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 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:
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RA (2000) DE Designation(s)
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17 30 -25.0 Pipe nebula = NAME PIPE Nebula
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File Summary:
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FileName Lrecl Records Explanations
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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 32 4143 Pipe 2 spectrum
pipe6.dat 32 4156 Pipe 6 spectrum
pipe7.dat 32 4144 Pipe 7 spectrum
pipe8.dat 32 4144 Pipe 8 spectrum
pipe14.dat 32 4143 Pipe 14 spectrum
pipe15.dat 32 4143 Pipe 15 spectrum
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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
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Bytes Format Units Label Explanations
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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
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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 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 2009ApJS..185..289R)
Note (4): obtained by comparing SED with stellar model by
Bressan et al. (2012MNRAS.427..127B 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.
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Byte-by-byte Description of file: pipe*.dat
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Bytes Format Units Label Explanations
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8- 16 F9.7 um lambda Wavelength
19- 33 E15.11 --- tau Optical depth
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Acknowledgements:
Miwa Goto, mgoto(at)usm.lmu.de
(End) Miwa Goto [USM, Germany], Patricia Vannier [CDS] 12-Dec-2017