Bibcode
Cabrera-Lavers, A.; Lara, L. M.; Licandro, J.; Moreno, F.; de León, J.; Tozzi, G. P.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 550, id.A17, 7 pp.
Fecha de publicación:
2
2013
Revista
Número de citas
33
Número de citas referidas
31
Descripción
Aims: We aim to study the dust ejected by main-belt comet (MBC)
(300163) 2006 VW139 to obtain information on the ejection
mechanism and the spectral properties of the object. This will help to
see if they are compatible with those of "normal" comets.
Methods: Broad-band images in the g and r band as well as a
low-resolution spectrum in the 0.35-0.9 μm region were obtained with
the GTC telescope (Roque de los Muchachos Observatory, La Palma, Spain).
Images were analyzed to produce a color map and derive a lower limit of
the absolute magnitude H. A Monte Carlo scattering model was used to
derive dust properties such as mass loss rates and ejection velocities
as a function of time. The reflectance spectrum was compared to that of
the well-studied MBC 133P/ Elst-Pizarro. The spectrum was also used to
search for CN emission and to determine the upper limit of the CN
production rate. Results: The reflectance spectrum of 2006
VW139 is typical of a C-class asteroid, with a spectral slope
S'V = 0.5 ± 1.0%/1000 Å. It is similar to the
spectrum of 133P and other MBCs. No CN emission is detected in the
spectrum. A CN production rate upper limit of 3.76 ×
1023 s-1 is derived. Images show that the MBC
present a narrow almost linear tail that extends up to 40 000 km in the
anti-solar direction and more than 80 000 km in the direction of the
object's orbital plane. The color of the tail is slightly redder than
the Sun (S' between 3-6%/1000 Å). The Monte Carlo dust tail model
derived the mass loss rates and ejection velocity as a function of time,
and the results show that the activity onset occurs shortly after
perihelion, and lasts about 100 days; the total ejected mass is ~2
× 106 kg. Conclusions: The spectrum of 2006
VW139 suggests that it is not a "normal" comet. The spectrum
is typical of the other observed MBCs. Even if no CN emission is
detected, the more likely activation mechanism is water-ice sublimation.
Like other well studied MBCs, (300163) 2006 VW139 is likely a
primitive C-class asteroid that has a water-ice subsurface depth
reservoir that has recently been exposed to sunlight or to temperatures
that produce enough heat to sublime the ice.
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