2017/07/01 by D. Bockelée-Morvan, D. Bockelée–Morvan, G. Rinaldi +21 · 73 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Coma (optics) #Comet #Ejecta #Infrared #Interplanetary dust cloud #Physics #Solar System #Stellar, planetary, and galactic studies #Supernova #astro-ph.EP
paper · pdf · doi:10.1093/mnras/stx1950
published in Monthly Notices of the Royal Astronomical Society 469(Suppl_2), S443-S458 (Oxford University Press) · Accepted for publication in the Monthly Notices of the Royal Astronomical Society
openalex publication_date 2017/07/01 · arxiv created 2017/08/01 · openalex created_date 2017/08/08 · arxiv updated 2018/05/08 · openalex updated_date 2026/08/05
We present 2–5 μm spectroscopic observations of the dust coma of 67P/Churyumov–Gerasimenko obtained with the VIRTIS-H instrument onboard Rosetta during two outbursts that occurred on 2015, 13 September 13.6 h ut and 14 September 18.8 h ut at 1.3 au from the Sun. Scattering and thermal properties measured before the outburst are in the mean of values measured for moderately active comets. The colour temperature excess (or superheat factor) can be attributed to submicrometre-sized particles composed of absorbing material or to porous fractal-like aggregates such as those collected by the Rosetta in situ dust instruments. The power-law index of the dust size distribution is in the range 2–3. The sudden increase of infrared emission associated with the outbursts is correlated with a large increase of the colour temperature (from 300 to 630 K) and a change of the dust colour at 2–2.5 μm from red to blue colours, revealing the presence of very small grains (≤100 nm) in the outburst material. In addition, the measured large bolometric albedos (∼0.7) indicate bright grains in the ejecta, which could either be silicatic grains, implying the thermal degradation of the carbonaceous material, or icy grains. The 3 μm absorption band from water ice is not detected in the spectra acquired during the outbursts, whereas signatures of organic compounds near 3.4 μm are observed in emission. The H2O 2.7 μm and CO2 4.3 μm vibrational bands do not show any enhancement during the outbursts.