[LINK] "Diamond star thrills astronomers"
Sep. 13th, 2010 07:32 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
rfmcdonaldThanks to Scott from Facebook for pointing me towards this remarkable story. The white dwarf BPM 37093, in the general direction of Alpha Centauri, I suppose (just keep going a total of fifty light years) has just provided proof of astronomers' theories of stellar evolution.
It's worth noting that most of the nearby white dwarfs are too young to have crystallized, particularly Sirius B and Procyon B. 40 Eridani B may be old enough--the whole system is estimated to be 5.6 billion years old, only a bit older than the sun--but I'm unaware of any estimates as to the timing of B's evolution, while the solitary white dwarf Van Maanen's Star certainly has crystallized if the two billion year timetable applies to it.
Twinkling in the sky is a diamond star of 10 billion trillion trillion carats, astronomers have discovered.
The cosmic diamond is a chunk of crystallised carbon, 4,000 km across, some 50 light-years from the Earth in the constellation Centaurus.
It's the compressed heart of an old star that was once bright like our Sun but has since faded and shrunk.
Astronomers have decided to call the star "Lucy" after the Beatles song, Lucy in the Sky with Diamonds.
[. . .]
The huge cosmic diamond - technically known as BPM 37093 - is actually a crystallised white dwarf. A white dwarf is the hot core of a star, left over after the star uses up its nuclear fuel and dies. It is made mostly of carbon.
For more than four decades, astronomers have thought that the interiors of white dwarfs crystallised, but obtaining direct evidence became possible only recently.
The white dwarf is not only radiant but also rings like a gigantic gong, undergoing constant pulsations.
"By measuring those pulsations, we were able to study the hidden interior of the white dwarf, just like seismograph measurements of earthquakes allow geologists to study the interior of the Earth.
"We figured out that the carbon interior of this white dwarf has solidified to form the galaxy's largest diamond," says Metcalfe.
Astronomers expect our Sun will become a white dwarf when it dies 5 billion years from now. Some two billion years after that, the Sun's ember core will crystallise as well, leaving a giant diamond in the centre of the solar system.
It's worth noting that most of the nearby white dwarfs are too young to have crystallized, particularly Sirius B and Procyon B. 40 Eridani B may be old enough--the whole system is estimated to be 5.6 billion years old, only a bit older than the sun--but I'm unaware of any estimates as to the timing of B's evolution, while the solitary white dwarf Van Maanen's Star certainly has crystallized if the two billion year timetable applies to it.
