J/ApJ/836/199 IRDC G028.23-00.19 NIR polarimetry analysis (Hoq+, 2017)
Tracing the magnetic field of IRDC G028.23-00.19 using NIR polarimetry.
Hoq S., Clemens D.P., Guzman A.E., Cashman L.R.
<Astrophys. J., 836, 199-199 (2017)>
=2017ApJ...836..199H 2017ApJ...836..199H (SIMBAD/NED BibCode)
ADC_Keywords: Polarization ; Photometry, infrared ; Velocity dispersion ;
Magnetic fields ; Molecular clouds
Keywords: dust, extinction; ISM: clouds;
ISM: individual objects: SNR G028.23-00.19 ;
ISM: magnetic fields; stars: formation; techniques: polarimetric
Abstract:
The importance of the magnetic (B) field in the formation of infrared
dark clouds (IRDCs) and massive stars is an ongoing topic of
investigation. We studied the plane-of-sky B field for one IRDC,
G028.23-00.19, to understand the interaction between the field and the
cloud. We used near-IR background starlight polarimetry to probe the B
field and performed several observational tests to assess the field
importance. The polarimetric data, taken with the Mimir instrument,
consisted of H-band and K-band observations, totaling 17160 stellar
measurements. We traced the plane-of-sky B-field morphology with
respect to the sky-projected cloud elongation. We also found the
relationship between the estimated B-field strength and gas volume
density, and we computed estimates of the normalized mass-to-magnetic
flux ratio. The B-field orientation with respect to the cloud did not
show a preferred alignment, but it did exhibit a large-scale pattern.
The plane-of-sky B-field strengths ranged from 10 to 165µG, and the
B-field strength dependence on density followed a power law with an
index consistent with 2/3. The mass-to-magnetic flux ratio also
increased as a function of density. The relative orientations and
relationship between the B field and density imply that the B field
was not dynamically important in the formation of the IRDC. The
increase in mass-to-flux ratio as a function of density, though,
indicates a dynamically important B field. Therefore, it is unclear
whether the B field influenced the formation of G28.23. However, it is
likely that the presence of the IRDC changed the local B-field
morphology.
Description:
NIR polarimetric observations in both the H band (1.6um) and K band
(2.2um) of G28.23-00.19 were obtained using the Mimir instrument on
the 1.8m Perkins Telescope in Flagstaff, AZ.
The H-band data were taken from Data Release 2 of the Galactic Plane
Infrared Polarization Survey (GPIPS, Clemens+ 2012ApJS..200...19C 2012ApJS..200...19C).
Targeted K-band observations were obtained over five nights in 2013
September and 2014 June.
In addition to NIR polarimetry, we used NIR and mid-IR (MIR)
photometry from the 2MASS (Skrutskie+ 2006, VII/233), UKIRT Infrared
Deep Sky Survey (UKIDSS; see II/319), and GLIMPSE (see II/293)
catalogs, dust continuum data from the Herschel infrared Galactic
Plane Survey (Hi-GAL) (Molinari+ 2010PASP..122..314M 2010PASP..122..314M) and the APEX
Telescope Large Area Survey of the Galaxy (ATLASGAL) (Schuller+ 2009,
see J/A+A/549/A45), and molecular line data from the 13CO Galactic
Ring Survey (GRS; Jackson+ 2006ApJS..163..145J 2006ApJS..163..145J).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 148 17160 Stellar polarimetric properties of G28.23 field of
view
table2.dat 127 17160 Stellar photometric properties of G28.23 field of
view
table3.dat 68 121 Properties of the pixels in the B-field map
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See also:
II/226 : Stellar polarization catalogs agglomeration (Heiles, 2000)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
J/ApJ/641/389 : Millimetric observations of IRDC cores (Rathborne+, 2006)
J/ApJS/186/406 : 350um polarimetry from CSO (Dotson+, 2010)
J/ApJ/723/1019 : Galactic SFR and gas surface densities (Heiderman+, 2010)
J/ApJ/741/21 : Polarization of stars in Taurus (Chapman+, 2011)
J/ApJ/756/60 : A 3mm line survey in 37 IR dark clouds (Sanhueza+, 2012)
J/MNRAS/424/2442 : Catalog of bubbles from Milky Way Project (Simpson+, 2012)
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/ApJ/793/126 : L204 - Cloud 3 polarimetry and photometry (Cashman+, 2014)
J/ApJS/213/13 : 1.3mm polarization maps of star-forming cores (Hull+, 2014)
J/ApJ/815/130 : High-mass molecular clumps from MALT90 (Guzman+, 2015)
