Institute of Astronomy

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A Neptune-sized transiting planet closely orbiting a 5–10-million-year-old star

Astronomy News - 30 June 2016 - 9:38am

A Neptune-sized transiting planet closely orbiting a 5–10-million-year-old star

Nature 534, 7609 (2016). doi:10.1038/nature18293

Authors: Trevor J. David, Lynne A. Hillenbrand, Erik A. Petigura, John M. Carpenter, Ian J. M. Crossfield, Sasha Hinkley, David R. Ciardi, Andrew W. Howard, Howard T. Isaacson, Ann Marie Cody, Joshua E. Schlieder, Charles A. Beichman & Scott A. Barenfeld

Theories of the formation and early evolution of planetary systems postulate that planets are born in circumstellar disks, and undergo radial migration during and after dissipation of the dust and gas disk from which they formed. The precise ages of meteorites indicate that planetesimals—the building blocks of planets—are produced within the first million years of a star’s life. Fully formed planets are frequently detected on short orbital periods around mature stars. Some theories suggest that the in situ formation of planets close to their host stars is unlikely and that the existence of such planets is therefore evidence of large-scale migration. Other theories posit that planet assembly at small orbital separations may be common. Here we report a newly born, transiting planet orbiting its star with a period of 5.4 days. The planet is 50 per cent larger than Neptune, and its mass is less than 3.6 times that of Jupiter (at 99.7 per cent confidence), with a true mass likely to be similar to that of Neptune. The star is 5–10 million years old and has a tenuous dust disk extending outward from about twice the Earth–Sun separation, in addition to the fully formed planet located at less than one-twentieth of the Earth–Sun separation.

A hot Jupiter orbiting a 2-million-year-old solar-mass T Tauri star

Astronomy News - 30 June 2016 - 9:38am

A hot Jupiter orbiting a 2-million-year-old solar-mass T Tauri star

Nature 534, 7609 (2016). doi:10.1038/nature18305

Authors: J. F. Donati, C. Moutou, L. Malo, C. Baruteau, L. Yu, E. Hébrard, G. Hussain, S. Alencar, F. Ménard, J. Bouvier, P. Petit, M. Takami, R. Doyon & A. Collier Cameron

Hot Jupiters are giant Jupiter-like exoplanets that orbit their host stars 100 times more closely than Jupiter orbits the Sun. These planets presumably form in the outer part of the primordial disk from which both the central star and surrounding planets are born, then migrate inwards and yet avoid falling into their host star. It is, however, unclear whether this occurs early in the lives of hot Jupiters, when they are still embedded within protoplanetary disks, or later, once multiple planets are formed and interact. Although numerous hot Jupiters have been detected around mature Sun-like stars, their existence has not yet been firmly demonstrated for young stars, whose magnetic activity is so intense that it overshadows the radial velocity signal that close-in giant planets can induce. Here we report that the radial velocities of the young star V830 Tau exhibit a sine wave of period 4.93 days and semi-amplitude 75 metres per second, detected with a false-alarm probability of less than 0.03 per cent, after filtering out the magnetic activity plaguing the spectra. We find that this signal is unrelated to the 2.741-day rotation period of V830 Tau and we attribute it to the presence of a planet of mass 0.77 times that of Jupiter, orbiting at a distance of 0.057 astronomical units from the host star. Our result demonstrates that hot Jupiters can migrate inwards in less than two million years, probably as a result of planet–disk interactions.

Why ultra-powerful radio bursts are the most perplexing mystery in astronomy

Astronomy News - 30 June 2016 - 9:37am

Why ultra-powerful radio bursts are the most perplexing mystery in astronomy

Nature 534, 7609 (2016). http://www.nature.com/doifinder/10.1038/534610a

Author: Elizabeth Gibney

Strange signals are bombarding Earth. But where are they coming from?

NASA’s Juno spacecraft prepares to probe Jupiter’s mysteries

Astronomy News - 30 June 2016 - 9:37am

NASA’s Juno spacecraft prepares to probe Jupiter’s mysteries

Nature 534, 7609 (2016). http://www.nature.com/doifinder/10.1038/534599a

Author: Alexandra Witze

The mission will peek through the gas giant’s swirling clouds in search of a planetary core.

Homebrew meteorites reveal origins of Mercury’s weird crust

Astronomy News - 30 June 2016 - 9:16am

Mixing up a fake powdered version of rare meteorites in the lab has shown how a freak surface feature arose from deep within the planet

Prehistoric tombs may have doubled as star-gazing observatories

Astronomy News - 30 June 2016 - 9:16am

Ancient corridor-like “passage graves” could have helped early tribes see stars as they first rise above the horizon by blocking out the ambient light

Hubble nets a cosmic tadpole [heic1612]

Astronomy News - 29 June 2016 - 9:26am

This new image from the NASA/ESA Hubble Space Telescope shows a cosmic tadpole, with its bright head and elongated tail, wriggling through the inky black pool of space. Tadpole galaxies are rare and difficult to find in the local Universe. This striking example, named LEDA 36252, was explored as part of a Hubble study into their mysterious properties – with interesting results.

Hubble Reveals Stellar Fireworks in 'Skyrocket' Galaxy

Astronomy News - 29 June 2016 - 9:26am

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As we celebrate the Fourth of July by watching dazzling fireworks shows, another kind of fireworks display is taking place in a small, nearby galaxy.

