Featured Research

from universities, journals, and other organizations

Understanding Stellar Explosions Is Less Straightforward Than Previously Thought

Date:
May 13, 2009
Source:
CNRS (Délégation Paris Michel-Ange)
Summary:
Stellar explosions called nova are caused by nuclear reactions between the star's atoms. In order to better understand such violent phenomena, astrophysicists study the radiation emitted by certain types of atom, and in particular the fluorine-18 produced by these reactions. Now, researchers have determined that fluorine-18 appears to be less abundant than expected. This discovery therefore reduces the chances of observing the radiation emitted by this atom.

Stellar explosions called novć are caused by nuclear reactions between the star's atoms. In order to better understand such violent phenomena, astrophysicists study the radiation emitted by certain types of atom, and in particular the fluorine-18 produced by these reactions. Now, researchers at GANIL (1) (CEA-CNRS (2)), in collaboration with teams from the UK, Belgium, Romania and France, have determined that fluorine-18 appears to be less abundant than expected.

This discovery therefore reduces the chances of observing the radiation emitted by this atom. It implies new constraints for the observation and understanding of novć.

Observed since ancient times, novć are stellar explosions which occur in our galaxy around 20 times a year. Today, physicists think that they take place in stellar binary systems, which are made up of two stars, a red giant and a small, hot companion called a white dwarf. "Matter is torn off the red giant and falls onto the surface of the white dwarf," explains François de Oliveira Santos, a physicist working at GANIL. "This stellar matter accumulates on the surface of the white dwarf, leading to an increase in its temperature and density. A number of nuclear reactions, transforming one or more atomic nuclei into other particles, then take place: stable atomic nuclei (carbon, oxygen, etc) in the star are transformed into radioactive nuclei, such as fluorine-18." It is by observing the radiation emitted by these particles that researchers hope to better understand the physical processes taking place during novć.

Fluorine-18 is a radioactive atom whose unstable nucleus is deficient in neutrons compared to its stable form, fluorine-19. When it disintegrates, fluorine-18 emits specific electromagnetic radiation that astrophysicists study in order to get a better understanding of what goes on inside novć. "The amount of radiation emitted during the explosion depends on the amount of fluorine-18 present," de Oliveira Santos explains. In order to show this, researchers have tried to identify all the nuclear reactions that lead to the creation and destruction of fluorine-18. Since these reactions depend on the structure of the nuclei, they have been studied with the use of particle accelerators.

An experiment carried out at Louvain-la-Neuve University in Belgium, as part of an international collaboration, has led scientists to revise downwards their estimate of the amount of fluorine-18 present in novae. The conclusion is that nuclear reactions involving fluorine-18 in these explosions lead to its destruction to a greater degree than had previously been estimated. "Our result is in agreement with recent theoretical work," de Oliveira Santos points out. "We obtained this result thanks to a new experimental technique that uses beams of accelerated radioactve nuclei." It leads to new constraints for the observation and understanding of stellar explosions.

(1) The French large heavy-ion accelerator located in Caen.

(2) CNRS/IN2P3:. CNRS's National Institute of Nuclear and Particle Physics.


Story Source:

The above story is based on materials provided by CNRS (Délégation Paris Michel-Ange). Note: Materials may be edited for content and length.


Journal Reference:

  1. Dalouzy, L. Achouri, M. Aliotta, C. Angulo, H. Benhabiles, C. Borcea, R. Borcea, P. Bourgault, A. Buta, A. Coc, A. Damman, T. Davinson, F. de Grancey, F. de Oliveira Santos, N. de Séréville, J. Kiener, M. G. Pellegriti, F. Negoita, A. M. Sánchez-Benítez, O. Sorlin, M. Stanoiu, I. Stefan, and P. J. Woods. Discovery of a New Broad Resonance in 19Ne Implications for the Destruction of the Cosmic -Ray Emitter 18F. Physical Review Letters, 24 April 2009

Cite This Page:

CNRS (Délégation Paris Michel-Ange). "Understanding Stellar Explosions Is Less Straightforward Than Previously Thought." ScienceDaily. ScienceDaily, 13 May 2009. <www.sciencedaily.com/releases/2009/04/090430065820.htm>.
CNRS (Délégation Paris Michel-Ange). (2009, May 13). Understanding Stellar Explosions Is Less Straightforward Than Previously Thought. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2009/04/090430065820.htm
CNRS (Délégation Paris Michel-Ange). "Understanding Stellar Explosions Is Less Straightforward Than Previously Thought." ScienceDaily. www.sciencedaily.com/releases/2009/04/090430065820.htm (accessed September 2, 2014).

Share This




More Space & Time News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: NASA Captures Solar Flare

Raw: NASA Captures Solar Flare

AP (Sep. 1, 2014) — NASA reported the sun emitted a mid-level solar flare, on August 24th. NASA's Solar Dynamics Observatory captured the images of the flare, which erupted on the left side of the sun. (Sept. 1) Video provided by AP
Powered by NewsLook.com
Space Shuttle Discovery's Legacy, 30 Years Later

Space Shuttle Discovery's Legacy, 30 Years Later

Newsy (Aug. 30, 2014) — The space shuttle Discovery launched for the very first time 30 years ago. Here's a look back at its legacy. Video provided by Newsy
Powered by NewsLook.com
Experiment Tests Whether Universe Is Actually A Hologram

Experiment Tests Whether Universe Is Actually A Hologram

Newsy (Aug. 27, 2014) — Researchers at Fermilab are using a device called "The Holometer" to test whether our universe is actually a 2-D hologram that just seems 3-D. Video provided by Newsy
Powered by NewsLook.com
SpaceX’s Falcon 9 Rocket Explodes After Liftoff

SpaceX’s Falcon 9 Rocket Explodes After Liftoff

Newsy (Aug. 23, 2014) — The private spaceflight company says it is preparing a thorough investigation into Friday's mishap. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins