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A Whole New Jupiter: First Science Results from NASA’s Juno Mission

Astronomy News - 26 May 2017 - 9:18am
Early science results from NASA’s Juno mission to Jupiter portray the largest planet in our solar system as a complex, gigantic, turbulent world, with Earth-sized polar cyclones, plunging storm systems that travel deep into the heart of the gas giant.

Juno probe peers below Jupiter's clouds

Astronomy News - 26 May 2017 - 9:17am

Scientists say the Solar System's biggest planet is showing itself to be far more complex than anyone thought.

Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding 6

Astronomy News - 25 May 2017 - 9:29am
The existence of massive (1011 solar masses) elliptical galaxies by redshift z ≈ 4 (refs 1, 2, 3; when the Universe was 1.5 billion years old) necessitates the presence of galaxies with star-formation rates exceeding 100 solar masses per year at z > 6 (corresponding to an age of the Universe of less than 1 billion years). Surveys have discovered hundreds of galaxies at these early cosmic epochs, but their star-formation rates are more than an order of magnitude lower. The only known galaxies with very high star-formation rates at z > 6 are, with one exception, the host galaxies of quasars, but these galaxies also host accreting supermassive (more than 109 solar masses) black holes, which probably affect the properties of the galaxies. Here we report observations of an emission line of singly ionized carbon ([C ii] at a wavelength of 158 micrometres) in four galaxies at z > 6 that are companions of quasars, with velocity offsets of less than 600 kilometres per second and linear offsets of less than 100 kiloparsecs. The discovery of these four galaxies was serendipitous; they are close to their companion quasars and appear bright in the far-infrared. On the basis of the [C ii] measurements, we estimate star-formation rates in the companions of more than 100 solar masses per year. These sources are similar to the host galaxies of the quasars in [C ii] brightness, linewidth and implied dynamical mass, but do not show evidence for accreting supermassive black holes. Similar systems have previously been found at lower redshift. We find such close companions in four out of the twenty-five z > 6 quasars surveyed, a fraction that needs to be accounted for in simulations. If they are representative of the bright end of the [C ii] luminosity function, then they can account for the population of massive elliptical galaxies at z ≈ 4 in terms of the density of cosmic space.

Astronomy: Quasars signpost massive galaxies

Astronomy News - 25 May 2017 - 9:28am
The neighbourhoods of extremely bright astronomical objects called quasars in the early Universe have been incompletely probed. Observations suggest that these regions harbour some of the most massive known galaxies. See Letter p.457

Astronomy: An all-American eclipse

Astronomy News - 25 May 2017 - 9:27am
Jay Pasachoff enjoys four books heralding this summer's US total solar eclipse.

Eighty-eight days till the next total eclipse of the Sun

Astronomy News - 25 May 2017 - 9:26am
Nature won’t repeat the mistake of its founding editor when this summer’s totality is visible in the United States.

New NELIOTA project detects flashes from lunar impacts

Astronomy News - 25 May 2017 - 9:23am

Using a system developed under an ESA contract, the Greek NELIOTA project has begun to detect flashes of light caused by small pieces of rock striking the Moon's surface. NELIOTA is the first system that can determine the temperature of these impact flashes.

Schiaparelli: Crashed lander was ill-prepared for Mars

Astronomy News - 25 May 2017 - 9:22am

The crashed European spacecraft Schiaparelli was ill-prepared for its attempt at landing on the surface of Mars, a report suggests.

Tangoing pairs of hungry supermassive black holes grow in number

Astronomy News - 24 May 2017 - 9:16am

The discovery of more of these deadly duos through a fresh data-sifting technique raises the hope that their secret recipe might soon be unlocked

New details of TRAPPIST-1 system’s outmost planet confirm earlier predictions

Astronomy News - 23 May 2017 - 9:24am

The observations confirm, as had been predicted, that the seventh and outermost planet, TRAPPIST-1h, orbits its star every 18.77 days. The results are reported in the journal Nature Astronomy.

