As our knowledge of the universe beyond our Solar System expands, the true wonder and complexity of it is slowly revealed. At one time, scientists believed that other systems would be very much like our own, with planets taking on either a rocky or gaseous form, and stars conforming to basic classifications that determined their size, mass, and radiation output. However, several discoveries of late have confounded these assumptions, and led us to believe that just about anything could exist out there.
For example, a team of astronomers at the University of Wisconsin-Milwaukee recently identified the coldest, faintest white dwarf star ever detected, some 900 light years from Earth. Hovering near a much larger pulsar, this ancient stellar remnant has a temperature of less than 3,000 K, or about 2,700 degrees Celsius, which made it extremely difficult to detect. But what is especially impressive about this ancient stellar remnant is the fact that it is so cool that its carbon has crystallized.
This means, in effect, that this star has formed itself into an Earth-size diamond in space. The discovery was made by Prof. David Kaplan and his team from the UofW-M using the National Radio Astronomy Observatory’s (NRAO) Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA), as well as other observatories. All of these instruments were needed to spot this star because its low energy output means that it is essentially “a diamond in the rough”, the rough being the endless vacuum of space, that is.
White dwarves like this one are what happens after a star about the size of our Sun spends all of its nuclear fuel and throws its outer layers off, leaving behind a tiny, super-dense core of elements (like carbon and oxygen). They burn at an excruciatingly slow pace, taking billions and billions of years to finally go out. Even newly transformed white dwarfs are incredibly hard to spot compared to active stars, and this one was only discovered because it happens to be nestled right up next to a pulsar.
By definition, a pulsar is what is left over when a neutron star when a slightly larger sun also runs its course. Those that spin are given the name of “pulsar” because their magnetic fields force radio waves out in tight beams that give the illusion of pulsations as they whir around, effectively strobing the universe like lighthouse. The pulsar that sits next to the diamond-encrusted white dwarf is known as PSR J2222-0137, and is 1.2 times the mass of our sun, but even smaller than the white dwarf.
Astronomers were tipped off to the presence of something near the pulsar by distortions in its radio waves, and an old-fashioned space hunt was then mounted for the culprit. The low mass made a white dwarf the most likely cause, but astronomers couldn’t see it because of its incredibly low luminosity. Because of this, the UofW-M team estimated the age of this object had to be upward of 11 billion years, the same age as the Milky Way Galaxy.
This meant that the object was already old when our galaxy was just beginning to coalesce. After all those eons to cool off, the star has likely collapsed into a crystallized chunk of carbon mixed with oxygen and some other elements. It could actually be possible, though extremely difficult, to land a spacecraft on an object like this. There may be many more stars in the sky with diamonds, perhaps some even older than this one.
Spotting this white dwarf was a bit of a fluke, though. Until more powerful instruments are devised that can see an incredibly dim, burnt out star, they’ll remain shrouded in the vast darkness of space. However, this is not the first time that an object composed of diamond was found in space by sheer stroke of luck. Remember the diamond planet, a body located some 40 light years from Earth that orbits the binary star 55 Cancri?
Yep that one! Like I said, such discoveries are demonstrating that the universe is a much more interesting, awesome, and complex place than previously thought. Between diamond worlds, diamond planets, lakes of methane and atmospheres of plastic, it seems that just about anything is possible. Good to know, seeing as how so much of our plans for the future depend upon on getting out there!