Showing posts with label astrophysics. Show all posts
Showing posts with label astrophysics. Show all posts

Tuesday, January 31, 2017

The new supercomputer “Minerva” has been put into operation at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI).

The new supercomputer “Minerva” has been put into operation at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI). 
With 9,504 compute cores, 38 TeraByte memory and a peak performance of 302.4 TeraFlop/s it is more than six times as powerful as its predecessor. The scientists of the department “Astrophysical and Cosmological Relativity” can now compute significantly more gravitational waveforms and also carry out more complex simulations.

Minerva is to solve Einstein’s equations

Above all, the new computer cluster – named after the Roman goddess of wisdom – is used for the calculation of gravitational waveforms. These ripples in space time – measured for the first time directly in September 2015 – originate when massive objects such as black holes and neutron stars merge. Obtaining the exact forms of the emitted gravitational waves requires numerically solving Einstein’s complicated, non-linear field equations on supercomputers like Minerva. The AEI has been at the forefront of this field for many years and its researchers have been making important contributions to the software tools of the trade.

Tracking down faint signals in the detectors’ background noise and inferring information about astrophysical and cosmological properties of their sources requires calculating the mergers of many different binary systems such as binary black holes or pairs of a neutron star and a black hole, with different combinations of mass ratios and individual spins.

“Such calculations need a lot of compute power and are very time-consuming. The simulation of the first gravitational wave measured by LIGO lasted three weeks – on our previous supercomputer Datura,” says AEI director Professor Alessandra Buonanno. “Minerva is significantly faster and so we can now react even quicker to new detections and can calculate more signals.”

Ready for the gravitational wave detectors’ second science run
The gravitational wave detectors Advanced LIGO in the USA (aLIGO) and GEO600 in Ruthe near Hanover started their second observational run (“O2”) on 30 November 2016. aLIGO is now more sensitive than ever before: The detectors will be able to detect signals from about 20% further away compared to O1, which increases the event rate by more than 70%.


Credit : mpg.de

Numerical simulation of the gravitational-wave event GW151226 associated to a binary black-hole coalescence. The strength of the gravitational wave is indicated by elevation as well as color, with cyan indicating weak fields and orange indicating strong fields. The sizes of the black holes as well as the distance between the two objects is increased by a factor of two to improve visibility. The colors on the black holes represent their local deformation due to their intrinsic rotation (spin) and tides.


 Numerical-relativistic Simulation: S. Ossokine , A. Buonanno (Max Planck Institute for Gravitational Physics) and the Simulating eXtreme Spacetime project; scientific visualization: T. Dietrich, R. Haas (Max Planck Institute for Gravitational Physics)

Researchers in the Astrophysical and Cosmological Relativity division at AEI have improved the capabilities of aLIGO detectors to observe and estimate parameters of gravitational-wave sources ahead of O2. For the search for binary black hole mergers, they have refined their waveform models using a synergy between numerical and analytical solutions of Einstein’s equations of general relativity. They calibrated approximate analytical solutions (which can be computed almost instantly) with precise numerical solutions (which take very long even on powerful computers). This allows the AEI researchers to use the available computing power more effectively and to search more quickly and discover more potential signals from merging black holes in O2, and to determine the nature of their sources. AEI researchers also have prepared simulations of merging neutron star and boson star binaries. These can be simultaneously observed in electromagnetic and gravitational radiation, and can provide new precise tests of Einstein’s theory of general relativity.

Other articles on the same theme:








Story source: 
The above post is reprinted from materials provided by Mpg . Note: Materials may be edited for content and length.

Monday, January 30, 2017

Researchers have found another planet (Wolf 1061c) that can sustain life: Located just 14 light-years away

Credit: The Wolf 1061 system. Credit: UNSW Sydney
An exoplanet with the prime conditions for life could be located just 14 light-years away, scientists report, in one of the closest neighbouring solar systems to our own.

New research suggests that a planet circling the star Wolf 1061 falls within what's called the star's habitable zone - making it one of the most likely neighbouring candidates for a planet that supports life.


This artist's concept illustrates a young, red dwarf star surrounded by three planets. Credit: wikipedia

"The Wolf 1061 system is important, because it is so close, and that gives other opportunities to do follow-up studies to see if it does indeed have life," says lead researcher Stephen Kane from San Francisco State University.

