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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 (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: ------------------------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------------------------ 05 35 14.16 -05 22 21.5 Orion BN-KL = NAME Orion BN/KL ------------------------------------------------------------ File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 90 16 Frequency bands and beam parameters list.dat 105 16 List of datacubes fits/* 0 16 Individual datacubes
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
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).
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
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
Acknowledgements: Laurent Pagani, laurent.pagani(at)
(End) Patricia Vannier [CDS] 23-May-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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