The surface of Pluto-twin TNOs 2005 FY 9 and 2003 UB 313 Javier Licandro (1,2), N. Pinilla-Alonso (3), M. Pedani (3), E. Oliva (3), P. Leisy (1), G.P. Tozzi (4) and W. Grundy (5) (1)Isaac Newton Group of Telescopes (2)Instituto de Astrofísica de Canarias (3)Fundación Galileo Galilei (4)INAF-Oss di Arcetri (5)Lowel Observatory

Pluto’s spectrum deep CH 4 ice bands, shifted by about 15A respect to laboratory. weak N 2 (2.15 microns) and CO (1.58, 2.35 microns) no deep water ice or CO 2 red in the visible  organics (tholins, irradiated CH 4 )?

2005 FY 9 Licandro et al Observed simultaneously with the TNG and WHT at La Palma on Aug. 1st, Deep CH 4 ice bands, some of them not seen in Pluto’s spectrum ( e.g microns) Red colour in the visible, similar to Pluto

2003 UB 313 Licandro et al Brown et al Near infrared spectrum of 2003 UB 313 similar to our 2005 FY 9 spectrum

2003 UB 313 Licandro et al. 2006, in preparation Observed with the WHT on Oct. 20th, 2005.

COLOURS Licandro et al. 2006, in preparation All present slightly red slope in the visible S’ measured using the 0.59 and microns reflectance S’(UB 313 )= 4 %/1000A S’(FY 9 )= 8.9 %/1000A S’(Pluto)= 8.9 %/1000A Posible organics in the surface, probably irradiated methane (Brunetto et al. this meeting). Less abuntant in 2003 UB 313

Band depths Licandro et al. 2006, in preparation FY9/Pluto (0.73) = 6 FY9/Pluto (0.89) = 3 FY9/UB313 (0.73)= 1.9 FY9/UB313 (0.89)= 1.1 Indicative of abundance and/or grain sizes

Band depths In the infrared the differences are smaller but consistent, light reflected from the 3 objects samples different mean optical pathlengths Saturation of deeper bands Different concentration of CH 4 and or thickness of the CH 4 layers

Band depths and saturation effects In the infrared the bands are highly saturated  visible spectral range is very important Weaker bands sample deeper layers

Band shifts: 2005 FY9 Licandro et al Band shifts respect to laboratory pure CH 4 ones indicative of dilusion in N 2 Shifts < 5 A  high concetration of CH 4 or no N 2 on 2005 FY 9 surface Atmosphere? Crucial to determine if there is some N 2

SHIFTED ? Band shifts: 2003 UB 313

Band shifts: 0.73 micron band Pluto CH4 (0.05cm) 2005 FY9 CH4 (4.5cm) 2003 UB313 CH4 (1.5cm)

Band shifts: 0.89 micron bands Pluto CH4 (0.05cm) 2005 FY9 CH4 (4.5cm) 2003 UB313 CH4 (1.5cm) NO!!!! Uncertainties on Sky lines < 1A Problems with wl calibration? NO!!!! Uncertainties on Sky lines < 1A

2003 UB313 shifted by 15 A CH4 (1.5cm) Band shifts: 2003 UB 313 Narower?

Band shifts: 2003 UB 313 There is CH4 diluted in N2 ice in the surface of 2003 UB 313 Weaker bands sample deeper layers  evidence of a vertical compositional gradient ? Colapse of the atmosphere?

Charons

Band shifts

La atmósfera de Plutón atmósfera de CH4, N2 y CO Condiciones suficientes de tamaño, masa, y temperatura

La atmósfera de Caronte? No se ha detectado

La superficie de Plutón bandas desplazadas  metano diluido en N 2 inhomogeneidades superficiales relacionadas con diferente composición y albedo

Observations Visible 4.2 William Herschel Telescope ISIS Infrarred 3.6 m Telescopio Nazionale Galileo NICS

Los TNOs grandes

Diferent composition or diferent surface evolution?