J/ApJ/651/L125 Water masers associated with IR dark cloud cores (Wang+, 2006)
Water masers associated with infrared dark cloud cores.
Wang Y., Zhang Q., Rathborne J.M., Jackson J., Wu Y.
<Astrophys. J., 651, L125-L128 (2006)>
=2006ApJ...651L.125W 2006ApJ...651L.125W
ADC_Keywords: Molecular clouds ; Masers
Keywords: ISM: clouds - ISM: kinematics and dynamics - stars: formation
Abstract:
We present a survey of the 616-523 H2O maser transition toward a
sample of 140 compact cores in infrared dark clouds using the Very
Large Array. Strong (>1Jy) H2O maser emission was found associated
with 17 cores, indicative of star formation in these cores. We infer
that the cores with H2O masers have embedded protostars. Cores
associated with maser emission have masses of 12 to 2x103M☉,
similar to the mass range in the entire sample. The H2O maser
detection rate (12%) toward the compact, cold cores is much lower than
that toward high-mass protostellar objects and ultracompact H ii
regions. The detection rate of H2O masers is significantly higher
for higher mass cores than for lower mass cores. We suggest that some
of the most massive infrared dark cloud cores without H2O maser
emission are at an evolutionary stage earlier than the protostellar
phases. They are prime candidates for high-mass starless cores.
Description:
We observed a sample of 140 compact, cold cores in the H2O maser
616-523 line at 22.235GHz with the VLA of the National Radio
Astronomy Observatory (NRAO) in its C configuration. The observations
were carried out during two tracks on 2005 September 21 and 22.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 133 139 Properties of the MSXDC cores and water maser
emission
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See also:
J/ApJ/639/227 : MSX IRDC candidate catalog (Simon+, 2006)
J/ApJ/641/389 : Properties of IRDC cores (Rathborne+, 2006)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [MSXDC]
7- 19 A13 --- MSXDC Infrared Dark Cloud identification,
GLLL.ll-BB.bbb
21- 24 A4 --- Core Compact core identification, MMNN (1)
26- 27 I2 h RAh Compact core Hour of Right Ascension (J2000)
29- 30 I2 min RAm Compact core Minute of Right Ascension (J2000)
32- 35 F4.1 s RAs Compact core Second of Right Ascension (J2000)
37 A1 --- DE- Sign of the Compact core Declination (J2000)
38- 39 I2 deg DEd Compact core Degree of Declination (J2000)
41- 42 I2 arcmin DEm Compact core Arcminute of Declination (J2000)
44- 45 I2 arcsec DEs Compact core Arcsecond of Declination (J2000)
47- 50 I4 mJy P1.2C Compact core 1.2mm peak flux
52- 55 F4.2 Jy I1.2C Compact core 1.2mm Integrated flux
57- 61 F5.1 km/s VLSRC Cloud local standard of rest velocity
63- 64 I2 h RAMh ? Water Maser Hour of Right Ascension (J2000)
66- 67 I2 min RAMm ? Water Maser minute of Right Ascension (J2000)
69- 74 F6.3 s RAMs ? Water Maser second of Right Ascension (J2000)
76 A1 --- DEM- Sign of the Water Maser Declination (J2000)
77- 78 I2 deg DEMd ? Water Maser Degree of Declination (J2000)
80- 81 I2 arcmin DEMm ? Water Maser arcmin of Declination (J2000)
83- 87 F5.2 arcsec DEMs ? Water Maser arcsec of Declination (J2000)
89- 95 F7.2 Jy P1.2W ? Water Maser Peak flux (2)
97-101 F5.1 km/s VelW ? Water Maser velocity
103-133 A31 km/s TVelM Total Water Maser velocity range
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Note (1): Includes the compact cores obtained by the 1.2mm continuum
observations toward 38 MSXDCs (Rathborne et al., 2006,
Cat. J/ApJ/641/389, [RJS2006]).
Sources identified as [RJS2006] MSXDC GLLL.ll+BB.bb MMNN in Simbad
In original table, MSXDC G015.05-00.07 is a misprint for
MSXDC G015.05+00.07
Note (2): The detection limit is ∼1Jy.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 22-Jul-2008