Institute of Astronomy

Astronomy News

Discoverer of Neptune's rings dies

16 May 2016 - 9:08am

Andre Brahic, one of the people who discovered the rings of Neptune, has died aged 73, his publisher says.

Cannibal stars explode violently – as predicted by Darwin’s son

16 May 2016 - 9:07am

We now think one star swallowing another causes rare, bright red novae, but George Darwin had worked out the key details in the 19th century

Hubble Catches Views of a Jet Rotating with Comet 252P/LINEAR

13 May 2016 - 9:21am

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For thousands of years, humans have recorded sightings of mysterious comets sweeping across the nighttime skies. These celestial wanderers, "snowballs" of dust and ice, are swift-moving visitors from the cold depths of space. Some of them periodically visit the inner solar system during their journeys around the sun.

Unnamed dwarf planet may be third largest in the solar system

13 May 2016 - 9:19am

A body known only as 2007 OR10 has been given a boost by recent space telescope observations that peg it smaller than only Pluto and Eris

Temperate Earth-sized planets transiting a nearby ultracool dwarf star

12 May 2016 - 9:38am

Temperate Earth-sized planets transiting a nearby ultracool dwarf star

Nature 533, 7602 (2016). doi:10.1038/nature17448

Authors: Michaël Gillon, Emmanuël Jehin, Susan M. Lederer, Laetitia Delrez, Julien de Wit, Artem Burdanov, Valérie Van Grootel, Adam J. Burgasser, Amaury H. M. J. Triaud, Cyrielle Opitom, Brice-Olivier Demory, Devendra K. Sahu, Daniella Bardalez Gagliuffi, Pierre Magain & Didier Queloz

Star-like objects with effective temperatures of less than 2,700 kelvin are referred to as ‘ultracool dwarfs’. This heterogeneous group includes stars of extremely low mass as well as brown dwarfs (substellar objects not massive enough to sustain hydrogen fusion), and represents about 15 per cent of the population of astronomical objects near the Sun. Core-accretion theory predicts that, given the small masses of these ultracool dwarfs, and the small sizes of their protoplanetary disks, there should be a large but hitherto undetected population of terrestrial planets orbiting them—ranging from metal-rich Mercury-sized planets to more hospitable volatile-rich Earth-sized planets. Here we report observations of three short-period Earth-sized planets transiting an ultracool dwarf star only 12 parsecs away. The inner two planets receive four times and two times the irradiation of Earth, respectively, placing them close to the inner edge of the habitable zone of the star. Our data suggest that 11 orbits remain possible for the third planet, the most likely resulting in irradiation significantly less than that received by Earth. The infrared brightness of the host star, combined with its Jupiter-like size, offers the possibility of thoroughly characterizing the components of this nearby planetary system.

Celestial mechanics: Fresh solutions to the four-body problem

12 May 2016 - 9:38am

Celestial mechanics: Fresh solutions to the four-body problem

Nature 533, 7602 (2016). doi:10.1038/nature17896

Authors: Douglas P. Hamilton

Describing the motion of three or more bodies under the influence of gravity is one of the toughest problems in astronomy. The report of solutions to a large subclass of the four-body problem is truly remarkable.

No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry

12 May 2016 - 9:37am

No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry

Nature 533, 7602 (2016). doi:10.1038/nature17444

Authors: R. M. Roettenbacher, J. D. Monnier, H. Korhonen, A. N. Aarnio, F. Baron, X. Che, R. O. Harmon, Zs. Kővári, S. Kraus, G. H. Schaefer, G. Torres, M. Zhao, T. A. ten Brummelaar, J. Sturmann & L. Sturmann

Sunspots are cool areas caused by strong surface magnetic fields that inhibit convection. Moreover, strong magnetic fields can alter the average atmospheric structure, degrading our ability to measure stellar masses and ages. Stars that are more active than the Sun have more and stronger dark spots than does the Sun, including on the rotational pole. Doppler imaging, which has so far produced the most detailed images of surface structures on other stars, cannot always distinguish the hemisphere in which the starspots are located, especially in the equatorial region and if the data quality is not optimal. This leads to problems in investigating the north–south distribution of starspot active latitudes (those latitudes with more starspot activity); this distribution is a crucial constraint of dynamo theory. Polar spots, whose existence is inferred from Doppler tomography, could plausibly be observational artefacts. Here we report imaging of the old, magnetically active star ζ Andromedae using long-baseline infrared interferometry. In our data, a dark polar spot is seen in each of two observation epochs, whereas lower-latitude spot structures in both hemispheres do not persist between observations, revealing global starspot asymmetries. The north–south symmetry of active latitudes observed on the Sun is absent on ζ And, which hosts global spot patterns that cannot be produced by solar-type dynamos.

Planetary science: Solar wind hits Pluto hard

12 May 2016 - 9:36am

Planetary science: Solar wind hits Pluto hard

Nature 533, 7602 (2016). doi:10.1038/533148a

The solar wind is diverted by Pluto, suggesting that, like some larger planets, the dwarf planet has a shield against the stream of energized particles emanating from the Sun.Before NASA's New Horizons spacecraft visited the dwarf planet (pictured) in 2015, most scientists thought that

Planetary science: Planet 9 may glow from within

12 May 2016 - 9:35am

Planetary science: Planet 9 may glow from within

Nature 533, 7602 (2016). doi:10.1038/533149d

The hypothetical ninth planet of the Solar System could shine brightly.Planet 9, if it exists, is thought to be an ice planet that is slightly smaller than Neptune, orbiting in the far outer Solar System. Esther Linder and Christoph Mordasini of the University of

The rise and fall of Martian lakes

12 May 2016 - 9:24am

There is a wealth of evidence, collected over the past few decades, that suggests liquid water was abundant in the early history of Mars – one of our nearest and most studied neighbours. However, the size, evolution and duration of standing bodies of water, such as lakes, on Mars' surface are still a matter of great debate. A recent study, using data from several spacecraft operating at Mars, paints a detailed picture of the rise and fall of standing bodies of water in a region of Mars which once hosted one of its largest lakes.

Shooting stars show Earth had oxygen eons before we thought

12 May 2016 - 9:22am

Tiny meteorites discovered in Australia show that Earth's air had some oxygen in it at a time when no one thought it did – 2.7 billion years ago

NASA's Kepler Mission Announces Largest Collection of Planets Ever Discovered

11 May 2016 - 9:21am
NASA's Kepler mission has verified 1,284 new planets – the single largest finding of planets to date.

Kepler doubles exoplanet population with 1284 new planets

11 May 2016 - 9:17am

The new planet haul is the biggest yet, bringing the number of confirmed worlds outside our solar system over 3200 - and edges us closer to knowing how many stars host other Earths

More than 100 Earth-sized planets found

11 May 2016 - 9:16am

Nasa announces the discovery of more than 100 Earth-sized planets orbiting alien stars.

First global Mercury map shows its hills and valleys in detail

10 May 2016 - 9:31am

The team behind NASA's Messenger mission to Mercury has released the first global topographic map of the planet – just in time for its biggest show of the decade

Stars burn away the atmospheres of close-in super-Earths

9 May 2016 - 9:07am

We haven’t seen any super-Earth orbiting close to their host stars because the stars have shredded the planets’ atmospheres, making them look smaller

Mercury completes journey across Sun

9 May 2016 - 9:05am

The Solar System's smallest planet has made one of its irregular passes between the Earth and Sun.