“TRAPPIST-1h was exactly where our team predicted it to be,” said Rodrigo Luger, a PhD student at the University of Washington and the paper’s lead author. The researchers discovered a mathematical pattern in the orbital periods of the inner six planets, which was strongly suggestive of an 18.77 day period for planet h.

TRAPPIST-1A is a middle-aged, ultra-cool dwarf star, much less luminous than the Sun and only a bit larger than Jupiter. The star, which is nearly 40 light years away in the constellation of Aquarius, is named after the ground-based Transiting Planets and Planetesimals Small Telescope (TRAPPIST), the facility that first found evidence of planets around it in 2015.

The TRAPPIST survey is led by Michaël Gillon of the University of Liège, Belgium, who is also a co-author on this research. In 2016, Gillon’s team announced the detection of three planets orbiting TRAPPIST-1 and this number was upped to seven in a paper published earlier this year. All seven planets are deemed temperate, meaning that under certain geologic and atmospheric conditions, water could exist in a liquid form. Three of the planets are particularly optimal. In addition the TRAPPIST-1 system is currently the most convenient to remotely explore the atmospheres of planets with sizes similar to Earth.

Such exoplanets are detected when they transit, or pass in front of, their host star, blocking a measurable portion of the light. “We only captured one transit of TRAPPIST-1h last autumn. However, the resonant pattern formed by the other six planets, and the time TRAPPIST-1h takes to pass in front of its star, allowed the team to deduce its orbital period with a precision of a few minutes,” said co-author Amaury Triaud, a Kavli Exoplanet fellow Amaury Triaud at Cambridge’s Institute of Astronomy. “This is absolutely remarkable! TRAPPIST-1h represents a perfect illustration of the power of the scientific method, of its ability to make predictions that can later be verified.”

The inner six planets occupy orbits consistent with being in ‘resonance’. All orbital periods are mathematically related and slightly influence each other. Orbital resonances can also be found in our solar system. For instance, Jupiter’s moons Io, Europa and Ganymede are set in a 1:2:4 resonance, meaning that while Ganymede orbits Jupiter once, Europa does so twice, and Io four times. The prediction of TRAPPIST-1h’s orbital period principally relied on extrapolating the known resonant configuration of the inner six planets, to the seventh. This prediction was later confirmed.

The team analysed 79 days of observation data from K2, the second mission of the Kepler Space Telescope, and was able to recover four transits of TRAPPIST-1h across its star. The K2 data was also used to further characterize the orbits of the other six planets, help rule out the presence of additional transiting planets, and learn the rotation period and activity level of the star.

TRAPPIST-1's seven-planet chain of resonances establishes a record among known planetary systems. The resonances strengthen the long-term stability of the planetary system. It is also likely that these orbital connections were forged early in the life of the TRAPPIST-1 system, when the planets and their orbits were not fully formed. 

“Observing TRAPPIST-1 with K2 was an ambitious task,” said Marko Sestovic, a PhD student at the University of Bern and second author of the study. In addition to the complicated signals introduced by the spacecraft’s wobble, the faintness of the star in the optical (the range of wavelengths where K2 observes) placed TRAPPIST-1h “near the limit of what we could detect with K2,” he said. To make matters worse, Sestovic said, one transit of the planet coincided with a transit of TRAPPIST-1b, and one happened during a stellar flare, adding to the difficulty of the observation. “Finding the planet was really encouraging,” Luger said, “since it showed we can still do high-quality science with Kepler despite significant instrumental challenges.”

The research was funded by the NASA Astrobiology Institute via the UW-based Virtual Planetary Laboratory as well as a National Science Foundation Graduate Student Research Fellowship, the Swiss National Science Foundation, the European Research Council and the UK Science and Technology Facilities Council, among other agencies. This work was partially supported by a grant from the Simons Foundation.

