Some young stars seem to spend a brief portion of their lives undergoing dramatic, flaring outbursts. A new study has used the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile to get the closest look yet at one of these systems — possibly identifying the cause of the flares.
Artist’s impression of a young star throwing a temper tantrum as it suddenly increases its accretion rate and flares. [Caltech/T. Pyle (IPAC)]
Young Stellar Temper Tantrums
FU Orionis (FU Ori, for short) objects are young, pre-main-sequence stars that grow suddenly brighter — by several magnitudes! — over the span of perhaps a year. These flaring states can last on the order of decades, and they’re thought to be related to a period of increased accretion onto the star during its early years. A star may gain a significant portion of its final mass during these events.
Beyond this general picture, there’s much we don’t understand about how or why this increase in accretion occurs. Does every star undergo a FU Ori phase early in its lifetime, accumulating extra mass in spurts and brightening each time it does? Or do only some stars behave this way? What causes the change in accretion rate? ...