A MONSTROUS pulsating star has been spotted near the centre of our galaxy, confirming a prediction that had almost been discarded as a theoretical blunder.
In 2000, Ernst Dorfi and Alfred Gautschy of the University of Vienna in Austria used a computer model to predict that the most massive stars in the universe should start pulsating as they reach the end of their lives. While this is a commonly observed phenomenon among low-mass stars such as the sun, there was no evidence for such behaviour in more massive stars, raising doubts about the theory behind the model.
Now, Darren DePoy and colleagues from Ohio State University in Columbus have found a giant pulsating star named IRS16SW that is consistent with Dorfi鈥檚 prediction. Pulsations occur as different nuclear reactions ignite towards the end of a star鈥檚 life. The energy produced lifts the star鈥檚 surface and cools its interior. This allows the star to shrink again, and the cycle restarts. In IRS16SW that cycle takes 9.725 days and alters its brightness by a factor of about 1.5. On average, the star is 90 times the sun鈥檚 diameter, and is estimated to be between 10 and 50 times the sun鈥檚 mass. The work will appear in the Astrophysical Journal.
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