Water outburst activity in Comet 17P/Holmes

Autor(es)

de Almeida, Amaury A. ^[1] ; Boice, Daniel C. ^{[1, 2, 3]} ; Picazzio, Enos ^[1] ; Huebner, Walter F. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, IAG, Rua Matao 1226, BR-05508090 Sao Paulo, SP - Brazil

^[2] Trinity Univ, Dept Phys & Astron, One Trinity Pl, San Antonio, TX 78212 - USA

^[3] Sci Studies & Consulting, 171 Harmon Dr, San Antonio, TX 78209 - USA

^[4] Southwest Res Inst, Space Sci & Engn Div, 6220 Culebra Rd, San Antonio, TX 78228 - USA

• Tipo de documento: Artigo Científico
• Fonte: Advances in Space Research; v. 58, n. 3, p. 444-452, AUG 1 2016.
• Citações Web of Science: 2

Resumo

Cometary outbursts are sporadic events whose mechanisms are not well known where the activity and consequently the brightness can increase hundreds of thousands of times within a few hours to several days. This indicates a dramatic departure from thermal equilibrium between the comet and interplanetary space and is usually documented by ``light curves{''}. In a typical cometary outburst, the brightness can increase by 2-5 magnitudes (Whitney, 1955; Gronkowski and Wesolowski, 2015). In only 42 h, Comet 17P/Holmes was reported to brighten from a magnitude of about 17 to about 2.4 at the height of the burst, representing the largest known outburst by a comet. We present the H2O production rate of Holmes for the megaburst occurring between 23 and 24 October 2007. For this, we selected more than 1900 photometric observations from the International Comet Quarterly Archive of Photometric Data (Green, 2007) and use the Semi-Empirical Method of Visual Magnitudes (SEMVM; de Almeida et al., 2007). We clearly show that the comet achieved an average water production rate of 5 x 10(29) molecules s(-1) , corresponding to a water gas loss rate of 14,960 kg s(-1), in very good agreement with Schleicher (2009) who derived the water production rate using OH measurements on 1 Nov 2007 (about 8 days after the outburst). We discuss possible physical processes that might cause cometary outbursts and propose a new qualitative mechanism, the Pressurized Obstructed Pore (POP) model. The key feature of POP is the recrystallization of water in the surface regolith as it cools, plugging pores and blocking the release of subsurface gas flow. As the interior gas pressure increases, an outburst is eventually triggered. POP is consistent with current observations and can be tested in the future with observations (e.g., Rosetta in situ measurements) and detailed simulations. (C) 2016 COSPAR. Published by Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 15/03176-8 - Estudo de compostos portadores de fósforo em cometas e um curso completo em astrobiologia
• Beneficiário: Amaury Augusto de Almeida
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional