Institute of Astronomy

Astronomy News

Spotted: First quadruple star image produced by gravity

3 December 2014 - 6:25pm
A newly discovered supernova and its four gravitationally lensed images may give researchers a way to pin down the universe's expansion rate

Hayabusa 2 probe begins journey to land on an asteroid

3 December 2014 - 1:20pm
Japanese space agency JAXA has successfully launched Hayabusa 2, which will land on asteroid 1993 JU3 in 2018

Astrophysics: Stars fight back

3 December 2014 - 12:00am

Astrophysics: Stars fight back

Nature 516, 7529 (2014). doi:10.1038/516044a

Authors: Philip F. Hopkins

Galaxies contain fewer stars than predicted. The discovery of a massive galactic outflow of molecular gas in a compact galaxy, which forms stars 100 times faster than the Milky Way, may help to explain why. See Letter p.68

Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy

3 December 2014 - 12:00am

Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy

Nature 516, 7529 (2014). doi:10.1038/nature14012

Authors: J. E. Geach, R. C. Hickox, A. M. Diamond-Stanic, M. Krips, G. H. Rudnick, C. A. Tremonti, P. H. Sell, A. L. Coil & J. Moustakas

Recent observations have revealed that starburst galaxies can drive molecular gas outflows through stellar radiation pressure. Molecular gas is the phase of the interstellar medium from which stars form, so these outflows curtail stellar mass growth in galaxies. Previously known outflows, however, involve small fractions of the total molecular gas content and have typical scales of less than a kiloparsec. In at least some cases, input from active galactic nuclei is dynamically important, so pure stellar feedback (the momentum return into the interstellar medium) has been considered incapable of rapidly terminating star formation on galactic scales. Molecular gas has been detected outside the galactic plane of the archetypal starburst galaxy M82 (refs 4 and 5), but so far there has been no evidence that starbursts can propel substantial quantities of cold molecular gas to the same galactocentric radius (about 10 kiloparsecs) as the warmer gas that has been traced by metal ion absorbers in the circumgalactic medium. Here we report observations of molecular gas in a compact (effective radius 100 parsecs) massive starburst galaxy at redshift 0.7, which is known to drive a fast outflow of ionized gas. We find that 35 per cent of the total molecular gas extends approximately 10 kiloparsecs, and one-third of this extended gas has a velocity of up to 1,000 kilometres per second. The kinetic energy associated with this high-velocity component is consistent with the momentum flux available from stellar radiation pressure. This demonstrates that nuclear bursts of star formation are capable of ejecting large amounts of cold gas from the central regions of galaxies, thereby strongly affecting their evolution by truncating star formation and redistributing matter.

Is Jupiter's Great Red Spot a Sunburn?

28 November 2014 - 5:54pm
The ruddy color of Jupiter's Great Red Spot is likely a product of simple chemicals being broken apart by sunlight in the planet's upper atmosphere, according to a new analysis of data from NASA's Cassini mission. The results contradict the other leading theory for the origin of the spot's striking color -- that the reddish chemicals come from beneath Jupiter's clouds.

Naked nebula reveals astronomy's colour tricks

28 November 2014 - 4:10pm
A raw picture of the Helix nebula reveals the processing involved in creating stunning astronomical images

Conference Announcement: Planck 2014 - The microwave sky in temperature and polarization

28 November 2014 - 8:46am
The Planck Collaboration will present the latest scientific results from ESA’s Planck satellite during a conference to be held from 1 to 5 December 2014 in Ferrara, Italy.

JUICE mission gets green light for next stage of development

27 November 2014 - 2:00pm
The European Space Agency's JUICE (JUpiter ICy moons Explorer) mission has been given the green light to proceed to the next stage of development. This approval is a milestone for the mission, which aims to launch in 2022 to explore Jupiter and its potentially habitable icy moons.

A Colourful Gathering of Middle-aged Stars

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

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

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

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

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

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

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

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]

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

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

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

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.