J/A+A/667/A137 Ammonia emission of dense cores in the RMC (Boegner+, 2022)
Ammonia characterisation of dense cores in the Rosette Molecular Cloud.
Boegner R., Csengeri T., Montillaud J., Wienen M., Schneider N.,
Wyrowsky F., Motte F., Toth L.V.
<Astron. Astrophys. 667, A137 (2022)>
=2022A&A...667A.137B 2022A&A...667A.137B (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Radio lines
Keywords: stars: formation - ISM: clouds - ISM: molecules
Abstract:
The Rosette molecular cloud complex is a well-known Galactic star
forming region with a morphology pointing towards triggered star
formation. The distribution of its young stellar population and the
gas properties question whether star formation could be globally
triggered in the region.
We focus on the characterisation of the most massive pre- and
protostellar cores distributed throughout the molecular cloud to help
the understanding of the star formation processes in the region.
We observed a sample of 33 dense cores, identified in Herschel
continuum maps, with the Effelsberg 100-m telescope. Using NH3 (1,1)
and (2,2) measurements we characterise the dense core population
computing rotational and gas kinetic temperatures and NH3 column
density with multiple methods. We also estimate the gas pressure ratio
and virial parameters to examine the stability of the cores. Using
results from Herschel data we examine possible correlations between
gas and dust parameters.
Ammonia emission is detected toward 31 out of the 33 selected targets.
We estimate kinetic temperatures between 12 and 20K, and column
densities within the 1014-2x1015cm-2 range in the selected
targets. The virial analysis suggests that most sources are likely to
be gravitationally bound, while the linewidths are dominated by
non-thermal motions. Our results are compatible with large scale dust
temperature maps suggesting that the temperature decreases and column
density increases with distance from NGC 2244 except for the densest
protoclusters. We also identify a small spatial shift between the
ammonia and dust peaks in the regions most exposed to irradiation from
the nearby NGC 2244 stellar cluster. However, we find no trends in
terms of core evolution with spatial location, in the number of
prestellar to protostellar core ratio or the virial parameter.
Star formation is more likely based on the primordial structure of the
cloud in spite of the impact of irradiation from the nearby cluster,
NGC 2244. The physical parameters from the NH3 measurements suggest
gas properties in between those of low- and high-mass star forming
regions, suggesting that the Rosette molecular cloud could host
on-going intermediate mass star formation, and is unlikely to form
high-mass stars.
Description:
The NH3 observations were carried out with the Effelsberg 100m
telescope. We observed the NH3 (1,1) and (2,2) inversion lines at
about 24GHz simultaneously using single pointing observations in
frequency switching mode with a frequency throw of 7.5MHz. We used the
K-band receiver frontend and the fast Fourier transform spectrometer
(FFTS) backend with a total bandwidth of 100MHz. We calculate a
velocity resolution of 0.08km/s using 3.5kHz effective spectral
resolution at the observing frequency of 23.7GHz, and we smoothed the
data to a resolution of 0.15km/s. Altogether we observed 33 sources
with an integration time of 30 minutes for each source. The beamwidth
of the telescope is 40" at the frequencies of the NH3 lines,
corresponding to a linear scale of about 0.28pc at a distance of
1.6kpc.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 71 33 The parameters of the RMC dense cores from
Motte et al. (2010A&A...518L..77M 2010A&A...518L..77M) and
Hennemann et al. (2010A&A...518L..84H 2010A&A...518L..84H)
selected for our sample
table2.dat 98 22 Parameters calculated from the NH3 (1,1) and
(2,2) lines with errors obtained from
Monte Carlo (MC) calculation
tableb1.dat 110 33 The parameters of the NH3 (1,1) and (2,2)
lines obtained from CLASS
sp/* . 66 Individual spectra
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Source number
4- 5 I2 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 14 F5.2 s RAs Right ascension (J2000)
16 A1 --- DE- Declination sign (J2000)
17- 18 I2 deg DEd Declination (J2000)
20- 21 I2 arcmin DEm Declination (J2000)
23- 26 F4.1 arcsec DEs Declination (J2000)
28- 37 A10 --- Area Location of the source
38- 51 A14 --- Type Evolutionary stage
53- 56 F4.2 pc FWHM Geometric average of deconvolved major and
minor FWHM of the source Gaussian ellipse
58- 59 I2 K Tdust Dust temperature
61- 64 I4 Lsun Lbol ? Bolometric luminosity
66- 69 F4.1 Msun M350 Mass
70 A1 --- n_M350 Note on Mass (1)
71 A1 --- Sample [rce] Sample (2)
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Note (1): Core #39 has a mass designation of 12-5.7M☉.
