One of the most poorly understood progresses in low-mass star formation is how multiple-star systems are formed.
Here we present the results of Atacama Large Millimeter/submillimeter Array (ALMA) Band-6 observations towards a forming quadruple protostellar system, G206.93-16.61E2, in the Orion B molecular cloud. ALMA 1.3 mm continuum emission reveals four compact objects. Two of them are Class 0/I young stellar objects (YSOs) and the other twos are likely at prestellar stage. The 1.3 mm continuum emission also shows three trailing and asymmetric streamers that are connected with these compact objects, whose lengths range from 500 au to 2200 au. By comparing with MHD simulations, we suggest that two of these streamers may trace accretion flows, and the other one is a gas bridge connecting member protostars.
Additionally, the CO (J=2-1) line emission reveals a complicated molecular outflow, which may be greatly affected by the dynamics among member protostars. The quadruple system could have been formed via flyby of two protostars and continuous accretion through gas streamers.