J/MNRAS/450/1926 Infall motions in massive star-forming regions (He+, 2015)
Infall motions in massive star-forming regions:
results from years 1 and 2 of the MALT90 survey.
He Y.-X., Zhou J.-J., Esimbek J., Ji W.-G., Wu G., Tang X.-D., Yuan Y.,
Li D.-L., Baan W.A.
<Mon. Not. R. Astron. Soc., 450, 1926-1936 (2015)>
=2015MNRAS.450.1926H 2015MNRAS.450.1926H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Millimetric/submm sources ; Spectroscopy ;
Radio lines
Keywords: stars: formation - ISM: kinematics and dynamics - ISM: molecules -
radio lines: ISM
Abstract:
Massive star-forming regions with observed infall motions are good
sites for studying the birth of massive stars. In this paper, 405
compact sources have been extracted from the APEX Telescope Large Area
Survey of the Galaxy (ATLASGAL) compact sources that also have been
observed in the Millimetre Astronomy Legacy Team 90-GHz (MALT90)
survey during years 1 and 2. These observations are complemented with
Spitzer GLIMPSE/MIPSGAL mid-IR survey data to help classify the
elected star-forming clumps into three evolutionary stages:
pre-stellar, proto-stellar and UCHII regions. The results suggest that
0.05g/cm2 is a reliable empirical lower bound for the clump surface
densities required for massive-star formation to occur. The optically
thick HCO+(1-0) and HNC(1-0) lines, as well as the optically thin
N2H+(1-0) line were used to search for infall motions towards
these sources. By analysing the asymmetries of the optically thick
HCO+(1-0) and HNC(1-0) lines and the mapping observations of
HCO+(1-0), a total of 131 reliable infall candidates have been
identified. The HCO+(1-0) line shows the highest occurrence of
obvious asymmetric features, suggesting that it may be a better infall
motion tracer than other lines such as HNC(1-0). The detection rates
of infall candidates towards pre-stellar, proto-stellar and UCHII
clumps are 0.3452, 0.3861 and 0.2152, respectively. The relatively
high detection rate of infall candidates towards UCHII clumps
indicates that many UCHII regions are still accreting matter. The peak
column densities and masses of the infall candidates, in general,
display an increasing trend with progressing evolutionary stages.
However, the rough estimates of the mass infall rate show no obvious
variation with evolutionary stage.
Description:
ATLASGAL is the first systematic survey of the inner Galactic plane at
sub-millimetre wavelengths. Using the 12-m APEX telescope, the aim of
this survey was to study continuum emission from the highest density
regions of dust at 345GHz.
The MALT90 Survey is a large international project that obtains
molecular line maps to characterize the physical and chemical
conditions of high-mass star-formation regions over a wide range of
evolutionary stages. The sample for this survey is a sub-sample of the
ATLASGAL catalogue. The MALT90 data were obtained from the online
archive (http://atoa.atnf.csiro.au/MALT90/).
The Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE)
survey is a Spitzer/IRAC Legacy survey of the Galactic mid-plane
(Benjamin et al., 2003PASP..115..953B 2003PASP..115..953B, Churchwell et al.
