J/A+A/664/A88 LOFAR 148MHz Cygnus X region image (Emig+, 2022)
Filamentary structures of ionized gas in Cygnus X.
Emig K.L., White G.J., Salas P., Karim R.L., van Weeren R.J., Teuben P.J.,
Zavagno A., Chiu P., Haverkorn M., Oonk J.B.R., Orru E., Polderman I.M.,
Reich W., Roettgering H.J.A., Tielens A.G.G.M.
<Astron. Astrophys. 664, A88 (2022)>
=2022A&A...664A..88E 2022A&A...664A..88E (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Associations, stellar ; H II regions ; Radio sources
Keywords: radio continuum: ISM - H II regions - ISM: general -
Galaxy: open clusters and associations: individual: Cygnus OB2 -
techniques: image processing
Abstract:
Ionized gas probes the influence of massive stars on their
environment. The Cygnus X region (d∼1.5kpc) is one of the most massive
star forming complexes in our Galaxy, in which the Cyg OB2 association
(age of 3-5Myr and stellar mass 2x104M☉) has a dominant
influence.
We observe the Cygnus X region at 148 MHz using the Low Frequency
Array (LOFAR) and take into account short-spacing information during
image deconvolution. Together with data from the Canadian Galactic
Plane Survey, we investigate the morphology, distribution, and
physical conditions of low-density ionized gas in a 4'x4'
(∼100pcx100pc) region at a resolution of 2' (0.9pc).
The Galactic radio emission in the region analyzed is almost entirely
thermal (free-free) at 148 MHz, with emission measures (EM) of
103<EM[pc/cm6]<106. As filamentary structure is a prominent
feature of the emission, we use DisPerSE and FilChaP to identify
filamentary ridges and characterize their radial (EM) profiles.
The distribution of radial profiles has a characteristic width of
4.3pc and a power-law distribution (β=-1.8±0.1) in peak EM down
to our completeness limit of 4200pc/cm6. The electron densities of
the filamentary structure range between 10≤ne[cm-3]≤400 with a
median value of 35cm-3, remarkably similar to [NII] surveys of
ionized gas.
Cyg OB2 may ionize at most two-thirds of the total ionized gas and the
ionized gas in filaments. More than half of the filamentary structures
are likely photoevaporating surfaces flowing into a surrounding
diffuse (5cm-3) medium. However, this is likely not the case for all
ionized gas ridges. A characteristic width in the distribution of
ionized gas points to the stellar winds of Cyg OB2 creating a fraction
of the ionized filaments through swept-up ionized gas or dissipated
turbulence.
Description:
LOFAR interferometric observations of one pointing centered
approximately on the massive star forming region DR 21 at
(RA, dec) = (309.5500°, +42.0708°) in J2000 coordinates. These
data were obtained with the high band antennas (HBA) covering
110-190MHz on July 19, 2013 under project LC0_032 (PI: G. White).
Continuous frequency coverage was obtained between 126-165MHz and
which we make use of in this analysis. 23 stations of the full Dutch
array recorded data during these observations, which have a maximum
baseline of 120km (4") and minimum baseline lengths of 70m
corresponding to largest angular scales of 96' (1.6°). The
on-source integration time is 6 hours and 50 minutes.
Objects:
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RA (2000) DE Designation(s)
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20 28 41 +41 10.2 Cygnus X = NAME Cyg X
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 150 1 Information of fits image
fits/* . 1 Fits image
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See also:
J/A+A/241/551 : Radio continuum in Cygnus X region (Wendker+ 1991)
J/A+A/375/539 : Compact HII regions in Cyg X JHK photometry (Comeron+, 2001)
J/ApJ/643/238 : Chandra/2MASS sources in Cygnus OB2 (Butt+, 2006)
J/A+A/474/495 : X-ray flares from Cygnus OB2 young stars
(Albacete Colombo+, 2007)
J/A+A/476/1243 : Millimeter continuum mapping of Cygnus X (Motte+, 2007)
J/ApJS/184/84 : X-ray sources in Cyg OB2 region (Wright+, 2009)
J/ApJ/713/871 : Sources in star-forming region Cyg-OB2 from X-ray
(Wright+, 2010)
J/A+A/527/A135 : Gas dynamics in Massive Dense Cores in Cygnus-X
(Csengeri+, 2011)
J/ApJ/727/114 : BLAST 2005: a 10deg2 survey in Cygnus X (Roy+, 2011)
J/A+A/570/A1 : Cygnus-X CO and SiO outflows datacubes
(Duarte-Cabral+, 2014)
J/AJ/148/11 : Infrared photometry in Cygnus-X (Kryukova+, 2014)
J/MNRAS/458/3027 : Young and embedded clusters in Cygnus-X (Maia+, 2016)
J/ApJS/234/8 : YSO jets from UWISH2. IV. Cygnus-X outflows (Makin+, 2018)
J/ApJ/883/156 : Nobeyama 45m Cygnus-X CO. II. C180 clumps (Takekoshi+, 2019)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [G]
2- 10 F9.5 deg GLON Galactic longitude
11- 19 F9.5 deg GLAT Galactic latitude
21- 23 I3 --- Nx Number of pixels along X-axis
25- 27 I3 --- Ny Number of pixels along Y-axis
29- 50 A22 "datime" Obs.date Observation date
52- 58 F7.3 MHz Freq [148.046] Observed frequency
60- 63 I4 Kibyte size Size of FITS file
65-101 A37 --- FileName Name of FITS file, in subdirectory fits
103-150 A48 --- Title Title of the FITS file
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Acknowledgements:
Kimberly L. Emig, kemig(at)nrao.edu
(End) Patricia Vannier [CDS] 03-Jun-2022