J/MNRAS/443/3218 NGC 7538 IRS 1-3 and IRS 9 sources (Mallick+, 2014)
NGC 7538: multiwavelength study of stellar cluster regions associated with
IRS 1-3 and IRS 9 sources.
Mallick K.K., Ojha D.K., Tamura M., Pandey A.K., Dib S., Ghosh S.K.,
Sunada K., Zinchenko I., Pirogov L., Tsujimoto M.
<Mon. Not. R. Astron. Soc., 443, 3218-3237 (2014)>
=2014MNRAS.443.3218M 2014MNRAS.443.3218M (SIMBAD/NED BibCode)
ADC_Keywords: Infrared sources ; X-ray sources ; Photometry, infrared
Keywords: stars: luminosity function, mass function -
ISM: individual objects: NGC 7538 - ISM: molecules - infrared: ISM -
radio continuum: ISM - X-rays: stars
Abstract:
We present deep and high-resolution (FWHM∼0.4-arcsec) near-infrared
(NIR) imaging observations of the NGC 7538 IRS 1-3 region (in
JHK bands), and IRS 9 region (in HK bands) using the 8.2m
Subaru telescope. The NIR analysis is complemented with Giant
Metrewave Radio Telescope (GMRT) low-frequency observations at 325,
610, and 1280MHz, molecular line observations of H13CO+ (J=1-0),
and archival Chandra X-ray observations. Using the 'J-H/H-K' diagram,
144 Class II and 24 Class I young stellar object (YSO) candidates are
identified in the IRS 1-3 region. Further analysis using 'K/H-K'
diagram yields 145 and 96 red sources in the IRS 1-3 and IRS 9
regions, respectively. A total of 27 sources are found to have X-ray
counterparts. The YSO mass function (MF), constructed using a
theoretical mass-luminosity relation, shows peaks at substellar
(∼0.08-0.18M☉) and intermediate (∼1-1.78M☉) mass ranges
for the IRS 1-3 region. The MF can be fitted by a power law in the
low-mass regime with a slope of Γ ∼0.54-0.75, which is much
shallower than the Salpeter value of 1.35. An upper limit of 10.2 is
obtained for the star to brown dwarf ratio in the IRS 1-3 region. GMRT
maps show a compact HII region associated with the IRS 1-3 sources,
whose spectral index of 0.87±0.11 suggests optical thickness. This
compact region is resolved into three separate peaks in higher
resolution 1280MHz map, and the 'east' subpeak coincides with the
IRS 2 source. H13CO+ (J=1-0) emission reveals peaks in both IRS 1-3
and IRS 9 regions, none of which are coincident with visible nebular
emission, suggesting the presence of dense cloud nearby. The virial
masses are approximately of the order of 1000 and 500M☉ for the
clumps in IRS 1-3 and IRS 9 regions, respectively.
Description:
Deep NIR imaging observations of the NGC 7538 IRS 1-3 region (centred
on RA2000=23:13:43, DE2000=+61:28:22) in J (λ=1.25um),
H (λ=1.64um), and K (λ=2.21um) bands, and the NGC 7538
IRS 9 region (centred on RA2000=23:13:58, DE2000=+61:27:26) in H
and K bands were obtained on 2005 August 19, using the Cooled Infrared
Spectrograph and Camera for OHS (CISCO) mounted at the Cassegrain
focus of the 8.2m Subaru telescope.
Radio continuum observations were carried out using the Giant
Metrewave Radio Telescope (GMRT) for the frequency bands 325MHz (2004
July 03), 610MHz (2004 September 18), and 1280MHz (2004 January 25).
The H13CO+ (J=1-0) (formylium) molecular line (86.754GHz)
observations were carried out on 2004 May 02 with the Nobeyama 45m
radio telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 110 27 X-ray sources with NIR counterparts in the NIR FoV
table4.dat 88 564 YSOs in IRS 1-3 FoV
table5.dat 88 95 YSOs in IRS 9 FoV
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See also:
J/ApJ/696/471 : MIR spectroscopy of NGC 7538 IRS 1 (Knez+, 2009)
J/A+A/543/A88 : NGC 7538 IRS1 and NGC 7538S 1.36mm maps (Beuther+, 2012)
J/A+A/558/A81 : NGC 7538 IRS1 maps in CH3OH, HCN and HCO+ (Beuther+, 2013)
J/A+A/567/A116 : Maps and datacubes of NGC 7538 IRS 1 (Frau+, 2014)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- XName IAU designation (HHMMSS.ss+DDMMSS.s, J2000)
20- 29 F10.6 deg RAdeg Right ascension (J2000)
31- 39 F9.6 deg DEdeg Declination (J2000)
41- 44 F4.1 ct Nct [3.8/88] Net counts extracted (0.5-8keV)
46- 48 F3.1 keV Emed [1.9/5] Background-corrected median photon
energy (total band)
50- 55 F6.3 [cm-2] logNHs [21.2/23.2] H column density calculated
using XSPEC
57- 61 F5.3 keV kT1 [0.5/9.6] Plasma temperature calculated
using XSPEC
63- 68 F6.3 [10-7W] logLh1 Apparent hard band luminosity
70- 75 F6.3 [10-7W] logLt1 Apparent total band luminosity
77- 82 F6.3 [10-7W] logLhc1 Intrinsic hard band luminosity
84- 89 F6.3 [10-7W] logLtc1 Intrinsic total band luminosity
91- 96 F6.3 [10-7W] logLhc2 ? Intrinsic hard band luminosity
calculated using Xphot
98-103 F6.3 [10-7W] logLtc2 ? Intrinsic total band luminosity
calculated using Xphot
105-110 F6.3 [cm-2] logNHp [21.1/23.5]? H column density calculated
using Xphot
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Byte-by-byte Description of file: table4.dat table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.6 deg RAdeg Right ascension (J2000)
12- 20 F9.6 deg DEdeg Declination (J2000)
22- 27 F6.3 mag Jmag ?=- J magnitude (only in table4)
29- 33 F5.3 mag e_Jmag ? rms uncertainty on Jmag (for IRS 1-3 field)
35- 40 F6.3 mag Hmag ?=- H magnitude
42- 46 F5.3 mag e_Hmag ? rms uncertainty on Hmag
48- 53 F6.3 mag Kmag ?=- K magnitude
55- 59 F5.3 mag e_Kmag ? rms uncertainty on Kmag
61- 68 A8 --- YSO YSO classification (for IRS 1-3 field)
71- 88 A18 -- XName X-ray IAU designation (HHMMSS.ss+DDMMSS.s)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 20-Apr-2015