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Eagle Nebula, Pleiades, V838 Monocerotis, Helix Nebula, Crab Nebula

Image credits (from top): The Eagle Nebula, NASA and the Hubble Heritage Team (STScI/AURA); The Pleiades or Seven Sisters, NASA, ESA and AURA/Caltech; V838 Monocerotis, NASA, the Hubble Heritage Team (AURA/STScI) and ESA; The Helix Nebula, NASA, NOAO, ESA, the Hubble Helix Nebula Team, M Meixner (STScI) and T A Rector (NRAO); The Crab Nebula, NASA and STScI.

Podcasts - The Birth, Life and Death of Stars

by Dr Paul Ruffle
Jodrell Bank Centre for Astrophysics, University of Manchester

The life cycle of stars that creates the elements from which we are made

"Twinkle, twinkle, little star, how I wonder what you are!" How often did we sing that as a child without realising what we were asking? The wonder of how stars are born, live their lives and finally die is revealed in these highly informative discussions between astronomer Paul Ruffle and broadcaster Sara Hinchliffe.

Published 8 January 2011. Copyright ℗ & © 2011 Paul Ruffle. All Rights Reserved.

Part 1: Introduction

Astronomer Paul Ruffle explains how he does his research using radio telescopes.

Paul Ruffle explains how he became an astronomer and how he does his research using radio telescopes in far flung places throughout the world. He also discusses how the construction of radio telescopes enables them to be upgraded to improve their sensitivity.

Introduction.mp3 (right click to download) 5.1 MB 5:25 mins

Part 2: Molecular Clouds

Molecular clouds in the interstellar medium are the only place where stars can form.

Although the space between the stars looks empty, tenuous clouds of dust and molecular gas in the interstellar medium are the only place where stars can form. Gravity causes these clouds to collapse and eventually form protostars.

Molecular Clouds.mp3 (right click to download) 10.0 MB 10:46 mins

Part 3: Triggers for Star Formation

Energetic solar winds or supernova shockwaves provide energy to initiate star formation.

Clouds of dust and gas need an external energy input to initiate gravitational collapse. Nearby massive stars provide this as highly energetic solar winds or supernova shockwaves. Surveys using radio telescopes identify such regions of potential star formation.

Triggers for Star Formation.mp3 (right click to download) 9.2 MB 9:56 mins

Part 4: Star and Planet Formation

A star is born when a protostellar core gets hot enough to fuse hydrogen into helium.

The random motions in a cloud lead to a rotating disk of gas and dust around the protostellar core. A star is born when the core gets hot enough to fuse hydrogen into helium. Planets, asteroids, and comets form from the leftover debris disk.

Star and Planet Formation.mp3 (right click to download) 3.9 MB 4:05 mins

Part 5: Stars on the Main Sequence

A star's colour is related to its temperature, so blue stars are hot and red stars are cooler.

The colour of stars is related to their temperature, which is dictated by their mass when on the main sequence (of the H-R diagram), where they spend most of their lives. High mass stars are hot and blue, whereas lower mass stars are cooler and redder.

Stars on the Main Sequence.mp3 (right click to download) 6.2 MB 6:35 mins

Part 6: Stellar Nucleosynthesis

All stars fuse hydrogen into helium. More massive stars create heavier elements.

Stars like our Sun will only ever fuse hydrogen into helium, but more massive stars can fuse heavier elements like carbon, oxygen, silicon and iron. This process provides radiation pressure to support a star's core from gravitational collapse.

Stellar Nucleosynthesis.mp3 (right click to download) 6.6 MB 7:06 mins

Part 7: Stellar Lifetimes

Depending on their mass stars live in either the fast or the slow lane.

Our Sun is half way through its 10 billion year lifetime, but massive stars only live for a few tens of millions of years. Towards the end of its life a star will swell into a red giant with a lower surface temperature.

Stellar Lifetimes.mp3 (right click to download) 9.9 MB 10:41 mins

Part 8: Planetary Nebulae

A lower mass star becomes a planetary nebula after its core has collapsed into a white dwarf.

Helium fusion in red giants generates pulsations that expel more material to produce an AGB star. Heavier elements get caught up in this outflow that eventually becomes a planetary nebula. Ultimately this material is returned to the interstellar medium, increasing its metallicity.

Planetary Nebulae.mp3 (right click to download) 9.5 MB 10:11 mins

Part 9: Supernovae

A massive star explodes when fusion reactions cease and its core collapses into a neutron star or black hole.

Iron fusion is the end of the road for massive stars. Their core collapses to form a neutron star or black hole, generating an highly energetic explosion of the star's outer layers. This produces shockwaves that can trigger star formation elsewhere.

Supernovae.mp3 (right click to download) 3.3 MB 3:25 mins

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