Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hydrocarbons in the Horsehead mane

22.02.2005


Observing the edge of the famous Horsehead Nebula with the IRAM interferometer located on the Plateau de Bures (France), a team of French and Spanish astronomers discovered a large quantity of small hydrocarbon molecules. This is a surprise because the intense UV radiation illuminating the Nebula should destroy the small hydrocarbons near the edge. The astronomers suggest that these molecules might result from the fragmentation of giant molecules, called “polycyclic aromatic hydrocarbons” (PAHs).



More than 120 molecules have been observed in the interstellar medium, of which about twenty are small hydrocarbons. These hydrocarbons are an important component of the interstellar chemistry as they furnish a carbon skeleton needed to build more complex molecules. However, these small hydrocarbons are easily broken apart by the UV radiation from young stars. Therefore, astronomers try to understand how these molecules are regenerated in spite of their destruction by UV radiation.

In addition to these small hydrocarbons, giant molecules, called polycyclic aromatic hydrocarbons (PAHs), were detected in the early 1980’s, at infrared wavelengths. PAHs are aggregates made of tens to hundreds of mainly carbon and hydrogen atoms. Previous theoretical studies suggested that radiative fragmentation of the PAHs lead to small hydrocarbons. Jérôme Pety (IRAM, France) and his colleagues [1] have now provided one major step toward validating this theoretical hypothesis. They observed the famous Horsehead Nebula with the IRAM Interferometer (Plateau de Bures, France) [2], to search for hydrocarbons and to compare their location with that of PAHs detected a few years ago with the ISO satellite in the same region.


The Horsehead Nebula is one of the most famous and easily-recognizable shapes in the sky. In addition, for astronomers, its light-bathed silhouette is above all a fantastic interstellar chemistry laboratory where high density gas and stellar light interact. More precisely, the Horsehead appears as a dark patch against a bright region (named IC 434). It also undergoes strong ultraviolet radiation that mainly comes from the nearby star σ Orionis. Thanks to the high spatial resolution of the IRAM interferometer, the team was able to explore the edge of the nebula, “the horse mane”, where the gas density increases and the temperature and illumination decrease within a few hundredths of a light-year.

The team discovered three small hydrocarbons (C2H, C3H2, C4H) in the illuminated edge of the nebula. The abundance of these molecules is close to that measured inside interstellar dark clouds. The team was very surprised by the high abundance of C2H, C3H2, C4H in the Horsehead “mane”: these molecules should be destroyed by the intense UV radiation in the edge of the nebula.

Where do the hydrocarbons come from? In their article, Jérôme Pety and his colleagues compare the places where the hydrocarbons have been detected to the places where the ISO satellite detected PAHs. The correspondence between the hydrocarbons’ and the PAHs’ sites is very good and confirms the hypothesis that the hydrocarbons come from the fragmentation of PAHs. Under strong interstellar radiation, PAHs might be eroded and free a large number of small hydrocarbons. This mechanism would be more efficient in regions similar to the edge of the Horsehead Nebula, named “photo-dissociation regions”, in which UV radiation is stronger. This scenario now has to be confirmed by laboratory experiments, such as the experimental set-up PIRENEA in Toulouse (France) [3], for the study of the chemical reactions in the interstellar medium.

Jennifer Martin | alfa
Further information:
http://www.edpsciences.org

More articles from Physics and Astronomy:

nachricht UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>