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Telecopes: A giant leap for Africa

Astronomy News - 23 July 2016 - 8:23am

Currently under construction, the MeerKAT telescope in South Africa is establishing its role in scientific research.

Space... the final frontier [heic1615]

Astronomy News - 22 July 2016 - 8:56am

Fifty years ago Captain Kirk and the crew of the starship Enterprise began their journey into space – the final frontier. Now, as the newest Star Trek film hits cinemas, the NASA/ESA Hubble space telescope is also exploring new frontiers, observing distant galaxies in the galaxy cluster Abell S1063 as part of the Frontier Fields programme.

NASA's Hubble Looks to the Final Frontier

Astronomy News - 22 July 2016 - 8:56am

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Celebrating its 50th anniversary this year, the TV series "Star Trek" has captured the public's imagination with the signature phrase, "To boldly go where no one has gone before." The Hubble Space Telescope simply orbits Earth and doesn't "boldly go" deep into space. But it looks deeper into the universe than ever before possible to explore the fabric of time and space and find the farthest objects ever seen. This is epitomized in this Hubble image that is part of its Frontier Fields program to probe the far universe. This view of a massive cluster of galaxies unveils a very cluttered-looking universe filled with galaxies near and far. Some are distorted like a funhouse mirror through a warping-of-space phenomenon first predicted by Einstein a century ago.

Hubble telescope looks back in time to see far-off galaxies

Astronomy News - 22 July 2016 - 8:55am

NASA's greatest telescope has turned its eye on a distant patch of the universe, revealing a gaggle of galaxies, some of which date back to 1 billion years after the big bang

Relativistic reverberation in the accretion flow of a tidal disruption event

Astronomy News - 21 July 2016 - 11:54am

Relativistic reverberation in the accretion flow of a tidal disruption event

Nature 535, 7612 (2016). doi:10.1038/nature18007

Authors: Erin Kara, Jon M. Miller, Chris Reynolds & Lixin Dai

Our current understanding of the curved space-time around supermassive black holes is based on actively accreting black holes, which make up only ten per cent or less of the overall population. X-ray observations of that small fraction reveal strong gravitational redshifts that indicate that many of these black holes are rapidly rotating; however, selection biases suggest that these results are not necessarily reflective of the majority of black holes in the Universe. Tidal disruption events, where a star orbiting an otherwise dormant black hole gets tidally shredded and accreted onto the black hole, can provide a short, unbiased glimpse at the space-time around the other ninety per cent of black holes. Observations of tidal disruptions have hitherto revealed the formation of an accretion disk and the onset of an accretion-powered jet, but have failed to reveal emission from the inner accretion flow, which enables the measurement of black hole spin. Here we report observations of reverberation arising from gravitationally redshifted iron Kα photons reflected off the inner accretion flow in the tidal disruption event Swift J1644+57. From the reverberation timescale, we estimate the mass of the black hole to be a few million solar masses, suggesting an accretion rate of 100 times the Eddington limit or more. The detection of reverberation from the relativistic depths of this rare super-Eddington event demonstrates that the X-rays do not arise from the relativistically moving regions of a jet, as previously thought.

Origin and implications of non-radial Imbrium Sculpture on the Moon

Astronomy News - 21 July 2016 - 11:51am

Origin and implications of non-radial Imbrium Sculpture on the Moon

Nature 535, 7612 (2016). doi:10.1038/nature18278

Authors: Peter H. Schultz & David A. Crawford

Rimmed grooves, lineations and elongate craters around Mare Imbrium shape much of the nearside Moon. This pattern was coined the Imbrium Sculpture, and it was originally argued that it must have been formed by a giant oblique (~30°) impact, a conclusion echoed by later studies. Some investigators, however, noticed that many elements of the Imbrium Sculpture are not radial to Imbrium, thereby implicating an endogenic or structural origin. Here we use these non-radial trends to conclude that the Imbrium impactor was a proto-planet (half the diameter of Vesta), once part of a population of large proto-planets in the asteroid belt. Such independent constraints on the sizes of the Imbrium and other basin-forming impactors markedly increase estimates for the mass in the asteroid belt before depletion caused by the orbital migration of Jupiter and Saturn. Moreover, laboratory impact experiments, shock physics codes and the groove widths indicate that multiple fragments (up to 2% of the initial diameter) from each oblique basin-forming impactor, such as the one that formed Imbrium, should have survived planetary collisions and contributed to the heavy impact bombardment between 4.3 and 3.8 billion years ago.

NASA's Hubble Telescope Makes First Atmospheric Study of Earth-Sized Exoplanets

Astronomy News - 21 July 2016 - 11:49am

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The possibility of life on other worlds has fueled humankind's imagination for centuries. Over the past 20 years, the explosion of discoveries of planets orbiting other stars has sparked the search for worlds like Earth that could sustain life. Most of those candidates were found with other telescopes, including NASA's Kepler space observatory. NASA's Hubble Space Telescope has also made some unique contributions to the planet hunt. Astronomers used Hubble, for example, to make the first measurements of the atmospheric composition of extrasolar planets.