2009PASP..121..213C 2009PASP..121..213C, Cat. II/293) at 3.6, 4.5, 5.8 and 8.0um. The
highly reliable point-source catalogues released from the GLIMPSE
survey and the mosaicked images of MIPSGAL at 24um have been used in
the analysis.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 88 405 Derived clump parameters
tablea2.dat 85 405 The derived line parameters and profiles of
the observed sources
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See also:
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
J/ApJS/197/25 : MALT90 pilot survey (Foster+, 2011)
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- --- [AGAL]
5- 18 A14 --- AGAL ATLASGAL name (LLL.lll+BB.bbb)
20 A1 --- n_Clump [*] * indicates infall candidates
21- 34 A14 --- Clump Clump name (GLLL.lll+B.bbb), sources are
named by galactic coordinates of
ATLASGAL sources
36- 40 F5.2 Jy/beam Fpeak Peak submillimetric emission flux at 870um
42- 47 F6.2 Jy Fint Integrated submillimetric emission flux
at 870um
49- 53 F5.2 kpc Dist ?=- Heliocentric distance
55- 56 I2 --- r_Dist ?=- Distance reference (1)
58- 61 F4.2 pc Rad ?=- Effective physical radius
63- 67 F5.2 [cm-2] logN(H2) H2 column density
69- 72 F4.2 [Msun] log(Mclump) ?=- Clump mass derived from the integrated
870um emission
74- 85 A12 --- Class Spitzer classification
86 A1 --- n_Class [I] I indicates a source with an IRAS
counterpart
88 I1 --- r_Class ?=- Reference for classification (2)
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Note (1): References for distance as follows:
1 = Urquhart et al. (2013, Cat. J/MNRAS/431/1752)
2 = Urquhart et al. (2013, Cat. J/MNRAS/435/400)
3 = this paper
4 = Minier et al. (2005A&A...429..945M 2005A&A...429..945M)
5 = Sanchez-Monge et al. (2013, Cat. J/A+A/550/A21)
6 = Faundez et al. (2004, Cat. J/A+A/426/97)
7 = He, Takahashi & Chen (2012, Cat. J/ApJS/202/1)
8 = Ragan et al. (2012, Cat. J/A+A/547/A49)
9 = Russeil (2003, Cat. J/A+A/397/133)
10 = Busfield et al. (2006, Cat. J/MNRAS/366/1096)
11 = Harju et al. (1998, Cat. J/A+AS/132/211)
12 = Blitz, Fich & Stark (1982ApJS...49..183B 1982ApJS...49..183B, Cat. VII/50)
Note (2): References for Spitzer classification as follows:
1 = Becker et al. (1994, Cat. J/ApJS/91/347)
2 = Forster & Caswell (2000ApJ...530..371F 2000ApJ...530..371F)
3 = Walsh et al. (1997, Cat. J/MNRAS/291/261)
4 = Anderson et al. (2011, Cat. J/ApJS/194/32)
5 = Kim & Koo (2001ApJ...549..979K 2001ApJ...549..979K)
6 = Chini, Kruegel & Wargau (1987A&A...181..378C 1987A&A...181..378C)
7 = Urquhart et al. (2009, Cat. J/A+A/501/539)
8 = Wu et al. (2007ApJ...669L..37W 2007ApJ...669L..37W)
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Clump Clump name
16- 22 F7.2 km/s VHCO+ Peak velocity of HCO+(1-0)
24- 26 F3.2 km/s e_VHCO+ rms uncertainty on VHCO+
28- 34 F7.2 km/s VHNC Peak velocity of HNC(1-0)
36- 38 F3.2 km/s e_VHNC rms uncertainty on VHCN
40- 46 F7.2 km/s VN2H+ Peak velocity of N2H+(1-0)
48- 50 F3.2 km/s e_VN2H+ rms uncertainty on VN2H+
52- 55 F4.2 km/s DVN2H+ FWHM of N2H+(1-0)
57- 59 F3.2 km/s e_DVN2H+ rms uncertainty on DVN2H+
61- 65 F5.2 --- dvHCO+ Asymmetry of HCO+(1-0)
67- 69 F3.2 --- e_dvHCO+ rms uncertainty on dvHCO+
71- 75 F5.2 --- dvHCN Asymmetry of HNC(1-0)
77- 79 F3.2 --- e_dvHCN rms uncertainty on dvHCN
81 A1 --- PHCO+ [BRN] Profile of HCO+(1-0) (3)
83 A1 --- PHNC [BRN] Profile of HNC(1-0) (3)
85 A1 ---- n_Clump [*] * indicates infall candidates
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Note (3): Profile is judged from our HCO+(1-0) and HNC(1-0) as follows:
B = blue profile
R = red profile
N = neither blue nor red
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 19-May-2016