The young FU Orionis star in the constellation of Orion is the prototype example, which showed an increase in brightness by a factor of 250 over a time period of just one year, staying in this high-luminosity state now for almost a century.
Using high-resolution, adaptive optics observations in the polarized light, an international group of astronomers led by Hauyu Liu from European Space Observatory (Garching, Germany) has verified the presence of the key features associated with the disk fragmentation model -- large-scale arms and arcs surrounding four young stars undergoing luminous outbursts, including the prototype FU Orionis star itself.
amp;nbsp;In the case of FU Orionis
, located in the constellation Orion, an increased brightness of 250-fold lasted for almost 100 years.
Z Canis Majoris is a unique pre-main-sequence binary system consisting of an FU Orionis
star and a young Herbig Be star still embedded in a dust cocoon.
Astronomers in the 1930s saw an unexplained light burst in a star known as FU Orionis
, and since then researchers have observed a sudden and dramatic brightening in five more stars in other constellations.
One such object is the star/disk combination known as FU Orionis
and its associated nebula Cederblad 59.
T Tauri stars show outbursts of this kind, and so do FU Orionis
stars, but FU Orionis
spectra show absorption of light by calcium, whereas Object 50 shows emission by calcium.
Spectroscopic observations with the 8-meter Gemini North telescope on Mauna Kea last November 6th indicate that the highly reddened object is undergoing a rare, violent accretion episode known as an FU Orionis
Second, the nebula flares into view only when its illuminating star (possibly an FU Orionis
variable) experiences an outburst.
Sixty years ago, a modest 16th-magnitude T Tauri star (or so we believe) now named FU Orionis
brightened by 6 magnitudes over a period of a year.
T Tau S flared in the late 1980s in an outburst that may have been like that of the famous young, eruptive variable FU Orionis
A handful of Class II objects appear to be FU Orionis