ESO Planetary Group News Letters

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The next Journal Club takes place on 19 November (Friday) at 11 am at Vitacura.


Abstract of a past Journal club talk by A. Alvarez:

The 'dwarf planet' Eris through the eyes of XSHOOTER

The 'dwarf planet' Eris is the largest body in the trans-Neptunian
population (D~2500 km, Brown et al. 2006) and orbits the Solar System
farthest than any other object in this region (a ~ 67 AU). The low
temperature of Eris' surface (T< 35K) hints the presence of high amounts
of volatile ices (e.g. methane, nitrogen, carbon monoxide) in
equilibrium with an atmosphere (Schaller & Brown, 2007), similar to what
happens in Pluto (the best known trans-Neptunian object). The search for
these ices has been a bit discouraging up to this moment as visible and
near-infrared spectra of Eris show strong absorption bands
characteristics only of methane ice. Previous studies (e.g., Licandro et
al. 2006) suggest that methane ice is diluted in nitrogen but not traces
of the characteristic absorptions of this ice at 2.15 microns or of
carbon monoxide (1.579 and 2.35 micron) have been detected. So where are
the volatiles? Using data obtained during the commissioning of XSHOOTER,
we studied the location of several absorption bands. The high spectral
resolution of XSHOOTER confirms the existence of a solid dilution of
CH4-N2 on Eris's surface. Moreover, a detailed analysis of these new
spectra of Eris, comes out with a new and fascinating landscape where
the surface of Eris would be an heterogeneous mixture of pure methane,
plus a dilution of methane, nitrogen and carbon monoxide in accordance
with initial predictions from physical models. -

M. E. Brown, E. L. Schaller, H. G. Roe, D. L. Rabinowitz and C. A.
Trujillo (2006). ApJ, 643, L61 - J. Licandro, W. M. Grundy, N.
Pinilla-Alonso, P. Leisy (2006). A&A, 458, L5-L8. - E. L. Schaller &
M.E. Brown (2007). ApJ, 659 L61-L64.

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