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Are 2I/Borisov and Oort Cloud Comets Alike?
(Submitted on 18 Oct 2019)
The interstellar comet 2I/Borisov bears a strong resemblance to Oort Cloud comets, judging from its appearance in images taken over the first six weeks of observation. To test the proposed affinity in more diagnostic terms, 2I is compared with Oort Cloud comets of similar perihelion distance, near 2 AU. Eight such objects are identified among the cataloged comets whose orbits have been determined with high accuracy. This work focuses on three particular characteristics: the light curve, the geometry of the dust tail, and the dust parameter Afrho. It is found that activity signatures of Oort Cloud comets with perihelia near 2 AU differ from those of Oort Cloud comets with perihelia beyond the snow line in that evidence of the original halo of slow-moving, millimeter-sized and larger icy-dust grains is limited to early observations only, with later images showing instead the products of subsequent activity nearer perihelion but not of activity just preceding observation, which suggests the absence of microscopic-dust ejecta. Comet 2I fits, in broad terms, the properties of the Oort Cloud comets with perihelia near 2 AU and of fairly low activity. Future tests of the preliminary conclusions are proposed.
Comments: 13 pages, 7 figures, 3 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:1910.08208 [astro-ph.EP] (or arXiv:1910.08208v1 [astro-ph.EP] for this version)
From: Zdenek Sekanina
[v1] Fri, 18 Oct 2019 00:43:43 UTC (660 KB)