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Primitive Asteroids: the puzzling case of asteroids belonging to the C-complex. Elisabetta Dotto INAF – Osservatorio Astronomico di Roma. ASI – 4 June 2014. Primitive classes : C, P, D. d ark – low albedo. Chondritic meteorites: temperatures and evolution. C. D.
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Primitive Asteroids: the puzzling case of asteroids belonging to the C-complex ElisabettaDotto INAF – OsservatorioAstronomico di Roma ASI – 4 June 2014
Primitive classes: C, P, D dark – low albedo Chondritic meteorites: temperatures and evolution C D Primitive Objects 2 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
21 Lutetia • Old object (about 3.5 Gy ) • Albedo 0.22 (variations of up to 30%) • Classification: M – C • Highly complex surface composition: • mixture of “incompatible” • types of materials; • carbonaceous and enstatite • chondrites; • aggregated due to impacts. 3 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
175706 1996FG3 • Albedo pv= 0.029+0.026 • -0.012 • Diameter: primary 1.9 +0.55 km • -0.42 (L. Benner, JPL Courtesy) • secondary ~ 0.5 km • Rot. Periods: Ppri = 3.5942 ± 0.0001 h • Psec = 16.14 h a variegated surface 4 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
175706 1996FG3: variegated surface Maybe we were looking at a compacted/cemented region (1996 FG3 has a circular polarization ratio similar to that of Itokawa). The evidence for dust coming from the quite low thermal inertia could support the hypothesis of the presence of both rough and smooth terrains. 5 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
341843 2008EV5 • Spectral type: C complex • Size and shape from radar: • 400 ± 50 m oblate spheroid • Rot Period = 3.725 ± 0.001 h • Albedo: 0.12 ± 0.04 It couldbesimilar to the CI meteorite Orgueil parent body accretedin a volatile-richregion Mas Jupiter It is an possible transition object between asteroids and comets 6 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
7 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
MP-R Current exobiological scenarios for the origin of life invoke the exogenous delivery of organic matter to the early Earth The planets of the inner solar system experienced an intense influx of organic-rich material for several hundred million years after they formed. The earliest evidence for life on Earth coincides with the decline of this bombardment. Many biologically important molecules are present in the organic materials. 8 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
V-NIR-IR photometry and spectroscopy from ground-based and spaceobservatories 9 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR
NEXT STEP A sample return from a primitive object More than 99% of material lost in the atmosphere; only the <1% strongest survives CM Chondrites Primitivematerial Ordinary chondrites Explosion of a cometaryparticle in Stardust aerogel Atmospheric Entry Filter 4 mm Compressive strength Tsuchiyama et al. 2008 Carbonaceous chondrites are under-represented on Earth (5%) compared to the abundance of carbonaceous-type asteroids 10 ASI – 4 June 2014 Elisabetta Dotto – INAF-OAR