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Dust devils on Mars may be boosted by their own shadows

Astronomy News - 4 April 2016 - 8:52am

Scientists have struggled to explain how dust devils get so strong in the thin Martian air - now it seems they could be sustaining themselves









Comet 67P presented in silhouette

Astronomy News - 4 April 2016 - 8:52am

Perfectly backlit by our star, Comet 67P was photographed in dramatic fashion this week by the Rosetta spacecraft - 260 million km from Earth.

Found: Andromeda's first spinning neutron star

Astronomy News - 1 April 2016 - 10:43am

Decades of searching in the Milky Way's nearby 'twin' galaxy Andromeda have finally paid off, with the discovery of an elusive breed of stellar corpse, a neutron star, by ESA's XMM-Newton space telescope.

Journey to the centre of our galaxy [heic1606]

Astronomy News - 1 April 2016 - 10:42am

Peering deep into the heart of our home galaxy, the Milky Way, the NASA/ESA Hubble Space Telescope reveals a rich tapestry of more than half a million stars. Apart from a few, blue, foreground stars, almost all of the stars pictured in the image are members of the Milky Way nuclear star cluster, the densest and most massive star cluster in the galaxy. Hidden in the centre of this cluster is the Milky Way's resident supermassive black hole.

ALMA’s Most Detailed Image of a Protoplanetary Disc

Astronomy News - 1 April 2016 - 10:41am
This new image from the Atacama Large Millimeter/submillimeter Array (ALMA) shows the finest detail ever seen in the planet-forming disc around the nearby Sun-like star TW Hydrae. It reveals a tantalising gap at the same distance from the star as the Earth is from the Sun, which may mean that an infant version of our home planet, or possibly a more massive super-Earth, is beginning to form there.

Hubble's Journey to the Center of Our Galaxy

Astronomy News - 1 April 2016 - 10:41am

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Hubble's infrared vision pierced the dusty heart of our Milky Way galaxy to reveal more than half a million stars at its core. Except for a few blue, foreground stars, the stars are part of the Milky Way's nuclear star cluster, the most massive and densest stellar cluster in our galaxy. Located 27,000 light-years away, this region is so packed with stars, it is equivalent to having a million suns crammed into the volume of space between us and our closest stellar neighbor, Alpha Centauri, 4.3 light-years away. At the very hub of our galaxy, this star cluster surrounds the Milky Way's central supermassive black hole, which is about 4 million times the mass of our sun.

To learn even more about the Milky Way's nuclear star cluster and Hubble, join astronomers and scientists during a live Hubble Hangout discussion at 3pm EDT on Thurs., March 31 at http://hbbl.us/y6k.

More evidence for Planet Nine as odd celestial alignment emerges

Astronomy News - 1 April 2016 - 10:40am

Another celestial object has been found in a group with strangely similar orbits, implying they are shepherded by something - possibly a mysterious ninth planet









Long-term view of extreme cosmic burst challenges astronomers

Astronomy News - 1 April 2016 - 10:40am

Several years of observations from the afterglow of one of the most powerful explosions in the universe could upend the standard view of how these bursts work









R-process enrichment from a single event in an ancient dwarf galaxy

Astronomy News - 31 March 2016 - 9:08am

R-process enrichment from a single event in an ancient dwarf galaxy

Nature 531, 7596 (2016). doi:10.1038/nature17425

Authors: Alexander P. Ji, Anna Frebel, Anirudh Chiti & Joshua D. Simon

Elements heavier than zinc are synthesized through the rapid (r) and slow (s) neutron-capture processes. The main site of production of the r-process elements (such as europium) has been debated for nearly 60 years. Initial studies of trends in chemical abundances in old Milky Way halo stars suggested that these elements are produced continually, in sites such as core-collapse supernovae. But evidence from the local Universe favours the idea that r-process production occurs mainly during rare events, such as neutron star mergers. The appearance of a plateau of europium abundance in some dwarf spheroidal galaxies has been suggested as evidence for rare r-process enrichment in the early Universe, but only under the assumption that no gas accretes into those dwarf galaxies; gas accretion favours continual r-process enrichment in these systems. Furthermore, the universal r-process pattern has not been cleanly identified in dwarf spheroidals. The smaller, chemically simpler, and more ancient ultrafaint dwarf galaxies assembled shortly after the first stars formed, and are ideal systems with which to study nucleosynthesis events such as the r-process. Reticulum II is one such galaxy. The abundances of non-neutron-capture elements in this galaxy (and others like it) are similar to those in other old stars. Here, we report that seven of the nine brightest stars in Reticulum II, observed with high-resolution spectroscopy, show strong enhancements in heavy neutron-capture elements, with abundances that follow the universal r-process pattern beyond barium. The enhancement seen in this ‘r-process galaxy’ is two to three orders of magnitude higher than that detected in any other ultrafaint dwarf galaxy. This implies that a single, rare event produced the r-process material in Reticulum II. The r-process yield and event rate are incompatible with the source being ordinary core-collapse supernovae, but consistent with other possible sources, such as neutron star mergers.

