J/ApJ/832/187 ALMA and VLA radio continuum obs. of NGC 6334I (Brogan+, 2016)
The massive protostellar cluster NGC 6334I at 220au resolution: discovery of
further multiplicity, diversity, and a hot multi-core.
Brogan C.L., Hunter T.R., Cyganowski C.J., Chandler C.J., Friesen R.,
Indebetouw R.
<Astrophys. J., 832, 187 (2016)>
=2016ApJ...832..187B 2016ApJ...832..187B
ADC_Keywords: Interstellar medium; Masers; Radio continuum;
Millimetric/submm sources
Keywords: infrared: stars ; ISM: individual objects (NGC 6334I) ;
radio continuum: ISM ; stars: formation ; submillimeter: ISM
Abstract:
We present Very Large Array and Atacama Large Millimeter/submillimeter
Array imaging of the deeply embedded protostellar cluster NGC 6334I
from 5cm to 1.3mm at angular resolutions as fine as 0.17" (220au). The
dominant hot core MM1 is resolved into seven components at 1.3mm,
clustered within a radius of 1000au. Four of the components have
brightness temperatures >200K, radii ∼300au, minimum luminosities
∼104L☉, and must be centrally heated. We term this new
phenomenon a "hot multi-core." Two of these objects also exhibit
compact free-free emission at longer wavelengths, consistent with a
hypercompact HII region (MM1B) and a jet (MM1D). The spatial
kinematics of the water maser emission centered on MM1D are consistent
with it being the origin of the high-velocity bipolar molecular
outflow seen in CO. The close proximity of MM1B and MM1D (440au)
suggests a proto-binary or a transient bound system. Several
components of MM1 exhibit steep millimeter spectral energy
distributions indicative of either unusual dust spectral properties or
time variability. In addition to resolving MM1 and the other hot core
(MM2) into multiple components, we detect five new millimeter and two
new centimeter sources. Water masers are detected for the first time
toward MM4A, confirming its membership in the protocluster. With a
1.3mm brightness temperature of 97K coupled with a lack of thermal
molecular line emission, MM4A appears to be a highly optically thick
240L☉ dust core, possibly tracing a transient stage of massive
protostellar evolution. The nature of the strongest water maser source
CM2 remains unclear due to its combination of non-thermal radio
continuum and lack of dust emission.
Description:
We observed NGC 6334I using the VLA at three wavelengths: 5cm (on 2011
Jul 7), 1.5cm (on 2011 May 29), and 7mm (on 2011 Feb 12, Mar 25 and
May 20). We also observed this source using ALMA in Cycle 2 at 3mm (on
2015 Aug 11) and 1.3mm (2015 Aug 29).
Objects:
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RA (ICRS) DE Designation(s)
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17 20 53.35 -35 47 01.5 NGC 6334I = NAME NGC 6334-I
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 131 21 Fitted properties of the continuum emission
table3.dat 62 47 Fitted H2O maser properties
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See also:
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/A+A/316/102 : JHK Photometry in NGC 6334 (Tapia+, 1996)
J/A+AS/137/43 : OH/H2O masers database (Forster+, 1999)
J/A+A/440/121 : K magnitudes of OB stars in UCHIIs (Bik+, 2005)
J/AJ/131/1872 : Fourth VLBA calibrator survey: VCS4 (Petrov+, 2006)
J/A+A/466/989 : Hot ammonia from NGC6334I & NGC6334I(N) (Beuther+, 2007)
J/A+A/481/169 : ATCA 3mm obs. of NGC6334I & NGC6334I(N) (Beuther+, 2008)
J/A+A/490/213 : 1.4 and 3.4mm interferometry of W3 IRS5 (Rodon+, 2008)
J/ApJ/707/1 : Water and Methanol masers in NGC 6334I(N) (Brogan+, 2009)
J/other/PASA/26.454 : Precise positions of methanol masers (Caswell, 2009)
J/AJ/138/227 : Stellar clusters in NGC 6334 complex (Feigelson+, 2009)
J/ApJ/715/310 : Early stages of star formation in IRDC (Rathborne+, 2010)
J/A+A/515/A55 : NGC 6334-NGC 6357 complex (Russeil+, 2010)
J/A+A/538/A142 : OB stars in NGC 6334 and NGC 6357 (Russeil+, 2012)
J/ApJ/778/96 : Spitzer & NEWFIRM obs. of NGC 6334 (Willis+, 2013)
J/ApJ/783/130 : Plx of high mass star forming regions (Reid+, 2014)
J/ApJS/213/1 : The MSFRs Omnibus X-ray Catalog (MOXC) (Townsley+, 2014)
J/A+A/577/A30 : SDC335.579-0.292 6, 8, 23 & 25GHz images (Avison+, 2015)
J/A+A/588/A30 : Properties of cores in OMC 2/3 (Sadavoy+, 2016)