Strange ‘dark hydrogen’ may exist deep inside giant gas planets

Astronomy News - 29 June 2016 - 9:25am

Experiments on Earth reveal a new state of hydrogen that doesn’t reflect or absorb light – which could explain how planets like Jupiter cooled after formation

LISA Pathfinder completes first operations phase

Astronomy News - 27 June 2016 - 9:27am

On Saturday 25 June, the LISA Technology Package (LTP) – a European payload on ESA's LISA Pathfinder – completes its nominal operations phase, passing the baton to the Disturbance Reduction System, an additional experiment provided by NASA. This won't be the last time the European experiment is run – the recently approved mission extension will see the LTP back in action for seven months starting in November this year.

Jupiter Awaits Arrival of Juno

Astronomy News - 27 June 2016 - 9:24am
In preparation for the imminent arrival of NASA’s Juno spacecraft, astronomers have used ESO’s Very Large Telescope to obtain spectacular new infrared images of Jupiter. They are part of a campaign to create high-resolution maps of the giant planet. These observations will inform the work to be undertaken by Juno over the coming months, helping astronomers to better understand the gas giant ahead of Juno’s close encounter.

NASA approves five more years for Hubble Space Telescope

Astronomy News - 27 June 2016 - 9:22am

Extra funds for the world’s most famous observatory mean it will be able to work in tandem with its upcoming successor, the James Webb Space Telescope

Hubble Confirms New Dark Spot on Neptune

Astronomy News - 24 June 2016 - 9:05am

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Pancake-shaped clouds not only appear in the children's book "Cloudy With a Chance of Meatballs," but also 3 billion miles away on the gaseous planet Neptune. When they appeared in July 2015, witnessed by amateur astronomers and the largest telescopes, scientists suspected that these clouds were bright companions to an unseen, dark vortex. The dark vortex is a high-pressure system where the flow of ambient air is perturbed and diverted upward over the vortex. This forms huge, lens-shaped clouds, that resemble clouds that sometimes form over mountains on Earth.

NASA Extends Hubble Space Telescope Science Operations Contract

Astronomy News - 24 June 2016 - 8:58am
NASA is contractually extending science operations for its Hubble Space Telescope an additional five years. The agency awarded a sole source contract extension Thursday to the Association of Universities for Research in Astronomy for continued Hubble science operations support at the Space Telescope Science Institute in Baltimore.

I smelled comet 67P’s deadly pong and lived to tell the tale

Astronomy News - 24 June 2016 - 8:58am

Researchers with ESA's Rosetta mission have commissioned a perfume that mimics the odour of 67P/Churyumov–Gerasimenko. Jacob Aron shares his first sniff

Hubble spots a new long-lived storm raging on Neptune

Astronomy News - 24 June 2016 - 8:56am

Neptune is known for its Great Dark Spot, but a new blemish appeared last summer and has been roiling ever since

LIGO detects whispers of another black-hole merger

Astronomy News - 23 June 2016 - 9:23am

LIGO detects whispers of another black-hole merger

Nature 534, 7608 (2016). http://www.nature.com/doifinder/10.1038/nature.2016.20093

Author: Davide Castelvecchi

After historic first discovery last September, twin observatories detected gravitational waves again on Boxing Day.

The first gravitational-wave source from the isolated evolution of two stars in the 40–100 solar mass range

Astronomy News - 23 June 2016 - 9:22am

The first gravitational-wave source from the isolated evolution of two stars in the 40–100 solar mass range

Nature 534, 7608 (2016). doi:10.1038/nature18322

Authors: Krzysztof Belczynski, Daniel E. Holz, Tomasz Bulik & Richard O’Shaughnessy

The merger of two massive (about 30 solar masses) black holes has been detected in gravitational waves. This discovery validates recent predictions that massive binary black holes would constitute the first detection. Previous calculations, however, have not sampled the relevant binary-black-hole progenitors—massive, low-metallicity binary stars—with sufficient accuracy nor included sufficiently realistic physics to enable robust predictions to better than several orders of magnitude. Here we report high-precision numerical simulations of the formation of binary black holes via the evolution of isolated binary stars, providing a framework within which to interpret the first gravitational-wave source, GW150914, and to predict the properties of subsequent binary-black-hole gravitational-wave events. Our models imply that these events form in an environment in which the metallicity is less than ten per cent of solar metallicity, and involve stars with initial masses of 40–100 solar masses that interact through mass transfer and a common-envelope phase. These progenitor stars probably formed either about 2 billion years or, with a smaller probability, 11 billion years after the Big Bang. Most binary black holes form without supernova explosions, and their spins are nearly unchanged since birth, but do not have to be parallel. The classical field formation of binary black holes we propose, with low natal kicks (the velocity of the black hole at birth) and restricted common-envelope evolution, produces approximately 40 times more binary-black-holes mergers than do dynamical formation channels involving globular clusters; our predicted detection rate of these mergers is comparable to that from homogeneous evolution channels. Our calculations predict detections of about 1,000 black-hole mergers per year with total masses of 20–80 solar masses once second-generation ground-based gravitational-wave observatories reach full sensitivity.

Astrophysics: Recipe for a black-hole merger

Astronomy News - 23 June 2016 - 9:21am

Astrophysics: Recipe for a black-hole merger

Nature 534, 7608 (2016). doi:10.1038/534478a

Authors: J. J. Eldridge

The detection of a gravitational wave was a historic event that heralded a new phase of astronomy. A numerical model of the Universe now allows researchers to tell the story of the black-hole system that caused the wave. See Letter p.512

Giant SKA telescope rattles South African community

Astronomy News - 23 June 2016 - 9:21am

Giant SKA telescope rattles South African community

Nature 534, 7608 (2016). http://www.nature.com/doifinder/10.1038/534444a

Author: Sarah Wild

Struggle in Northern Cape province highlights a balancing act that scientists leading gigantic projects face.