J/A+A/604/A32 Orion BN-KL ALMA view (Pagani+, 2017)
The complexity of Orion: an ALMA view. I. Data and first results.
Pagani L., Favre C., Goldsmith P.F., Bergin E.A., Snell R., Melnick G.
<Astron. Astrophys. 604, A32 (2017)>
=2017A&A...604A..32P 2017A&A...604A..32P (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interstellar medium
Keywords: ISM: clouds - ISM: structure -
ISM: individual objects : Orion-KL (except planetary nebulae) -
astrochemistry - molecular processes
Abstract:
We wish to improve our understanding of the Orion central star
formation region (Orion-KL) and disentangle its complexity.
We collected data with ALMA during cycle 2 in 16GHz of total
bandwidth spread between 215.1 and 252.0GHz with a typical
sensitivity of 5mJy/beam (2.3mJy/beam from 233.4 to 234.4GHz) and a
typical beam size of 1.7"x1.0" (average position angle of 89). We
produced a continuum map and studied the emission lines in nine
remarkable infrared spots in the region including the Hot Core and the
Compact Ridge, plus the recently discovered Ethylene Glycol Peak.
We present the data, and report the detection of several species not
previously seen in Orion, including n- and i-propyl cyanide
(C3H7CN), and the tentative detection of a number of other species
including glycolaldehyde (CH2(OH)CHO). The first detections of gGg'
ethylene glycol (gGg' (CH2OH)2) and of acetic acid (CH3COOH) in
Orion are presented in a companion paper. We also report the possible
detection of several vibrationally excited states of cyanoacetylene
(HC3N), and of its 13C isotopologues. We were not able to detect
the 16O18O line predicted by our detection of O2 with Herschel,
due to blending with a nearby line of vibrationally excited ethyl
cyanide. We do not confirm the tentative detection of hexatriynyl
(C6H) and cyanohexatriyne (HC7N) reported previously, or of
hydrogen peroxide (H2O2) emission.
We report a complex velocity structure only partially revealed before.
Components as extreme as -7 and +19km/s are detected inside the hot
region. Thanks to different opacities of various velocity components,
in some cases we can position these components along the line of
sight. We propose that the systematically redshifted and blueshifted
wings of several species observed in the northern part of the region
are linked to the explosion that occurred ∼500 years ago. The compact
ridge, noticeably farther south displays extremely narrow lines
(∼1km/s) revealing a quiescent region that has not been acted by this
explosion. This probably indicates that the compact ridge is either
over 10,000 au in front of or behind the rest of the region.
Many lines remain unidentified, and only a detailed modeling of all
known species, including vibrational states of isotopologues combined
with the detailed spatial analysis offered by ALMA enriched with
zero-spacing data, will allow new species to be detected.
Description:
The observations were performed on 29 December 2014 with 37 antennas
for the first four scheduling blocks and on 30 December 2014 for the
last block with 39 antennas
Objects:
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RA (2000) DE Designation(s)
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05 35 14.16 -05 22 21.5 Orion BN-KL = NAME Orion BN/KL
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 90 16 Frequency bands and beam parameters
list.dat 105 16 List of datacubes
fits/* . 16 Individual datacubes
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See also:
J/AJ/120/1426 : Chandra sources in ONC + BN-KL (Garmire+, 2000)
J/A+A/579/A130 : Near-IR BN/KL outflow images (Bally+, 2015)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Band [1/16] Band sequential number
4 I1 --- Window Window (spw)
5 A1 --- n_Window [d] Note on Window (1)
7- 9 A3 --- Block Block (sg) (2)
11- 20 F10.3 MHz bFreq Lower value of frequency range (3)
22- 31 F10.3 MHz BFreq Upper value of frequency range (3)
33- 35 F3.1 arcsec Beam1 Beam shape
36 A1 --- --- [x]
37- 39 F3.1 arcsec Beam2 Beam shape
41- 43 I3 deg PA Position angle
45- 47 F3.1 mJy/beam Noise in mJy/beam (4)
49- 52 F4.1 K/Jy Conv Conversion factor
54- 56 I3 mK Noise2 Noise in mK (4)
58- 90 A33 --- FileName Name of the fits file in subdirectory fits
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Note (1): d: A last minute change of frequency introduced an error in setting
the bands creating a hole from 216087MHz to 216342MHz and an overlap from
219784 to 220064MHz.
Note (2): Observing block: all frequency windows with the same observing block
number have been observed simultaneously
Note (3): the frequency range is given for Vlsr=9km/s.
Note (4): Noise is not corrected for primary beam coupling and is therefore a
lower limit to the actual noise in each source. Corrections run from 1% (IRc7)
to 41% (MF10).
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 31 I4 --- Nz Number of pixels along Z-axis
33- 44 E12.6 m/s bVRAD Lower value of radial velocity interval
46- 56 E11.6 m/s BVRAD Upper value of radial velocity interval
58- 64 F7.3 m/s dVRAD Radial velocity resolution
66- 71 I6 Kibyte size Size of FITS file
73-105 A33 --- FileName Name of FITS file, in subdirectory fits
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Acknowledgements:
Laurent Pagani, laurent.pagani(at)obspm.fr
(End) Patricia Vannier [CDS] 23-May-2017