Mapping Orion’s winds
For the past few months, Bob O’Dell has been mapping the winds blowing in the Orion Nebula, the closest stellar nursery similar to the one in which the sun was born.
New data from the Hubble Orion Heritage Program, a major observational effort by the Hubble Space Telescope in 2004 and 2005, have given the Vanderbilt astronomer the information he needs to measure the stellar winds with unprecedented detail, and he reported his early results on Jan. 11 at the annual meeting of the American Astronomical Society in Washington D.C.
"Determining how stellar winds interact with the ambient material in stellar nurseries like Orion is a critical factor in understanding the process of star creation," says O’Dell, distinguished research professor of astrophysics and an international authority on Orion.
All stars, including the Sun, give off a stream of particles as they burn. In young, hot stars like those that form the "Trapezium" at the heart of Orion this stream of particles is millions of times more dense and energetic than the solar wind. Newborn stars, which are still shrouded in thick veils of dust and gas, often eject gas and dust from their polar regions in narrow jets, rather than broadcasting them outward in all directions. When these stellar winds impact floating clouds of dust and gas, they produce shock waves that erode and shape the clouds in a fashion similar to the way in which terrestrial winds sculpt sand dunes. When they are strong enough, such shock waves also can compress the free-floating clouds of dust and gas, triggering the formation of new stars.
O’Dell is using these shock waves as celestial "wind socks" to plot the direction of these winds in different parts of the nebula. By back-tracking older, more distant shock waves to their likely points of origin, the astronomer can also get an idea of how long major currents have been flowing.
"When you look closely enough, you see that the nebula is filled with hundreds of visible shock waves," the astronomer says.
In his analysis, O’Dell has identified three different types of shock waves:
- Bow-shocks are stationary shock waves that are formed by the collision of two steady winds and are excellent indicators of wind direction. They are present near the hottest stars in the center of the nebula where they show winds flowing outward at velocities of thousands of kilometers per second. They are also present in the outer nebula where they are produced by low velocity stellar winds of tens of kilometers per second.
- Jet-driven shocks are produced when narrow streams of gas and particles traveling at hundreds of kilometers per second pass through gas that is relatively stationary. There are many shockwaves of this type in the nebula that are produced by jets of material ejected by newly formed stars.
- Warped shocks are jet-driven shocks located in areas where the ambient gas is not stationary but is moving in a cross current. This bends the jets and shocks into bow-like shapes.
Using these markers, the astronomer has mapped the outflow from two of the three regions of star formation in the nebula. Both of these regions, labeled BN-KL and Orion-South, are located behind the glowing region of the nebula where the light from the central stars ionizes the outer layers of the parent molecular cloud. The specific objects that are producing these winds in the two regions are not visible to optical telescopes but they stand out as hot spots in infrared images.
By tracking back the farthest shockwaves produced by these outflows, O’Dell has established that the winds blowing from BN-KL have been doing so for 900 to 1,100 years, while those from Orion-South have been going on for 200 to 1,500 years. These observations were made during 104 orbits of the Hubble and provide the most comprehensive picture ever obtained of the Orion Nebula. The data will be combined with other Hubble and ground-based telescope observations to create a widely available archive for research scientists interested in this region, in addition to acting as a base for a detailed study that should provide new insights into the conditions required for creating stars like the sun.
David F. Salisbury | EurekAlert!
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
Layered 2D material improves efficiency for solar cells and LEDs
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...