There are three planets orbiting Wolf 1061, but the planet Wolf 1061c is of particular interest.

Discovered in 2015, and with an estimated mass that's more than four times Earth's mass, Wolf 1061c is located right in the middle of Wolf 1061's habitable zone: the region where a planet's distance from its host star makes conditions suitable for liquid water and other life-supporting elements.

Our own Solar System runs by the same rules: conditions on Earth are just right for liquid water, whereas Mars is too cold.

To investigate whether Wolf 1061c might offer the same kind of habitability, the researchers analysed seven years of luminosity data from its host star and ran calculations of the exoplanet's orbit to figure out what the temperature and pressure on the surface could be.


The findings add weight to previous speculation that Wolf 1061c could be habitable – but just because the exoplanet is within a habitable zone, that doesn't necessarily mean it's one like Earth's.

The new data suggest that Wolf 1061c could have an atmosphere similar to what Venus had in its earliest days, meaning that any liquid water on the planet might not stick around for long. 

Previous research has suggested that high temperatures caused excessive water evaporation on Venus, and the newly formed water vapour in the atmosphere increased temperatures even further - a process known as a runaway greenhouse effect.

Now, the team thinks the same thing could be happening on Wolf 1061c, which is "close enough to the star that it's looking suspiciously like a runaway greenhouse", says Kane.

In addition, Wolf 1061c's orbit of its star varies much more quickly than Earth's orbit of the Sun, which would lead to chaotic climate changes such as a rapidly encroaching ice age (or warm phase).

So, is there life on Wolf 1061c?

We don't yet know, and to find out, we'll need more detailed measurements than what we have so far. To that end, Kane says NASA's James Webb telescope is one of the ways we'll be able to learn more about the exoplanet in the future.

Wolf 1061c Credit: Centauri Dreams

The telescope is launching next year, and its advanced optics should be able to reveal the atmospheric conditions on Wolf 1061c, and give us a better idea about whether water (and life) could really exist there.

Meanwhile, scientists from METI - the Messaging Extraterrestrial Intelligence organisation - are also interested in Wolf 1061c, and have been keeping a close eye on the exoplanet as they try to reach out to any alien life that might exist beyond our Solar System.

"I'm not holding my breath that we'll ever find evidence of life on Wolf 1061c," METI president Doug Vakoch told Rae Paoletta at Gizmodo.

"But the fact that there's a roughly Earth-like planet in the habitable zone of a star so close to our own Solar System is a good omen as we continue our search for life on other planets."

Other articles on the same theme:




Story source: 
The above post is reprinted from materials provided by Sciencealert . Note: Materials may be edited for content and length.

Saturday, December 31, 2016

Vera Rubin, the American astronomer who confirmed the existence of dark matter, died at the age of 88 years.



Vera Rubin, the American astronomer who confirmed the existence of dark matter,  died at the age of 88 years, on the December 25, 2016.

First, the existence of this material was proposed by astrophysicist Fritz Zwicky in the 30s, but Rubin is one that confirmed his hypothesis. The observations made by scientists in the 70s were met with skepticism, but were confirmed in the decades that followed.


BBC - Universe - Vera Rubin photo: bbc


Reaching for the Stars - Vera Rubin photo: vq.vassar.edu

First, the existence of this material was proposed by astrophysicist Fritz Zwicky in the 30s, but Rubin is one that confirmed his hypothesis. The observations made by scientists in the 70s were met with skepticism, but were confirmed in the decades that followed.

Dark matter is invisible and impossible to detect because it does not absorb or emit light, so even until this day no one knows exactly what it consists of.

Proof of its existence came when astronomers began to weigh galaxies and noticed that they are much heavier than was originally thought. Vera Rubin worked with a new spectrographs to determine the stars from the edge moves faster than was observed since the first calculations use only the visible matter. It is argued that this difference in speed is due to dark matter.

Rubin's discovery was presented in 1980 in an influential paper that supported the idea that dark matter is an essential mystery that astronomers need to solve.


Other articles on the same theme:







Story source:
The above post is reprinted from materials provided by Curiosity . Note: Materials may be edited for content and length.