EDP Sciences
Free access
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. Boehnhardt2, 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




© ESO 2003