J/MNRAS/452/637 Distance-limited sample of MYSOs (Maud+, 2015)
A distance-limited sample of massive star-forming cores from the RMS survey.
Maud L.T., Lumsden S.L., Moore T.J.T., Mottram J.C., Urquhart J.S.,
Cicchini A.
<Mon. Not. R. Astron. Soc., 452, 637-655 (2015)>
=2015MNRAS.452..637M 2015MNRAS.452..637M (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Abundances ; Infrared sources ; Stars, masses
Keywords: stars: abundances - stars: formation - stars: massive -
stars: protostars
Abstract:
We analyse C18O (J=3-2) data from a sample of 99 infrared
(IR)-bright massive young stellar objects (MYSOs) and compact HII
regions that were identified as potential molecular-outflow sources in
the Red MSX Source survey. We extract a distance-limited (D<6kpc)
sample shown to be representative of star formation covering the
transition between the source types. At the spatial resolution probed,
Larson-like relationships are found for these cores, though the
alternative explanation, that Larson's relations arise where
surface-density-limited samples are considered, is also consistent
with our data. There are no significant differences found between
source properties for the MYSOs and HII regions, suggesting that the
core properties are established prior to the formation of massive
stars, which subsequently have little impact at the later evolutionary
stages investigated. There is a strong correlation between
dust-continuum and C18O-gas masses, supporting the interpretation
that both trace the same material in these IR-bright sources. A clear
linear relationship is seen between the independently established core
masses and luminosities. The position of MYSOs and compact HII regions
in the mass-luminosity plane is consistent with the luminosity
expected from the most massive protostar in the cluster when using an
∼40 percent star formation efficiency and indicates that they are at
a similar evolutionary stage, near the end of the accretion phase.
Description:
The sources were chosen from all MYSOs and HII regions in the RMS
survey that are located within a distance of ∼6kpc, have luminosities
≳3000 L{sun}, and are observable with the James Clerk Maxwell
Telescope (JCMT; declinations -25° to +65°), with some
additional right ascension constraints set by the observing dates. In
addition, for the HII regions, only those sources which appear compact
in higher resolution mid-IR images were selected. Finally although all
of the sources with L>10000L{sun} were observed, only a random
sample of the less luminous ones were included
All 99 sources were observed with the JCMT as part of projects
M07AU08, M07BU16, M08AU19 and M08BU18 during 2007 and 2008. The 15m
dish yields a full-width at half-maximum (FWHM) beam size of
15.3-arcsec at ∼329GHz for the C18O (3-2) line.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 109 99 Source parameters for all objects in the sample,
taken from the RMS survey online archive
table2.dat 106 94 Optical depths, main-beam brightness temperatures,
excitation temperatures and abundance ratios for
all source with strong C18O emission
table3.dat 82 94 Measured parameters for all sources
table4.dat 41 70 Continuum masses for a number of sources in the
sample from BOLOCAM, SCUBA and other 1.2mm
observation
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See also:
J/A+A/461/11 : Radio observations of MYSO candidates (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- 17 A17 ---- MSX MSX source name (GLLL.llll+BB.bbbb)
18 A1 --- n_MSX [*] Note on MSX (1)
20- 21 I2 h RAh Right ascension (J2000)
23- 24 I2 min RAm Right ascension (J2000)
26- 27 I2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 37 I2 arcsec DEs Declination (J2000)
39- 45 A7 --- Type Source type
48- 52 F5.1 km/s VLSR LSR velocity
54- 57 F4.1 kpc Dist Distance
59- 64 I6 Lsun Lum Luminosity
66- 76 A11 --- IRAS IRAS source name (HHMMm+DDMMA)
78- 79 I2 arcsec Offset ? MSX-IRAS sources offset
81-109 A29 --- OName Other association
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Note (1): * highlights sources where multiple IR targets have been identified.
