurement of the distance to a nearby galaxy implies a larger mass for its central black hole than previously calculated, and a consequent increase for most other masses of such black holes. See Letter p.528

A dust-parallax distance of 19 megaparsecs to the supermassive black hole in NGC 4151

Astronomy News - 26 November 2014 - 12:00am

A dust-parallax distance of 19 megaparsecs to the supermassive black hole in NGC 4151

Nature 515, 7528 (2014). doi:10.1038/nature13914

Authors: Sebastian F. Hönig, Darach Watson, Makoto Kishimoto & Jens Hjorth

The active galaxy NGC 4151 has a crucial role as one of only two active galactic nuclei for which black hole mass measurements based on emission line reverberation mapping can be calibrated against other dynamical techniques. Unfortunately, effective calibration requires accurate knowledge of the distance to NGC 4151, which is not at present available. Recently reported distances range from 4 to 29 megaparsecs. Strong peculiar motions make a redshift-based distance very uncertain, and the geometry of the galaxy and its nucleus prohibit accurate measurements using other techniques. Here we report a dust-parallax distance to NGC 4151 of megaparsecs. The measurement is based on an adaptation of a geometric method that uses the emission line regions of active galaxies. Because these regions are too small to be imaged with present technology, we use instead the ratio of the physical and angular sizes of the more extended hot-dust emission as determined from time delays and infrared interferometry. This distance leads to an approximately 1.4-fold increase in the dynamical black hole mass, implying a corresponding correction to emission line reverberation masses of black holes if they are calibrated against the two objects with additional dynamical masses.

#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). http://www.nature.com/doifinder/10.1038/515319a

Author: Elizabeth Gibney

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

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






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.