Morphology and kinematics of the gas envelope of protostar L1527 as obtained from ALMA observations of the C${}^{18}$O(2-1) line emission

Abstract

Using ALMA observations of the C${}^{18}$O(2-1) line emission of the gas envelope of protostar L1527, we have reconstructed its morphology and kinematics under the assumption of axisymmetry about the west-east axis. The main original contribution to our understanding of the formation process of L1527 is the presentation of a simple 3D parameterisation based solely on regions that are not dominated by absorption. In the explored range ($\sim$0.7 to 5 arcsec from the star) the model reproduces observations better than earlier attempts. The main results include: a measurement of the rotation velocity that confirms its evolution to Keplerian toward short distances; a measurement of the mean in-fall velocity, 0.43$\pm$0.10 kms${}^{-1}$, lower than free fall velocity, with no evidence for the significant $r$-dependence suggested by an earlier analysis; a measurement of the central mass, 0.23$\pm$0.06 M${}_{\odot }$ within a distance of 1.5 arcsec from the star, in agreement with earlier estimates obtained from a different range of distances; evidence for a strong disc plane depression of the in-falling flux resulting in an $X$ shaped flow possibly caused by the freeze-out of CO molecules on dust grains; a measurement of the accretion rate, 3.5$\pm$1.0 10${}^{-7}$ M${}_{\odot }$yr${}^{-1}$ at a distance of 1 arcsec (140 au) from the star; evidence for a 10${}^{\circ }$ tilt of the symmetry plane of the envelope about the line of sight, cancelling below $\sim$3 arcsec from the star, but matching infrared observations and being also apparent on the sky map of the mean Doppler velocity.

11 pages, 12 figures, MNRAS accepted

References in corpus (6)

• Formation of a Keplerian disk in the infalling envelope around L1527 IRS: transformation from infalling motions to Kepler motions
• Molecule sublimation as a tracer of protostellar accretion: Evidence for accretion bursts from high angular resolution C18O images
• Constraining the Envelope Structure of L1527 IRS: Infrared Scattered Light Modeling
• The Magnetic Field in the Class 0 Protostellar Disk of L1527
• The shadow of the Flying Saucer: A very low temperature for large dust grains
• Testing Magnetic Field Models for the Class 0 Protostar L1527

Cited by in corpus (4)

• ALMA Observations of the Protostar L1527 IRS: Probing Details of the Disk and the Envelope Structures
• Space reconstruction of the morphology and kinematics of axisymmetric radio sources
• High resolution ALMA observation of the ${}^{12}$CO(3-2) and 350 GHz continuum emissions of the debris disc of 49 Ceti
• Sulfur oxides tracing streamers and shocks at low mass protostellar disk-envelope interfaces