Based on a press release by the University of Washington.

Reference:
Rodrigo Luger et al. 'A seven-planet resonant chain in TRAPPIST-1.' Nature Astronomy (2017). DOI: 10.1038/s41550-017-0129

An international team of astronomers, including researchers from the University of Cambridge, used data gathered by the Kepler Space Telescope to observe and confirm details of the outermost of seven exoplanets orbiting the star TRAPPIST-1.

TRAPPIST-1h represents a perfect illustration of the power of the scientific method, of its ability to make predictions that can later be verified.Amaury TriaudIoA/Amanda SmithArtist's impression of TRAPPIST-1


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Weird energy beam seems to travel five times the speed of light

Astronomy News - 23 May 2017 - 9:22am

The galaxy M87 emits a jet of plasma that looks like it’s breaking the cosmic speed limit – here’s how it manages the trick

NASA to Discuss First Science Results from Juno Mission to Jupiter

Astronomy News - 23 May 2017 - 9:21am
Scientists from NASA’s Juno mission to Jupiter will discuss their first in-depth science results in a media teleconference at 2 p.m. EDT Thursday, May 25, when multiple papers with early findings will be published online by the journal Science and Geophysical Research Letters.

Secondary Mirror of ELT Successfully Cast

Astronomy News - 23 May 2017 - 9:19am
The casting of the secondary mirror blank for ESO’s Extremely Large Telescope (ELT) has been completed by SCHOTT at Mainz, Germany. The completed mirror will be 4.2 metres in diameter and weigh 3.5 tonnes. It will be the largest secondary mirror ever employed on an optical telescope and also the largest convex mirror ever produced.

‘Saddle-shaped’ universe could undermine general relativity

Astronomy News - 22 May 2017 - 9:15am

The researchers, from the University of Cambridge, have used computer simulations to predict the existence of a so-called naked singularity, which interferes with Einstein’s general theory of relativity. This is the first time that a naked singularity, which causes the laws of physics to break down, has been predicted in three-dimensional space. The findings are reported in the journal Physical Review Letters.

Einstein’s general theory of relativity underpins our current understanding of gravity: everything from the estimation of the age of the stars in the universe, to the GPS signals we rely on to help us navigate, is based on his equations. In part, the theory tells us that matter warps its surrounding spacetime, and what we call gravity is the effect of that warp. In the 100 years since it was published, general relativity has passed every test that has been thrown at it, but one of its limitations is the existence of singularities.

A singularity is a point where gravity is so intense that space, time, and the laws of physics, break down. General relativity predicts that singularities exist at the centre of black holes, and that they are surrounded by an event horizon – the ‘point of no return’, where the gravitational pull becomes so strong that escape is impossible, meaning that they cannot be observed from the outside.

For more than 40 years, mathematicians have proposed that whenever singularities form, they will always be hidden from view in this way – this is known as the ‘cosmic censorship conjecture.’ If true, cosmic censorship means that outside of black holes, these singularities have no measurable effect on anything, and the predictions of general relativity remain valid.

In recent years, researchers have used computer simulations to predict the existence of ‘naked singularities’ – that is, singularities which exist outside an event horizon. Naked singularities would invalidate the cosmic censorship conjecture and, by extension, general relativity’s ability to explain the universe as a standalone theory. However, all of these predictions have been modelled on universes which exist in higher dimensions. For example, in 2016, two Cambridge PhD students predicted the existence of a naked singularity, but their predictions were based on a five-dimensional universe.

The new research, by Toby Crisford and Jorge Santos from Cambridge’s Department of Applied Mathematics and Theoretical Physics, has predicted the existence of a naked singularity in a four-dimensional universe - three spatial dimensions, plus time - for the first time.

Their predictions show that a naked singularity can form in a special kind of curved space known as anti-de Sitter space, in which the universe has a distinctive ‘saddle’ shape. According to general relativity, universes can have various shapes, and anti-de Sitter space is one of these possible shapes.

