An international team of astronomers has produced the most detailed infrared image of the Orion nebula, using the European Southern Observatory's (ESO) Very Large Telescope in Chile.
And, in doing so, the researchers discovered a large number of faint brown dwarfs and isolated planetary-mass objects, which provides a revolutionary new insight into how stars of different masses form in large gas nebulae. The research will be published in the Monthly Notices of the Royal Astronomical Society and is available as a pre-print online.
“Understanding how many low-mass objects are found in the Orion nebula is very important to constrain current theories of star formation,” said co-author Amelia Bayo in a statement. “We now realize that the way these very low-mass objects form depends on their environment.”
By counting the number of objects of a certain mass, astronomers can evaluate the "Initial Mass Function", which allows them to predict what type of stars should form in a gas cloud.
The astronomers found 760 new potential brown dwarfs (large objects that didn't quite become stars) and 160 free-floating planets, 10 times more low-mass objects than previously known. This a far greater number than predicted, and even observations in closer and less active star-forming regions have not shown such a large substellar population.
The Orion nebula, which is 24 light-years across and has a mass of 2,000 Suns, must have something special going on. The researchers suggest that these low-mass objects come from material ejected during the star-formation process and from circumstellar disks, indicating that the stellar density and star-formation efficiency are responsible for it.
“Our result feels to me like a glimpse into a new era of planet and star formation science,” said lead scientist Holger Drass.
“The huge number of free-floating planets at our current observational limit is giving me hope that we will discover a wealth of smaller Earth-sized planets with the E-ELT.”
E-ELT stand for European Extremely Large Telescope, a new observatory currently under construction in Chile. It is scheduled to begin operation in 2024, and with its 39-meter (128 feet) mirror, it will allow us to observe all of these new objects in detail.
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