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J/A+A/610/A9        Water ice spectra toward the Pipe Nebula       (Goto+, 2018)

The first frost in the Pipe Nebula. Goto M., Bailey J.D., Hocuk S., Caselli P., Esplugues G.B., Cazaux S., Spaans M. <Astron. Astrophys. 610, A9 (2018)> =2018A&A...610A...9G (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Infrared sources ; Spectra, millimetric/submm Keywords: astrochemistry - ISM: clouds - ISM: individual objects: the Pipe Nebula - ISM: molecules - infrared: ISM - solid state: volatile Abstract: Spectroscopic studies of ices in nearby star-forming regions indicate that ice mantles form on dust grains in two distinct steps, starting with polar ice formation (H2O rich) and switching to apolar ice (CO rich). We test how well the picture applies to more diffuse and quiescent clouds where the formation of the first layers of ice mantles can be witnessed. Medium-resolution near-infrared spectra are obtained toward background field stars behind the Pipe Nebula. The water ice absorption is positively detected at 3.0um in seven lines of sight out of 21 sources for which observed spectra are successfully reduced. The peak optical depth of the water ice is significantly lower than those in Taurus with the same AV. The source with the highest water-ice optical depth shows CO ice absorption at 4.7um as well. The fractional abundance of CO ice with respect to water ice is 16+7-6%, and about half as much as the values typically seen in low-mass star-forming regions. A small fractional abundance of CO ice is consistent with some of the existing simulations. Observations of CO2 ice in the early diffuse phase of a cloud play a decisive role in understanding the switching mechanism between polar and apolar ice formation. Description: Water ice spectra at 3.0um for seven sources obtained by SpeX spectrometer at the IRTF. Objects: ------------------------------------------------------- RA (2000) DE Designation(s) ------------------------------------------------------- 17 30 -25.0 Pipe nebula = NAME PIPE Nebula ------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 117 7 Summary of targets and optical depths of ices with spectra (extract of table1) pipe1.dat 33 4147 Pipe 1 spectrum pipe2.dat 33 4143 Pipe 2 spectrum pipe6.dat 33 4156 Pipe 6 spectrum pipe7.dat 33 4144 Pipe 7 spectrum pipe8.dat 33 4144 Pipe 8 spectrum pipe14.dat 33 4143 Pipe 14 spectrum pipe15.dat 33 4143 Pipe 15 spectrum
See also: J/ApJ/699/742 : Properties of cores in the Pipe Nebula (Rathborne+, 2009) J/ApJ/725/2232 : Deep NIR survey of the Pipe Nebula. II. (Roman-Zuniga+, 2010) Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 2 I2 --- ID ID number 4- 19 A16 --- 2MASS 2MASS designation (HHMMSSss+DDMMSSs) 21- 25 F5.3 mag Ksmag Ks magnitude 27- 33 A7 --- SpType Spectral type (from SpeX) 35- 39 F5.2 mag AVce Absorption in V band (CE) (1) 41- 44 F4.2 mag AKce Absorption in K band (CE) (2) 46- 49 F4.2 mag AKsx Absorption in K band (SpeX) (3) 51- 54 F4.2 mag AKsed ?=- Absorption in K band (SED) (4) 56- 59 F4.2 --- tau3.0 Peak optical depth of water ice at 3.0um 60 A1 --- --- [+] 61- 64 F4.2 --- E_tau3.0 1σ error on tau3.0 (upper value) 65 A1 --- --- [-] 66- 69 F4.2 --- e_tau3.0 1σ error on tau3.0 (lower value) 71- 74 F4.2 10+17cm-2 N(H2O) H2O column density 75 A1 --- --- [+] 76- 79 F4.2 10+17cm-2 E_N(H2O) Error on N(H2O) (upper value) 80 A1 --- --- [-] 81- 84 F4.2 10+17cm-2 e_N(H2O) Error on N(H2O) (lower value) 86 A1 --- l_tau4.7 Limit flag on tau4.7 (3σ) 87- 90 F4.2 --- tau4.7 Peak optical depth of water ice at 4.7um 92- 95 F4.2 --- e_tau4.7 ? 1σ rms uncertainty on tau4.7 97 A1 --- l_N(CO) Limit flag on N(CO) (3σ) 98-101 F4.1 10+16cm-2 N(CO) CO ice column density (5) 103-105 F3.1 10+16cm-2 e_N(CO) ? rms uncertainty on N(CO) 106 A1 --- n_N(CO) [b] Note on N(CO) (6) 108-117 A10 --- FileName Name of the file with spectrum
Note (1): by Roman-Zuniga et al. (2010, Cat. J/ApJ/725/2232) with color excess technique. Note (2): calculated by multiplying AV by the factor 0.112 (Rieke & Lebofsky, 1985ApJ...288..618R). Note (3): obtained by comparing the observed SpeX spectra with the templates spectra of IRTF Spectral Library (Rayner et al., 2009ApJS..185..289R) Note (4): obtained by comparing SED with stellar model by Bressan et al. (2012MNRAS.427..127B). Note (5): The CO ice spectra at 4.7um are obtained by NIRSPEC at Keck II telescope for the sources in which the water ice is positively detected (#2, 6, 15, 1, 8, 7, 14). Other upper limits are based on SpeX/IRTF observations. Note (6): Broad absorption solution without the short-wavelength shoulder 4.655-4.665um included in the continuum (see Sect. 2.2.3). If the shoulder is counted as a continuum, the column density is reduced to N(CO)=(6.4±3.3)x1016cm-2.
Byte-by-byte Description of file: pipe*.dat
Bytes Format Units Label Explanations
8- 16 F9.7 um lambda Wavelength 19- 33 E15.11 --- tau Optical depth
Acknowledgements: Miwa Goto, mgoto(at)usm.lmu.de
(End) Miwa Goto [USM, Germany], Patricia Vannier [CDS] 12-Dec-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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