Anti-de Sitter space has a very different structure to flat space. In particular it has a boundary which light can reach, at which point it is reflected back. “It’s a bit like having a spacetime in a box,” said Crisford. “At the boundary, the walls of the box, we have the freedom to specify what the various fields are doing, and we use this freedom to add energy to the system and eventually force the formation of a singularity.”

 

 

While the results are not directly applicable to our universe, as ‘forcing’ a singularity is not a procedure which is possible to simulate in flat space, they do open up new opportunities to study other theories to understand the universe. One such theory could involve quantum gravity, which provides new equations close to a singularity.

“The naked singularity we see is likely to disappear if we were to include charged particles in our simulation – this is something we are currently investigating,” said Santos. “If true, it could imply a connection between the cosmic censorship conjecture and the weak gravity conjecture, which says that any consistent theory of quantum gravity must contain sufficiently charged particles. In anti-de Sitter space, the cosmic censorship conjecture might be saved by the weak gravity conjecture.”

Inset image: Image of (1 + 1)-dimensional anti-de Sitter space embedded in flat (1 + 2)-dimensional space. Credit: Wikimedia Commons.

Reference: 
Toby Crisford and Jorge E. Santos. 'Violating the Weak Cosmic Censorship Conjecture in Four-Dimensional Anti–de Sitter Space.' Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.118.181101. 

Researchers have shown how singularities – which are normally only found at the centre of black holes and hidden from view – could exist in highly curved three-dimensional space.

It’s a bit like having spacetime in a box.Toby CrisfordNASA/JPL-CaltechArtist's concept of a supermassive black hole


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

LIGO could detect gravitational waves’ permanent space-time warp

Astronomy News - 22 May 2017 - 9:14am

When gravitational waves permanently distort space-time, it causes a “memory” signal – which may help LIGO find some of the universe’s most exotic objects

Astronomers scramble as ‘alien megastructure’ star dims again

Astronomy News - 22 May 2017 - 9:11am

Tabby’s star’s weird behaviour has been blamed on everything from asteroids to aliens. Now astronomers are racing to watch its dimming in action

Titan’s riverbeds show a terrain built more like Mars than Earth

Astronomy News - 19 May 2017 - 9:14am

Saturn’s largest moon resembles Earth with its rivers and mountains, but it came by its topography very differently - and could still be active today

Icy ring around young planetary system has similar chemical fingerprint to our solar system

Astronomy News - 19 May 2017 - 9:11am

Earlier observations of the star, known as Fomalhaut and located 25 light years from Earth, were taken in 2012 by astronomers using the Atacama Large Millimetre/submillimetre Array (ALMA), located in Chile. The 2012 results were gathered when the telescope was still under construction, and while they only revealed about half of the debris disc, the observations provided hints about the nature and possible origin of the disc.

The new observations offer a far more complete view of this glowing band of debris, a band of rubble resulting from comets smashing together near the outer edges of the planetary system. The gases observed within the ring by the team suggest that there are chemical similarities between its icy contents and comets in our own solar system.

“We can finally see the well-defined shape of the disc, which may tell us a great deal about the underlying planetary system responsible for its highly distinctive appearance,” said Meredith MacGregor, an astronomer at the Harvard-Smithsonian Center for Astrophysics, and lead author on one of two papers accepted for publication in the Astrophysical Journal describing these observations.

Fomalhaut is a relatively nearby star system and one of only about 20 in which planets have been imaged directly. The entire system is approximately 440 million years old, or about one-tenth the age of our solar system. As revealed in the new ALMA image, a brilliant band of icy dust about two billion kilometres wide has formed approximately 20 billion kilometres from the star.

