Page 1 of 1

Is this real?

Posted: 10.01.2007, 18:57
by PlutonianEmpire
http://www.theregister.co.uk/2004/02/18 ... _in_space/

The biggest ever diamond has been found floating in space. The gem, estimated at close to 10 billion trillion trillion carats, is at the core of a dead star (BPM 37093) - a crystallised white dwarf.
The newly-discovered diamond in the sky is a whopping great chunk of crystallised carbon 50 light-years from the Earth in the constellation Centaurus. It is 2,500 miles across (the moon is approximately 2,200 miles across) and weighs 5 million trillion trillion pounds. It has been dubbed "Lucy" in reference to the Beatles' song, "Lucy in the Sky with Diamonds". Diamond specialists told the research team that if nothing else, the diamond was much too big to wear.

Theorists have long speculated that the cores of extinct white dwarves would crystallise, but until now have had no way to prove it. However, the white dwarf is not only radiant but also harmonious. It 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," explained Travis Metcalfe, head of the team at Harvard Smithsonian Centre for Astrophysics.

Our own Sun will become a white dwarf when it dies 5 billion years from now, having first expanded to engulf almost everything in the solar system. Two billion years after that, the core will crystallise, leaving a giant diamond in its place.

8O

after 2 billion years, do white dwarves still give off heat or light? What's currently the biggest known white dwarf out there?

Posted: 10.01.2007, 21:08
by selden
A quick Web search should find you the answers:

white dwarf lifetime

Posted: 10.01.2007, 21:47
by PlutonianEmpire
selden wrote:A quick Web search should find you the answers:

white dwarf lifetime

Don't wanna do a web search. It usually brings up unrelated bs anyway.

Posted: 10.01.2007, 21:51
by t00fri
PlutonianEmpire wrote:
selden wrote:A quick Web search should find you the answers:

white dwarf lifetime
Don't wanna do a web search. It usually brings up unrelated bs anyway.


That I cannot confirm. It all depends on the questions you ask to the net. The latter requires a certain practice like most things.

Bye Fridger

Posted: 10.01.2007, 21:58
by PlutonianEmpire
t00fri wrote:
PlutonianEmpire wrote:
selden wrote:A quick Web search should find you the answers:

white dwarf lifetime
Don't wanna do a web search. It usually brings up unrelated bs anyway.

That I cannot confirm. It all depends on the questions you ask to the net. The latter requires a certain practice like most things.

Bye Fridger

Sorry. Anyhoo, i found what i needed (for the most part) on wikipedia.

I still need info about my second question: what's the largest white dwarf that we have found, in terms of radius in km?

Posted: 10.01.2007, 22:33
by t00fri
Since we got the Chandrasekhar limit for the maximum possible mass of white dwarfs, why don't you simply convert it into a Radius with some plausible assumptions about the density?

I am sure you know that this familiar limit derives from the electron degeneracy pressure and amounts to ~3x10^30 kg or 1.44 times the mass of the Sun.

Bye Fridger

Posted: 10.01.2007, 22:37
by PlutonianEmpire
t00fri wrote:Since we got the Chandrasekhar limit for the maximum possible mass of white dwarfs, why don't you simply convert it into a Radius with some plausible assumptions about the density?

I am sure you know that this familiar limit derives from the electron degeneracy pressure and amounts to ~3x10^30 kg or 1.44 times the mass of the Sun.

Bye Fridger

Well, what I DO know from reading the articles I have found is that the greater the mass, the smaller the the radius, thus, what I really ask is, "what's the lowest mass white dwarf that we have found so far?"

Am i right?

Posted: 10.01.2007, 23:04
by ajtribick
A very quick Google search for low mass white dwarf turned up the following:

A Helium White Dwarf of Extremely Low Mass

Mass = 0.196 solar masses
Radius = 0.047 solar radii = 32700 km

Interestingly it seems that the lowest mass helium-core white dwarfs tend to be in binary systems.

Posted: 10.01.2007, 23:20
by PlutonianEmpire
Ahhh, thanks :)

Any simple formulae I can use to determine a white dwarf mass by using a radius as a starting number? I ask 'cuz i have a fictional white dwarf system that I wanna have as realistic as possible....