Astronomy: Protoplanet imaged in infancy

Astronomy News - 31 March 2016 - 9:05am

Astronomy: Protoplanet imaged in infancy

Nature 531, 7596 (2016). doi:10.1038/531552c

Astronomers have captured images of a young star system in the earliest stages of planet formation.Researchers in 2014 used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to image the star HL Tau and its dusty disk, some 138 parsecs (450 light years) from

INTEGRAL sets limits on gamma rays from merging black holes

Astronomy News - 31 March 2016 - 9:00am

Following the discovery of gravitational waves from the merging of two black holes, ESA's INTEGRAL satellite has revealed no simultaneous gamma rays, just as models predict.

NASA’s Spitzer Maps Climate Patterns on a Super-Earth

Astronomy News - 31 March 2016 - 8:59am
Observations from NASA's Spitzer Space Telescope have led to the first temperature map of a super-Earth planet -- a rocky planet nearly two times as big as ours. The map reveals extreme temperature swings from one side of the planet to the other, and hints that a possible reason for this is the presence of lava flows.

Lost Japanese satellite Hitomi shows unexpected signs of life

Astronomy News - 31 March 2016 - 8:58am

The satellite seemed to be missing or out of control after debris was spotted around it shortly after it was due to call Earth - but it may still be alive  









Bubbling ocean on Saturn’s moon could explain vanishing island

Astronomy News - 31 March 2016 - 8:57am

The oceans of ethane and methane found on Titan may be bubbling with nitrogen – which could explain a mysterious disappearing island spotted on its surface









Map of rocky exoplanet reveals a lava world

Astronomy News - 31 March 2016 - 8:56am

An international team of astronomers, led by the University of Cambridge, has obtained the most detailed ‘fingerprint’ of a rocky planet outside our solar system to date, and found a planet of two halves: one that is almost completely molten, and the other which is almost completely solid.

According to the researchers, conditions on the hot side of the planet are so extreme that it may have caused the atmosphere to evaporate, with the result that conditions on the two sides of the planet vary widely: temperatures on the hot side can reach 2500 degrees Celsius, while temperatures on the cool side are around 1100 degrees. The results are reported in the journal Nature.

Using data from NASA’s Spitzer Space Telescope, the researchers examined a planet known as 55 Cancri e, which orbits a sun-like star located 40 light years away in the Cancer constellation, and have mapped how conditions on the planet change throughout a complete orbit, the first time this has been accomplished for such a small planet. 

55 Cancri e is a ‘super Earth’: a rocky exoplanet about twice the size and eight times the mass of Earth, and orbits its parent star so closely that a year lasts just 18 hours. The planet is also tidally locked, meaning that it always shows the same face to its parent star, similar to the Moon, so there is a permanent ‘day’ side and a ‘night’ side. Since it is among the nearest super Earths whose composition can be studied, 55 Cancri e is among the best candidates for detailed observations of surface and atmospheric conditions on rocky exoplanets.

Uncovering the characteristics of super Earths is difficult, since they are so small compared to the parent star and their contrast relative to the star is extremely small compared to larger, hotter gas giant planets, the so-called ‘hot Jupiters’.

“We haven’t yet found any other planet that is this small and orbits so close to its parent star, and is relatively close to us, so 55 Cancri e offers lots of possibilities,” said Dr Brice-Olivier Demory of the University’s Cavendish Laboratory, the paper’s lead author. “We still don’t know exactly what this planet is made of – it’s still a riddle. These results are like adding another brick to the wall, but the exact nature of this planet is still not completely understood.”

55 Cancri e has been extensively studied since it was discovered in 2011. Based on readings taken at different points in time, it was thought to be a water world, or even made of diamond, but researchers now believe that it is almost completely covered by lava.

“We have entered a new era of atmospheric remote sensing of rocky exoplanets,” said study co-author Dr Nikku Madhusudhan, from the Institute of Astronomy at Cambridge. “It is incredible that we are now able to measure the large scale temperature distribution on the surface of a rocky exoplanet.”

