Butterfly in Scorpius
Jan 6, 2010
A few thousand years ago, a star in the constellation Scorpius ran out of gas. "Ran out of gas" is technically not quite correct--the star still has plenty of gas in its core that is burning hotter and brighter than ever--at an estimated temperature of 250,000 degrees Centigrade. But the star is dying; away from its core, its layers of gases have been torn loose and are now floating away, flung out into space. When some stars die, the fleeing gases expand spherically but oftentimes, as here, the gases are flung out asymmetrically, giving the impression of butterfly wings. In ultraviolet light, the core of the dying star would show up as a white-hot disc in the center of this nebula, but here in an image from the newly upgraded Hubble Space Telescope, the central star cannot be seen at all; it is shrouded by a dense cloud of cosmic dust.
The gases in the butterfly wings are escaping the old star at the rate of 400 kilometers per second--almost 900,000 miles per hour. They will eventually be lost in space. The core will flame out and perhaps collapse in on itself, creating an extremely dense object that is incomprehensible to me and my non-physicist friends.
When our own sun starts behaving this way and flinging out dust and hot gases in our direction, we'll have perhaps a week or two before we're swallowed up in the wings of a butterfly. But our sun is believed to be a middle-aged star, so we've still got plenty of time to think of nebulae as awesome instead of dangerous.