A tiny flame shines light on supernovae explosions

Nov 22, 2011
This figure shows four snapshots in time as the flame propagates initially subsonically outward reaching a specified density (green) at which point the flame transitions to a detonation. Shown in color is a reaction progress variable describing the burning of nuclear statistical quasi-equilibrium (NSQE) products to nuclear statistical equilibrium (NSE) products. The blue contour marks the separation between the previously convective core and the isothermal outer layer. Note that the scale of the right-most figure is larger than the other three.

Starting from the behavior of small flames in the laboratory, a team of researchers has gained new insights into the titanic forces that drive Type Ia supernova explosions. These stellar explosions are important tools for studying the evolution of the universe, so a better understanding of how they behave would help answer some of the fundamental questions in astronomy.

Type Ia supernovae form when a white dwarf star – the left-over cinder of a star like our Sun – accumulates so much mass from a companion star that it reignites its collapsed stellar furnace and detonates, briefly outshining all other stars in its host galaxy. Because these have a characteristic brightness, astronomers use them to calculate cosmic distances. (It was by studying Type Ia supernovae that two independent research teams determined that the expansion of the Universe was accelerating, earning them the 2011 Nobel Prize in Physics).

To better understand the complex conditions driving this type of supernova, the researchers performed new 3-D calculations of the turbulence that is thought to push a slow-burning flame past its limits, causing a rapid detonation -- the so-called deflagration-to-detonation transition (DDT). How this transition might occur is hotly debated, and these calculations provide insights into what is happening at the moment when the makes this spectacular transition to supernova. "Turbulence properties inferred from these simulations provides insight into the DDT process, if it occurs," said Aaron Jackson, currently an NRC Research Associate working in the Laboratory for Computational Physics and Fluid Dynamics at the Naval Research Laboratory in Washington, D.C. At the time of this research, Jackson was a graduate student at Stony Brook University on Long Island, New York.

Jackson and his colleagues Dean Townsley from the University of Alabama at Tuscaloosa, and Alan Calder also of Stony Brook, will present their data at the American Physical Society's (APS) Division of Fluid Dynamics (DFD) meeting in Baltimore, Nov. 20-22, 2011.

While the deflagration-detonation transition mechanism is still not well understood, a prevailing hypothesis in the astrophysics community is that if turbulence is intense enough, DDT will occur. Extreme turbulent intensities inferred in the white dwarf from the researchers' simulations suggest DDT is likely, but the lack of knowledge about the process allows a large range of outcomes from the explosion. Matching simulations to observed supernovae can identify likely conditions for DDT.

"There are a few options for how to simulate how they [supernovae] might work, each of which has different advantages and disadvantages," said Townsley. "Our goal is to provide a more realistic simulation of how a given supernova scenario will perform, but that is a long-term goal and involves many different improvements that are still in progress."

The researchers speculate that this better understanding of the physical underpinnings of the explosion mechanism will give us more confidence in using Type Ia supernovae as standard candles, and may yield more precise distance estimates.

Explore further: Tiny particles have big potential in debate over nuclear proliferation

More information: The talk, "Turbulence and Combustion in Type Ia Supernovae," is on Tuesday, Nov. 22, 2011. Abstract: absimage.aps.org/image/MWS_DFD11-2011-001839.pdf

Provided by American Institute of Physics

4 /5 (1 vote)

Related Stories

Are stellar explosions created equal?

Aug 22, 2011

Cosmic distances are difficult to grasp and no less difficult to measure. When it comes to other galaxies or even remote parts of our own Milky Way, distance measurements are nothing but assessments, derived from indirect ...

Team finds Type Ia supernovae parents

Aug 11, 2011

Type Ia supernovae are violent stellar explosions whose brightness is used to determine distances in the universe. Observing these objects to billions of light years away has led to the discovery that the universe is expanding ...

Our galaxy might hold thousands of ticking 'time bombs'

Sep 06, 2011

(PhysOrg.com) -- In the Hollywood blockbuster "Speed," a bomb on a bus is rigged to blow up if the bus slows down below 50 miles per hour. The premise - slow down and you explode - makes for a great action ...

Supernovae mystery solved

Jun 30, 2010

(PhysOrg.com) -- Supernovae are gigantic stellar explosions that can be seen across the entire universe. Type Ia supernovae are a relatively homogeneous class of stellar explosions, which researchers use as ...

The best way to measure dark energy just got better

Jan 13, 2011

(PhysOrg.com) -- Dark energy is a mysterious force that pervades all space, acting as a "push" to accelerate the Universe's expansion. Despite being 70 percent of the Universe, dark energy was only discovered ...

Recommended for you

What time is it in the universe?

Aug 29, 2014

Flavor Flav knows what time it is. At least he does for Flavor Flav. Even with all his moving and accelerating, with the planet, the solar system, getting on planes, taking elevators, and perhaps even some ...

Watching the structure of glass under pressure

Aug 28, 2014

Glass has many applications that call for different properties, such as resistance to thermal shock or to chemically harsh environments. Glassmakers commonly use additives such as boron oxide to tweak these ...

Inter-dependent networks stress test

Aug 28, 2014

Energy production systems are good examples of complex systems. Their infrastructure equipment requires ancillary sub-systems structured like a network—including water for cooling, transport to supply fuel, and ICT systems ...

User comments : 6

Adjust slider to filter visible comments by rank

Display comments: newest first

rawa1
1 / 5 (3) Nov 22, 2011
I'm not sure, the burst of supernova can be modelled with fluid dynamics, because the dynamics of charged particle system (i.e. the plasma) differs significantly from the behaviour of neutral gas due the lack of magnetic fields. For example, the neutral fluid will never form the artefacts similar to sun spots.
aroc91
5 / 5 (3) Nov 22, 2011
I'm not sure, the burst of supernova can be modelled with fluid dynamics, because the dynamics of charged particle system (i.e. the plasma) differs significantly from the behaviour of neutral gas due the lack of magnetic fields. For example, the neutral fluid will never form the artefacts similar to sun spots.


Where is it implied that can't, and hasn't been modeled?
Callippo
1 / 5 (4) Nov 22, 2011
Technically, you can model the nanotubes with cat whiskers for example, but the result will not be quite relevant from physical perspective, not to say about cost of computer time and people involved.
Parsec
5 / 5 (1) Nov 24, 2011
Technically, you can model the nanotubes with cat whiskers for example, but the result will not be quite relevant from physical perspective, not to say about cost of computer time and people involved.

So... just so I understand the implication here, your implying that computer modeling is a waste of time and manpower? Have you ever noticed that you consistently get rated a 1 out of 5 on the merit scale for your comments? You might try thinking about what you post before you post.
rawa1
1 / 5 (2) Nov 24, 2011
your implying that computer modelling is a waste of time and manpower?
Of course at the case, you're modelling the the behaviour of charged particles in plasma with neutral ones. It's like modelling the behaviour of fluid with behaviour of gas, etc. Important aspect of system behaviour is missing, the results are unphysical, therefore the simulation is waste of money of tax payers from its very beginning.

Is it so difficult to understand it?
aroc91
5 / 5 (1) Nov 26, 2011
your implying that computer modelling is a waste of time and manpower?
Of course at the case, you're modelling the the behaviour of charged particles in plasma with neutral ones. It's like modelling the behaviour of fluid with behaviour of gas, etc. Important aspect of system behaviour is missing, the results are unphysical, therefore the simulation is waste of money of tax payers from its very beginning.

Is it so difficult to understand it?


Refer to my first post again.