http://gpips0.bu.edu/Data_Release/ : GPIPS data releases
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq Polarimetric Catalog Star Number
7- 13 F7.4 deg GLON Galactic Longitude
15- 21 F7.4 deg GLAT Galactic latitude
23- 24 A2 --- fPos Band Match (1)
26- 32 F7.2 % Pk ?=9999 K-band Polarization Percent
34- 40 F7.2 % e_Pk ?=9999 Uncertainty in Pk
42- 47 F6.1 deg GPAk [63/243]?=9999 K-band Galactic Polarization
Position Angle
49- 54 F6.1 deg e_GPAk [1/178]?=9999 Uncertainty in GPAk
56- 62 F7.2 % Qk [-83/91]?=9999 K-band Stokes Q parameter
64- 70 F7.2 % e_Qk [0/100]?=9999 Uncertainty in Qk
72- 78 F7.2 % Uk [-96/96]?=9999 K-band Stokes U parameter
80- 86 F7.2 % e_Uk ?=9999 Uncertainty in Uk
88- 94 F7.2 % Ph ?=9999 H-band Polarization Percent
96-102 F7.2 % e_Ph ?=9999 Uncertainty in Ph
104-109 F6.1 deg GPAh [62/243]?=9999 H-band Galactic Polarization
Position Angle
111-116 F6.1 deg e_GPAh [0.8/179]?=9999 Uncertainty in GPAh
118-124 F7.2 % Qh [-100/100]?=9999 H-band Stokes Q parameter
126-132 F7.2 % e_Qh ?=9999 Uncertainty in Qh
134-140 F7.2 % Uh [-100/94]?=9999 H-band Stokes U parameter
142-148 F7.2 % e_Uh ?=9999 Uncertainty in Uh
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Note (1): Band Match as follows:
H = Entry only in H-pol (12554 occurrences),
K = Entry only in K-pol (1326 occurrences),
HK = Entries in both H and K-pol (3280 occurrences).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq Polarimetric Catalog Star Number
7- 29 A23 --- AName NIR source cross-match designation (1)
31- 36 F6.3 mag Jmag [6.4/21.6]?=99.99 J-Band magnitude in
NIR source catalog
38- 43 F6.3 mag e_Jmag [0.001/0.9]?=99.99 Uncertainty in Jmag
45- 50 F6.3 mag Hmag ?=99.99 H-Band magnitude in NIR source catalog
52- 56 F5.3 mag e_Hmag ?=99.99 Uncertainty in H-Band magnitude
58- 63 F6.3 mag Kmag [4.3/17.4]?=99.99 K-Band magnitude in
NIR source catalog
65- 69 F5.3 mag e_Kmag [0.001/0.3]?=99.99 Uncertainty in Kmag
71- 76 F6.3 mag [4.5]mag [6.5/14.6]?=99.99 GLIMPSE IRAC 4.5um magnitude
78- 83 F6.3 mag e_[4.5]mag [0.02/0.4]?=99.99 Uncertainty in [4.5]mag
85- 90 F6.3 mag (H-K) ?=99.99 H-K color index
92- 96 F5.3 mag e_(H-K) ?=99.99 Uncertainty in (H-K)
98-103 F6.3 mag (H-4.5) ?=99.99 H-4.5 color index
105-110 F6.3 mag e_(H-4.5) ?=99.99 Uncertainty in (H-4.5)
112-115 F4.1 mag Av [0/75] Extinction in V-Band
117-119 F3.1 mag e_Av [0/5] Uncertainty in V-Band Extinction
121-125 A5 --- Meth Color excess extinction method
("H-K": 4843 occurrences, or "H-4.5")
127-127 A1 --- RD Relative Distance classification (2)
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Note (1): NIR Designation from either 2MASS (JHHMMSSss+DDMMSSs) or UKIDSS
Galactic Plane Survey (UGPS) DR8 Catalogs. The UGPS identifiers are given
using the unique "sourceID" for that catalog.
Note (2): Relative locations of stars with respect to the cloud along the
line of sight. Code as follows:
B = Background Star (10597 occurrences);
F = Foreground Star (6255 occurrences);
U = Unknown (308 occurrences).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 7 F7.4 deg GLON Galactic Longitude of Pixel
9- 15 F7.4 deg GLAT Galactic Latitude of Pixel
17- 20 F4.1 deg PA [8/38]? Position Angle Dispersion
22- 25 F4.1 deg e_PA [1/18]? Uncertainty in PA
27- 30 I4 cm-3 n(H2) [0/1192]? Volume Density, H2 / cm3
32- 34 I3 cm-3 e_n(H2) [0/238]? Uncertainty in n(H2)
36- 39 F4.1 km/s sig(13CO) [1/15]? 13CO gas velocity dispersion
41- 44 F4.1 km/s e_sig(13CO) [0/19]? Uncertainty in sig(13CO)
46- 50 F5.1 10-10T BPOS [13/164]? plane-of-sky B-field strength,
in microGauss units
52- 55 F4.1 10-10T e_BPOS [3/43]? Uncertainty in BPOS
57- 60 F4.2 --- Mphip [0.09/7.6]? normalized Mass-to-Flux ratio
62- 65 F4.2 --- e_Mphip [0.03/2]? Uncertainty in Mphip
67- 68 A2 --- Lim Limits (1)
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Note (1): Indicates whether the PA dispersion (PA) or density (n) used to
calculate BPOS limited the BPOS calculation as follows:
PA = indicates the PA dispersion was greater than 25deg, but PA dispersion
minus its uncertainty was less than or equal to 25deg.
n = indicates that the volume density was less than 50∼H2/cm^3, but the
density plus its uncertainty was greater than or equal to 50∼H2/cm^3.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 06-Oct-2017