J/A+A/602/A61 Radio spectra of globulettes in Carina nebula (Haikala+, 2017)
Radio observations of globulettes in the Carina nebula.
Haikala L.K., Gahm G.F., Grenman T., Makela M.M., Persson C.M.
<Astron. Astrophys. 602, A61 (2017)>
=2017A&A...602A..61H 2017A&A...602A..61H (SIMBAD/NED BibCode)
ADC_Keywords: H II regions; Molecular clouds ; Interstellar medium ;
Carbon monoxide ; Radio lines
Keywords: HII regions- ISM: molecules - ISM: kinematics and dymnamics -
evolution - ISM: individual objects: Carina nebula
Abstract:
The Carina nebula hosts a large number of globulettes. An optical
study of these tiny molecular clouds shows that the majority are of
planetary mass, but there are also those with masses of several tens
up to a few hundred Jupiter masses.
We seek to search for, and hopefully detect, molecular line emission
from some of the more massive objects; in case of successful detection
we aim to map their motion in the Carina nebula complex and derive
certain physical properties. Methods.We carried out radio observations
of molecular line emission in 12CO and 13CO (2-1) and (3-2) of
12 globulettes in addition to positions in adjacent shell structures
using APEX.
All selected objects were detected with radial velocities shifted
relative to the emission from related shell structures and background
molecular clouds. Globulettes along the western part of an extended
dust shell show a small spread in velocity with small velocity shifts
relative to the shell. This system of globulettes and shell structures
in the foreground of the bright nebulosity surrounding the cluster
Trumpler 14 is expanding with a few km/s relative to the cluster. A
couple of isolated globulettes in the area move at similar speed.
Compared to similar studies of the molecular line emission from
globulettes in the Rosette nebula, we find that the integrated line
intensity ratios and line widths are very different. The results show
that the Carina objects have a different density/temperature structure
than those in the Rosette nebula. In comparison the apparent size of
the Carina globulettes is smaller, owing to the larger distance, and
the corresponding beam filling factors are small. For this reason we
were unable to carry out a more detailed modelling of the structure of
the Carina objects in the way as performed for the Rosette objects.
The Carina globulettes observed are compact and denser than objects of
similar mass in the Rosette nebula. The distribution and velocities of
these globulettes suggest that they have originated from eroding
shells and elephant trunks. Some globulettes in the Trumpler 14 region
are quite isolated and located far from any shell structures. These
objects move at a similar speed as the globulettes along the shell,
suggesting that they once formed from cloud fragments related to the
same foreground shell.
Description:
Radio spectral lines of globulettes in the Carina nebula are
presented. The spectra were obtained with the Atacama Pathfinder
Experiment (APEX), Llano Chajnantor, Chile (O-091.F-9316A and
O-094.F-9312A) The observed molecular lines were 12CO(3-2),
12CO(2-1), 13CO(3-2), and 13CO (2-1). The APEX 350 and 230GHz
single sideband heterodyne APEX-1 and APEX-2 SIS receivers and the
32768 channel RPG eXtended bandwidth Fast Fourier Transform
Spectrometer (XFFTS) with a bandwidth of 2.5 GHz were used. The
channel spacing 76.3kHz corresponds to velocity spacing of 0.1 and
0.07km/s at 230 and 345GHz, respectively. All observations were
performed in position-switching mode. The telescope FWHM is 27" at
230GHz, and 18" at 345GHz, and the corresponding main beam
efficiencies are 0.75 and 0.73. Second order baseline was subtracted
from the spectra. The temperature scale is in Ta* units, i.e.
corrected to outside of the atmosphere but not for beam coupling. The
spectra are presented in one binary table FITS file.
Objects:
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RA (2000) DE Designation(s)
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10 43 39.1 -59 32 57 38 = [GG2014] 38
10 43 56.4 -59 36 53 78 = [GG2014] 78
10 43 56.4 -59 39 03 79 = [GG2014] 79
10 43 56.6 -59 36 33 80 = [GG2014] 80
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 109 21 List of spectra
list.fits 2880 1630 FITS table with spectra
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See also:
J/A+A/565/A107 : Globulettes in the Carina nebula (Grenman+, 2014)
Byte-by-byte Description of file:list.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Scan Scan number
7- 15 A9 --- Line Observed line
17- 26 A10 --- Object Object name, NN, NN-OFF, NN-OFF2, NN-SHELL_N
([GG2014] NN in Simbad)
28- 39 A12 --- Tel Telescope
41- 50 F10.6 deg RAdeg Right ascension (J2000)
52- 61 F10.6 deg DEdeg Declination (J2000)
63- 74 E12.6 Hz RestFreq Rest frequency
76- 87 E12.6 Hz ImagFreq Image frequency
89- 98 F10.6 km/s DeltaV Velocity resolution
100-109 A10 "date" Obs.Date Observation date
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Acknowledgements:
Lauri Haikala, lauri.haikala(at)uda.cl
(End) Lauri Haikala [Universida de Atacama], Patricia Vannier [CDS] 10-Apr-2017