TOWARDS A MULTI-DIMENSIONAL CLASSIFICATION SCHEME FOR MINOR PLANETS Max Mahlke Centro de Astrobiología (CSIC-INTA) in collaboration with Enrique Solano, Benoit Carry, Bruno Merín, Remi Flamary, the Spanish Virtual Observatory and the ESASky team TOWARDS A MULTI-DIMENSIONAL CLASSIFICATION SCHEME FOR MINOR PLANETS Max Mahlke Centro de Astrobiología (CSIC-INTA) in collaboration with Enrique Solano, Benoit Carry, Bruno Merín, Remi Flamary, the Spanish Virtual Observatory and the ESASky team NASA/JPL-Caltech/UCLA/MPS/DLR/IDA !1 Ceres DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas Pallas Mercury Venus Earth Mars Ceres Juno Jupiter Saturn Uranus Vesta DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas Pallas Mercury Venus Earth Mars Ceres Juno Jupiter Saturn UranusNeptune Vesta DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas Mercury Venus Earth Mars Jupiter Saturn UranusNeptune DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas Mercury Venus Earth Mars Jupiter Saturn UranusNeptune Pluto DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas 1992 QB Mercury Venus Earth Mars Jupiter Saturn UranusNeptune Pluto Albion DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas Mercury Venus Earth Mars Jupiter Saturn UranusNeptune DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas Mercury Venus Earth Mars Jupiter Saturn UranusNeptune June 2019: 795,000 DeMeo+ 2015 Max Mahlke | ESAC Science Seminar | 13 June 2019 !2 Pallas Centaurs Trans-Neptunian Objects // DeMeo & Carry 2014 Heterogeneous in heliocentric distance: <1AU to >100AU in shapes in orbital inclination: 0° to 33° for Main Belt asteroids in rotation: hours to days in orbital eccentricity: 0. to 0.3 for Main Belt asteroids in size: m to 103km in composition: carbon- / silicate-compound rocks, ices Max Mahlke | ESAC Science Seminar | 13 June 2019 !3 Juno Centaurs Trans-Neptunian Objects // DeMeo & Carry 2014 Heterogeneous in heliocentric distance: <1AU to >100AU in shapes in orbital inclination: 0° to 33° for Main Belt asteroids in rotation: hours to days in orbital eccentricity: 0. to 0.3 for Main Belt asteroids in size: m to 103km in composition: carbon- / silicate-compound rocks, ices in common: they are all witnesses of the formation of the Solar System Max Mahlke | ESAC Science Seminar | 13 June 2019 !3 Juno Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta DeMeo & Carry 2014 Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Planet migration Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Planet migration Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Planet migration Orbital instabilities Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Planet migration Orbital instabilities Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Dust Gas DeMeo & Carry 2014 Pebbles Planetesimals Planetary Embryos Gas Giants Terrestrial Planets Planet migration Orbital instabilities Asteroid puzzle -4 Little mass in Main Belt (5x10 MEarth) Dynamically excited Main Belt Compositionally diverse Main Belt Compositionally homogeneous Trojans Max Mahlke | ESAC Science Seminar | 13 June 2019 !4 Vesta Previous Taxonomies: What features did they use, how many classes, how large were their samples Chapman+ 1975 S C U "stony", "silicaceous" "carbonaceous" "unclassified" Max Mahlke | ESAC Science Seminar | 13 June 2019 !5 Astraea Previous Taxonomies: What features did they use, how many classes, how large were their samples Chapman+ 1975 S C U "stony", "silicaceous" "carbonaceous" "unclassified" V P X A B M R D E + composite classes K L + hydrated cases DeMeo+ 2009 Max Mahlke | ESAC Science Seminar | 13 June 2019 !5 Astraea Previous Taxonomies: What features did they use, how many classes, how large were their samples Chapman+ 1975 S C U "stony", "silicaceous" "carbonaceous" "unclassified" V P X A B M R D E + composite classes K L + hydrated cases Classes are defined by features in the asteroid spectra VIS / NIR slope Absorption bands, most importantly at 1mu (olivine) 2mu (pyroxene) DeMeo+ 2009 Some caveats Classes are degenerate when regarding only VIS or only NIR In general, low number of asteroid spectra to define classes Max Mahlke | ESAC Science Seminar | 13 June 2019 !5 Astraea Previous Taxonomies: What features did they use, how many classes, how large were their samples Chapman+ 1975 S C U "stony", "silicaceous" "carbonaceous" "unclassified" V P X A B M R D E + composite classes K L + hydrated cases Classes are defined by features in the asteroid spectra VIS / NIR slope Absorption bands, most importantly at 1mu (olivine) 2mu (pyroxene) DeMeo+ 2009 Some caveats Classes are degenerate when regarding only VIS or only NIR In general, low number of asteroid spectra to define classes Max Mahlke | ESAC Science Seminar | 13 June 2019 !5 Astraea Previous Taxonomies: What features did they use, how many classes, how large were their samples Chapman+ 1975 S C U "stony", "silicaceous" "carbonaceous" "unclassified" V P X A B M DeMeo+ 2009 R D E + composite classes K L + hydrated cases Classes are defined by features in the asteroid spectra VIS / NIR slope Absorption bands, most importantly at 1mu (olivine) 2mu (pyroxene) DeMeo+ 2009 Some caveats Classes are degenerate when regarding only VIS or only NIR In general, low number of asteroid spectra to define classes Max Mahlke | ESAC Science Seminar | 13 June 2019 !5 Astraea Tholen 1984 Asteroids can also be classified by their albedos albedo is the "capability to reflect light" visual albedo, infrared albedo, and their ratios the albedo carries less information, but is more readily available than the spectra Max Mahlke | ESAC Science Seminar | 13 June 2019 !6 Hebe Tholen 1984 Asteroids can also be classified by their albedos albedo is the "capability to reflect light" visual albedo, infrared albedo, and their ratios the albedo carries less information, but is more readily available than the spectra Mainzer+ 2012 Max Mahlke | ESAC Science Seminar | 13 June 2019 !6 Hebe Tholen 1984 Asteroids can also be classified by their albedos albedo is the "capability to reflect light" visual albedo, infrared albedo, and their ratios the albedo carries less information, but is more readily available than the spectra Masiero+ 2011 Mainzer+ 2012 Max Mahlke | ESAC Science Seminar | 13 June 2019 !6 Hebe Asteroids can also be classified by their phase curves slope parameters G1 and G2 defining the decrease in brightness as the solar phase angle increases less information than than albedos and spectra, but available from serendipitous observations Buchheim 2010 Muinonen 2010+ Max Mahlke | ESAC Science Seminar | 13 June 2019 !7 Iris Asteroids can also be classified by their phase curves slope parameters G1 and G2 defining the decrease in brightness as the solar phase angle increases less information than than albedos and spectra, but available from serendipitous observations Buchheim 2010 Penttilä+ 2016 Muinonen 2010+ Max Mahlke | ESAC Science Seminar | 13 June 2019 !7 Iris Courtesy of B. Carry VISNIR: Available for 800 objects Available for 200,000 objects Available for 500,000 objects VIS/NIR: Available for 4,000 objects Our data collection so far includes 7,500 spectra of 3,500 unique objects, including 1,000 VISNIR spectra, provided to us by >30 PIs Compared to the DeMeo classification from 2009 Larger sample size (factor 2 for VISNIR, factor 10 for VIS/NIR) Multi-dimensional: spectra, albedo, phase curve Give probabilistic classifications