Astronomers have discovered several faint candidates for low-mass brown dwarfs in the star cluster IC 348. Scientists were surprised by the presence of an unknown hydrocarbon in their atmosphere. One of the objects is potentially the smallest free-flying brown dwarf ever observed. Brown dwarfs form as stars but do not gain sufficient mass to initiate a sustained fusion reaction. They never catch fire. Usually these objects are 75 times more massive than Jupiter, but there are also small ones up to 15 Jupiter masses.

The lower limit of their masses continues to be carefully studied by astronomers. Ultimately, when we understand the formation, evolution and atmospheres of low-mass brown dwarfs, we will better understand the formation of planets. The problem is that these faint objects are very difficult to find. They “shine” most strongly in the infrared range due to the low temperature. As a result of infrared sky research, scientists detected brown dwarfs with a mass of approximately 5-10 Jupiter masses. However, the resolution of these observations was not sufficient to accurately determine its parameters. Astronomers now have the powerful James Webb Orbital Infrared Observatory.

Young brown dwarfs “burn” the brightest. Of course, it is easier to look for the smallest of these in the closest regions of active star formation. According to the authors of the new study, the star cluster IC 348 in the Perseus molecular cloud is best suited for this.

This cluster has been well studied. About 500 objects are known, including low-mass objects with about 10 Jupiter masses. It is also suitable for a number of other parameters. In particular, there are no ionized hydrogen regions and no bright background radiation behind it. Both interfere with observations.

An international team of scientists used the James Webb Telescope to examine the cluster’s dense central region for low-mass brown dwarf candidates. Among other things, they identified three promising objects with masses between three and eight Jupiter masses and temperatures between 830 and 1500 degrees Celsius. These objects with such mass may turn out to be giant planets ejected from star systems. The authors of the article claim that this is unlikely. First, the cluster is only five million years old; This time is not enough for such a planet to form and leave the system. Second, both giant planets and the massive stars in which they form are much rarer than less massive objects.

However, there are anomalies in the spectra of two candidates in the observational data. Scientists explained the unusual signals by the presence of an unknown hydrocarbon in the atmospheres of the first and third objects. None of the known models for the evolution of young brown dwarfs explain the possible appearance of these compounds in their atmospheres.

The authors hypothesized that hydrocarbon formation is triggered by the coincidence of some parameters: low temperature, weak surface gravity and thin clouds. Such indicators are characteristic of more “summer” dwarfs, which carry out the transition of bodies from the L class to the colder T class, but the researchers were not able to explain from a physical point of view how this transition could simultaneously trigger its formation. hydrocarbons and weak signs of hotter spectral belonging to the first object. M class. Additional and longer observations will be necessary to understand the problems and confirm the hypotheses of the new study’s authors. The results of the research were published in the journal Astronomy Magazine.