Imaging and spectroscopy of comet C/2001 Q4 (NEAT) at 8.6 AU from the Sun

Free access article

Issue		A&A Volume 398, Number 3, February II 2003


Page(s)		L41 - L44
Section		Letters
DOI		http://dx.doi.org/10.1051/0004-6361:20021878

A&A 398, L41-L44 (2003)
DOI: 10.1051/0004-6361:20021878

Letter

Imaging and spectroscopy of comet C/2001 Q4 (NEAT) at 8.6 AU from the Sun

G. P. Tozzi¹, H. Boehnhardt^{2, 3} and G. Lo Curto²

¹ INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
² European Southern Observatory ESO, Alonso de Cordova 3107, Santiago de Chile, Chile
e-mail: hboehnha@eso.org, glocurto@eso.org
³ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
e-mail: hboehnha@mpia-hd.mpg.de

(Received 20 November 2002 / Accepted 19 December 2002 )

Abstract
Comet C/2001 Q4 (NEAT) was observed inbound at an heliocentric distance of 8.6 AU. Broadband filter images in the visible and long slit spectroscopy in the 3500-7000 Å range was recorded. No sign of CN emission was detected and an upper limit for CN production rate of $1.4\times10^{25}$ molecules s ^-1 is estimated. The color of the dust in the inner coma is very red with a spectral index of 29%/1000 Å. The radial profile of the dust coma displays steep gradients of 1.7 (inner part) to 2.4 (outer part). The af $\rho$ value, a proxy for the dust production, is measured to be 1500 cm. The coma shows a weak and short conic structure in the northern hemisphere that is interpreted as dust fan produced by an active region on the nuclear surface.

Key words: comets -- C/2001 Q4 (NEAT) -- distant activity

Offprint request: G. P. Tozzi, tozzi@arcetri.astro.it

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