The Unusual Volatile Composition of the Halley-Type Comet 8P/Tuttle: Addressing the Existence of an Inner Oort Cloud

• Published in: The Astrophysical journal Vol. 683; no. 1; pp. L71 - L74
• Main Authors: Böhnhardt, H, Mumma, M. J, Villanueva, G. L, DiSanti, M. A, Bonev, B. P, Lippi, M, Käufl, H. U
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 10.08.2008; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Oort cloud; Solar system; astrochemistry-comets: general-comets: individual (8P/Tuttle)- infrared: solar system; molecular data; Halley comet
• ISSN: 1538-4357; 0004-637X; 1538-4357
• DOI: 10.1086/591446

We measured organic volatiles (CH sub(4), CH sub(3)OH, C sub(2)H sub(6), H sub(2)CO), CO, and water in comet 8P/Tuttle, a comet from the Oort Cloud reservoir now in a short-period Halley-type orbit. We compare its composition with two other comets in Halley-type orbits, and with comets of the "organics-normal" and "organlcs-depleted" classes. Chemical gradients are expected in the comet-forming region of the protoplanetary disk, and an individual comet should reflect its specific heritage. If Halley-type comets came from the inner Oort Cloud as proposed, we see no common characteristics that could distinguish such comets from those that were stored in the outer Oort Cloud.