J/MNRAS/452/4029 RMS survey (Urquhart+, 2015)
The RMS survey: ammonia mapping of the environment of massive young stellar
objects.
Urquhart J.S., Figura C.C., Moore T.J.T., Csengeri T., Lumsden S.L.,
Pillai T., Thompson M.A., Eden D.J., Morgan L.K.
<Mon. Not. R. Astron. Soc., 452, 4029-4053 (2015)>
=2015MNRAS.452.4029U 2015MNRAS.452.4029U (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Radio sources ; Infrared sources ; Morphology
Keywords: stars: early-type - stars: formation - ISM: molecules -
radio lines: ISM
Abstract:
We present the results of ammonia observations towards 66 massive star
forming regions identified by the Red Midcourse Space Experiment
Source survey. We have used the Green Bank Telescope and the K-Band
Focal Plane Array to map the ammonia (NH3) (1,1) and (2,2) inversion
emission at a resolution of 30 arcsec in 8 arcmin regions towards the
positions of embedded massive star formation. We have identified a
total of 115 distinct clumps, approximately two-thirds of which are
associated with an embedded massive young stellar object or compact
HII region, while the others are classified as quiescent. There is a
strong spatial correlation between the peak NH3 emission and the
presence of embedded objects. We derive the spatial distribution of
the kinetic gas temperatures, line widths, and NH3 column densities
from these maps, and by combining these data with dust emission maps
we estimate clump masses, H2 column densities and ammonia
abundances. The clumps have typical masses of ∼1000M☉ and radii
∼0.5pc, line widths of ∼2km/s and kinetic temperatures of ∼16-20K. We
find no significant difference between the sizes and masses of the
star-forming and quiescent subsamples; however, the distribution maps
reveal the presence of temperature and line width gradients peaking
towards the centre for the star-forming clumps while the quiescent
clumps show relatively uniform temperatures and line widths
throughout. Virial analysis suggests that the vast majority of clumps
are gravitationally bound and are likely to be in a state of global
free fall in the absence of strong magnetic fields. The similarities
between the properties of the two subsamples suggest that the
quiescent clumps are also likely to form massive stars in the future,
and therefore provide an excellent opportunity to study the initial
conditions of massive pre-stellar and protostellar clumps.
Description:
Derived clump parameters for clumps associated with compact HII
regions and massive YSOs identified by the RMS survey.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 60 66 Observed field parameters
table2.dat 82 115 *The FellWalker source catalogue
table3.dat 101 115 Detected NH3 clump parameters
table4.dat 61 88 Matches between NH3 clumps and RMS sources
table6.dat 53 115 Derived clump parameters
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Note on table2.dat: The parameters given in this table have been obtained from
the higher signal-to-noise NH3 (1,1) integrated emission maps.
