Spectroscopy and structure of hibonite, grossite, and CaAl2O4: Implications for astronomical environments

Hofmeister, Anne M.; Wopenka, B.; Locock, Andrew J.

doi:10.1016/j.gca.2004.03.011

Cited by 69 publications

(45 citation statements)

References 50 publications

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“…Infrared dust emissions of the exploded circumstellar dust of NGC 6302 contain many peaks, consistent with the presence of pure, magnesium endmember silicates (forsterite, enstatite, and diopside), possibly calcium carbonate (Molster et al, 2001;Kemper et al, 2002), along with CAI minerals (Hofmeister et al, 2004). Hydrosilicates are possible (Hofmeister & Bowey, 2006).…”

Section: Explanation Of Solar System Gradients and Trendsmentioning

confidence: 75%

Origin of HED Meteorites from the Spalling of Mercury - Implications for the Formation and Composition of the Inner Planets

Hofmeister¹,

Criss²

2012

New Achievements in Geoscience

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Section: Explanation Of Solar System Gradients and Trendsmentioning

confidence: 75%

Origin of HED Meteorites from the Spalling of Mercury - Implications for the Formation and Composition of the Inner Planets

Hofmeister¹,

Criss²

2012

New Achievements in Geoscience

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“…As it can be seen from Figure 6, the strong absorption bands due to AlO 6 octahedra are centered near 640 and 604 cm -1 [21]. This spectrum has also bands centered at about 465, 528, 552, 618, 704, and 777 cm -1 , due to synthetic calcium hexaaluminate, CaAl 12 O 19 (CA 6 ) [30]. One additional absorption band centered at about 739 cm -1 is distinctive for the monoclinic ZrO 2 polymorph [31].…”

Section: X-ray Diffraction (Xrd) and Ft-ir Studiesmentioning

confidence: 86%

PREPARATION OF Al₂O₃-CaAl₁₂O₁₉-ZrO₂ COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca₇ZrAl₆O₁₈-REACTIVE ALUMINA MIXTURE

Madej¹

2016

Ceramics - Silikaty

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“…Recent observations of infrared emissions have enabled the dust in the planetary formation region to be identified as rock-forming minerals, such as forsterite, ortho-pyroxene, diopside or hibonite; these are frequently observed in chondritic meteorites (e.g., Hanner et al, 1995;Malfait et al, 1998;Sitko et al, 1999;Honda et al, 2003;Hofmeister et al, 2003). The observations indicated that these silicates had Mg-rich components.…”

Section: Introductionmentioning

confidence: 99%

Magnetic alignment of nonmagnetic silicates caused by paramagnetic anisotropy: Origin of polarization observed in planetary formation region

2010

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Possible dust alignment in dense regions due to paramagnetic anisotropy χ PARA is discussed based on the results of a laboratory experiment on ortho-pyroxene grains containing a small amount of Fe 2+ ions (1.8 mol%). Ortho-pyroxene has been detected in circum-stellar regions by infrared emission spectroscopy. Our experiment was performed at room temperature using He gas as the dispersing medium. Although the grains do not contain strong magnetic moments, alignment was achieved at low field strength (<2000 G). The alignment efficiency of ortho-pyroxene was compared with those of various rock-forming minerals. The magnitude of diamagnetic anisotropy χ DIA , free of paramagnetic ions, is generally <10 −8 emu/g for various silicates. In contrast, χ PARA increases considerably with increasing Fe 2+ concentration, reaching 10 −5 emu/g for many of the silicates when the concentration of Fe 2+ is >1 mol%; this increasing χ PARA is the cause of the above-mentioned alignment obtained at the low field strength. Based on our observations, we infer the field intensity needed to obtain partial dust alignment of sufficient size to explain the observed polarization in astrophysical environments. Due to temperature dependences caused by a Curie Law and a rotational Brownian motion, the field intensity required to cause the alignment is expected to decrease considerably at low-temperature conditions assumed for a proto-planetary disk. The results of our experiment performed at room temperature provide a technical basis to reproduce grain alignment under such temperature conditions.

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Spectroscopy and structure of hibonite, grossite, and CaAl2O4: Implications for astronomical environments

Cited by 69 publications

References 50 publications

Origin of HED Meteorites from the Spalling of Mercury - Implications for the Formation and Composition of the Inner Planets

Origin of HED Meteorites from the Spalling of Mercury - Implications for the Formation and Composition of the Inner Planets

PREPARATION OF Al₂O₃-CaAl₁₂O₁₉-ZrO₂ COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca₇ZrAl₆O₁₈-REACTIVE ALUMINA MIXTURE

Magnetic alignment of nonmagnetic silicates caused by paramagnetic anisotropy: Origin of polarization observed in planetary formation region

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