An international team of astronomers has discovered a new subsidy object that is a companion to one of the stars of the open star cluster the Pleiades. This discovery may shed light on the mechanisms of formation of this star cluster.
Due to its proximity to our planet, the famous star cluster the Pleiades often watch and learn how astronomers Amateur and professional scientists. The age of this cluster of stars located at a distance of 440 light years from us, is approximately 120 million years, making it one of the youngest open star clusters known to science. It is also an excellent target for the search for new subsidy of small mass objects such as brown dwarfs.
In the period from 2011 to 2015 an international team of astronomers, led Mihoko Konishi of the National astronomical Observatory, Japan, conducted a series of observations one of the stars of this cluster, called the Pleiades HII 3441 in search of companions subsidy or planetary masses with 8.2 meter telescope “Subaru” located on Hawaii.
This newly discovered object was designated the Pleiades HII 3441B. According to the study it was discovered “South-East” from the primary star at a distance of approximately 66 astronomical unit (distance Sun-Earth) from her.
The approximate mass of an object the Pleiades HII 3441B was 68 Jupiter masses, and its temperature is estimated according to the photometric data of approximately 2700 degrees Kelvin. Moreover, as the researchers note, in the emission spectrum of this object there is no line absorption corresponding to methane. The authors emphasize that the absence of methane, decomposing at temperatures above 1300 K, in the atmosphere of this object also indicates a high temperature at its surface.
This object was classified as a brown dwarf of spectral class M7, since its mass is below the threshold 72 the mass of Jupiter, corresponding to the beginning of thermonuclear burning of hydrogen. However, as the researchers note, the object of the Pleiades HII 3441B “close to the border between the stellar and subsidy object.”