Kinematic Analysis of a Protostellar Multiple System: Measuring the Protostar Masses and Assessing Gravitational Instability in the Disks of L1448 IRS3B and L1448 IRS3A

摘要: We present new Atacama Large Millimeter/submillimeter Array (ALMA) observations towards a compact (230~au separation) triple protostar system, L1448 IRS3B, at 879~\micron with \contbeam~resolution. Spiral arm structure within the circum-multiple disk is well resolved in dust continuum toward and we detect known wide (2300~au) companion, IRS3A, also resolving possible spiral substructure. Using dense gas tracers, C17O, H13CO$+$, H13CN, resolve Keplerian rotation for both circum-triple IRS3B around IRS3A. Furthermore, use molecular line kinematic data radiative transfer modeling of emission to confirm that disks are fitted masses $1.19^{+0.13}_{-0.07}$ IRS3B-ab, $1.51^{+0.06}_{-0.07}$~Msun place an upper limit on central mass tertiary IRS3B-c 0.2~Msun. measure fragmenting be 0.29~Msun from estimate clump surrounding 0.07~Msun. find IRS3A has 0.04~Msun. By analyzing Toomre~Q parameter, circumstellar gravitationally stable (Q$>$5), while consistent unstable (Q$<$1) between radii 200-500~au. This coincides location arms companion IRS3B-c, supporting hypothesis was formed situ via fragmentation disk.