Astrochemistry Flashcards
When was CH, the first known interstellar molecule, discovered?
In 1937
When was H2 discovered?
In 1970. It was found in diffuse clouds by optical spectroscopy
How many interstellar molecules are known?
218 (as of 02/2020)
The core in interstellar dust is usually made of…
silicate
Why are interstellar dust important?
Because they catalize other processes
How are interstellar dust created?
By heavy particles (such as iron) attracting other particles that stucks on its surface
How many amino acids have been identified in meteorites?
over 200
When did the earth form?
4.567 billion years ago
RNA polymers may have formed more than ___ billion years ago
4.17
The formation of RNA polymers presumes what?
Seasonal cycles of dry and wet creating photodissociation and hydrolysis.
What are exo-/endothermic reactions?
Reactions with less/more energy in the product than in the reactants.
Why are ion-neutral reactions favorable in the interstellar medium?
Because they do not possess activation energy
How is H2 formed?
On the surface of interstellar dust
What is the most likely reaction with H2 in cold clouds?
0+ + H2 –> OH+ + H (this is exothermic)
97% of the times a cosmic ray hits H2 it creates…
H2+
How is H3+ created?
H2+ + H2 –> H3+ + H
How is H3O+ created?
H3+ + O + H2 + H2 –> H3O + something
What three products do H3O+ form?
H2O, OH (becoming O2), and O
How is CH+ formed?
By C reacting with H3+
How is CH3+ formed?
C + H3+ + H2 + H2 –> CH3+ + something
Why are hydrogen abstraction reactions common?
Because H2 is the most common molecule in the universe
What chemical process is the most important source of CO?
HCO+ + e –> CO + H
Given a number density of hydrogen, arrange the timescales ambipolar diffusion, free-fall and freeze-out in declining order
ambipolar diffusion, free-fall and freeze-out
What is diffusion?
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) from a region of higher concentration to a region of lower concentration.
What is ambipolar diffusion?
Ambipolar diffusion is diffusion of positive and negative species with opposite electrical charge due to their interaction via an electric field.
What is the opposite of accretion?
Desorption
