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.
Perhaps another T Tauri star will flare up within your lifetime; if so, you will see it changing forever.
The secondary star seems to be an ordinary, less-massive T Tauri star
no more than 300,000 years old.
He presented evidence that the T Tauri stars as a class are newly formed.
T Tauri stars are usually found in groups, embedded in dense patches of gas and dust from which they formed.
Unlike the Orion Nebula, it isn't forming massive stars but contains hosts of low-mass protostars in the process of formation: so-called T Tauri stars
Classical T Tauri stars
are often surrounded by dust and gas.
The pair say that "naked" T Tauri stars
, those that seem to have lost their disks, actually do have them; they've just turned invisible.
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.
Its spectrum shows anomalously intense blue emission lines of neutral iron at 4046 and 4132 angstroms, as well as other unusual features shared by many young, premain-sequence variables - which have become known as the T Tauri stars
5-meter Isaac Newton Telescope in the Canary Islands to take high-dispersion spectra of 36 T Tauri stars
Much slower, broader bipolar outflows are found in many well-studied protostars, particularly the famous T Tauri stars