StarDate: ‘New’ Stars

FROM THE UNIVERSITY OF TEXAS McDONALD OBSERVATORY, AS HEARD ON KCBS RADIO WEEKDAYS @ 9:52 A.M., 7:35 P.M. & 2:52 A.M

STARDATE 7/18/14: At Christmas of 1934, a bright “new” star exploded to life in Hercules. For a few days, it was one of the brightest stars in the night sky. It made the front pages of newspapers, and astronomers tracked it for months as it slowly faded from sight.

The star is known as DQ Herculis, and astronomers are still tracking it today. In fact, a team of astronomers has used Hubble Space Telescope to study DQ Herculis and three similar stars. Their work has demonstrated that some of the ideas about this class of stars are wrong.

Each of these stars erupted as a nova — a powerful explosion on the surface of a dead star known as a white dwarf. The white dwarf stole gas from a nearby companion star. When enough gas piled up on the star’s surface, it triggered a runaway nuclear explosion.

But when the four target stars first appeared, in the early 20th century, the cause of these outbursts was still unknown. All that astronomers knew was that a bright star suddenly appeared where no star had been seen before.

Yet they observed these enigmatic objects in detail. Using their eyes and their knowledge of the night sky, they tracked how bright each nova looked as it faded from view over the weeks or months.

In the decades since, other astronomers have used those observations and those of similar stars to try to draw some conclusions about all novae. But the recent Hubble observations demonstrated that some of those conclusions were wrong. More about that tomorrow.

Script by Damond Benningfield Copyright ©2014 The University of Texas McDonald Observatory