NASA’s Hubble Telescope Makes First Atmospheric Study of Earth-Sized Exoplanets

Astronomy News - 21 July 2016 - 11:48am
Using NASA’s Hubble Space Telescope, astronomers have conducted the first search for atmospheres around temperate, Earth-sized planets beyond our solar system and found indications that increase the chances of habitability on two exoplanets.

First atmospheric study of Earth-sized exoplanets excites researchers

Astronomy News - 21 July 2016 - 11:41am

Embarking on the first attempt at detecting the atmospheres of planets outside our solar system, a team of Cambridge and international researchers discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres such as those usually found on gaseous worlds like Jupiter or Saturn.  

The lack of a hydrogen-helium envelope increases the Earth-likeliness of these planets and has caused considerable excitement among researchers taking part in the study. The results of their findings are published today in the journal Nature.

“Humanity’s remote exploration of alien environments has truly started,” said Amaury Triaud, a research fellow at Cambridge’s Institute of Astronomy. “It is tantalizing to think that with another ten similar observations, we would start distinguishing whether those planets are more Venus-like, more Earth-like, or if they are radically different.”

Researchers observed the planets in near-infrared light and used spectroscopy to decode a change of light as the planets transited in front of their stars. During transit, starlight shines through a planet’s atmosphere making it possible to deduce its chemical makeup.

Both planets orbit TRAPPIST-1 – an ultracool dwarf star that is much cooler and redder than the sun, and barely larger than Jupiter. TRAPPIST-1 has a mass 8% that of the Sun and is located in the constellation of Aquarius. The planets orbiting the star were discovered in late 2015 through a series of observations by the TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST), a Belgian robotic telescope located at ESO’s (European Southern Observatory’s) La Silla Observatory in Chile. The small size of the star TRAPPIST-1 boosts the signal produced by the planets’ atmospheres, easing their study by nearly 100 times compared to similar planets orbiting stars like the Sun.

TRAPPIST-1b completes a circuit around its red dwarf star in 1.5 days and TRAPPIST-1c in 2.4 days. Thanks to the faintness of the star they orbit, and to the planet’s short orbits, it is possible that parts of their surfaces have temperatures similar to the Earth. While it remains unclear whether the planets are habitable, they are the first worlds for which we can determine the existence of a habitable climate.

On May 4, astronomers took advantage of a rare simultaneous transit, when both planets crossed the face of their star within minutes of each other, to measure starlight as it filtered through any existing atmosphere. This double transit, which occurs only once every two years, provided a chance to hasten the atmospheric study of TRAPPIST-1b and TRAPPIST-1c.

The researchers now hope to use Hubble to conduct follow-up observations to search for thinner atmospheres, composed of elements heavier than hydrogen, like those of Earth and Venus.

Observations from future telescopes, including NASA’s James Webb Space Telescope, will help determine the full composition of these atmospheres and hunt for potential biosignatures, such as carbon dioxide and ozone, in addition to water vapor and methane. Webb also will analyze a planet’s temperature and surface pressure – key factors in assessing its habitability.

“Our observations demonstrate that Hubble has the capacity to play a central role,” said lead researcher Julien de Wit, of the Massachusetts Institute of Technology. “It can carry-out an atmospheric pre-screening, to tell astronomers which of these Earth-sized planets are prime candidates for more detailed study with the Webb telescope.”

The TRAPPIST telescope identified these two Earth-sized worlds during a prototype run for a more ambitious venture, called SPECULOOS, which is currently in construction at Cerro Paranal, Chile. SPECULOOS will monitor 1,000 nearby red dwarf stars seeking additional Earth-sized worlds.

Professor Didier Queloz, Professor of Physics at the Cavendish Laboratory, and a founding member of the project, said: “Within the next five years, SPECULOOS will likely detect 20-30 new Earth-sized planets. All of them will have atmospheres that can be investigated by the James Webb.”

Dr Brice-Olivier Demory, a senior research associate at the Cavendish Laboratory, said: “Soon we will have the right targets, and the right telescopes to start investigating rocky planet atmospheres beyond our Solar system. Finding out whether other worlds are indeed Earth-like is only a matter of time.”

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. Goddard manages the telescope and STScI conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

Two Earth-sized exoplanets have become the first rocky worlds to have their atmospheres studied using the Hubble Space Telescope.

Humanity’s remote exploration of alien environments has truly started.Amaury TriaudNASAArtist's View of Planets Transiting Red Dwarf Star in TRAPPIST-1 System

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Vast asteroid created 'Man in Moon's eye' crater

Astronomy News - 21 July 2016 - 11:38am

One of the biggest craters on the Moon's surface was created by an asteroid more than 250km across, a study suggests.

