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Primeur weekly 2014-05-12

The Cloud

HP launches HP Helion portfolio of Cloud products and services ...

New EMC Hybrid Cloud solution helps speed IT delivery ...

Pivotal and VMware accelerate enterprise application time to market with hybrid Cloud Platform-as-a-Service ...

SAP and VMware announce SAP HANA for production use on VMware vSphere 5.5 ...

Desktop Grids

Citizen science portal launches crowdfunding campaign ...

EuroFlash

Calibre brings real-world innovation to InfoComm 2014 ...

Top global weather service selects Altair for petascale workload management ...

Altair announces keynote presentations and detailed agenda for the 7th European Altair Technology Conference in Munich ...

Still time to save on ISC'14 registration - Register online by May 15 ...

Cosmic simulation using GADGET on a supercomputer ...

Toshiba Research Europe, BT, NPL and ADVA explore 'quantum leap' in encryption technology ...

3D modelling of the Sun: from the core to the surface ...

USFlash

UTSA Cloud and BigData Laboratory launches one of the largest open Clouds in academia ...

Astronomers create first realistic virtual universe ...

SDSC resources and expertise used in genomic analysis of 115 year-old woman ...

Teen mentored by UC San Diego professors wins $250,000 in science prizes ...

First-of-a-kind supercomputer at Lawrence Livermore available for collaborative research ...

Seven of the USA's leading technology institutions unveil cognitive computing courses leveraging IBM Watson ...

Computer scientists develop tool for uncovering bot-controlled Twitter accounts ...

Molecular, neural and bacterial networks provide insights for computer network security, Carnegie Mellon researchers find ...

HP extends industry-leading Z Workstation family into virtualization realm ...

Collaborative 'metasurfaces' grant to merge classical and quantum physics ...

EMC to acquire DSSD Inc. and extends Flash storage leadership ...

Superconducting qubit array points the way to quantum computers ...

Graphene for real-world devices ...

3D modelling of the Sun: from the core to the surface

5 May 2014 Paris - A team at the Astrophysics, Instrumentation and Modelling Laboratory (CEA/CNRS/Université Paris Diderot) has successfully modelled, in 3D, the effects of gravity waves in an extremely comprehensive simulation of the Sun, from its nuclear core to its convective surface. The results make very highly precise information accessible and provide a rigorous and unprecedented description of the Sun's internal dynamics. This research, published inAstronomy and Astrophysics, should make it possible to substantially refine theoretical models and to plan future space missions (Solar-Orbiter, Plato) to observe solar-like stars more efficiently.

The waves which propagate within stars, in this case the Sun, influence their structure, their dynamics and how they evolve. Since they can generate global pulsations, they provide us with precious information for studying dynamic phenomena within stars. There are two types of these waves:

1. acoustic waves, which are exactly the same as sound waves;

2. and gravity waves, which propagate in any density-stratified fluid, without large-scale (macroscopic) convective motion.

These waves play an important role in changes in the rotation and mixing of chemical elements within the deep layers of stars similar to our Sun. Like acoustic waves, gravity waves can, depending on their frequency, resonate within the Sun in what are known as "g modes": this produces the same phenomenon as that seen with a guitar string, which resonates according to certain harmonics and its own specific modes.

Thanks to the non-linear simulations carried out by the Astrophysics, Instrumentation and Modelling team as part of the ERC STARS 2 project, it is possible to compare the amplitude of these waves within the Sun's core and track their presence and their dynamics from core to surface. These results provide a solid base on which to refine theoretical models and open the way forward to more targeted observations, thus helping to develop increasingly more accurate knowledge of solar-like stars and how they evolve.

These simulations are not only unprecedented but also represent a genuine tour de force given the number of phenomena and the spatial scale taken into account: turbulence, convection, thermal, radiative and viscous effects, differential rotation, to name but a few. For the very first time, the results provide an extremely rich and comprehensive 3D simulation (97% of the Sun's volume) of stellar dynamics in three dimensions. From a purely numerical angle, these results are so impressive because of the ASH code, jointly developed and used by the team.

This involves high-performance simulations, requiring 5 million computing hours using the GENCI Ada computer, installed at the CNRS's Scientific Computing Resources and Development Institute (IDRIS), and 15 million hours using the Curie supercomputer made available by GENCI to the European researchers within the framework of PRACE, the Partnership for Advanced Computing in Europe.

The interior of a star consists of two zones, whose dimensions depend on the star's mass:

  • In the case of solar-like stars, as simulated here, the outermost zone is convective and turbulent: heat is transferred by the motion of matter, in the same way as air moves in a house heated by convection heaters.
  • The inner zone is stratified and stable: it is a radiative zone in which energy is pushed outwards mainly by photons (light). Only within this stable zone can gravity waves be generated and propagate, but they are very difficult to detect from the outside since the convective zone forms a barrier which weakens them considerably.

Furthermore, how the radiative zone and the convective zone are coupled together is one of the key questions in solar Physics today, one that is a major numerical challenge given the vast range of space-time scales implied. Indeed, there are numerous phenomena to be taken into account, and they do not all occur at the same scale, but each is influenced by the others in highly complex ways.

These results open up many new prospects for exploration, such as the potential to also factor in the magnetic field and its interaction with gravity waves, and thus come even closer to reality.

Source: CEA

Back to Table of contents

Primeur weekly 2014-05-12

The Cloud

HP launches HP Helion portfolio of Cloud products and services ...

New EMC Hybrid Cloud solution helps speed IT delivery ...

Pivotal and VMware accelerate enterprise application time to market with hybrid Cloud Platform-as-a-Service ...

SAP and VMware announce SAP HANA for production use on VMware vSphere 5.5 ...

Desktop Grids

Citizen science portal launches crowdfunding campaign ...

EuroFlash

Calibre brings real-world innovation to InfoComm 2014 ...

Top global weather service selects Altair for petascale workload management ...

Altair announces keynote presentations and detailed agenda for the 7th European Altair Technology Conference in Munich ...

Still time to save on ISC'14 registration - Register online by May 15 ...

Cosmic simulation using GADGET on a supercomputer ...

Toshiba Research Europe, BT, NPL and ADVA explore 'quantum leap' in encryption technology ...

3D modelling of the Sun: from the core to the surface ...

USFlash

UTSA Cloud and BigData Laboratory launches one of the largest open Clouds in academia ...

Astronomers create first realistic virtual universe ...

SDSC resources and expertise used in genomic analysis of 115 year-old woman ...

Teen mentored by UC San Diego professors wins $250,000 in science prizes ...

First-of-a-kind supercomputer at Lawrence Livermore available for collaborative research ...

Seven of the USA's leading technology institutions unveil cognitive computing courses leveraging IBM Watson ...

Computer scientists develop tool for uncovering bot-controlled Twitter accounts ...

Molecular, neural and bacterial networks provide insights for computer network security, Carnegie Mellon researchers find ...

HP extends industry-leading Z Workstation family into virtualization realm ...

Collaborative 'metasurfaces' grant to merge classical and quantum physics ...

EMC to acquire DSSD Inc. and extends Flash storage leadership ...

Superconducting qubit array points the way to quantum computers ...

Graphene for real-world devices ...