J/ApJ/606/929 IR to mm observations of IRAS 18317-0757 (Hunter+, 2004)
IRAS 18317-0757: a cluster of embedded massive stars and protostars.
Hunter T.R., Zhang Q., Sridharan T.K.
<Astrophys. J., 606, 929-942 (2004)>
=2004ApJ...606..929H 2004ApJ...606..929H
ADC_Keywords: Infrared sources ; Interstellar medium
Keywords: infrared: stars - stars: formation -
ISM: individual (AFGL 2194, G23.95+0.15, IRAS 18317-0757)
Abstract:
We present high-resolution, multiwavelength-continuum, and
molecular-line images of the massive star forming region
IRAS 18317-0757. The global infrared through millimeter spectral
energy distribution can be approximated by a two-temperature model
(25 and 63K) with a total luminosity of approximately
log(L/L☉)=5.2. Previous submillimeter imaging resolved this
region into a cluster of five dust cores, one of which is associated
with the ultracompact HII region G23.955+0.150, and another with a
water maser. In our new 2.7mm continuum image obtained with BIMA, only
the UCHII region is detected, with total flux and morphology in good
agreement with the free-free emission in the VLA centimeter-wave maps.
For the other four objects, the nondetections at 2.7mm and in the MSX
mid-infrared bands are consistent with cool dust emission with a
temperature of 13-40K and a luminosity of 1000-40000L☉. By
combining single-dish and interferometric data, we have identified
over two dozen virialized C18O cores in this region that contain
∼40% of the total molecular gas mass present.
Description:
With the Berkeley-Illinois-Maryland Association (BIMA) Millimeter
Array, IRAS 18317-0757 was simultaneously observed in 110GHz continuum
and C18O (1-0). The continuum bandwidth was 600MHz. The spectral
resolution for the line data was 0.2MHz (0.53km/s).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 7 Observed emission properties of submillimeter
clumps
table5.dat 77 26 Position and mass of C18O (1-0) clumps
table7.dat 23 44 Stars detected in all three 2MASS bands
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Source Source name (1)
10- 11 I2 h RAh ? Right ascension (J2000.0)
13- 14 I2 min RAm ? Right ascension (J2000.0)
16- 19 F4.1 s RAs ? Right ascension (J2000.0)
21 A1 --- DE- Declination sign (J2000.0)
22- 23 I2 deg DEd ? Declination (J2000.0)
25- 26 I2 arcmin DEm ? Declination (J2000.0)
28- 29 I2 arcsec DEs ? Declination (J2000.0)
31- 33 I3 Jy S350um Flux density at 350µm, within 22" aperture
35- 36 I2 Jy e_S350um rms uncertainty on S350um
38 A1 --- l_S2.7mm Limit flag on S2.7mm
(upper limits are 3σ)
39- 43 F5.3 Jy S2.7mm Flux density at 2.7mm, within 22" aperture
45- 48 F4.2 Jy e_S2.7mm ? rms uncertainty on S2.7mm
50- 53 I4 solMass Mass Mass (2)
55- 57 I3 solMass e_Mass rms uncertainty on Mass
59- 63 F5.2 [cm-2] logNH ? Hydrogen column density (3)
65- 68 F4.2 [cm-2] e_logNH ? rms uncertainty on logNH
70- 72 I3 --- AV [52/144]? Extinction in V band, in magnitudes,
AV=NH/(4*1021) (4)
74- 77 F4.1 mag AK ? Extinction in K band, AK=0.112*AV (4)
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Note (1): Clumps are identified as [HCW2000] IRAS 18317-0757 SMM N in Simbad.
"Total" represents the total flux including extended emission within
dotted region of Fig.2.
Note (2): Mass, Assuming T=25K and grain emissivity Q=1.0x10-4 at 350um
(Hildebrand, 1983QJRAS..24..267H 1983QJRAS..24..267H)
Note (3): Hydrogen column density Assuming uniform emission of diameter 11"
(0.25pc).
Note (4): Extinction to a star at the center of the dust core, i.e.,
half the column density, reduced by a factor of 2 to more accurately
estimate the extinction toward a young star at the center of the
clump, rather than behind it.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- C18O Sequential number, [HZS2004] C18O NN
4- 5 I2 h RAh Right ascension (J2000.0)
7- 8 I2 min RAm Right ascension (J2000.0)
10- 15 F6.3 s RAs Right ascension (J2000.0)
17 A1 --- DE- Declination sign (J2000.0)
18- 19 I2 deg DEd Declination (J2000.0)
21- 22 I2 arcmin DEm Declination (J2000.0)
24- 28 F5.2 arcsec DEs Declination (J2000.0)
30- 33 F4.1 Jy.km/s Emi Emission
35- 39 F5.2 [cm-2] logN(C18O) C18O column density
41- 44 F4.1 mag AK Extinction in K band
46- 48 I3 solMass MH2 H2 mass
50- 53 F4.1 km/s Vel Velocity
55- 57 F3.1 km/s e_Vel rms uncertainty on Vel
59- 61 F3.1 Jy PFlux Peak flux, in Jy/beam
63- 65 F3.1 Jy e_PFlux rms uncertainty on PFlux, in Jy/beam
67- 69 F3.1 km/s Width Line width
71- 73 F3.1 km/s e_Width rms uncertainty on Width
75- 77 I3 solMass Mvirial Virial mass (1)
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Note (1):
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Emission MH2 Mvirial
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Total clump component 352 2930 2915
Extended component 527 4410
Total emission 879 7340
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Star Star number given in Figure 12 and 13,
[HZS2004] Star NNN
5 A1 --- f_Star [a] Flag on Star (1)
7- 22 A16 --- 2MASS The 2MASS PSC name
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Note (1): a: Stars with AV>10, according to the color-color diagram
shown in Figure 12.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 02-Jul-2004