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 stellar explosions 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 white dwarf star 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.
The talk, “Turbulence and Combustion in Type Ia Supernovae,” is at 8 a.m. on Tuesday, Nov. 22, 2011, in Room 308.Abstract: http://absimage.aps.org/image/MWS_DFD11-2011-001839.pdf
Charles E. Blue | Newswise Science News
Neutron star merger directly observed for the first time
17.10.2017 | University of Maryland
Breaking: the first light from two neutron stars merging
17.10.2017 | American Association for the Advancement of Science
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
17.10.2017 | Life Sciences
17.10.2017 | Life Sciences
17.10.2017 | Earth Sciences