J/ApJ/602/850 JHK' photometry near IRAS 18507+0121 (Shepherd+, 2004)
Discovery of a massive protostar near IRAS 18507+0121.
Shepherd D.S., Nurnberger D.E.A., Bronfman L.
<Astrophys. J., 602, 850-859 (2004)>
=2004ApJ...602..850S 2004ApJ...602..850S
ADC_Keywords: Radio sources ; H II regions ; Stars, pre-main sequence ;
Photometry, infrared
Keywords: H II regions - ISM: molecules - stars: formation -
stars: pre-main-sequence
Abstract:
We have observed the massive star-forming region IRAS 18507+0121 at
millimeter wavelengths in 3mm continuum emission, H13CO+ (J=1-0) and
SiO (v=0,J=2-1) line emission, and at near-infrared (NIR) wavelengths
between 1.2 and 2.1µm. Two compact molecular cores are detected:
one north and one south, separated by ∼40". The northern molecular
core contains a newly discovered, deeply embedded, B2 protostar
surrounded by several hundred solar masses of warm gas and dust,
G34.4+0.23 MM. Based on the presence of warm dust emission and the
lack of detection at NIR wavelengths, we suggest that G34.4+0.23 MM
may represent the relatively rare discovery of a massive protostar
(e.g., analogous to a low-mass "Class 0" protostar). The southern
molecular core is associated with an NIR cluster of young stars and an
ultracompact HII region, G34.4+0.23, with a central B0.5 star. The
fraction of NIR stars with excess infrared emission indicative of
circumstellar material is greater than 50%, which suggests an upper
limit on the age of the IRAS 18507+0121 star-forming region of 3Myr.
Description:
Simultaneous observations in the 3mm continuum band and H13CO+
(J=1-0) and SiO (v=0, J=2-1) lines were made with the Owens Valley
Radio Observatory (OVRO) array of six 10.4m telescopes on 1998 April
19 and 1998 May 17.
Broadband J, H, and K' (λc=1.25, 1.65, and 2.10µm,
respectively) observations were performed in 1999 May at the Las
Campanas 2.5m Du Pont Telescope using the facility NIR camera equipped
with a NICMOS 3256x256 HgCdTe array detector.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 57 146 Positions and JHK' photometry of all detected
sources
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [SNB2004] Source number (1)
5- 9 F5.1 arcsec DelX The X position offset (2)
11- 15 F5.1 arcsec DelY The Y position offset (2)
17- 18 I2 h RAh Hour of Right Ascension (J2000)
20- 21 I2 min RAm Minute of Right Ascension (J2000)
23- 27 F5.2 s RAs Second of Right Ascension (J2000)
29 A1 --- DE- Sign of the Declination (J2000)
30- 31 I2 deg DEd Degree of Declination (J2000)
33- 34 I2 arcmin DEm Arcminute of Declination (J2000)
36- 39 F4.1 arcsec DEs Arcsecond of Declination (J2000)
41- 44 F4.1 mag Jmag ? The J band magnitude (3)
46- 49 F4.1 mag Hmag ? The H band magnitude (3)
51 A1 --- l_K'mag Limit flag on K
52- 55 F4.1 mag K'mag ? The K' band magnitude (3)
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Note (1): Sources 54, 41, 43, 47, 49, 50, 53 and 55 are likely cluster members.
Note (2): Relative to the position of the brightest member of the cluster (54).
Note (3): Typical photometric errors are
σ(J)∼1.2±0.5 magnitudes
σ(H)∼1.4±0.6 magnitudes
σ(K')∼1.6±0.6 magnitudes
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 07-May-2004