Note (2): Samples are as follows:
r = reliable
c = candidate
e = excluded
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Source number
4- 12 A9 --- Sample Sample
14- 18 F5.2 K Trot Rotational temperature
20- 23 F4.2 K e_Trot Error in rotational temperature
25- 29 F5.2 K TkinO Kinetic temperature calculated according to
Ott et al. (2011ApJ...742...95O 2011ApJ...742...95O)
31- 34 F4.2 K e_TkinO Error in kinetic temperature calculated
according to Ott et al.
(2011ApJ...742...95O 2011ApJ...742...95O), from MC
calculations
36- 40 F5.2 K TkinT Kinetic temperature calculated according to
Tafalla et al. (2004A&A...416..191T 2004A&A...416..191T)
42- 45 F4.2 K e_TkinT Error in kinetic temperature calculated
according to Tafalla et al.
(2004A&A...416..191T 2004A&A...416..191T) from MC calculations
47- 51 F5.2 10+14cm-2 NtotFr NH3 column density calculated according
to Friesen et al. (2009ApJ...697.1457F 2009ApJ...697.1457F)
53- 57 F5.2 10+14cm-2 e_NtotFr Error in NH3 column density calculated
according to Friesen et al.
(2009ApJ...697.1457F 2009ApJ...697.1457F) from MC calculations
59- 63 F5.2 10+14cm-2 NtotL NH3 column density calculated according
to Lu et al. (2014ApJ...790...84L 2014ApJ...790...84L,
Cat. J/ApJ/790/84) from MC calculations
65- 69 F5.2 10+14cm-2 e_NtotL Error in NH3 column density calculated
according to Lu et al.
(2014ApJ...790...84L 2014ApJ...790...84L, Cat. J/ApJ/790/84)
from MC calculations
71- 73 F3.1 --- Rp Gas pressure ratio
75- 79 F5.2 Msun Mvir Virial mass
81- 85 F5.2 --- alphavir Virial parameter
87- 90 F4.2 K Tex Excitation temperature
92 A1 --- Flag [*] Flag (1)
94- 98 F5.2 10+3cm-3 nH2 H2 volume density
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Note (1): * for tau=0.1 lower limit, original values replaced with the median
excitation temperature of the rest of the cores, 4.5K
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID Source number
4 A1 --- Type [0/2] Evolutionary stage (1)
6- 9 F4.2 --- Tantxtau ?=- Antenna temperature times optical depth
11- 14 F4.2 --- e_Tantxtau ?=- Antenna temperature times
optical depth error
16- 20 F5.2 km/s v11 ?=- NH3 (1,1) line velocity
22- 25 F4.2 km/s e_v11 ?=- NH3 (1,1) line velocity error
27- 30 F4.2 km/s FWHM11 ?=- NH3 (1,1) FWHM
32- 35 F4.2 km/s e_FWHM11 ?=- NH3 (1,1) FWHM error
37- 40 F4.2 --- tau11 ?=- NH3 (1,1) main hyperfine component
optical depth
42- 45 F4.2 --- e_tau11 ?=- NH3 (1,1) main hyperfine component
optical depth error
47- 50 F4.2 K T11 ?=- NH3 (1,1) main beam brightness
temperature
52- 55 F4.2 K e_T11 ?=- NH3 (1,1) main beam brightness
temperature error
57- 61 F5.2 --- SN11 ?=- signal to noise ratio of NH3 (1,1) line
63- 66 F4.2 K.km/s Area22 ?=- NH3 (2,2) line area
68- 71 F4.2 K.km/s e_Area22 ?=- NH3 (2,2) line area error
73- 77 F5.2 km/s v22 ?=- NH3 (2,2) line velocity
79- 82 F4.2 km/s e_v22 ?=- NH3 (2,2) line velocity error
84- 87 F4.2 km/s FWHM22 ?=- NH3 (2,2) FWHM
89- 92 F4.2 km/s e_FWHM22 ?=- NH3 (2,2) FWHM error
94- 97 F4.2 K T22 ?=- NH3 (2,2) main beam brightness
temperature
99-102 F4.2 K e_T22 ?=- NH3 (2,2) main beam brightness
temperature error
104-108 F5.2 --- SN22 ?=- signal to noise ratio of NH3 (2,2) line
110 A1 --- Sample [rce] Sample (2)
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Note (1): Evolutionary stages as follows:
0 = warm-starless
1 = prestellar
2 = protostellar
Note (2): Samples are as follows:
r = reliable
c = candidate
e = excluded
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Byte-by-byte Description of file: sp/*
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Bytes Format Units Label Explanations
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1- 11 E11.5 km/s Vel Velocity
13- 23 E11.5 K Tmb Main beam brightness temperature
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Acknowledgements:
Rebeka Boegner, bogner.rebeka(at)ttk.elte.hu
(End) Patricia Vannier [CDS] 15-Sep-2022