A New Analysis Of Spitzer Observations Of Comet 29P/Schwassmann-Wachmann 1

Keywords

Comets, dust; Comets, nucleus; Infrared observations

Abstract

We present a new analysis of Spitzer observations of Comet 29P/Schwassmann-Wachmann 1 taken on UT 2003 November 21, 23, and 24, similar to a previous investigation of the observations (Stansberry et al., 2004), but using the most recent Spitzer data pipeline products and intensive image processing techniques. Analysis of images from the IRAC 5.8 and 8.0μm bands and the MIPS 24.0 and 70.0μm bands resulted in photometry measurements of the nucleus after a suite of coma modeling and removal processes were implemented. SW1 was not identified in the 5.8μm image from the previous work so its incorporation into this analysis is entirely new. Using the Near Earth Asteroid Thermal Model (Harris, 1998) resulted in a nucleus radius measurement of R=30.2-2.9+3.7km and an infrared beaming parameter value of η=0.99-0.19+0.26. We also measured an infrared geometric albedo, p5.8=0.5±0.5. Extrapolating a 0.04V-band albedo and using a normalized reflectivity gradient S'=14.94±1.09 [% (1000Å)-1] (Duffard, R., et al. [2014]. Astron. Astrophys. 564, A92) we recover an infrared albedo of p5.8=0.31 in the near infrared consistent with the value recovered from thermal modeling. The dust composition extracted from IRS spectra are very comet-like, containing mainly amorphous ferromagnesian silicates (but with a minority of crystalline silicates as well), water ice, and metal sulfides.

Publication Date

11-1-2015

Publication Title

Icarus

Volume

260

Number of Pages

60-72

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1016/j.icarus.2015.06.038

Socpus ID

84937782917 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84937782917

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