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Title: A KEPLERIAN-LIKE DISK AROUND THE FORMING O-TYPE STAR AFGL 4176

We present Atacama Large Millimeter/submillimeter Array line and continuum observations at 1.2 mm with ∼0.″3 resolution that uncover a Keplerian-like disk around the forming O-type star AFGL 4176. The continuum emission from the disk at 1.21 mm (source mm1) has a deconvolved size of 870 ± 110 AU × 330 ± 300 AU and arises from a structure ∼8 M{sub ⊙} in mass, calculated assuming a dust temperature of 190 K. The first-moment maps, pixel-to-pixel line modeling, assuming local thermodynamic equilibrium (LTE), and position–velocity diagrams of the CH{sub 3}CN J = 13–12 K-line emission all show a velocity gradient along the major axis of the source, coupled with an increase in velocity at small radii, consistent with Keplerian-like rotation. The LTE line modeling shows that where CH{sub 3}CN J = 13–12 is excited, the temperatures in the disk range from ∼70 to at least 300 K and that the H{sub 2} column density peaks at 2.8 × 10{sup 24} cm{sup −2}. In addition, we present Atacama Pathfinder Experiment {sup 12}CO observations that show a large-scale outflow from AFGL 4176 perpendicular to the major axis of mm1, supporting the disk interpretation. Finally, we present a radiative transfer model of a Keplerianmore » disk surrounding an O7 star, with a disk mass and radius of 12 M{sub ⊙} and 2000 AU that reproduces the line and continuum data, further supporting our conclusion that our observations have uncovered a Keplerian-like disk around an O-type star.« less
Authors:
;  [1] ; ; ; ; ;  [2] ;  [3] ;  [4]
  1. School of Physics and Astronomy, E.C. Stoner Building, The University of Leeds, Leeds LS2 9JT (United Kingdom)
  2. Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
  3. Ural Federal University, Astronomical Observatory, 51 pr. Lenina, Ekaterinburg (Russian Federation)
  4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22518710
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 813; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACETONITRILE; CARBON 12; CARBON MONOXIDE; DENSITY; DIAGRAMS; EMISSION; HYDROGEN; JETS; LTE; MASS; RADIANT HEAT TRANSFER; ROTATION; STAR EVOLUTION; STARS; VELOCITY