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Observational Evidence for Grain Growth
Meeus, Gwendolyn
Discs around young stars are the sites of planet formation. The first step in this process is the growth of submicron grains to larger sized grains. I will review evidence for dust growth in CS discs, based on ISO and Spitzer infrared spectroscopic observations. Intermediate-mass stars, solar-type stars and even brown dwarfs will be discussed in t…
Thermal Emission From The Dust Coma Of Comet Hale-Bopp And The Composition Of The Silicate Grains
Hayward, T. L.; Gehrz, R. D.; Hanner, M. S. +7 more
The dust coma of comet Hale-Bopp was observed in the thermal infrared over a wide range in solar heating (R = 4.9–0.9 AU) and over the full wavelength range from 3 µm to 160 µm. Unusual early activity produced an extensive coma containing small warm refractory grains; already at 4.9 AU, the 10 µm silicate emission feature was str…
Infrared Observations Of Volatile Molecules In Comet Hale-Bopp
Crovisier, J.
Infrared observations of comets C/1996 B2 (Hyakutake) and C/1995 O1 (Hale-Bopp) benefited from the high spectral resolution and sensitivity of échelle spectrometers now equipping ground-based telescopes and from the availability of the Infrared Space Observatory (ISO). From the ground, several hydrocarbons were unambiguously detected for the first…
Comet Hale-Bopp, Circumstellar Dust, and the Interstellar Medium
Waters, L. B. F. M.; Waelkens, C.; Malfait, K.
The infrared spectrum of comet Hale-Bopp, as observed with the Infrared Space Observatory (ISO), presents astonishing similarities with those of the dusty disks surrounding young stars. The prominent spectral features of crystalline silicates that occur in comets, have been observed in the circumstellar media of young and old stars, yet not in the…
The Infrared Spectrum of Comet Hele–Bopp as Seen by the Infrared Space Observatory
Altieri, B.; Keller, H. U.; Lellouch, E. +6 more
Spectra of comet C/1995 O1 (Hale-Bopp) were obtained with the Infrared Space Observatory (ISO) at medium resolution with the grating spectrometer in the photometer (PHT-S) and/or at high resolution with the short wavelength spectrometer (SWS) and long wavelength spectrometer (LWS) in April 1996 (Crovisier et al., 1996), September–October 1996 (Cro…
Discovery Of Mg-Rich Pyroxenes In Comet C/1995 O1 (Hale-Bopp): Pristine Grains Revealed At Perihelion
Woodward, Charles E.; Koike, Chiyoe; Wooden, Diane H. +2 more
The NASA Ames HIFOGS spectrometer observed comet C/1995 O1 (Hale-Bopp) at epochs including 96 Oct 7–14 UT (2.8 AU), 97 Feb 14–15 UT (1.2 AU), 97 Apr 11 UT (0.93 AU), and 97 Jun 22, 25 UT (1.7 AU). The HIFOGS 7.5–13.5 µm spectrophotometry (R = 360 - 180) of the silicate feature at 2.8 AU is identical in shape to the ISO SWS spectra of comet H…
Isophot Observations Of Comet Hale-Bopp
Lemke, D.; Leinert, Ch.; Heinrichsen, I. +11 more
Comet Hale-Bopp has been observed five times with ISOPHOT, the photometer on board the Infrared Space Observatory (ISO), four times before its perihelion passage at heliocentric distances of 4.92, 4.58, 2.93 and 2.81 AU, and at 3.91 AU postperihelion. Each time, multi-filter photometry covering the range between 3.6–175 µm with eight to ten …