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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- 17 A17 --- MSX MSX source name
18 A1 --- n_MSX [*] Note on MSX (1)
20- 24 F5.2 K Tmb13 Main-beam brightness temperature for 13CO
26- 29 F4.2 K e_Tmb13 rms uncertainty on Tmb13
31- 35 F5.2 K Tmb18 Main-beam brightness temperature for C18O
37- 40 F4.2 K e_Tmb18 rms uncertainty on Tmb18
42- 46 F5.2 --- tau13 ?=- Optical depth for 13CO
48- 51 F4.2 --- E_tau13 ? Error on tau13 (upper value)
52 A1 --- nEtau13 [i] i for infinity
54- 57 F4.2 --- e_tau13 ? Error on tau13 (lower value)
59 A1 --- l_tau18 [~] Limit flag on tau18
60- 63 F4.2 --- tau18 ? Optical depth for C18O
65- 68 F4.2 --- E_tau18 ? Error on tau18 (upper value)
69 A1 --- nEtau18 [i] i for infinity
71- 74 F4.2 --- e_tau18 ? Error on tau18 (lower value)
76- 80 F5.2 J Tex Excitation temperature
82- 86 F5.2 J E_Tex Error on Tex (upper value)
88- 91 F4.2 J e_Tex Error on Tex (lower value)
93- 95 A3 --- Abs [yes/no ] Self absorption
97- 99 F3.1 --- 13CO/C18O 13CO/C18O abundance ratio
102-106 F5.1 10+4 H2/C18O H2/C18O abundance ratio
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Note (1): Sources with optically thin 13CO emission are flagged with an asterisk
(*) to indicate that 12CO is used to calculate Tex.
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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- 17 A17 --- MSX MSX source name
19- 25 A7 --- Type Source type
27- 29 F3.1 K SpNoise Spectral noise
31- 35 F5.1 km/s b_VelC Lower value of velocity range
37- 41 F5.1 km/s B_VelC Upper value of velocity range
43- 45 F3.1 K.km/s MNoise Map noise
47- 49 F3.1 km/s FWHM FWHM
51- 55 F5.1 km/s VelC Centroid velocity
57- 61 I5 Msun Amass Mass determined with polygon aperture method
63- 65 I3 Msun e_Amass Aperture mass error
67- 71 I5 Msun Gmass Mass determined with Gaussian summation fitting
73- 75 I3 Msun e_Gmass Gaussian mass error
77- 80 F4.2 pc Drad Deconvolution radius
82 I1 --- Flag Mass flag (1)
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Note (1): Mass flags follow the scheme:
0 = masses calculated directly from within aperture tracing the
3σMAP level.
1 = faint filamentary structures are not included in mass calculation and are
outside the aperture. In extreme cases the aperture is more circular.
2 = highlights cores with multiple IR-bright sources within JCMT beam
(classically flag type 0 or 1).
3 = source mass estimated within a 3-pixel-diameter aperture (slightly over
1 beam FWHM) aperture centred on the source due to the source being part
of a complex filamentary cloud complex.
4 = complex/multiple source regions of significant emission. Masses are split
where emission peaks are separated by more than 3 pixels or are circular
with a radius set as the shortest distance between the RMS source
location and the 3σMAP.
5 = two or more inseparable continuum cores very close within the aperture.
6 = luminosity estimates not from SED fitting.
7 = morphology suggesting that gas located at the source position has already
been blown away or eroded.
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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- 17 A17 --- MSX MSX source name
19- 25 A7 --- Type Source type
27- 30 I4 Msun MBOLOCAM ?=- Mass, from 1.1mm BOLOCAM observation (1)
32- 35 I4 Msun MSCUBA ?=- Mass, from 850um SCUBA observation(1)
37- 41 I5 Msun M1.2mm ?=- Mass, from other 1.2 mm observation (1)
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Note (1): Masses are reasonably consistent between continuum observations.
Dependent upon dust opacity, temperature and observable uncertainties a
generous error estimate of ∼50 per cent can be assumed (as Fig. 5).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 14-Jan-2016