The origin of crystalline silicates in the Herbig Be star HD 100546 and in comet Hale-Bopp

By J. Bouwman, A. D. Koter, C. Dominik, L. Pannekoek, U. Amsterdam, The Netherlands., Ceadsmdapnia, S. d’Astrophysique, France., Instituut voor Sterrenkunde and 2 more. 2003

153 citations recorded by the source corpus.

the date of receipt and acceptance should be inserted later Abstract. We have investigated the spatial distribution, and the properties and chemical composition of the dust orbiting HD100546. This system is remarkably different from other isolated Herbig Ae/Be stars in both the strength of the mid-IR excess and the composition of the circumstellar dust. To explain spectral features and the amount of mid-IR dust emission the presence of a component of small (< 10 µm) grains radiating at ∼200 K is required, which is not seen in other well investigated Herbig Ae/Be systems. This additional component is inconsistent with a uniform flaring disk model. The fraction of intercepted stellar light that is absorbed and re-emitted in the mid-IR is so large (∼ 70%) that it requires the disk to be more 'puffed up' at about 10AU, where the grains have T ∼ 200 K. This may occur if a proto-Jupiter clears out a gap at this distance allowing direct stellar light to produce an extended rim at the far side of the gap. The other remarkable difference with other isolated Herbig Ae/Be systems is the presence of a much larger mass fraction of the crystalline silicate forsterite in the circumstellar dust. We find that the mass fraction of crystalline silicates in HD100546 increases with decreasing temperature, i.e. with larger radial distances from the central star. This distribution of crystalline dust is inconsistent with radial mixing models where the crystalline silicates are formed by thermal annealing above the glass temperature in the very inner parts of the disk, and are subsequently transported outwards and mixed with amorphous material. We speculate that the formation and spatial distribution of the crystalline dust may be linked to the formation of a proto-Jupiter in the disk around HD100546. Such a proto-Jupiter could gravitationally stir the disk leading to a collisional cascade of asteroidal sized objects producing small crystalline grains, or it could cause shocks by tidal interaction with the disk which might produce crystalline dust grains through flash heating. As shown by Malfait et al. (1998), the infrared spectrum of HD100546 is very similar to that of C/1995 O1 Hale-Bopp (Crovisier et al. 1997). Using an identical methodology, we have therefore also studied this solar system comet. Both objects have an almost identical grain composition, but with the important difference that the individual dust species in Hale-Bopp are in thermal contact with each other, while this is not the case in HD100546. This suggests that if similar processes leading to the dust composition as seen in HD100546 also occurred in our own solar system, that Hale-Bopp formed after the formation of one or more proto-gas giants.

Subfields: Astronomy and Astrophysics

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2. Simon Bruderer
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4. L. Hartmann
5. D. Wilner
6. N. Calvet
7. Philip Armitage
8. G. Herczeg

Citations in the corpus

• Cold Disks: Spitzer Spectroscopy of Disks around Young Stars with Large Gaps (2007, methodology): “Further examples and some spectra (e.g., HD 100546; Bouwman et al. 2003) were obtained of a few Herbig Ae/Be stars with theISO.”
• A YOUNG PROTOPLANET CANDIDATE EMBEDDED IN THE CIRCUMSTELLAR DISK OF HD 100546 (2013, background): “A massive planet was suggested to be orbiting in the gap (Bouwman et al. 2003).”
• Mid-infrared sizes of circumstellar disks around Herbig Ae/Be stars measured with MIDI on the VLTI (2004, background): “HD 100546 The infrared spectrum of this group I source is characterized by strong emission from crystalline forsterite (Mg2SiO4, see Malfait et al. 1998a), that seems to be located at a typical distance of ∼10 AU from the star (Bouwman et al. 2003).”
• Dust filtration at gap edges: Implications for the spectral energy distributions of discs with embedded planets (2006, methodology): “A similar effect is seen in at least one Herbig Ae/Be star, HD100546 (Bouwman et al. 2003; Grady et al. 2005).”
• Dust Growth and Settling in Protoplanetary Disks and Disk Spectral Energy Distributions. I. Laminar Disks (2005, background): “The rapid dust growth in inner regions might also be responsible for inner holes identified by Calvet et al. (2002) in TW Hydra and by Bouwman et al. (2003) in HD 1000546.”
• The Truncated Disk of CoKu Tau/4 (2004, result): “The qualitative nature of the SED of CoKu Tau/4 is reminiscent of that of the Classical T Tauri stars TW Hya (Calvet et al. 2002; Uchida et al. 2004), GM Aur (Marsh & Mahoney 1992, 1993; Rice et al. 2003), and the Herbig Ae star HD 100546 (Bouwman et al. 2003).”
• The warm gas atmosphere of the HD 100546 disk seen by Herschel - Evidence of a gas-rich, carbon-poor atmosphere? (2012, background): “Bouwman et al. (2003) suggested that the size distributions vary with radii, employing a population of smaller grains in the inner 40 AU and larger grains in the outer disk.”
• A 10 μm spectroscopic survey of Herbig Ae star disks: Grain growth and crystallization (2005, background): “The emission spectra from small crystalline olivine and pyroxene grains show strong, narrow resonances that are observed in for example circumstellar disks (Waters & Waelkens 1998; Bouwman et al. 2001) and comets (Crovisier et al. 1997; Bouwman et al. 2003).”
• Volatile carbon locking and release in protoplanetary disks. A study of TW Hya and HD 100546 (2016, background): “Large dust grains are depleted inside of 13 au, and again from 35 to 150 au (e.g. Bouwman et al. 2003; Walsh et al. 2014a), with a small inner disk from 0.26 to 0.7 au containing 3 × 10−10 M of dust (Benisty et al. 2010; Panić et al. 2014).”
• ISO Spectroscopy of Gas and Dust: From Molecular Clouds to Protoplanetary Disks (2004, background): “One possibility is that a proto-Jovian planet has cleared out a gap around 10 AU, leading to a ‘puffed-up’ rim on the far-side of the gap (Bouwman et al. 2003).”