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Using numerical hydrodynamic simulations, we study the gravitational fragmentation of an unstable protostellar disc formed during the collapse of a pre-stellar core with a mass of 1.2 M_sun. The forming fragments span a mass range from about a Jupiter mass to very-low-mass protostars and are located at distances from a few tens to a thousand AU, with a dearth of objects at < 100 AU. We explore the possibility of observational detection of the fragments in discs viewed through the outflow cavity at a distance of 250 pc. We demonstrate that one hour of integration time with the Atacama Large Millimeter/sub-millimeter Array (ALMA) is sufficient to detect the fragments with masses as low as 1.5 M_Jup at orbital distances up to 800 AU from the protostar. The ALMA resolution sets the limit on the minimum orbital distance of detectable fragments. For the adopted resolution of our simulated ALMA images of 0.1, the fragments can be detected at distances down to 50 AU. At smaller distances, the fragments usually merge with the central density peak. The likelihood for detecting the fragments reduces significantly for a lower resolution of 0.5. Some of the most massive fragments, regardless of their orbital distance, can produce characteristic peaks at approximately 5 micron and hence their presence can be indirectly inferred from the observed spectral energy distributions of protostars.
Water is a key volatile that provides insights into the initial stages of planet formation. The low water abundances inferred from water observations toward low-mass protostellar objects may point to a rapid locking of water as ice by large dust grai
The early evolution of protostellar disks with metallicities in the $Z=1.0-0.01~Z_odot$ range was studied with a particular emphasis on the strength of gravitational instability and the nature of protostellar accretion in low-metallicity systems. Num
I calculate the spectral energy distributions (SEDs) of accreting circumplanetary disks using atmospheric radiative transfer models. Circumplanetary disks only accreting at $10^{-10} M_{odot} yr^{-1}$ around a 1 M$_{J}$ planet can be brighter than th
We present a mechanism for the crystalline silicate production associated with the formation and subsequent destruction of massive fragments in young protostellar disks. The fragments form in the embedded phase of star formation via disk fragmentatio
We perform a comparative numerical hydrodynamics study of embedded protostellar disks formed as a result of the gravitational collapse of cloud cores of distinct mass (M_cl=0.2--1.7 M_sun) and ratio of rotational to gravitational energy (beta=0.0028-