It's a solid doomsday prediction that in about 5 billion
years the dying sun will expand as a bloated red giant and engulf the Earth.
But imagine if in just a few weeks the middle-aged sun suddenly
ballooned out to the orbit of Saturn and immediately vaporized Earth and most
of the other planets in the solar system! And, even before this happened, imagine
that every morning you awoke the sun was ever more sweltering until it began
evaporating the oceans, spontaneously starting forests ablaze, and melting
This sounds like the stuff of a far-out science fiction movie.
But astronomers think that they actually witnessed such an event in 2002. A
sun-like star on the edge of our galaxy abruptly grew 600,000 times brighter in
a few weeks and ballooned 1,000 times its diameter. Alien astronomers on
neighboring galaxies would have dutifully noted it as it briefly becoming one
of the brightest stars in our Milky Way galaxy.
Now, eight years later astronomers remain puzzled as to what
happened to the star, called V838 Monocerotis, and are still doing interstellar
forensic detective work.
The blast was not a supernova — the explosive death of a
massive star — because a red giant is now in the location of the outburst. The event
was too powerful to be a nova, where a white dwarf companion to a giant star explodes.
The brilliant hiccup of light from the flashbulb-like outburst
continues reverberating off interstellar dust clouds. This light echo has been
photo documented by the Hubble Space Telescope as one of the most bizarre faster-than-light illusions ever seen in space.
The dilemma has been to explain how a star can go rogue — or
rather go rouge — almost literally overnight.
Things have gotten only stranger. A team has just published their observations of X-rays coming from the red giant star. Red giants are cool stars and don’t emit X-rays. To do so they would have to
spin rapidly and have entangled magnetic fields. The loopy fields would entrap
gas, heat it to millions of degrees, and then snap like rubber bands to emit
titanic stellar flares.
But the spin rate of a red giant should be slow. By swelling
in size the rotational rate slows down to conserve angular momentum, like a
twirling figure skater extending their arms to de-spin. A rapidly spinning red giant
could be forensic evidence for a stellar head on collision that preceded the
The idea being kicked around is that V838 Mon. was
originally a triple-star system. A gravitational billiard game among the three
stars sent two of them careening together and explosively merge into a single
star. The heat from the impact caused the new star to swell up, like a runaway
hot air balloon. This is supported by the observation that a few weeks after
the initial burst, the stars suddenly got an additional 1,000 times brighter in
just one day. This might have been from the nuclear cores of the stars merging.
There is a stellar companion that could be the culprit that
started the mess. It was observed as a hot blue star in the vicinity of the
precursor star to the red giant. But it mysteriously vanished after the blast.
The belief is that it was engulfed in a cloud of dust blown out by the
collision and is hidden from view for now.
Thankfully, V838 Mon is only a few million years old and dwells
in a young open stars cluster. So it is not old enough for life as we know it
to have arisen and evolved.
But imagine the terror and gloom of living under a planet-wide
death sentence by knowing the exact time your entire world and planetary system
was going to go up in smoke!
Artwork credit: Black Cat Studios