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Astron. Astrophys. 321, 652-659 (1997)

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(7) Iris: a possible source of ordinary chondrites?

F. Migliorini 1, A. Manara 2, A. Cellino 3, M. Di Martino 3 and V. Zappalà 3

1 Armagh Observatory, College Hill, BT61 9DG, Armagh UK (pat@star.arm.ac.uk)
2 Osservatorio Astronomico di Brera, via Brera, 28, I-20121 Milano, Italy (manara@brera.mi.astro.it)
3 Osservatorio Astronomico di Torino, strada Osservatorio, 20, I-10025 Torino, Italy
(cellino@to.astro.it - dimartino@to.astro.it - zappala@to.astro.it)

Received 5 August 1996 / Accepted 22 October 1996


Rotationally resolved visible spectroscopy ([FORMULA] Å) of (7) Iris is presented. Within a few percents, no variation in Iris' visible spectrum over a rotational period has been found. These data suggest that the mineralogic properties of Iris' surface are globally homogeneous, although we cannot exclude the presence of some texture and/or albedo variegation as suggested by previous photometric and polarimetric studies available in the literature. From a dynamical point of view, we estimate the ejection velocity required for collisional fragments from this asteroid to be injected into the surrounding chaotic regions. The resulting velocity values are fairly high, but not incompatible with the values suggested by the present knowledge of catastrophic break-up phenomena and by the observational constraints put by asteroid families. Taking into account the close similarity between Iris' spectrum and that of (6) Hebe, a typical S(IV)-type object according with the most modern spectral classifications, we believe that (7) Iris may be a not negligible source of ordinary chondrite meteorites.

Key words: asteroids – meteorites – planets: (7) Iris

Send offprint requests to: A. Manara

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998