Dec 15

XXL Hunt for Galaxy Clusters

Source: ESO Science Release eso1548

eso1548aX-ray image of the XXL-South Field.
Image credits: ESA/XMM-Newton/XXL survey consortium/(S. Snowden, L. Faccioli, F. Pacaud).

ESO telescopes have provided an international team of astronomers with the gift of the third dimension in a plus-sized hunt for the largest gravitationally bound structures in the Universe — galaxy clusters. Observations by the VLT and the NTT complement those from other observatories across the globe and in space as part of the XXL survey — one of the largest ever such quests for clusters.(read more)

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Dec 15

Hubble reveals diversity of exoplanet atmospheres

Source: ESA/Hubble

Clear to cloudy hot Jupiters
Image credits: ESA/Hubble & NASA

Astronomers have used the NASA/ESA Hubble Space Telescope and the NASA Spitzer Space Telescope to study the atmospheres of ten hot, Jupiter-sized exoplanets in detail, the largest number of such planets ever studied. The team was able to discover why some of these worlds seem to have less water than expected — a long-standing mystery. The results are published in "Nature".(read more)

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Dec 15

A Curious Cosmic Collision

Source: ESO Photo Release eso1547

eso1547aThe surroundings of the interacting galaxy NGC 5291.
Image credits: ESO

The spectacular aftermath of a 360 million year old cosmic collision is revealed in great detail in new images from ESO’s Very Large Telescope at the Paranal Observatory. Among the debris is a rare and mysterious young dwarf galaxy. This galaxy is providing astronomers with an excellent opportunity to learn more about similar galaxies that are expected to be common in the early Universe, but are normally too faint and distant to be observed by current telescopes. (read more)

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Dec 15

Galactic politics

Source: ESA/Hubble

Only rarely does an astronomical object have a political association. However, the spiral galaxy NGC 7252 acquired exactly that when it was given an unusual nickname. In December 1953, the US President Dwight D. Eisenhower gave a speech advocating the use of nuclear power for peaceful purposes. This  “Atoms for Peace” speech was significant for the scientific community, as it brought nuclear research into the public domain, and NGC 7252, which has a superficial resemblance to an atomic nucleus surrounded by the loops of electronic orbits, was dubbed the Atoms for Peace galaxy in honour of this. These loops are well visible in a wider field of view image. This nickname is quite ironic, as the galaxy’s past was anything but peaceful. Its peculiar appearance is the result of a collision between two galaxies that took place about a billion years ago, which ripped both galaxies apart. The loop-like outer structures, likely made up of dust and stars flung outwards by the crash, but recalling orbiting electrons in an atom, are partly responsible for the galaxy’s nickname. This NASA/ESA Hubble Space Telescope image shows the inner parts of the galaxy, revealing a pinwheel-shaped disc that is rotating in a direction opposite to the rest of the galaxy. This disc resembles a spiral galaxy like our own galaxy, the Milky Way, but is only about 10 000 light-years across — about a tenth of the size of the Milky Way. It is believed that this whirling structure is a remnant of the galactic collision. It will most likely have vanished in a few billion years’ time, when NGC 7252 will have completed its merging process.

Only rarely does an astronomical object have a political association. However, the spiral galaxy NGC 7252 acquired exactly that when it was given an unusual nickname.(learn more)

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Dec 15

New Horizons returns the best images of Pluto ever

Source: NASA-New Horizons

Pluto-MountainousShorlinePluto-The Mountainous Shoreline of Sputnik Planum
Image credits:NASA/Johns Hopkins University Applied
Physics Laboratory/Southwest Research Institute

NASA’s New Horizons spacecraft has sent back the first few of a series of the sharpest views of Pluto it obtained during its July flyby – and this image sequence forms the best close-ups of Pluto that humans may see for decades.

Every week the piano-sized New Horizons spacecraft transmits data stored on its digital recorders from its flight through the Pluto system on July 14. These latest pictures are part of a sequence taken near New Horizons’ closest approach to Pluto, with resolutions of about 250-280 feet (77-85 meters) per pixel – revealing features less than half the size of a city block on the diverse surface of the distant planet. In these new images, New Horizons captured a wide variety of spectacular, cratered, mountainous and glacial terrains. (learn more)

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Dec 15

LISA Pathfinder en route to gravitational wave demonstration

Source: ESA

The LISAPathfinder spacecraft separates from its propulsion module as it arrives at its destination orbit located at the L1 Lagrange point.

The LISAPathfinder spacecraft separates from its propulsion module as it arrives at its destination orbit located at the L1 Lagrange point. Image credits: ESA.

ESA's LISA Pathfinder lifted off earlier today on a Vega rocket from Europe's spaceport in Kourou, French Guiana, on its way to demonstrate technology for observing gravitational waves from space.

Gravitational waves are ripples in the fabric of spacetime, predicted a century ago by Albert Einstein's General Theory of Relativity, published on 2 December 1915.

Einstein's theory predicts that these fluctuations should be universal, generated by accelerating massive objects. However, they have not been directly detected to date because they are so tiny. For example, the ripples emitted by a pair of orbiting black holes would stretch a million kilometre-long ruler by less than the size of an atom.

LISA Pathfinder will test the extraordinary technology needed to observe gravitational waves from space. At its core is a pair of identical 46 mm gold-platinum cubes separated by 38 cm, which will be isolated from all external and internal forces acting on them except one: gravity.

The mission will put these cubes in the purest free-fall ever produced in space and monitor their relative positions to astonishing precision, laying the foundations for gravitational wave observatories in space.

Such future missions will be key partners to the ground sites already searching for these elusive cosmic messengers. Space and ground experiments are sensitive to different sources of gravitational waves, both opening up new possibilities to study some of the most powerful phenomena in the Universe.

