Circumbinary Disks of the Protostellar Binary Systems in the L1551 Region

Abstract

We report ALMA Cycle 4 observations of the Class I binary protostellar system L1551 IRS 5 in the 0.9-mm continuum emission, C18O (J=3-2), OCS (J=28-27), and four other Band 7 lines. At ~0.07" (= 10 au) resolution in the 0.9 mm emission, two circumstellar disks (CSDs) associated with the binary protostars are separated from the circumbinary disk (CBD). The CBD is resolved into two spiral arms, one connecting to the CSD around the northern binary source, Source N, and the other to Source S. As compared to the CBD in the neighboring protobinary system L1551 NE, the CBD in L1551 IRS 5 is more compact (r ~150 au) and the m=1 mode of the spirals found in L1551 NE is less obvious in L1551 IRS 5. Furthermore, the dust and molecular-line brightness temperatures of CSDs and CBD reach >260 K and >100 K, respectively, in L1551 IRS 5, much hotter than those in L1551 NE. The gas motions in the spiral arms are characterized by rotation and expansion. Furthermore, the transitions from the CBD to the CSD rotations at around the L2 and L3 Lagrangian points and gas motions around the L1 point are identified. Our numerical simulations reproduce the observed two spiral arms and expanding gas motion as a result of gravitational torques from the binary, transitions from the CBD to the CSD rotations, and the gas motion around the L1 point. The higher temperature in L1551 IRS 5 likely reflects the inferred FU-Ori event.

22 pages, 13 figures

References in corpus (16)

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Cited by in corpus (11)

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• Chemical survey of Class I protostars with the IRAM-30m
• A high HDO/H${}_2$O ratio in the Class I protostar L1551 IRS5
• Evolution of the atomic component in protostellar outflows
• Atomic Shocks in the Outflow of L1551 IRS 5 Identified with SOFIA-upGREAT Observations of [OI]
• Chemical inventory of the envelope of the Class I protostar L1551 IRS 5
• A high-resolution radio study of the L1551 IRS 5 and L1551 NE jets
• The hot corino-like chemistry of four FUor-like protostars
• Misaligned Circumstellar Disks and Orbital Motion of the Young Binary XZ Tau
• Exploring the 100 au Scale Structure of the Protobinary System NGC 2264 CMM3 with ALMA
• A VLA View of the Flared, Asymmetric Disk Around the Class 0 Protostar L1527 IRS