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PHYSICAL CHARACTERIZATION OF ASTEROIDS NEON Group 5: Koraljka Mužić Nikola Vitas Grzegorz Nowak

PHYSICAL CHARACTERIZATION OF ASTEROIDS NEON Group 5: Koraljka Mužić Nikola Vitas Grzegorz Nowak Mario Mars Simone Marchi (tutor). 5 th NEON SCHOOL, OHP, 2006. PHYSICAL CHARACTERIZATION OF ASTEROIDS. OUTLINE. # Introduction. # Photometry of 1980 Tezcatlipoca.

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PHYSICAL CHARACTERIZATION OF ASTEROIDS NEON Group 5: Koraljka Mužić Nikola Vitas Grzegorz Nowak

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  1. PHYSICAL CHARACTERIZATION OF ASTEROIDS NEON Group 5: Koraljka Mužić Nikola Vitas Grzegorz Nowak Mario Mars Simone Marchi (tutor) 5th NEON SCHOOL, OHP, 2006

  2. PHYSICAL CHARACTERIZATION OF ASTEROIDS OUTLINE #Introduction #Photometry of 1980 Tezcatlipoca # Spectroscopy of 2 Pallas and 25 Phocaea 5th NEON SCHOOL, OHP, 2006

  3. PHYSICAL CHARACTERIZATION OF ASTEROIDS # Asteroid observations # Photometry: information about the shape of the body and scattering properties of the surface # Spectroscopy: information about the chemical composition and homogeneity of the surface 5th NEON SCHOOL, OHP, 2006

  4. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: INTRODUCTION Asteroidclassification Three spectral complexes: Asteroid classification S – type: consisted mostly of silicates, with addition of different elements Moderately steep slope for λ<0.7μm, silicon absorption feature at 1 μm C - type:carbon rich silicate composition Flat spectra, shallow absorption features, if present at all Very low albedos X – type: carbon rich and metal rich; a generally featureless spectra, with slight to moderately red slope; A subtle UV absorption feature, at λ<0.55μm; occasionally shallow absorption feature at λ>0.85μm 5th NEON SCHOOL, OHP, 2006

  5. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # 1980 Tezcatlipoca (NEO): DATA # Absolute magnitude, 13.92 # Diameter, D = 4.3 km (Gehrels, 1994) # Rotation period, P = 7.2523 h (Wisniewski et al, 1997) # Geometric albedo, g = 0.25 # Spectral type, S # Discovered 19/06/1950 by Wilson, A. G. at Palomar 5th NEON SCHOOL, OHP, 2006

  6. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # Orbit of Tezcatlipoca [25/07/2006] Sun – Target – Earth angle = 59º 5th NEON SCHOOL, OHP, 2006

  7. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # Observations of 1980 Tezcatlipoca at OHP # Two nights: 25/07/2006 (63 frames), 30/07/2006 (55 frames) # Telescope: 1.20 cm # Detector: CCD TK1024 # Filter: R # Exposure time: 120 s 5th NEON SCHOOL, OHP, 2006

  8. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # 1980 Tezcatlipoca in 12’x12’ star field 5th NEON SCHOOL, OHP, 2006

  9. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # 1980 Tezcatlipoca in 12’x12’ star field 5th NEON SCHOOL, OHP, 2006

  10. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # Selected reference stars and 1980 Tezcatlipoca # Photometry: information about the shape of the body and homogeneity of the surface # Spectroscopy: information about the chemical composition 5th NEON SCHOOL, OHP, 2006

  11. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # The instrumental magnitude variation of 20 selected reference stars [25/07/2006] 5th NEON SCHOOL, OHP, 2006

  12. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # Tezcatlipoca / photometric observations: line = original data, squares = corrected values 5th NEON SCHOOL, OHP, 2006

  13. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # Previous observations (Kaasalainen et al, 2004) 5th NEON SCHOOL, OHP, 2006

  14. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # Composite light curve plot of the two observations of Tezcatlipoca 5th NEON SCHOOL, OHP, 2006

