J/MNRAS/493/5045 Properties of giant molecular clouds in NGC 1300 (Maeda+, 2020)
Properties of giant molecular clouds in the strongly barred galaxy NGC 1300.
Maeda F., Ohta K., Fujimoto Y., Habe A.
<Mon. Not. R. Astron. Soc., 493, 5045-5061 (2020)>
=2020MNRAS.493.5045M 2020MNRAS.493.5045M (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interferometry ; Millimetric/submm sources ;
Positional data ; Velocity dispersion ; Star Forming Region
Keywords: ISM: clouds - galaxies: individual: NGC1300 -
galaxies: star formation
Abstract:
Star formation activity depends on galactic-scale environments. To
understand the variations in star formation activity, comparing the
properties of giant molecular clouds (GMCs) among environments with
different star formation efficiency (SFE) is necessary. We thus focus
on a strongly barred galaxy to investigate the impact of the galactic
environment on the GMC properties, because the SFE is clearly lower in
bar regions than in arm regions. In this paper, we present the
12CO(1-0) observations towards the western bar, arm, and bar-end
regions of the strongly barred galaxy NGC1300 with ALMA 12-m array at
a high angular resolution of ∼40pc. We detected GMCs associated with
the dark lanes not only in the arm and bar-end regions but also in the
bar region, where massive star formation is not seen. Using the CPROPS
algorithm, we identified and characterized 233 GMCs across the
observed regions. Based on the Kolmogorov-Smirnov test, we find that
there is virtually no significant variations in GMC properties (e.g.
radius, velocity dispersion, molecular gas mass, and virial parameter)
among the bar, arm, and bar-end region. These results suggest that
systematic differences in the physical properties of the GMCs are not
the cause for SFE differences with environments, and that there should
be other mechanisms which control the SFE of the GMCs such as fast
cloud-cloud collisions in NGC1300.
Description:
We carried out 12CO(1-0) line observations of NGC1300 on 2017
December 30 and 2018 January 6, 7, 13, and 16 with ALMA (program ID:
2017.1.00248.S, PI=F. Maeda). To cover the regions observed with
12CO(1-0) by Maeda et al. (2018PASJ...70...37M 2018PASJ...70...37M), two pointings were
centred at (RA, Dec.)=(3h19m37.435s, -19°24'33.24") and
(3h19m36.326s, -19°24'01.42").
The ALMA observations were taken during five separated periods with
seven execution blocks in total. The total on-source time was 5.31h
(2.65h for each position). For all observations, we used about 44
antennas with C43-5 configuration. The projected baseline length
ranged from 15.1m to 2.5km, which corresponds to a maximum recoverable
scale of ∼21.4arcsec at 115GHz. We used the Band 3 receiver with the
central frequency of 114.664GHz, channel width of 244.1kHz
(∼0.64km/s), and bandwidth of 468.8MHz (∼1225km/s). Bandpass and phase
were calibrated with J0423-0120 and J0340-2119, respectively.
J0423-0120 was also used as a flux calibrator. The Tsys and PWV were
typically 100-150K and 1-5mm during the observations, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 106 233 GMC catalogue
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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- 3 I3 --- ID [1/233] GMC identification 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- 27 F4.1 arcsec DEs Declination (J2000)
29- 34 F6.1 km/s vLSR Local Standard of Rest velocity
36- 38 F3.1 K Tpeak Peak brightness temperature
40- 43 F4.1 --- S/N Peak signal-to-noise ratio
45- 48 F4.1 km/s sigv Deconvolved, extrapolated velocity dispersion
50- 53 F4.1 km/s e_sigv Error on sigv
55 A1 --- l_R Limit flag on R
57- 60 F4.1 pc R Deconvolved, extrapolated effective radius
62- 65 F4.1 pc e_R ? Error on R
67- 71 F5.1 10+5Msun Mmol Mass from CO luminosity (1)
73- 76 F4.1 10+5Msun e_Mmol Error on Mmol
78- 82 F5.1 10+5Msun Mvir ? Mass from virial theorem
84- 87 F4.1 10+5Msun e_Mvir ? Error on Mvir
89- 91 F3.1 --- alpha ? Virial parameter
93- 96 F4.1 --- e_alpha ? Error on alpha
98- 104 A7 --- Reg Region where a given GMC has been
identified (2)
106 A1 --- f_R Flag on R (3)
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Note (1): We assume the CO-to-H2 conversion factor of 4.4M☉/(K.km/s.pc2)
Note (2): GMCs outside the Bar, Arm, and Bar-end regions are represented as
'other'
Note (3): Flag as follows:
0 = An actual measurement of the GMC radius
1 = the radius is an upper limit.
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 11-May-2023