SCIENCE : Going out with an extremely big bang

Heather Couper and Nigel Henbest chart the cataclysmic suicide and gradual rebirth of a star

Almost exactly eight years ago, a new star appeared in the southern hemisphere, where it brightened to become one of the most prominent objects. It reached maximum brightness in May 1987, then faded back into obscurity. But radio astronomers in Australia have found it is making a comeback.

"SN 1987A" was actually a mature star on its way out. And it went by the most spectacular means of suicide in the universe - going "supernova", literally blowing itself apart. 1987A was the first supernova visible to the unaided eye for nearly 400 years. The last was observed by the mathematician Johannes Kepler in 1604 - four years before Galileo turned the first telescope skywards. But 1987A's timing was immaculate: it appeared just as astronomy was undergoing a hi-tech revolution. Every telescope, satellite and detector that could be pressed into service was trained on the supernova.

Even before the blast became visible, two underground tanks of water, in Ohio and Japan, started to scintillate with flashes early on 23 February. The flashes were caused by a flood of penetrating particles, neutrinos, which hardly ever interact with matter. But the Japanese detector stopped 12 neutrinos; the Ohio tank, eight. To catch this number, something like 300 million million neutrinos must have passed through each tank.

The flood of neutrinos confirmed ideas about what makes certain stars explode. All stars are giant nuclear reactors. In its central core, a star converts hydrogen to helium through nuclear fusion, and the energy created by the reaction emerges as heat and light. But when a star like the Sun runs out of hydrogen fuel, that is more or less it. Using its powerful gravity, it may be able to "squeeze" its helium core and generate a little more energy for a short time, but its gravity is insufficient to take things further.

In the case of massive stars - more than 10 times heavier than the Sun - not only do these giants rip through their fuel in record time; they can also generate more "squeezing power". When their helium is used up, they can fuse the resulting carbon "ash" into neon and oxygen.

Squeeze tighter, and you get a core of silicon. Eventually, the star ends up with a core of iron. When the star tries to squeeze its iron core to generate energy, all hell breaks loose. To fuse iron, you must take in energy, which the star tries to obtain by squeezing its core even tighter. In seconds, the core catastrophically collapses, and in the searing heat, iron nuclei are broken down into subatomic particles. Among these are billions of neutrinos, which flood out of the dying star at the speed of light, and lift off its outer layers.

This is the fate that overtook SN 1987A. Since then, debris from the supernova has been hurtling outwards into space. Astronomers are picking up an ever-increasing signal of radio waves. These waves are generated as gases from the supernova crash into the surrounding interstellar gas. As time passes, this "remnant" will grow in radio brightness until it looks like a glowing ring.

Thousands of years on, the remnant will have swept up so much gas that starbirth becomes possible. Among the ashes of the supernova, young stars will come into being. But they are subtly different from the generation that preceded them. Their gases are enriched with the elements such as silicon and carbon that the old star forged to go on living. They also contain rare elements - such as gold - that can be created only in the fury of the supernova explosion.

It was a supernova that made our own existence possible. The carbon in our bones, the minerals that make up Earth's rocks, the precious metals we adorn ourselves with - all are the products of a suicidal star.

The Moon

The moon moves in front of the bright star Spica on 18 March and hides it from view for more than half an hour. This is known as an "occultation" of Spica.

From London, Spica disappears at 11.06pm and reappears at 11.42; from Edinburgh it vanishes at 11.01, reappearing at 11.46. From the South-west, the occultation will be much shorter; from Cornwall, the Moon only just hides Spica; people in the Scilly Isles will see nothing at all.

The planets

Mars dominates the evening sky, shining as a deep orange "star", high in the south. Earth is pulling away from its slower-moving neighbour, and as a result Mars is rapidly fading: its brightness drops by half during March.

If you have a moderate telescope, this will be your last chance to see any details on the planet's tiny disc.

Jupiter rises in the South-east around 2am and is brilliant in the pre- dawn skies. Early in the month, you may spot the even brighter Venus to the lower left of Jupiter as the sky brightens.

Mercury is technically a "morning star" this month as well, but from Britain it will be lost in the morning twilight. It will be a splendid object as seen from the southern hemisphere. Saturn passes behind the Sun on 6 March and is not visible.

The stars

To the north, the seven-star Plough is hanging almost upside down. In North America it is known as the Big Dipper, and to many British schoolchildren - who have never seen a plough - it is the Saucepan!

In classical Greece and Rome this shape was part of a larger constellation, the Great Bear (Ursa Major).

