EDP Sciences
Free access
Volume 430, Number 3, February II 2005
Page(s) 1129 - 1132
Section Planets and planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20041766

A&A 430, 1129-1132 (2005)
DOI: 10.1051/0004-6361:20041766

A neck-line structure in the dust tail of Comet C/2004 F4 (Bradfield)

L. Pansecchi and M. Scardia

INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate LC, Italy
    e-mail: luigi.pansecchi@libero.it; scardia@merate.mi.astro.it

(Received 1 August 2004 / Accepted 4 September 2004 )

Three CCD images of Comet C/2004 F4 (Bradfield), taken on three different dates close to the time of the Earth crossing through the plane of the comet orbit (2004 May 2.9280 UT), show a ray-shaped structure (RSS) in the dust tail, accompanied by a short, sunward spike (SWS). This morphology and behaviour strongly recall a Neck-Line Structure (NLS; Kimura & Liu 1977; Pansecchi et al. 1987). Astrometric measurements of the images show that, on all the three dates, the position on the sky of the observed RSS is consistent with several sky-projected points of a theoretical Neck-Line, computed for the precise date of each observation. Furthermore, the SWS turns out to be a real (not caused by perspective) antitail, which is predicted by NLS models.

Key words: comets: general -- comets: individual: C/2004 F4 (Bradfield)

© ESO 2005