This diffuse nebula, also known as M42, has been studied by astronomers for many years. As a result, astronomers have learned a lot about the formation of stars, planetary systems and other basic topics in astronomy and astrophysics. Now there is a new discovery, which runs counter to the existing theory: the wind of newly formed massive stars may prevent other stars from forming near them. They also play a much bigger role in the formation of stars and the evolution of galaxies than previously thought.
The Orion nebula is easy to see. If you can see Orion, you can see the nebula without blowing off the dust. Depending on where you live, you can observe it with binoculars or small telescopes. Looking through the telescope, it looks like a thin gray cloud.
But more powerful instruments reveal all the complexities inside the nebula. This is a good example of a star nursery. Young stars are born in a gas cloud called molecular cloud. Around these young stars are young protoplanetary disks, where planets like ours may be forming.
When these young stars are born and merge, they will release stellar winds. This new study shows that this stellar wind plays a greater role than previously thought.
The study, published in Nature, was led by Cornelia Pabst, a doctoral student at Leiden University in the Netherlands. She is the main author of this paper. In this paper, the author describes how newly formed stars inhibit the formation of other stars in a process called "stellar feedback".
The current view is that supernovae can dominate the formation of stars. A huge supernova explosion sends out a powerful shock wave through the molecular cloud, producing dense gas and then forming stars. Although this is still true, it seems that stellar feedback from new stars may also affect this process.
This research is based on the work of the Stratospheric Infrared Astronomical Observatory (SOFIA) of NASA. Sofia is a customized flight observation station for Boeing 747. There is a German instrument called "Great" in Sofia, which is a German terahertz frequency astronomical receiver.
The amazing gas clouds of different shapes in Orion Nebula make it beautiful, but it also makes it difficult for us to see its interior. This picture of Orion Nebula was taken by Hubble telescope.
Orion Nebula is a very beautiful celestial body in astronomy, but its beauty is hard to see. Those gas clouds that look so brief and beautiful play a strange role in the light. Astronomers can observe the interior of Orion Nebula more clearly and observe the newly formed star θ 1 Orion is C (θ 1 Orion C) in detail.
They found that the star wind from θ 1 Ori C formed a bubble around itself, which basically blew away all the gas and prevented the formation of any new stars.
Pabst explained: "Stellar wind is the chief culprit in blowing huge bubbles around the central star. It disturbed the birth cloud and prevented the birth of new stars. "
Because Sophia conducts scientific research from high altitude, its flying height exceeds 99% of the water vapor in the earth's atmosphere. This, coupled with the sensitivity of the "great" instrument, enables it to stare at θ 1 Ori C more clearly. The team behind this paper combined a lot of data from Herschel and Spitzer Space Observatory to get their results.
They can determine the speed of the gas that produces bubbles and track their growth and origin. Alexander Tielens, a senior scientist in the paper and an astronomer in Leiden Observatory, explained: "Astronomers use' great' instruments just like police use radar guns. The radar pops up from your car, and the signal tells the police whether you are speeding. "
The chart of this study helps to explain these findings. θ 1 Ori C is a member of trapezoidal cluster. The black arrow represents the fast stellar wind ejected from the star. Yellow stands for plasma bubble, which is the gas blown by the stellar wind, forming a red veil bubble. Please note that bubbles do not expand evenly in all directions. The blue OMC- 1 region is the dense gas on the core side of Orion molecule, which is too dense to be shaped by the stellar wind of young stars.
This process is called "stellar feedback" because of the interaction between bubbles and surrounding gas. As shown in the above picture, the stellar wind (black arrow) leaves the star from all directions. But when it hits the dense OMC- 1 area on the right side of the image, other young stars will fight back, which is marked as BN/KL. This will create a red-gray arrow vertical column, representing the combined bubbles of θ 1 Oric and BN/KL bubbles.
When these stellar winds feed back to each other, they form the interstellar medium (ISM) and any molecular clouds nearby. This forms a local area that encourages or prevents the formation of more stars.
The bubble itself is huge. This is a half shell with a diameter of 4 parsec. In this area, it is impossible to form stars because all the gas is squeezed out. But at the edge of the bubble, the gas density is higher. In those areas with high density, it is easier to form stars. This is similar to the way shock waves from supernovae produce dense gas regions, which leads to an increase in star formation.
Strong winds from the newly formed star in the center of the Orion Nebula are forming bubbles (black) and preventing the formation of new stars nearby. At the same time, the wind pushes the molecular gas (color) to the edge, forming a dense shell around the bubble, where future generations of stars can be formed.
The bubble of θ 1 Ori C is in a larger bubble, which is called Orion-Bojiang supercell and consists of overlapping supernova remnants. Eventually, small bubbles will explode and release gas into super bubbles. Millions of years later, another supernova will explode, bringing the substance θ 1 Ori C in the bubble into the wall of the super bubble. The gas wall that forms the edge of the super bubble will become denser and may lead to the formation of more stars. Therefore, although it seems that supernovae have played a more direct role in the formation of stars, the bubbles of young stars have already played its role.
As the conclusion of the paper says, "the star wind from O-type massive stars is very effective in destroying molecular nuclei and star formation. Since the energy input of the stellar wind is controlled by the most massive star in the cluster, and the energy input of the supernova is controlled by more B-type stars, the interruption advantage caused by the stellar wind has a direct impact on cosmological simulation. "
This is just an example of the stellar feedback process. As the paper says, "We have analyzed a specific case here, that is, the interaction between the wind of a massive star and its environment. Whether this conclusion is more generally applicable needs to be evaluated. "