Planet Nine may have tilted entire solar system except the sun

Astronomy News - 20 July 2016 - 8:47am

The sun's spin isn't totally upright compared with the orbits of the planets. Could this be because a jealous, distant world shoved its siblings?

What lies beneath: Venus' surface revealed through the clouds

Astronomy News - 19 July 2016 - 9:07am

Using observations from ESA's Venus Express satellite, scientists have shown for the first time how weather patterns seen in Venus' thick cloud layers are directly linked to the topography of the surface below. Rather than acting as a barrier to our observations, Venus' clouds may offer insight into what lies beneath.

Einstein’s clock: The doomed black hole to set your watch by

Astronomy News - 19 July 2016 - 9:05am

Every 12 years, a black hole at the centre of a distant galaxy completes an orbit around an even bigger black hole, marking this with a violent outburst

Baby stars grow big and strong by eating their own burst bubbles

Astronomy News - 18 July 2016 - 9:14am

A new simulation suggests the most massive stars in the universe got so big by taking advantage of the same physics that makes mushroom clouds

Mysterious swoosh caused by pulsars hugging companions close

Astronomy News - 18 July 2016 - 9:12am

A pair of dead stars give off bizarre radio signals, which could be the calling card of ultra-dense companions orbiting them at near the speed of light

Five incredible things we know about Pluto since 2015’s fly-by

Astronomy News - 15 July 2016 - 9:19am

New Horizons buzzed by Pluto and its moons last July, giving us a front-row seat to see icy peaks, towering atmospheric haze, a kilometres-deep canyon and more

Largest-ever map of 1.2 million galaxies measures dark energy

Astronomy News - 15 July 2016 - 9:14am

A decade-long survey of galaxies in the universe has revealed the crispest measurements yet of how dark energy drives the expansion fo the universe

Imaging the water snow-line during a protostellar outburst

Astronomy News - 14 July 2016 - 9:16am

Imaging the water snow-line during a protostellar outburst

Nature 535, 7611 (2016). doi:10.1038/nature18612

Authors: Lucas A. Cieza, Simon Casassus, John Tobin, Steven P. Bos, Jonathan P. Williams, Sebastian Perez, Zhaohuan Zhu, Claudio Caceres, Hector Canovas, Michael M. Dunham, Antonio Hales, Jose L. Prieto, David A. Principe, Matthias R. Schreiber, Dary Ruiz-Rodriguez & Alice Zurlo

A snow-line is the region of a protoplanetary disk at which a major volatile, such as water or carbon monoxide, reaches its condensation temperature. Snow-lines play a crucial role in disk evolution by promoting the rapid growth of ice-covered grains. Signatures of the carbon monoxide snow-line (at temperatures of around 20 kelvin) have recently been imaged in the disks surrounding the pre-main-sequence stars TW Hydra and HD163296 (refs 3, 10), at distances of about 30 astronomical units (au) from the star. But the water snow-line of a protoplanetary disk (at temperatures of more than 100 kelvin) has not hitherto been seen, as it generally lies very close to the star (less than 5 au away for solar-type stars). Water-ice is important because it regulates the efficiency of dust and planetesimal coagulation, and the formation of comets, ice giants and the cores of gas giants. Here we report images at 0.03-arcsec resolution (12 au) of the protoplanetary disk around V883 Ori, a protostar of 1.3 solar masses that is undergoing an outburst in luminosity arising from a temporary increase in the accretion rate. We find an intensity break corresponding to an abrupt change in the optical depth at about 42 au, where the elevated disk temperature approaches the condensation point of water, from which we conclude that the outburst has moved the water snow-line. The spectral behaviour across the snow-line confirms recent model predictions: dust fragmentation and the inhibition of grain growth at higher temperatures results in soaring grain number densities and optical depths. As most planetary systems are expected to experience outbursts caused by accretion during their formation, our results imply that highly dynamical water snow-lines must be considered when developing models of disk evolution and planet formation.

Astrophysics: Variable snow lines affect planet formation

Astronomy News - 14 July 2016 - 9:16am

Astrophysics: Variable snow lines affect planet formation

Nature 535, 7611 (2016). doi:10.1038/535237a

Authors: Brenda Matthews

Observations of the disk of dust and gas around a nascent star reveal that the distance from the star at which water in the disk forms ice is variable. This variation might hinder the formation of planets. See Letter p.258

Chemistry: Cosmic rays breed organics in space

Astronomy News - 14 July 2016 - 9:14am

Chemistry: Cosmic rays breed organics in space

Nature 535, 7611 (2016). doi:10.1038/535203b

Cosmic rays help to form the Universe's complex organic molecules — the building blocks of life on Earth.The interstellar gas clouds that give birth to stars and planets are rich in organic molecules, but scientists have struggled to explain how these formed. A team