Formation of Binary Solar-Mass Protostellar Systems

Dr Lim, Jeremy Jin Leong   (Principal Investigator (PI))

Professor Momose Munetake   (Co-Investigator)

Professor Hanawa Tomoyuki   (Co-Investigator)

Dr Takakuwa Shigehisa   (Co-Investigator)

Professor Saigo Kazuya   (Co-Investigator)

Professor Matsumoto Tomoaki   (Co-Investigator)

36

2016-01-01

706972

Formation of Binary Solar-Mass Protostellar Systems

Accretion rate, Binary Protostellar Systems, Circumbinary Disk, Circumstellar DIsk, Star Formation

Others - Physical Sciences

Physical Sciences (P)

17305115

General Research Fund (GRF)

2015

Completed

1 Internal Structure and Kinematics of Circumbinary Disks: We have been awarded observing time on ALMA to study the circumbinary disk in the binary protostellar system L1551 IRS5. L1551 IRS5 exhibit interesting similarities (e.g., total mass, circular coplanar orbit), but also important differences (equal rather than different component masses, much larger pseudodisk), compared with L1551 NE. By comparing the two systems, we hope to gain insights on factors that give rise to their different physical properties. 2 Infall from Circumbinary Disk to Circumstellar Disks: We have been awarded observing time on ALMA to study L1551 NE at a higher angular resolution and sensitivity. Our primary goal is to address how matter penetrates the inner clearing in the circumbinary disk to accrete onto the circumstellar disks of the two protostars. This observation also will provide a better separation between the spiral and inter-arm regions in the circumbinary disk, allowing us to refine and check for ingredients not yet implemented into our theoretical model for this system. For the same reasons, we anticipate making a follow-up study of L1551 IRS5 at a higher angular resolution and sensitivity using ALMA. 3 Relative Accretion Rates onto Binary Protostars: We have been awarded observing time on the SMA to study the circumbinary environment of the binary protostellar systems IRAS 04239+2436 and IRAS304169+2702, and anticipate making follow-up studies of these systems using ALMA. Both these systems, like L1551 IRS5/NE, have total masses comparable with the Sun and orbital separations comparable with the most likely orbital separation of main-sequence binary solar-mass stars. We are planning to extend our work to even more binary protostellar systems having similar total masses and orbital separation. By intercomparing systems spread over a large range in mass ratios, we hope to gain insights on factors that affect relative accretion rates onto binary protostars. 4 Circumstellar Disks and Ionized Jets: We plan to image the circumstellar disks and ionized jets of the binary protostars in both IRAS 04239+2436 and IRAS304169+2702 (as well as other systems we plan to select for study) using the JVLA, which currently provides the highest angular resolution for imaging dust emission from circumstellar disks. The orientation of the circumstellar disks with respect to each other as well as their circumbinary disk (if any) will provide an important test for their formation through the rotational fragmentation of a pseudodisk. Furthermore, the relatively sizes of the circumstellar disks provide a measure of the mass ratio of the binary protostars. The orientations of their ionized jets provide independent constraints on the geometry of the system, and a measure of the accretion rates onto both protostars. 5 Orbital Parameters: From multi-epoch measurements of relative proper motions using the JVLA, we plan to determine whether the orbital motion of a given binary protostellar system is in the same direction as the rotational motion of its circumbinary disk, necessary if the system formed through the rotational fragmentation of a pseudodisk. Such measurements, together with the relative sizes of their circumstellar disks, also place constraints on the orbital separation (and hence total mass) and eccentricity of binary protostellar systems.