Based on these new infrared measurements, the ‘day’ side of the planet appears to be almost completely molten, while the ‘night’ side is almost completely solid. The heat from the day side is not efficiently circulated to the night side, however. On Earth, the atmosphere aids in the recirculation of heat, keeping the temperature across the whole planet within a relatively narrow range. But on 55 Cancri e, the hot side stays hot, and the cold side stays cold.

According to Demory, one possibility for this variation could be either a complete lack of atmosphere, or one which has been partially destroyed due to the strong irradiation from the nearby host star. “On the day side, the temperature is around 2500 degrees Celsius, while on the night side it’s about 1100 degrees – that’s a huge difference,” he said. “We think that there could still be an atmosphere on the night side, but temperatures on the day side are so extreme that the atmosphere may have evaporated completely, meaning that heat is not being efficiently transferred, or transferred at all from the day side to the night side.”

Another possibility for the huge discrepancy between the day side and the night side may be that the molten lava on the day side moves heat along the surface, but since lava is mostly solid on the night side, heat is not moved around as efficiently.

What is unclear however, is where exactly the ‘extra’ heat on 55 Cancri e comes from in the first place, since the observations reveal an unknown source of heat that makes the planet hotter than expected solely from the irradiation from the star – but the researchers may have to wait until the next generation of space telescopes are launched to find out.

For Demory, these new readings also show just how difficult it will be to detect a planet that is similar to Earth. The smaller a planet is, the more difficult it is to detect. And once a rocky planet has been found, there is the question of whether it lies in the so-called habitable zone, where life can be supported. “The problem is, people don’t agree on what the habitable zone is,” said Demory. “For example, some studies consider Mars and Venus to be in the habitable zone, but life as we know it is not possible on either of those planets. Understanding the surface and climate properties of these other worlds will eventually allow us to put the Earth’s climate and habitability into context.”

One possibility might be to look at stars which are much cooler and smaller than our sun, such as the M-dwarfs, which would mean that planets could be much closer to their star and still be in the habitable zone. The sizes of such planets relative to their star would be larger, which make them more detectable from Earth.

But for the time being, Demory and his colleagues plan to keep studying 55 Cancri e, in order to see what other secrets it might hold, including the possibility that it might be surrounded by a torus of gas and dust, which could account for some of the variations in the data. And in 2018, the successor to Hubble and Spitzer, the James Webb Space Telescope, will launch, allowing astronomers to look at planets outside our solar system with entirely new levels of precision.

Reference:
Brice-Olivier Demory et al. ‘A map of the extreme day-night temperature gradient of a super-Earth exoplanet.’ Nature (2016). DOI: 10.1038/nature17169

The most detailed map of a small, rocky ‘super Earth’ to date reveals a planet almost completely covered by lava, with a molten ‘hot’ side and solid ‘cool’ side.

We still don’t know exactly what this planet is made of – it’s still a riddle. These results are like adding another brick to the wall, but the exact nature of this planet is still not completely understood.Brice-Olivier Demory NASA/JPL-Caltech/R. HurtIllustration of the hot lava world 55 Cancri e


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

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VIDEO: Race to save Japan's lost satellite

Astronomy News - 31 March 2016 - 8:54am
Scientists and engineers in Japan are scrambling to save a satellite and more than a quarter of a billion dollars of investment tumbling out of control in space.

NASA and STScI Select Hubble Fellows for 2016

Astronomy News - 30 March 2016 - 10:48am

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NASA has selected 36 fellows for its prestigious Einstein, Hubble, and Sagan Fellowships. Each postdoctoral fellowship provides three years of support to awardees to pursue independent research in astronomy and astrophysics. The new fellows will begin their programs in the fall of 2016 at a host university or research center of their choosing in the United States.

Asteroid barrage may have birthed a short-lived ocean on Mars

Astronomy News - 30 March 2016 - 10:47am

How Mars acquired and then lost its water is a mystery, but a period of large asteroid impacts 4 billion years ago could provide an explanation









NASA Selects Instrument Team to Build Next-Gen Planet Hunter

Astronomy News - 30 March 2016 - 10:46am
NASA has selected a team to build a new, cutting-edge instrument that will detect planets outside our solar system by measuring the miniscule “wobbling” of stars. The instrument will be the centerpiece of a new partnership with the National Science Foundation called the NASA-NSF Exoplanet Observational Research program.

Japanese satellite lost in space?

Astronomy News - 30 March 2016 - 10:44am

Dozens of Japanese engineers and scientists are scrambling to save an X-ray satellite - and more than a quarter of a billion dollars of investment - tumbling out of control in space.