Debris discs are common features around young stars and represent a dynamic and chaotic period in the history of a solar system. Astronomers believe they are formed by the ongoing collisions of comets and other solid objects, known as planetesimals, in the outer reaches of a recently formed planetary system. The leftover debris from these collisions absorbs light from its central star and re-radiates that energy as a faint glow that can be studied with ALMA.

Using the new ALMA data and detailed computer modelling, the researchers could calculate the precise location, width, and geometry of the disc. These parameters confirm that such a narrow ring is likely produced through the gravitational influence of planets in the system.

The new observations are also the first to definitively show “apocenter glow,” a phenomenon predicted in a 2016 paper by Margaret Pan, a scientist at the Massachusetts Institute of Technology and co-author on the new papers. Like all objects with elongated orbits, the dusty material in the Fomalhaut disc travels more slowly when it is farthest from the star. As the dust slows down, it piles up, forming denser concentrations in the more distant portions of the disc. These dense regions can be seen by ALMA as brighter millimetre-wavelength emission.

Using the same dataset, but focusing on distinct millimetre-wavelength signals naturally emitted by molecules in space, the researchers also detected vast stores of carbon monoxide gas in precisely the same location as the debris disc.

“These data allowed us to determine that the abundance of carbon monoxide plus carbon dioxide around Fomalhaut is about the same as found in comets in our own solar system,” said Dr Luca Matrà of Cambridge’s Institute of Astronomy, and lead author of the team’s second paper. “This chemical kinship may indicate a similarity in comet formation conditions between the outer reaches of this planetary system and our own.” Matrà and his colleagues believe this gas is either released from continuous comet collisions or the result of a single, large impact between ‘supercomets’ hundreds of times more massive than Hale-Bopp.

The presence of this well-defined debris disc around Fomalhaut, along with its curiously familiar chemistry, may indicate that this system is undergoing its own version of the Late Heavy Bombardment, a period approximately four billion years ago when the Earth and other planets were routinely struck by swarms of asteroids and comets left over from the formation of our solar system.

“Twenty years ago, the best millimetre-wavelength telescopes gave the first fuzzy maps of sand grains orbiting Fomalhaut. Now with ALMA’s full capabilities the entire ring of material has been imaged,” said Paul Kalas, an astronomer at the University of California at Berkeley and principal investigator on these observations. “One day we hope to detect the planets that influence the orbits of these grains.”

Adapted from a National Radio Astronomy Observatory press release.

References:
Meredith A. MacGregor et al. 'A Complete ALMA Map of the Fomalhaut Debris Disk.' arXiv:1705.05867 
L. Matrà et al. 'Detection of exocometary CO within the 440 Myr-old Fomalhaut belt: a similar CO+CO2 ice abundance in exocomets and Solar System comets.' arXiv:1705.05868

An international team of astronomers, including researchers from the University of Cambridge, has made the most detailed image of the ring of dusty debris surrounding a young star and found that the ice content of colliding comets within it is similar to comets in our own solar system.

The chemical kinship may indicate a similarity in comet formation conditions between the outer reaches of this planetary system and our own.Luca MatraALMA (ESO/NAOJ/NRAO), M. MacGregor; NASA/ESA Hubble, P. Kalas; B. Saxton (NRAO/AUI/NSF)Composite image of the Fomalhaut star system. The ALMA data, shown in orange, reveal the distant and eccentric debris disk in never-before-seen detail. The central dot is the unresolved emission from the star, which is about twice the mass of our sun.


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Nasa seeks experiment ideas for Europa lander

Astronomy News - 19 May 2017 - 9:10am

Nasa is seeking the best ideas for experiments to fly on a mission that will land on Jupiter's moon Europa.

Rescue old data before it’s too late

Astronomy News - 18 May 2017 - 9:18am

Rescue old data before it’s too late

Nature 545, 7654 (2017). http://www.nature.com/doifinder/10.1038/545267a

Author: Elizabeth Griffin

If we don’t act soon to preserve past records, invaluable knowledge will be lost, warns Elizabeth Griffin.