The Vega launcher lifted off at 04:04 GMT (05:04 CET). About seven minutes later, after separation of the first three stages, the first ignition of Vega's upper stage propelled LISA Pathfinder into a low orbit, followed by another ignition about one hour and forty minutes into the flight.

The spacecraft separated from the upper stage at 05:49 GMT (06:49 CET). Controllers at ESA's operations centre in Darmstadt, Germany then established control.

Over the next two weeks, the spacecraft itself will raise the orbit's highest point in six critical burns.

The final burn will propel the spacecraft towards its operational location, orbiting around a stable virtual point in space called L1, some 1.5 million kilometres from Earth towards the Sun.

LISA Pathfinder is expected to reach its operational orbit about 10 weeks after launch, in mid-February. After final checks, it will begin its six-month scientific mission at the beginning of March.

En route to the final orbit, the two cubes will be released from the locking mechanisms that hold them during launch and cruise. Once in orbit around L1, the final mechanisms will be unlocked and the cubes will no longer be in mechanical contact with the spacecraft.

A complex system of laser beams bouncing between the two cubes will measure how close to true free-fall they are to within a billionth of a millimetre - never previously achieved in space.

"Fundamental research tries to understand our world," says Johann-Dietrich Woerner, ESA's Director General.

"Einstein' s theoretical findings are still very impressive. With LISA Pathfinder we will try to take a further step towards confirmation of one of Einstein's predictions: gravitational waves. "

The spacecraft itself will be an active part of the experiment, firing tiny thrusters about 10 times a second to adjust its position and avoid making contact with the cubes, thus shielding them from any forces that would prevent them from moving under the effect of gravity alone.

If these extraordinarily high-precision measurements and operations can be achieved by LISA Pathfinder, the door will be open to building a future space observatory, capable of detecting the minute disturbances in spacetime produced by gravitational waves, which are expected to be a few tens of a billionth of a millimetre over distances of millions of kilometres.

"Gravitational waves are the next frontier for astronomers. We have been looking at the Universe in visible light for millennia and across the whole electromagnetic spectrum in just the past century," says Alvaro Giménez Cañete, ESA's Director of Science and Robotic Exploration.

"But by testing the predictions made by Einstein one hundred years ago with LISA Pathfinder, we are paving the road towards a fundamentally new window on the Universe."

LISA Pathfinder will operate as a physics laboratory in space. Over an intense period of six months, mission scientists will analyse the data received on Earth from each day's operations to plan the experiments to be performed on the satellite during the following days.

"After many years of development and testing on the ground, we are looking forward to the ultimate test, which can only be run in space," says Paul McNamara, ESA's LISA Pathfinder project scientist.

"In a few weeks, we will be exploring the very nature of gravity in space, gaining the confidence to build a full-scale space observatory to study the gravitational Universe in the future."

An industrial team led by the prime contractor, Airbus Defence & Space Ltd, built the spacecraft. Airbus Defence & Space GmbH provided the integrated LISA Technology Package payload and a consortium of European companies and research institutes provided its subsystems NASA provided additional hardware and software that contributes to the mission by validating an alternative technological approach to keeping the spacecraft from making contact with the test masses.

"Integrating LISA Pathfinder posed many challenges, and we are extremely happy to see our trailblazing machine finally in space, ready to embark on its journey to L1, where it will pave the way for a new class of future space projects," concludes César García Marirrodriga, ESA's LISA Pathfinder project manager.

About the launcher

The launch of LISA Pathfinder was the last of five flights intended to demonstrate the capability and flexibility of the Vega launcher system, as part of ESA's Verta - Vega Research and Technology Accompaniment - programme.

During the Verta period, Vega has confirmed its versatility by delivering payloads into different orbits, demonstrating the full range of possible missions.

ESA was responsible for all Verta missions, which have refined and improved the launch system configuration and operations.

The Vega launches in 2015 (IXV, Sentinel-2A and LISA Pathfinder) have displayed the capacity of the system to reach three missions per year, providing confidence to customers and helping Arianespace to maintain its lead in this market segment.

The Vega launcher program is now fully qualified and ready for commercial exploitation by Arianespace.

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Dec 15

Eratosthenes results released

Earth-rulerThe organization of Eratosthenes in the International Year of Light has released the results of the measurements that were made by schools between the 14th and 25th of September 2015.

The data was collected by 174 schools from different countries, mostly from Europe and South America:  18 from Uruguay, 2 from Romania, 1 from Portugal, 5 from Peru, 1 from Morocco, 2 from Mexico, 1 from Italy, 1 from Honduras, 1 from France,  42 from Spain, 5 from Colombia, 45 from Brazil and 50 from Argentina.

Approximately 8000 students were involved in the activity and presented results about the size of the gnomon and the size of the shadow measured at solar noon.

With the results reported by schools the analysis were performed:

  1. Optimization of the NS component of distance and measurement day.
  2. Schools were paired maximizing the NS component of distance and considering that their measurements were made on the same day. Thus 200 pairs of schools were selected.
  3. Radius obtained are calculated from the measurements reported by schools. 28 results were discarded because they were clearly out of range of possible measurements and therefore must be bad measurements or bad registration of the measurements.
  4. A histogram was compiled with the remaining 172 values that ranged between 5,500km and 7,000km.
  5. The average value of the data is R = 6.363km and standard deviation S = 316km. The standard error of mean Sp, S obtained by dividing by the square root of the number of measurements, it turns Sp = 22km.

Only statistical errors were considered, as  schools were not asked to report on the estimates of the errors of their measurements.  According tabulated values the Earth's radius is R = 6371 km, very close to the calculated value obtained from the data of the school measurements.

Eratosthenes project has been performed by the EAAE in association with other organizations since 1997.

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