Lecture 11 Molecules in Space

What is amber and why is it significant?

Amber is fossilised tree resin that originated millions of years ago, trapping insects and seeds inside.

What did Cano and Borucki discover in 1995?

They extracted bacterial spores from bees preserved in amber from Costa Rica, dating back 25-40 million years.

How did the bacteria survive 40 million years in amber?

They converted themselves into spores (suspended animation) and revived when placed in a suitable culture.

What is the density of the interstellar medium?

Approximately one hydrogen atom per cubic metre.

Why is molecule formation difficult in the interstellar medium?

H atoms are heated by stellar UV radiation, moving at ~1000 m/s, making atomic bonding hard.

What are Giant Molecular Clouds (GMCs)?

Regions of space where molecules can form, and sites of star and planet formation.

What are the key facts about GMCs?

They are the largest structures in galaxies, typically 150 light-years across, and last 10-100 million years.

How do GMCs help molecule formation?

Graphite dust shields molecules from UV radiation and acts as a catalyst for reactions.

Why can't we recreate interstellar chemistry in labs?

We cannot achieve low enough densities or wait the millions of years required for the reactions.

What are the two main molecules in GMCs?

Molecular hydrogen (H₂) and carbon monoxide (CO).

How is H₂ inferred from CO observations?

CO emits radio lines when H₂ molecules collide with it; more H₂ means stronger CO emission.

How are molecules detected in space?

Molecules emit and absorb radiation at specific frequencies; radio observations at millimetre wavelengths are most practical.

What is a maser?

Microwave Amplification by Stimulated Emission of Radiation; it emits photons when a molecule interacts with an incident photon.

Why was OH the first interstellar molecule detected?

Forming OH requires less energy than forming H₂ or O₂, making it easier to produce.

What is ALMA?

The Atacama Large Millimeter Array, an interferometer of 66 radio telescopes in Chile.

What was ALMA's key discovery regarding molecules?

In 2015, it detected complex organic molecules in a protoplanetary disc around the young star MWC 480.

What was the timeline of key molecule discoveries in space?

OH detected in 1963, Ammonia in 1968, Formaldehyde in 1969.

What organic molecules have been detected in space?

Hydrogen cyanide (HCN), formic acid (HCOOH), methanol (CH₃OH), acetaldehyde, and ethanol.

What is the difference between organic and inorganic molecules?

Organic molecules have a carbon backbone with hydrogen; inorganic molecules do not have both.

What biologically important molecules have been found in space?

Glycine and glycoaldehyde.

What are the four main groups of organic molecules that build cells?

Carbohydrates, proteins, lipids, and nucleic acids.

What is the Murchison meteorite?

A C-type meteorite that landed in Australia in 1969, containing common amino acids.

What is chirality?

A property where amino acids exist in two mirror-image forms: L-type and D-type.

What did the Murchison meteorite reveal about chirality?

It contained approximately equal amounts of L-type and D-type amino acids, suggesting extraterrestrial origin.

What is the key open question raised by this lecture?

Is space the factory where the building blocks of life are made?