EDP Sciences
Free access
Issue
A&A
Volume 376, Number 2, September II 2001
Page(s) 672 - 685
Section The solar system
DOI http://dx.doi.org/10.1051/0004-6361:20011028


A&A 376, 672-685 (2001)
DOI: 10.1051/0004-6361:20011028

Detailed phase function of comet 28P/Neujmin 1

C. E. Delahodde1, 2, K. J. Meech3, O. R. Hainaut1 and E. Dotto4

1  European Southern Observatory, Casilla 19001, Santiago, Chile
2  Institut d'Astrophysique de Marseille, Traverse du Siphon, 13376 Marseille Cedex 12, France
3  Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
4  Osservatorio Astronomico di Torino, Strada Osservatorio 20, 100025 Pino Torinese (TO), Italy

(Received 11 April 2001 / Accepted 10 July 2001 )

Abstract
In 2000, comet 28P/Neujmin 1 was an ideal candidate for a phase function study: during its April opposition it reached a phase angle of $\alpha$ = 0.8$^{\circ}$, and previous observations at similar heliocentric distances ($r \geq 4$ AU) indicated that the comet was likely to be inactive. We observed this comet using ESO's NTT and 2.2m telescopes at La Silla, on 6 epochs from April to August 2000, covering $\alpha$ = 0.8-8$^{\circ}$. These data were combined with a large set of data from 1985 to 1997. In order to disentangle the rotation effects from the phase effects, we obtained complete rotation coverage at opposition, providing us with a lightcurve template. We have obtained an improved rotation period of $12.75 \pm 0.03$ hrs, with a full amplitude of $\Delta m = 0.45 \pm 0.05$ mag, which yields an axis ratio lower limit of 1.51 $\pm$ 0.07. For each subsequent epochs, we have obtained enough rotation coverage to re-synchronize the lightcurve fragments with the template, and determine the magnitude change caused by the phase function. The average colours of the nucleus, $V-R = 0.454 \pm 0.050$, and $R-I = 0.413 \pm 0.050$, are similar with those of D-type asteroids and other comet nuclei. The phase function obtained for the nucleus has a linear slope of $0.025 \pm 0.006$ mag deg-1, less steep than that of the mean C-type asteroids.


Key words: comets: general: surface properties -- comets: individual: P/Neujmin 1 -- techniques: photometric

Offprint request: C. Delahodde, catherine.delahodde@astrsp-mrs.fr

SIMBAD Objects in preparation



© ESO 2001

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.