J/ApJ/851/L46 : CH3OCH2OH ALMA detection in NGC6334I (McGuire+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Name Continuum source designation
4- 9 A6 --- m_Name Component designation within Name
11 A1 --- f_Name [eg] Flag on Name (1)
13- 18 A6 --- Band Fitting band (1.3mm, 7mm or 5cm) (2)
20- 21 I2 h RAh [17] Hour of right ascension (J2000) (3)
23- 24 I2 min RAm [20] Minute of right ascension (J2000)
26- 31 F6.3 s RAs [51.8/53.9] Second of right ascension (J2000)
33 A1 --- DE- [-] Sign of declination (J2000) (3)
34- 35 I2 deg DEd [35] Degree of declination (J2000) (3)
37- 38 I2 arcmin DEm [46/47] Arcminute of declination (J2000)
40- 44 F5.2 arcsec DEs Arcsecond of declination (J2000)
46 A1 --- l_S5cm Limit flag on S5cm (4)
48- 51 F4.2 mJy S5cm [0.06/5] VLA 5cm flux density (5)
53- 56 F4.2 mJy e_S5cm [0.02/0.2]? Formal fitting S5cm uncertainty
for detected source
58 A1 --- l_S1.5cm Limit flag on S1.5cm (4)
60- 63 F4.2 mJy S1.5cm [0.1/2] VLA 1.5cm flux density
65- 68 F4.2 mJy e_S1.5cm [0.06/0.2]? S1.5cm uncertainty
for detected source
70 A1 --- l_S7mm Limit flag on S7mm (4)
72- 75 F4.2 mJy S7mm [0.1/5.6] VLA 7mm flux density
77- 80 F4.2 mJy e_S7mm [0.05/0.2]? Formal fitting S7mm uncertainty
for detected source
82 A1 --- l_S3mm Limit flag on S3mm (4)
84- 88 F5.1 mJy S3mm [1/840]? ALMA 3mm flux density (5)
90- 93 F4.1 mJy e_S3mm [0.1/14]? Formal fitting S3mm uncertainty
for detected source
94 A1 --- f_S3mm [c] c="confused" (angular resolution
insufficient to make an estimate)
96 A1 --- l_S1.3mm Limit flag on S1.3mm (4)
98-104 F7.1 mJy S1.3mm [6/10975] ALMA 1.3mm flux density (5)
106-108 I3 mJy e_S1.3mm [1/140]? Formal fitting S1.3mm uncertainty
for detected source
110 A1 --- l_Size1 Limit flag on Size (6)
112-115 F4.2 arcsec Size1 [0.1/1.1]? Size on axis 1
116 A1 --- --- [x]
117 A1 --- l_Size2 Limit flag on Size2 (6)
118-121 F4.2 arcsec Size2 [0.1/0.6]? Size on axis 2
122 A1 --- f_Size [f] Flag on Size (1)
124-127 F4.2 arcsec e_Size [0.02/0.1]? Size uncertainty (7)
129-131 I3 deg PA [5/180]? Position angle (8)
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Note (1): Flag as follows:
e = The total flux densities of sources with complex morphologies are the
integrated flux densities measured inside the 3σ contour level for
each wavelength. MM4-Total includes the emission from MM6.
The position is the location of the peak pixel at 1.3mm.
f = The fitted size at 1.3mm is 0.27"x0.21" (0.04") [+89°]: this size is
used to determine the MM1B 1.3mm Tbrightness in Section 4.1.
g = MM8 is confused with the extended emission from the UCHII region MM3 at
wavelengths longer than 1.3mm.
Note (2): Reported fitted position and size are from the wavelength given in
this column, which corresponds to the most reliable fit for that
source.
Note (3): Position uncertainties are better than 50mas.
Note (4): Upper limits are 3x the local rms.
Note (5): The ALMA 3 and 1.3mm images are shown in Figure 1 along with
the VLA 5cm contours.
Note (6): When a fitted size is <3σ, that axis has been set to < the
geometric mean of the synthesized beam of the fitting band.
Note (7): Uncertainty in fitted size is the larger of the uncertainties for
the two axes.
Note (8): The position angle uncertainties are of order 20°.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Assoc Name of the continuum source associated with
this maser
5- 6 I2 --- Seq [1/47] Spot number (by increasing declination)
8- 9 I2 h RAh [17] Hour of right ascension (J2000) (1)
11- 12 I2 min RAm [20] Minute of right ascension (J2000)
14- 19 F6.3 s RAs [53.1/53.5] Second of right ascension (J2000)
21 A1 --- DE- [-] Sign of declination (J2000) (1)
22- 23 I2 deg DEd [35] Degree of declination (J2000) (1)
25- 26 I2 arcmin DEm [46/47] Arcminute of declination (J2000)
28- 32 F5.2 arcsec DEs Arcsecond of declination (J2000)
34- 39 F6.2 Jy Flux [0.2/493] Flux density (1)
41- 44 F4.2 Jy e_Flux [0.02/3.7] Flux uncertainty
46- 50 F5.1 km/s VelPk [-38.5/13.5] Velocity peak
52- 56 F5.1 km/s VelMin [-42/13] Minimum velocity
58- 62 F5.1 km/s VelMax [-37.5/13.5] Maximum velocity
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Note (1): Fitted value in the channel of peak emission.
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History:
From electronic version of the journal
(End) Prepared by Emmanuelle Perret [CDS] 02-Oct-2018