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See also:
J/A+A/461/11 : Radio observations of MYSO candidates (Urquhart+, 2007)
J/A+A/474/891 : 13CO observations of YSOs in South Gal. plane (Urquhart+, 2007)
J/A+A/487/253 : The RMS survey: 13CO observations of YSOs (Urquhart+ 2008)
J/A+A/501/539 : RMS survey. 6cm observations of YSOs (Urquhart+, 2009)
J/ApJS/208/11 : The Red MSX Source Survey: massive protostars (Lumsden+, 2013)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Field sequential number
4- 18 A15 --- Field Field name (GLLL.lll+BB.bbb)
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 30 F5.2 s RAs Right ascension (J2000)
32 A1 --- DE- Declination sign (J2000)
33- 34 I2 deg DEd Declination (J2000)
36- 37 I2 arcmin DEm Declination (J2000)
39- 42 F4.1 arcsec DEs Declination (J2000)
44- 47 F4.2 K.km/s Map Map sensitivity
49 I1 --- NClump Number of clumps
51- 55 F5.1 km/s VLSR ?=- LSR velocity
57- 60 F4.1 kpc Dist ?=- Distance
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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 --- Seq Field sequential number
4- 18 A15 --- Clump Clump name (GLLL.lll+BB.bbb)
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 30 F5.2 s RAs Right ascension (J2000)
32 A1 --- DE- Declination sign (J2000)
33- 34 I2 deg DEd Declination (J2000)
36- 37 I2 arcmin DEm Declination (J2000)
39- 42 F4.1 arcsec DEs Declination (J2000)
44- 45 I2 arcsec maj Semi-major axis
47- 48 I2 arcsec min Semi-minor axis
50- 52 I3 deg PA Position angle measured anticlockwise
from Galactic north
54- 56 F3.1 --- Aspect Aspect ratio
58- 61 F4.1 arcsec thetaR Effective radius of the source
63- 66 F4.1 K.km/s/beam NH3peak NH3 peak flux density
68- 71 F4.2 K.km/s/beam e_NH3peak rms uncertainty on NH3peak
73- 77 F5.1 K.km/s NH3int NH3 integrated flux density
79- 82 F4.1 --- SNR Signal-to-noise ratio
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Field sequential number
4- 18 A15 --- Clump Clump name (GLLL.lll+BB.bbb)
20- 24 F5.1 km/s VLSR LSR velocity
26- 28 F3.1 km/s DV Intrinsic FWHM line width
30- 32 F3.1 km/s e_DV rms uncertainty on DV
34- 36 F3.1 -- taumain Optical depth of the transition
38- 40 F3.1 -- e_taumain rms uncertainty on taumain
42- 45 F4.1 K Tex Excitation temperature
47- 50 F4.1 K e_Tex rms uncertainty on Tex
52- 55 F4.1 K Trot Rotation temperature
57- 60 F4.1 K e_Trot rms uncertainty on Trot
62- 65 F4.1 K Tkin Kinetic temperature
67- 70 F4.1 K e_Tkin rms uncertainty on Tkin
72- 75 F4.2 --- Bff Beam filling factor (Tex/Trot)
77- 81 F5.2 [cm-2] logN(NH3) NH3 column density measured towards
the emission peak
83- 87 F5.2 [cm-2] <logN(NH3)> NH3 column density median value
determined over the clump
89- 93 F5.2 [-] log(N(NH3)/N(H2)) ?=- NH3 abundance measured towards
the emission peak
95- 99 F5.2 [-] <log(N(NH3)/N(H2))> ? NH3 abundance median value
determined over the clump
101 I1 --- Notes [1/3]? Notes (1)
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Note (1): Note as follows:
1 = the emission profile appears to arise from a single clump
2 = the emission profile appears to arise from multiple distinct clumps
along the line of sight
3 = identifies sources that are associated with broad emission wings,
which are themselves indicative of outflow motion
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Field sequential number
4- 18 A15 --- Clump Clump name
20- 37 A18 --- RMS MSX Source Name
39- 42 F4.1 arcsec Offset ?=- Angular offset between RMS and Clump
positions
44- 61 A18 --- RMSType RMS source type
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq Field sequential number
4- 18 A15 --- Clump Clump name (GLLL.lll+BB.bbb)
20- 22 A3 --- RMS? [yes/no ] RMS association ?
24- 27 F4.1 kpc Dist ?=- Distance
29- 32 F4.2 kpc Rad ?=- Radius
34- 38 F5.2 [cm-2] log(PeakN(H2)) ?=- NH2 peak column density
40- 42 F3.1 [Msun] logMclump ?=- Clump mass
44- 48 F5.2 [Msun] logMvir ?=- Virial mass
50- 53 F4.2 [Lsun] logLbol ?=- Bobometric velocity (1)
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Note (1): The bolometric luminosity given is the sum of all RMS sources
embedded in each clump.
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Acknowledgements:
James Urquhart, j.s.urquhart(at)gmail.com
(End) Patricia Vannier [CDS] 14-Mar-2016