COMPLEX STRUCTURE IN CLASS 0 PROTOSTELLAR ENVELOPES. II. KINEMATIC STRUCTURE FROM SINGLE-DISH AND INTERFEROMETRIC MOLECULAR LINE MAPPING

Journal Article · Mon Oct 10 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/740/1/45; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21587407

Tobin, John J; Hartmann, Lee; Bergin, Edwin A ^[1]; Chiang, Hsin-Fang; Looney, Leslie W ^[2]; Chandler, Claire J ^[3]; Masque, Josep M ^[4]; Maret, Sebastien ^[5]; Heitsch, Fabian ^[6]

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1. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)
2. Department of Astronomy, University of Illinois, Urbana, IL 61801 (United States)
3. National Radio Astronomy Observatory, Socorro, NM 87801 (United States)
4. Departament d'Astronomia i Meteorologia, Universitat de Barcelona, 08028 Barcelona, Catalunya (Spain)
5. UJF-Grenoble 1/CNRS-INSU, Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble F-38041 (France)
6. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States)

We present a study of dense molecular gas kinematics in 17 nearby protostellar systems using single-dish and interferometric molecular line observations. The non-axisymmetric envelopes around a sample of Class 0/I protostars were mapped in the N{sub 2}H{sup +} (J = 1 {yields} 0) tracer with the IRAM 30 m, CARMA, and Plateau de Bure Interferometer, as well as NH{sub 3} (1,1) with the Very Large Array. The molecular line emission is used to construct line-center velocity and linewidth maps for all sources to examine the kinematic structure in the envelopes on spatial scales from 0.1 pc to {approx}1000 AU. The direction of the large-scale velocity gradients from single-dish mapping is within 45{sup 0} of normal to the outflow axis in more than half the sample. Furthermore, the velocity gradients are often quite substantial, the average being {approx}2.3 km s{sup -1} pc{sup -1}. The interferometric data often reveal small-scale velocity structure, departing from the more gradual large-scale velocity gradients. In some cases, this likely indicates accelerating infall and/or rotational spin-up in the inner envelope; the median velocity gradient from the interferometric data is {approx}10.7 km s{sup -1} pc{sup -1}. In two systems, we detect high-velocity HCO{sup +} (J = 1 {yields} 0) emission inside the highest-velocity N{sub 2}H{sup +} emission. This enables us to study the infall and rotation close to the disk and estimate the central object masses. The velocity fields observed on large and small scales are more complex than would be expected from rotation alone, suggesting that complex envelope structure enables other dynamical processes (i.e., infall) to affect the velocity field.

• OSTI ID: 21587407
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 740; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
79 ASTRONOMY AND ASTROPHYSICS
INTERFEROMETRY
MAPPING
PROTOSTARS
VELOCITY