  15. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: PHOTOMETRY # Model of Tezcatlipoca or What did we conclude? # Rough dimensions a/b = 1.4, b/c = 1.4 (Kaasalainen et al, 2004) # Considerable irregularities # The high solar phase angles and shadowing effects can explain high amplitudes of the light curve even if the model is not highly elongated. # The “barrel-like” model may also represent a “bone” shape of the asteroid… # …though we cannot expect narrow “waist” if the object is not highly elongated. # New observations are necessary to confirm the model and to explain the systematic effects indicated by the difference between data obtained with R and V filter. 5th NEON SCHOOL, OHP, 2006

  16. PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY Spectroscopy of Pallas (2) # General informations about Pallas. # Observations and data reduction. # Spectra and their slopes. # Variations of the spectrum. 5th NEON SCHOOL, OHP, 2006

  17. PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY Discovery Discoverer Heinrich Wilhelm Olbers Discovery date March 28, 1802 Orbital elements Eccentricity (e) 0.231 Semi-major axis (a) 2.773 AU Orbital period (P) 4.62 years Inclination (i) 34.840 Longitude of the ascending node (Ω) 173.150 Argument of perihelion 310.450 Physical characteristics Dimensions 570x525x500 km Mass 2.2x1020kg Density 2.8 g/cm3 Surface gravity 0.18 m/s2 Escape velocity 0.32 km/s Rotational period 7.81 h Absolute magnitude 4.18 Spectral class B-type asteroid 5th NEON SCHOOL, OHP, 2006

  18. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Size comparison: the first 10 asteroids profiled against Earth’s Moon. Pallas is the second on the left. 5th NEON SCHOOL, OHP, 2006

  19. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # B-type # Relatively uncommon type of carbonaceous asteroid, falling into the wider C-group, # generally similar to the C-type objects, # ultraviolet absorption below 0.5 um is small or absent, # spectra is rather slightly bluish than reddish, #the albedo also tends to be greater than the generally very dark C-type. 5th NEON SCHOOL, OHP, 2006

  20. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Reflectance spectra of C class asteroids (Gaffey et al, 1993) 5th NEON SCHOOL, OHP, 2006

  21. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY 1. The spectra were obtained with the 1.93 m telescope in conjunction with the CARELEC spectrograph 26/07/2006. 2. We used solar-like spectrum combined from three reference G2-type stars to divide the asteroid spectra and obtain the reflectivity of the asteroid. 5th NEON SCHOOL, OHP, 2006

  22. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Reflectance spectra of C class asteroids (Gaffey et al, 1993) 5th NEON SCHOOL, OHP, 2006

  23. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Reflectance spectra of C class asteroids (Gaffey et al, 1993) 5th NEON SCHOOL, OHP, 2006

  24. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY Spectroscopy of Phocaea (25) # Discovered by J. Chacornac on April 6, 1853 # Member of the main asteroid belt # Distance ~3 AU # Diameter 75.1 km # Rotation period 9.954 h # Inclination 21.58° # Silicaceous-type [spectral class S] 5th NEON SCHOOL, OHP, 2006

  25. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # S-type asteroids # 13-17% of known asteroids # Composition silicate & Fe-Ni core # Dominate the inner asteroid belt # Reflect ~15% 5th NEON SCHOOL, OHP, 2006

  26. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Phocaea group in main belt # Mean orbital radius between 2.25 and 2.5 AU # Inclination between 18° and 32° # Eccentricity >0.1 # Distribution is determined by Gravitational influence of Jupiter Phocaea group 5th NEON SCHOOL, OHP, 2006

  27. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Olivine & pyroxene # Fe2SiO4 [fayalite] and Mg2SiO4 [forsterite] # XY(Si; Al)2O6 [XY = calcium, sodium, magnesium, iron, chronium mixed mineral] Pyroxene Olivine 5th NEON SCHOOL, OHP, 2006

  28. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Reflectance spectra of C class asteroids (Gaffey et al, 1993) 5th NEON SCHOOL, OHP, 2006

  29. PHYSICAL CHARACTERIZATION OF ASTEROIDS PHYSICAL CHARACTERIZATION OF ASTEROIDS: SPECTROSCOPY # Reflectance spectra of C class asteroids (Gaffey et al, 1993) 5th NEON SCHOOL, OHP, 2006

  30. THANK YOU FOR YOUR ATTENTION! 5th NEON SCHOOL, OHP, 2006

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