J/A+A/595/A88 G345.45+1.50 13CO(3-2) clumps (Lopez-Calderon+, 2016)
G345.45+1.50: an expanding ring-like structure with massive star formation.
Lopez-Calderon C., Bronfman L., Nyman L.-A., Garay G.,
de Gregorio-Monsalvo I., Bergman P.
<Astron. Astrophys., 595, A88 (2016)>
=2016A&A...595A..88L 2016A&A...595A..88L (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Carbon monoxide
Keywords: ISM: clouds - stars: massive - stars: formation - dust, extinction -
ISM: kinematics and dynamics - ISM: molecules
Abstract:
Ring-like structures in the interstellar medium (ISM) are commonly
associated with high-mass stars. Kinematic studies of large structures
in giant molecular clouds (GMCs) toward these ring-like structures may
help us to understand how massive stars form.
The origin and properties of the ring-like structure G345.45+1.50 is
investigated through observations of the 13CO(3-2) line. The aim of
the observations is to determine the kinematics in the region and to
compare physical characteristics estimated from gas emission with
those previously determined using dust continuum emission. This area
in the sky is well suited for studies like this because the ring is
located 1.5° above the Galactic plane at 1.8kpc from the Sun, thus
molecular structures are rarely superposed on our line of sight, which
minimizes confusion effects that might hinder identifying of
individual molecular condensations.
The 13CO(3-2) line was mapped toward the whole ring using the
Atacama Pathfinder Experiment (APEX) telescope. The observations cover
17'x20' in the sky with a spatial resolution of 0.2pc and an rms of
∼1K at a spectral resolution of 0.1km/s.
The ring is found to be expanding with a velocity of 1.0km/s,
containing a total mass of 6.9x103M☉, which agrees well with
that determined using 1.2mm dust continuum emission. An expansion
timescale of ∼3x106yr and a total energy of ∼7x1046erg are
estimated. The origin of the ring might have been a supernova
explosion, since a 35.5cm source, J165920-400424, is located at the
center of the ring without an infrared counterpart. The ring is
fragmented, and 104 clumps were identified with diameters of between
0.3 and 1.6pc, masses of between 2.3 and 7.5x102M☉, and
densities of between ∼102 and ∼104cm-3. At least 18% of the
clumps are forming stars, as is shown in infrared images. Assuming
that the clumps can be modeled as Bonnor-Ebert spheres, 13 clumps are
collapsing, and the rest of them are in hydrostatic equilibrium with
an external pressure with a median value of 4x104K/cm3. In the
region, the molecular outflow IRAS 16562-3959 is identified, with a
velocity range of 38.4km/s, total mass of 13M☉, and kinematic
energy of 7x1045erg. Finally, five filamentary structures were found
at the edge of the ring with an average size of 3pc, a width of 0.6pc,
a mass of 2x102M☉, and a column density of 6x1021cm-2.
Description:
The 13CO(3-2) line observations were made at 330.588GHz using
on-the-fly (OTF) observing mode with the APEX-2A heterodyne receiver
mounted at the APEX telescope on October 17-19, 2005, May 28, June
24-26, and October 7-10, 2006.
To estimate the gas temperature in the region, the 12CO(3-2) line
was observed using ASTE toward 29 intensity peaks found in the
13CO(3-2) line map. Observations were made on August 27 2010.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablef1.dat 62 104 Physical properties of the 13CO clumps
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Byte-by-byte Description of file: tablef1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/104] Sequential number
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 15 F5.2 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 28 F5.2 arcsec DEs Declination (J2000)
30- 32 F3.1 pc Dc Clump diameter
34- 39 E6.2 Msun Mc Clump mass
41- 43 F3.1 km/s DVc Clump 13CO line velocity width
45- 50 E6.2 cm-3 nc Clump 13CO density
52- 58 E7.2 cm-2 Nc Clump 13CO column density
60 A1 --- Type [ABC] Clump type (1)
62 A1 --- B-E [Y/N] indicates if clumps are candidates to be
experimenting collapse (ξmax≥6.5)
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Note (1): The clumps are classified into three types as follows:
A = clumps have a counterpart seen in infrared and millimeter wavelengths
B = clumps only have a counterpart in the 1.2mm continuum
C = clumps are only seen in 13CO.
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History:
Prepared via OCR at CDS.
(End) Patricia Vannier [CDS] 15-Feb-2017