IAR   05382
INSTITUTO ARGENTINO DE RADIOASTRONOMIA
Unidad Ejecutora - UE
artículos
Título:
Light curves and colours of the faint Uranian irregular satellites Sycorax, Prospero, Stephano, Setebos, and Trinculo
Autor/es:
MARIS, M.; CARRARO, G.; PARISI, M. G.
Revista:
ASTRONOMY AND ASTROPHYSICS
Referencias:
Año: 2007 vol. 472 p. 311 - 319
ISSN:
0004-6361
Resumen:
Context: After the work of Gladman et al. (1998, Nature, 392, 897), it
is now assessed that many irregular satellites are orbiting around
Uranus. Aims: Despite many studies performed in past
years, very little is know about the light-curves of these objects and
inconsistencies are present between colours derived by different
authors. This situation motivated our effort to improve both the
knowledge of colours and light curves. Methods: We present and discuss,
the time series observations of Sycorax,
Prospero, Stephano,
Setebos, and Trinculo, five faint,
irregular satellites of Uranus, which were carried
out at VLT, ESO Paranal (Chile) on the nights between 29 and 30 July,
2005 and 25 and 30 November, 2005. Results: We derive light curves for
Sycorax and Prospero and colours
for all of these these bodies. Conclusions: For
Sycorax we obtain colours B-V = 0.839 ± 0.014,
V-R = 0.531 ± 0.005, and a light-curve which is suggestive of a
periodical variation with period ≈3.6 h and amplitude ≈0.067
± 0.004 mag. The periods and colours we derive also for
Sycorax are in agreement with our previous
determination in 1999 using NTT. We also derive a light-curve for
Prospero which suggests an amplitude of about 0.2 mag
and a periodicity of about 4 h. However, the sparseness of our data,
prevents a more precise characterization of the light-curves, and we can
not determine whether they are one-peaked or two-peaked. Hence, these
periods and amplitudes have to be considered preliminary estimates. As
for Setebos, Stephano, and
Trinculo the present data do not allow us to derive
any unambiguous periodicity, despite the fact that
Setebos displays a significant variability with
amplitude about as large as that of Prospero. Colours
for Prospero, Setebos,
Stephano, and Trinculo are in
marginal agreement with the literature.
Based on observations with the ESO Very Large Telescope + FORS2 at the
Paranal Observatory, Chile, under program 075.C-0023. Table [see full
text] is only available in electronic form at http://www.aanda.org