Diary

1 11.48am new moon; Mercury at greatest western elongation

6 Saturn at conjunction

9 10.13am moon at first quarter

17 1.26am full moon

18 11.06-11.42pm occultation of Spica

21 2.14am spring equinox

23 8.10pm moon at last quarter

31 2.08am new moon

Suggested Topics
Start your day with The Independent, sign up for daily news emails
News
i100
Arts and Entertainment
Billie Piper as Brona in Penny Dreadful
tvReview: It’s business as usual in Victorian London. Let’s hope that changes as we get further into the new series spoiler alert
Life and Style
A nurse tends to a recovering patient on a general ward at The Queen Elizabeth Hospital in Birmingham
health
News
science
Arts and Entertainment
No Offence
tvReview: No Offence has characters who are larger than life and yet somehow completely true to life at the same time spoiler alert
News
Chuck Norris pictured in 1996
people
ebooks
ebooksA celebration of British elections
Arts and Entertainment
Sarah Lucas, I SCREAM DADDIO, Installation View, British Pavilion 2015
artWhy Sarah Lucas is the perfect choice to represent British art at the Venice Biennale
News
A voter placing a ballot paper in the box at a polling station
i100
News
people
Arts and Entertainment
The Queen (Kristin Scott Thomas) in The Audience
theatreReview: Stephen Daldry's direction is crisp in perfectly-timed revival
Sport
football
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

SThree: Trainee Recruitment Consultant - Dublin

£13676.46 - £16411.61 per annum + OTE: SThree: SThree Trainee Recruitment Cons...

Ashdown Group: Marketing or Business Graduate Opportunity - Norwich - £22,000

£18000 - £22000 per annum + training: Ashdown Group: Business and Marketing Gr...

SThree: Trainee Recruitment Consultant

£20000 - £25000 per annum + Commission: SThree: Are you great at building rela...

Ashdown Group: Database Analyst - Birmingham - £22,000 plus benefits

£20000 - £22000 per annum + excellent benefits: Ashdown Group: Application Sup...

Day In a Page

General Election 2015: Ed Miliband's unlikely journey from hapless geek to heart-throb

Miliband's unlikely journey from hapless geek to heart-throb

He was meant to be Labour's biggest handicap - but has become almost an asset
General Election 2015: A guide to the smaller parties, from the the National Health Action Party to the Church of the Militant Elvis Party

On the margins

From Militant Elvis to Women's Equality: a guide to the underdogs standing in the election
Amr Darrag: Ex-Muslim Brotherhood minister in exile still believes Egypt's military regime can be replaced with 'moderate' Islamic rule

'This is the battle of young Egypt for the future of our country'

Ex-Muslim Brotherhood minister Amr Darrag still believes the opposition can rid Egypt of its military regime and replace it with 'moderate' Islamic rule, he tells Robert Fisk
Why patients must rely less on doctors: Improving our own health is the 'blockbuster drug of the century'

Why patients must rely less on doctors

Improving our own health is the 'blockbuster drug of the century'
Sarah Lucas is the perfect artist to represent Britain at the Venice Biennale

Flesh in Venice

Sarah Lucas has filled the British pavilion at the Venice Biennale with slinky cats and casts of her female friends' private parts. It makes you proud to be a woman, says Karen Wright
11 best anti-ageing day creams

11 best anti-ageing day creams

Slow down the ageing process with one of these high-performance, hardworking anti-agers
Juventus 2 Real Madrid 1: Five things we learnt, including Iker Casillas is past it and Carlos Tevez remains effective

Juventus vs Real Madrid

Five things we learnt from the Italian's Champions League first leg win over the Spanish giants
Ashes 2015: Test series looks a lost cause for England... whoever takes over as ECB director of cricket

Ashes series looks a lost cause for England...

Whoever takes over as ECB director of cricket, says Stephen Brenkley
Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

Fishing is on Nigel Farage's mind

Ukip leader casts a line to the disaffected
Who is bombing whom in the Middle East? It's amazing they don't all hit each other

Who is bombing whom in the Middle East?

Robert Fisk untangles the countries and factions
China's influence on fashion: At the top of the game both creatively and commercially

China's influence on fashion

At the top of the game both creatively and commercially
Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

The man known as GOD has a reputation for getting the job done

Lord O'Donnell's three principles of rule
Rainbow shades: It's all bright on the night

Rainbow shades

It's all bright on the night
'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

Bread from heaven

Dutch survivors thank RAF for World War II drop that saved millions
Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

How 'the Axe' helped Labour

UK will be 'run for the wealthy and powerful' if Tories retain power