2002A&A...382..222M


Query : 2002A&A...382..222M

2002A&A...382..222M - Astronomy and Astrophysics, volume 382, 222-240 (2002/1-4)

Crystalline silicate dust around evolved stars. II. The crystalline silicate complexes.

MOLSTER F.J., WATERS L.B.F.M. and TIELENS A.G.G.M.

Abstract (from CDS):

This is the second paper in a series of three in which we present an exhaustive inventory of the solid state emission bands observed in a sample of 17 oxygen-rich dust shells surrounding evolved stars. The data were taken with the Short and Long Wavelength Spectrographs on board of the Infrared Space Observatory (ISO) and cover the 2 to 200µm wavelength range. Apart from the broad 10 and 18 µm bands that can be attributed to amorphous silicates, at least 49 narrow bands are found whose position and width indicate they can be attributed to crystalline silicates. Most of these emission bands are concentrated in well defined spectral regions (called complexes). We define 7 of these complexes; the 10, 18, 23, 28, 33, 40 and 60 micron complex. We derive average properties of the individual bands. Almost all of these bands were not known before ISO. Comparison with laboratory data suggests that both olivines (Mg2xFe(2–2x)SiO4) and pyroxenes (MgxFe(1–x)SiO3) are present, withxclose to 1, i.e. the minerals are very Mg-rich and Fe-poor. This composition is similar to that seen in disks surrounding young stars and in the solar system comet Hale-Bopp. A significant fraction of the emission bands cannot be identified with either olivines or pyroxenes. Possible other materials that may be the carriers of these unidentified bands are briefly discussed. There is a natural division into objects that show a disk-like geometry (strong crystalline silicate bands), and objects whose dust shell is characteristic of an outflow (weak crystalline silicate bands). In particular, stars with the 33.5µm olivine band stronger than about 25 percent over continuum are invariably disk sources. Likewise, the 60 µm region is dominated by crystalline silicates in the disk sources, while it is dominated by crystalline H2O ice in the outflow sources. We show that the disk and outflow sources have significant differences in the shape of the emission bands. This difference must be related to the composition or grain shapes of the dust particles. The incredible richness of the crystalline silicate spectra observed by ISO allows detailed studies of the mineralogy of these dust shells, and is the origin and history of the dust.

Abstract Copyright:

Journal keyword(s): infrared: stars - circumstellar matter - stars: AGB and post-AGB - mass loss - Planetary nebulae: general - dust, extinction

Simbad objects: 20

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Number of rows : 20
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 HD 44179 pA* 06 19 58.2185496 -10 38 14.706068 9.51 9.33 9.02     B9Ib/II 764 0
2 HD 45677 Be* 06 28 17.4219710352 -13 03 11.128860972 7.86 8.52 8.50 8.11 8.01 B2IV/V[e] 330 0
3 IRAS 09425-6040 C* 09 44 01.6707336168 -60 54 25.639144812     12.6 11.81   C 60 0
4 MR 22 PN 10 21 33.85920 -58 05 47.6628           A2Ie 101 0
5 HD 302821 sg* 10 23 19.4847405144 -59 32 04.566918624   10.59 9.17     A7Ie 81 1
6 HD 100546 Be* 11 33 25.4408872296 -70 11 41.241297948   6.71 6.30   6.64 A0VaekB8_lB 806 1
7 CPD-56 8032 PN 17 09 00.9291677740 -56 54 47.868280757 11.24 11.48 11.04 11.067   [WC11] 267 0
8 NGC 6302 PN 17 13 44.5 -37 06 11           O-rich 795 1
9 HD 161796 pA* 17 44 55.4694563472 +50 02 39.482823336 8.00 7.68 7.21 6.77 6.51 F3Ib 326 0
10 * 89 Her pA* 17 55 25.1883476136 +26 02 59.968457664 5.36 5.70 5.36 5.06 4.94 F2Ibp 410 0
11 NGC 6537 PN 18 05 13.104 -19 50 34.88     13.58     ~ 425 1
12 EM* MWC 922 Be* 18 21 16.0519243728 -13 01 25.511760192     13.80 13.65   B[e] 92 0
13 EM* MWC 300 Ae* 18 29 25.6913480400 -06 04 37.290320796 12.55 12.67 13.795     B1Ia+[e] 138 0
14 V* AC Her RV* 18 30 16.2373118976 +21 52 00.599340000 8.00 7.79 7.01     F4Ibp 339 0
15 OH 026.5+00.6 OH* 18 37 32.50920 -05 23 59.1936           O-rich 301 1
16 HD 179821 pA* 19 13 58.6082398776 +00 07 31.935181836 10.81 9.694 8.19     G4_0-Ia 239 0
17 PN Vy 2-2 PN 19 24 22.2390166933 +09 53 56.259102426   14.02 12.65 13.38   O-rich 260 0
18 IRC +10420 pA* 19 26 48.0979492536 +11 21 16.758531216   13.98 11.66     F8Ia+e 476 0
19 NML Cyg s*r 20 46 25.5392819088 +40 06 59.464289232           M7/8 506 0
20 V* V1610 Cyg pA* 21 02 18.27 +36 41 37.0           F5Iae 872 1

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