Bok Globule Barnard 68
Interstellar grains Sub-micron sizes
Interstellar grains Sub-micron sizes Cabonaceous and silicate material et ????
Interstellar grains Sub-micron sizes Cabonaceous and silicate material et ???? Who knows?
Gr H…Gr H…Gr…H Gr…H2 H2 + Gr Charge transfer Exchange reaction 1 Exchange reaction 2 Exchange reaction 3
Gr H…Gr H…Gr…H Gr…H2 H2 + Gr Charge transfer Exchange reaction 1 Exchange reaction 2 Exchange reaction 3
Gr H…Gr H…Gr…H Gr…H2 H2 O+ O + Gr H H h Gr H…Gr H…Gr…H Gr…H2 H2 O+ O + Gr Charge transfer Exchange reaction 1 Exchange reaction 2 Exchange reaction 3
Gr H…Gr H…Gr…H Gr…H2 H2 + Gr H H h Gr H…Gr H…Gr…H Gr…H2 H2 + Gr Charge transfer Exchange reaction 1 Exchange reaction 2 Exchange reaction 3
h photon or energy of reaction Localised heating
Critical Temperature Tc for lift-off for various molecules adsorbed on grains by van der Waals interactions Tc(K) H2 < 3 N2 13 CO 14 CH4 19 NH3 60 H2O 92
Harry Kroto 2004
Photo dissociation tPD = 103 AB + h A + B Lifetimes (in yrs) Photo dissociation tPD = 103 AB + h A + B 2-body collisions t2B = 103/n A + B AB* A + B Radiative association tRA = 109/n yrs A + B AB* AB + h Grain catalysis tGC = 109/n yrs A + B + Gr AB + Gr 3 - body collision t3B = 1023/ n2 A + B + M MAB AB + M t(BIG U) = 1010 yrs n number of atoms or molecules per cm3 Harry Kroto 2004
Harry Kroto 2004
Harry Kroto 2004
Harry Kroto 2004