J/A+A/566/A45 Orion optical-depth and column-density maps (Lombardi+, 2014)
Herschel-Planck dust optical-depth and column-density maps.
I. Method description and results for Orion.
Lombardi M., Bouy H., Alves J., Lada C.J.
<Astron. Astrophys., 566, A45 (2014)>
=2014A&A...566A..45L 2014A&A...566A..45L
ADC_Keywords: Molecular clouds ; Extinction
Keywords: ISM: clouds - dust, extinction - ISM: structure -
ISM: individual: Orion molecular cloud
Abstract:
We present high-resolution, high dynamic range column-density and
color-temperature maps of the Orion complex using a combination of
Planck dust-emission maps, Herschel dust-emission maps, and 2MASS NIR
dust-extinction maps. The column-density maps combine the robustness
of the 2MASS NIR extinction maps with the resolution and coverage of
the Herschel and Planck dust-emission maps and constitute the highest
dynamic range column-density maps ever constructed for the entire
Orion complex, covering 0.01mag<AK<30mag, or
2x1020cm-2<N<5x1023cm-2. We determined the ratio of the
2.2µm extinction coefficient to the 850µm opacity and found that
the values obtained for both Orion A and B are significantly lower
than the predictions of standard dust models, but agree with newer
models that incorporate icy silicate-graphite conglomerates for the
grain population. We show that the cloud projected probability
distribution function, over a large range of column densities, can be
well fitted by a simple power law. Moreover, we considered the local
Schmidt-law for star formation, and confirm earlier results, showing
that the protostar surface density Σ* follows a simple law
Σ*∝Σgasβ, with β∼2.
Description:
Combination of Herschel and Planck optical depth and color-temperature
maps for the entire Orion complex. The resolution is 36" for the areas
covered by Herschel, and 5' for the remaning areas where the Planck
dust model has been used (Planck Collaboration, 2014A&A...571A..11P 2014A&A...571A..11P).
The results are combined in a multi-plane FITS file, with the
following structure:
PLANE1 = 'Opacity map at 353 GHz'
PLANE2 = 'Error on opacity map at 353 GHz'
PLANE3 = 'Color temperature [K]'
PLANE4 = 'Error on color temperature [K]'
PLANE5 = 'Modified black-body exponent (Planck)'
PLANE6 = 'Error on modified black-body exponent'
PLANE7 = 'Total chi-square'
Objects:
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RA (2000) DE Designation(s)
--------------------------------------------------------
05 35 17.3 -05 23 28 Orion A = M42
05 41 42.7 -01 54 44 Orion B = NAME Flame Nebula
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 193 1 Description of FITS file
maps.fits 2880 83442 FITS file with 7 images (planck_herschel.fit)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- --- [G]
2- 10 F9.5 deg GLON Galactic longitude
11- 19 F9.5 deg GLAT Galactic latitude
21- 22 I2 arcsec/pix Scale [15] Scale of the image
24- 27 I4 --- Nx [3444] Number of pixels along X-axis
29- 32 I4 --- Ny [2492] Number of pixels along Y-axis
34 I1 --- Nz [7] Number of images (1)
36- 41 I6 Kibyte size [234683] Size of the FITS file
43- 62 A20 --- FileName Name of the FITS file
64-193 A130 --- Title Title of the images of the FITS file
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Note (1): the 7 planes correspond to
PLANE#1 = Opacity map at 353 GHz
PLANE#2 = Error on opacity map at 353 GHz
PLANE#3 = Color temperature [K]
PLANE#4 = Error on color temperature [K]
PLANE#5 = Modified black-body exponent (Planck)
PLANE#6 = Error on modified black-body exponent
PLANE#7 = Total chi-square
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Acknowledgements:
Marco Lombardi, marco.lombardi(at)unimi.it
(End) Patricia Vannier [CDS] 17-Apr-2015