J/MNRAS/371/1744 Identification of nitride dust (Pitman+, 2006)
Challenging the identification of nitride dust in extreme carbon star spectra.
Pitman K.M., Speck A.K., Hofmeister A.M.
<Mon. Not. R. Astron. Soc., 371, 1744-1754 (2006)>
=2006MNRAS.371.1744P 2006MNRAS.371.1744P
ADC_Keywords: Interstellar medium ; Spectra, infrared
Keywords: methods: laboratory - techniques: spectroscopic - stars: carbon -
dust, extinction - infrared: general
Abstract:
Nitride dust is predicted to form in small amounts around carbon
stars, but the most likely candidate species such as aluminium nitride
(AlN) have not yet been detected. Recently, α-Si3N4 was
inferred to be the main carrier of the 8.5-12.5um absorption band(s)
of an extreme carbon star (AFGL 5625), based on comparison with
laboratory KBr dispersion spectra. However, this absorption band has
also been attributed to silicon carbide (SiC) and C3. To investigate
whether or not nitride dust has truly been detected and if it is
present in other extreme carbon stars, we (i) gathered new laboratory
infrared (IR) absorbance spectra from a suite of nitride compounds,
including Si3N4, using the thin film technique which provides
correct relative intensities of weak and strong peaks, and (ii)
compared these data to Infrared Space Observatory Short Wavelength
Spectrometer (ISO SWS) spectra of seven different extreme carbon stars
which also show broad absorption features around ∼11m.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tables1.dat 26 3154 Merged mid- and far-IR thin film absorbance spectra of
spectrally subtracted silicon nitride
(α-Si3N4)
tables2.dat 24 3154 *Calculated mass absorption coefficients for spectrally
subtracted silicon nitride (α-Si3N4)
tables3.dat 27 3122 Merged mid- and far- IR thin film absorbance spectra
of spectrally subtracted silicon nitride
(β-Si3N4)
tables4.dat 24 3122 *Calculated mass absorption coefficients for spectrally
subtracted silicon nitride (β-Si3N4)
tables5.dat 29 2412 Merged mid- and far-IR thin film absorbance spectra
of aluminium nitride (AlN)
tables6.dat 27 2495 *Calculated mass absorption coefficients for
aluminium nitride (AlN)
tables7.dat 26 2426 Merged mid- and far-IR thin film absorbance spectra
of magnesium nitride (Mg3N2)
tables8.dat 24 2426 *Calculated mass absorption coefficients for
magnesium nitride (Mg3N2)
tables9.dat 26 2444 Merged mid- and far-IR thin film absorbance spectra
of calcium nitride (Ca3N2)
tables10.dat 23 2444 *Calculated mass absorption coefficients for
calcium nitride (Ca3N2)
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Note on tables2.dat and tables4.dat: X-ray density: 3.170g/cm3, from
Yang et al., 1995, Ceram. Int., 21, 137.
Note on tables6.dat: X-ray density: 3.261g/cm3, from 1975, Natl. Bur. Stand.
(U.S.) Monogr. 25, 12, 5.
Note on tables8.dat: X-ray density: 2.709g/cm3, from 1985, Natl. Bur. Stand.
(U.S.) Monogr. 25, 21, 85.
Note on tables10.dat: using PCALC for orthorhombic Ca3N2 (Lide 2002).
For the cubic case, KABS can be calculated using the value of Laurent et al.
(1968, Rev. Chim. Miner., 5, 1019), given in Table 1.
X-ray density: 2.670g/cm3, from Laurent, 1968, Rev. Chim. Miner., 5, 1019.
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See also:
J/MNRAS/406/460 : IR laboratory absorbance spectra of olivine (Pitman+, 2010)
Byte-by-byte Description of file: tables[13579].dat
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Bytes Format Units Label Explanations
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5- 13 F9.4 cm-1 Freq Wavenumber
17- 29 F13.10 --- Abs Absorbance
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Byte-by-byte Description of file: tables[2468].dat tables10.dat
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Bytes Format Units Label Explanations
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5- 13 F9.4 cm-1 Freq Wavenumber
15- 27 F13.7 cm2/g mac Mass absorption coefficient
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-May-2007