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Title: THE ROTATING MOLECULAR STRUCTURES AND THE IONIZED OUTFLOW ASSOCIATED WITH IRAS 16547-4247

Abstract

We present Very Large Array 1.3 cm radio continuum and water maser observations as well as Submillimeter Array SO{sub 2} (226.300 GHz) and 1.3 mm dust continuum observations toward the massive star formation region IRAS 16547-4247. We find evidence of multiple sources in the central part of the region. There is evidence of a rotating structure associated with the most massive of these sources, traced at small scales ({approx}50 AU) by the water masers. At large scales ({approx}1000 AU), we find a velocity gradient in the SO{sub 2} molecular emission with a barely resolved structure that can be modeled as a rotating ring or two separate objects. The velocity gradients of the masers and of the molecular emission have the same sense and may trace the same structure at different size scales. The position angles of the structures associated with the velocity gradients are roughly perpendicular to the outflow axis observed in radio continuum and several molecular tracers. We estimate the mass of the most massive central source to be around 30 solar masses from the velocity gradient in the water maser emission. The main source of error in this estimate is the radius of the rotating structure. We alsomore » find water masers that are associated with the large-scale molecular outflow of the system, as well as water masers that are associated with other sources in the region. Our results suggest that the formation of this source, one of the most luminous protostars or protostellar clusters known, is taking place with the presence of ionized jets and disk-like structures.« less

Authors:
;  [1];  [2];  [3]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Centro de RadioastronomIa y AstrofIsica, UNAM, Apartado Postal 3-72 (Xangari), 58089 Morelia, Michoacan (Mexico)
  3. Departamento de AstronomIa, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago (Chile), E-mail: rfranco@cfa.harvard.edu
Publication Date:
OSTI Identifier:
21319601
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 701; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/701/2/974; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DUSTS; EMISSION; MASERS; MASS; MOLECULAR STRUCTURE; PROTOSTARS; STARS; VELOCITY; WATER

