Post-perihelion photometry of dust grains in the coma of 67P Churyumov–Gerasimenko

Frattin, E.; Cremonese, G.; Simioni, E.; Bertini, I.; Lazzarin, M.; Ott, T.; Drolshagen, E.; La Forgia, F.; Sierks, H.; Barbieri, C.; Lamy, P.; Rodrigo, Rafael; Koschny, D.; Rickman, H.; Keller, H. U.; Agarwal, J.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Da Deppo, V.; ... (2017). Post-perihelion photometry of dust grains in the coma of 67P Churyumov–Gerasimenko. Monthly notices of the Royal Astronomical Society, 469(Suppl_2), S195-S203. Oxford University Press 10.1093/mnras/stx1395

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We present a photometric analysis of individual dust grains in the coma of comet 67P/Churyumov–Gerasimenko using OSIRIS images taken from 2015 July to 2016 January. We analysed a sample of 555 taken during 18 d at heliocentric distances ranging between 1.25 and 2.04 au and at nucleocentric distances between 80 and 437 km. An automated method to detect the tracks was specifically developed. The images were taken by OSIRIS NAC in four different filters: Near-IR (882 nm), Orange (649 nm), FarOrange (649 nm) and Blue (480 nm). It was not always possible to recognize all the grains in the four filters, hence we measured the spectral slope in two wavelengths ranges: in the interval [480–649] nm, for 1179 grains, and in the interval [649–882] nm, for 746 grains. We studied the evolution of the two populations’ average spectral slopes. The data result scattered around the average value in the range [480–649] nm, while in the [649–882] nm we observe a slight decreasing moving away from the Sun as well as a slight increasing with the nucleocentric distance. A spectrophotometric analysis was performed on a subsample of 339 grains. Three major groups were defined, based on the spectral slope between [535–882] nm: (i) the steep spectra that may be related with organic material, (ii) the spectra with an intermediate slope, likely a mixture of silicates and organics and (iii) flat spectra that may be associated with a high abundance of water ice.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences

UniBE Contributor:

Rodrigo, Rafael and Thomas, Nicolas

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering

ISSN:

0035-8711

Publisher:

Oxford University Press

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

14 Nov 2017 16:57

Last Modified:

14 Nov 2017 16:57

Publisher DOI:

10.1093/mnras/stx1395

BORIS DOI:

10.7892/boris.106266

URI:

https://boris.unibe.ch/id/eprint/106266

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