Characterizing the Dust Coma of Comet C/2012 S1 (ISON) at 4.15 AU from the Sun

Li, J. -Y. and Kelley, M. S. P. and Knight, M. M. and Farnham, T. L. and Weaver, H. A. and A'Hearn, M. F. and Mutchler, M. J. and Kolokolova, L. and Lamy, P. and Tóth, Imre (2013) Characterizing the Dust Coma of Comet C/2012 S1 (ISON) at 4.15 AU from the Sun. ASTROPHYSICAL JOURNAL LETTERS, 779 (1). ISSN 2041-8205

Preview

Text 1311.0826v1.pdf Available under License Creative Commons Attribution. Download (1MB) | Preview

Abstract

We report results from broadband visible images of comet C/2012 S1 (ISON) obtained with the Hubble Space Telescope Wide Field Camera 3 on 2013 April 10. C/ISON’s coma brightness follows a 1/ρ (where ρ is the projected distance from the nucleus) profile out to 5000 km, consistent with a constant speed dust outflow model. The turnaround distance in the sunward direction suggests that the dust coma is composed of sub-micron-sized particles emitted at speeds of tens of meters s -1 . A(θ)fρ, which is commonly used to characterize the dust production rate, was 1340 and 1240 cm in the F606W and F438W filters, respectively, in apertures 10% per 100 nm 10,000 km down the tail. The colors are similar to those of comet C/1995 O1 (Hale-Bopp) and other long-period comets, but somewhat bluer than typical values for short-period comets. The spatial color variations are also reminiscent of C/Hale-Bopp. A sunward jet is visible in enhanced images, curving to the north and then tailward in the outer coma. The 1.6”-long jet is centered at a position angle of 291º, with an opening angle of ~45º. The jet morphology remains unchanged over 19 hours of our observations, suggesting that it is near the rotational pole of the nucleus, and implying that the pole points to within 30º of (RA, Dec) = (330º, 0º). This pole orientation indicates a high obliquity of 50º-80º.

Actions (login required)

Edit Item