Material composition assessment and discovering sublimation activity on asteroids 145 Adeona, 704 Interamnia, 779 Nina, and 1474 Beira

Busarev, V.V.; Barabanov, S.I.; Puzin, V.B.

Авторы: Busarev V.V., Barabanov S.I., Puzin V.B.
Журнал: Solar System Research
Том: 50
Номер: 4
Год издания: 2016
Издательство: Pleiades Publishing, Ltd
Местоположение издательства: Road Town, United Kingdom
Первая страница: 281
Последняя страница: 293
DOI: 10.1134/S003809461604002X
Аннотация: Spectrophotometric observations of 145 Adeona, 704 Interamnia, 779 Nina, and 1474 Beira—asteroids of close primitive types—allowed us to detect similar mineralogical absorption bands in their reflectancespectra centered in the range 0.35 to 0.92 μm; the bands are at 0.38, 0.44, and 0.67–0.71 μm. On thesame asteroids, the spectral signs of simultaneous sublimation activity were found for the first time. Namely,there are maxima at ~0.35–0.60 μm in the reflectance spectra of Adeona, Interamnia, and Nina and at~0.55–075 μm in the spectra of Beira. We connect this activity with small heliocentric distances of the asteroidsand, consequently, with a high insolation at their surfaces. Examination of the samples of probable analoguesallowed us to identify Fe3+ and Fe2+ in the material of these asteroids through the mentioned absorptionbands. For analogues, we took powdered samples of carbonaceous chondrites Orgueil (CI), Mighei(CM2), Murchison (CM2), and Boriskino (CM2), as well as hydrosilicates of the serpentine group. Laboratoryspectral reflectance study of the samples of low-iron Mg serpentines (<2 wt % FeO) showed that theequivalent width of the absorption band centered at 0.44–0.46 μm strongly correlates with the content of Fe3+in octahedral and tetrahedral coordinations. Our conclusion is that this absorption band can be used as aqualitative indicator of Fe3+ in the surface matter of asteroids and other solid celestial bodies. The comparisonof the listed analog samples and the asteroids by parameters of the spectral features suggests that the silicatecomponent of the asteroids' surface material is a mixture of hydrated and oxidized compounds, includingoxides and hydroxides of bivalent and trivalent iron and carbonaceous-chondritic material. At the same time,the sublimation activity of Adeona, Interamnia, Nina, and Beira at high surface temperatures points to a substantialcontent of water ice in their material. This contradicts the previously existing notions on the C-typeand similar asteroids as bodies containing water only in the bound state. Moreover, since the sublimation processsimultaneously occurs in four primitive-type bodies at small heliocentric distances, we may suppose thatthis phenomenon is common for the main-belt asteroids.
Добавил в систему: Бусарев Владимир Васильевич

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Material composition assessment and discovering sublimation activity on asteroids 145 Adeona, 704 Interamnia, 779 Nina, and 1474 Beiraстатья

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