Citation Formats

Franco-Hernandez, Ramiro, Moran, James M., RodrIguez, Luis F., and Garay, Guido. THE ROTATING MOLECULAR STRUCTURES AND THE IONIZED OUTFLOW ASSOCIATED WITH IRAS 16547-4247. United States: N. p., 2009. Web. doi:10.1088/0004-637X/701/2/974; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Franco-Hernandez, Ramiro, Moran, James M., RodrIguez, Luis F., & Garay, Guido. THE ROTATING MOLECULAR STRUCTURES AND THE IONIZED OUTFLOW ASSOCIATED WITH IRAS 16547-4247. United States. doi:10.1088/0004-637X/701/2/974; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Franco-Hernandez, Ramiro, Moran, James M., RodrIguez, Luis F., and Garay, Guido. Thu . "THE ROTATING MOLECULAR STRUCTURES AND THE IONIZED OUTFLOW ASSOCIATED WITH IRAS 16547-4247". United States. doi:10.1088/0004-637X/701/2/974; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21319601,
title = {THE ROTATING MOLECULAR STRUCTURES AND THE IONIZED OUTFLOW ASSOCIATED WITH IRAS 16547-4247},
author = {Franco-Hernandez, Ramiro and Moran, James M. and RodrIguez, Luis F. and Garay, Guido},
abstractNote = {We present Very Large Array 1.3 cm radio continuum and water maser observations as well as Submillimeter Array SO{sub 2} (226.300 GHz) and 1.3 mm dust continuum observations toward the massive star formation region IRAS 16547-4247. We find evidence of multiple sources in the central part of the region. There is evidence of a rotating structure associated with the most massive of these sources, traced at small scales ({approx}50 AU) by the water masers. At large scales ({approx}1000 AU), we find a velocity gradient in the SO{sub 2} molecular emission with a barely resolved structure that can be modeled as a rotating ring or two separate objects. The velocity gradients of the masers and of the molecular emission have the same sense and may trace the same structure at different size scales. The position angles of the structures associated with the velocity gradients are roughly perpendicular to the outflow axis observed in radio continuum and several molecular tracers. We estimate the mass of the most massive central source to be around 30 solar masses from the velocity gradient in the water maser emission. The main source of error in this estimate is the radius of the rotating structure. We also find water masers that are associated with the large-scale molecular outflow of the system, as well as water masers that are associated with other sources in the region. Our results suggest that the formation of this source, one of the most luminous protostars or protostellar clusters known, is taking place with the presence of ionized jets and disk-like structures.},
doi = {10.1088/0004-637X/701/2/974; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
number = 2,
volume = 701,
place = {United States},
year = {Thu Aug 20 00:00:00 EDT 2009},
month = {Thu Aug 20 00:00:00 EDT 2009}
}
  • We report molecular line observations in the CO J = 3 {yields} 2, 6 {yields} 5, and 7 {yields} 6 transitions, made using the Atacama Pathfinder Experiment Telescope, toward the massive and dense core IRAS 16562-3959. This core harbors a string of radio sources thought to be powered by a central collimated jet of ionized gas. The molecular observations show the presence of high-velocity gas exhibiting a quadrupolar morphology, most likely produced by the presence of two collimated outflows. The southeast-northwest (SE-NW) molecular outflow is aligned with the string of radio continuum sources, suggesting it is driven by the jet.more » We find that the excitation temperature of the gas in the SE-NW outflow is high, with values of 145 and 120 K for the blueshifted and redshifted lobes, respectively. This outflow has a total mass of 1.92 M{sub sun}, a total momentum of {approx}89 M{sub sun} km s{sup -1}, and an averaged momentum rate of {approx}3.0 x 10{sup -2} M{sub sun} km s{sup -1} yr{sup -1}, values characteristic of flows driven by young massive stellar objects with high luminosities (L{sub bol} {approx} 2 x 10{sup 4} L{sub sun}). Complementary data taken with the Atacama Submillimeter Telescope Experiment in high density and shock tracers support the picture that IRAS 16562-3959 is an accreting young massive star associated with an ionized jet, which is the energy source of a molecular outflow.« less
  • Rho Ophiuchi East is one of the molecular outflows discovered in the Nagoya CO survey of star formation regions (Fukui et al., 1986) and was independently discovered by Wootten and Loren (1987). IRAS 16293-2422 is the driving source of the outflow. A detailed observational study of this outflow source in the J = 1-0 and J = 2-1 transitions of CO and in the (J, K) = (1, 1) and (2, 2) transitions of NH3 was made with angular resolutions of 17-80 arcsecs. The high-velocity CO emission has been resolved into four compact separate lobes, consisting of two pairs ofmore » bipolar lobes, in addition to an extended monopolar blueshifted lobe. The NH3 cloud has a size of 2.5 x 2.5 arcmin being peaked at 1.7 arcmin east of IRAS 16293-2422. This NH3 peak is located just toward the edge of one of the compact blue CO lobes, showing a blueshift of 0.5 km/s from the rest of the NH3 cloud. The momentum involved in the NH3 peak is nearly equal to that of the CO lobe. It is suggested that the CO lobe has dynamically interacted with the NH3 core, resulting in the acceleration of the NH3 core by 0.5 km/s. 29 refs.« less
  • We present the results of continuum and {sup 12}CO(3-2) and CH{sub 3}OH(7-6) line observations of IRAS 16547–4247 made with the Atacama Large Millimeter/submillimeter Array (ALMA) at an angular resolution of ∼0.''5. The {sup 12}CO(3-2) emission shows two high-velocity outflows whose driving sources are located within the dust continuum peak. The alignment of these outflows does not coincide with that of the wide-angle, large-scale, bipolar outflow detected with the Atacama Pathfinder Experiment in previous studies. The CH{sub 3}OH(7-6) line emission traces an hourglass structure associated with the cavity walls created by the outflow lobes. Taking into account our results together with themore » position of the H{sub 2}O and class I CH{sub 3}OH maser clusters, we discuss two possible scenarios that can explain the hourglass structure observed in IRAS 16547–4247: (1) precession of a biconical jet, (2) multiple, or at least two, driving sources powering intersecting outflows. Combining the available evidence, namely, the presence of two cross-aligned bipolar outflows and two different H{sub 2}O maser groups, we suggest that IRAS 16547–4247 represents an early formation phase of a protocluster.« less
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