J/MNRAS/496/4637 Distances to molecular clouds in fourth quadrant (Chen+, 2020)
The distances to molecular clouds in the fourth Galactic quadrant.
Chen B., Wang S., Hou L., Yang Y., Li Z., Zhao H., Jiang B.
<Mon. Not. R. Astron. Soc., 496, 4637-4645 (2020)>
=2020MNRAS.496.4637C 2020MNRAS.496.4637C (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interstellar medium ; Extinction ; Milky Way ;
Infrared
Keywords: ISM: clouds - dust, extinction - Galaxy: structure
Abstract:
Distance measurements to molecular clouds are essential and important.
We present directly measured distances to 169 molecular clouds in the
fourth quadrant of the Milky Way. Based on the near-infrared
photometry from the Two Micron All Sky Survey and the Vista Variables
in the Via Lactea Survey, we select red clump stars in the overlapping
directions of the individual molecular clouds and infer the bin
averaged extinction values and distances to these stars. We track the
extinction versus distance profiles of the sightlines towards the
clouds and fit them with Gaussian dust distribution models to find the
distances to the clouds. We have obtained distances to 169 molecular
clouds selected from Rice et al. (2016ApJ...822...52R 2016ApJ...822...52R). The clouds
range in distances between 2 and 11kpc from the Sun. The typical
internal uncertainties in the distances are less than 5 per cent and
the systematic uncertainty is about 7 per cent. The catalogue
presented in this work is one of the largest homogeneous catalogues of
distant molecular clouds with the direct measurement of distances.
Based on the catalogue, we have tested different spiral arm models
from the literature.
Description:
Our work is based on near-IR photometry from 2MASS and VVV. 2MASS was
conducted with two 1.3m telescopes to provide full coverage of the
sky. It has three near-IR bands, J, H, and KS, centred at 1.25,
1.65, and 2.16µm, respectively. To trace the distance of far
molecular clouds, we combined the 2MASS data with the in-depth near-IR
VVV data. The VVV survey were carried out with the VISTA 4.1m
telescope. The survey took images in five bands, Z, Y, J, H, and KS.
In this work, we adopt the catalogue 'vvvPsfDophotZYJHKsSource' from
the Data Release 4 of Images and Source Lists from VVV.
In this work, the molecular clouds are selected from the work of Rice
et al. (2016ApJ...822...52R 2016ApJ...822...52R), who have created a catalogue of massive
molecular clouds in the Galactic plane (13°<l<348°) with a
consistent dendrogram-based decomposition of the CO data from the
12CO CfA-Chile survey (Dame et al. 2001ApJ...547..792D 2001ApJ...547..792D). The Rice et
al. (2016ApJ...822...52R 2016ApJ...822...52R) catalogue contains 1064 massive clouds. 247
of them are located inside the VVV survey footprint. All of them are
located in the fourth quadrant of the Galactic plane.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 59 169 Distances of molecular clouds in the fourth
Galactic quadrant
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/376 : VISTA Variable in the Via Lactea Survey (VVV) DR4.2 (Minniti+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 F6.2 deg GLON Galactic longitude
8- 12 F5.2 deg GLAT Galactic latitude
14- 17 F4.2 deg sigr Angular size of the molecular cloud
19- 23 F5.2 kpc d0 Distance of the cloud
25- 28 F4.2 kpc e_d0 Error on d0
30- 33 F4.2 mag dAKs Total extinction contributed by the dust
grains in the cloud
35- 37 I3 pc R Radius of the cloud
39- 45 F7.2 10+3Msun M ? Mass of the cloud
47- 53 F7.2 km/s vLSR Local Standard of Rest velocity
55- 59 F5.2 kpc dR16 ? Kinematic distance from Rice et al.
(2016ApJ...822...52R 2016ApJ...822...52R)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 20-Jul-2023