AstroBlonde

The last couple of days I've been sick. That has given me more time to update my homepage, AstronomiGuiden.

Screen print from AstronomiGuiden today

I've been asked some questions about a planet made of diamonds, that has an orbit around a neutron star. I can't say I know much about that planet, but I suspect it's an old star which has "died", leaving carbon and oxygen behind. Because of the last stages in a star's life, the core is belived to shrink and the density can get higher. From Wikipedia:

"In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice."

"Most natural diamonds are formed at high-pressure high-temperature conditions existing at depths of 140 to 190 kilometers (87 to 120 mi) in the Earth mantle."

So, my guess is that it's a dead star orbiting the neutron star. All gas might have been stolen by the neutron star as well. But, this is only what I think it might be.

For all you Swedes, you can read about this at Aftonbladet. I don't think Aftonbladet is especially good when it comes to science, but here's the link anyway:
Ny diamantplanet upptäckt
Scientific american has written about it here:
Diamond World Discovered by Astronomers

Something else that might be interesting is that Caffau et al. (Nature, today’s issue) report that a "mysterious" star has been discovered. Apparently a star in the Milkyway with very low metalicity, ie. low abundence in heavy elements. That means that the star contains almost exclusively of Hydrogen (H) and Helium (He). Those kind of stars are believed to be very old stars, because heavier elements are belived to form when stars dies.

Let's take it from the start:
It is belived that the Universe, when it was young, contained only light elements such as Hydrogen (H), Helium (He), Lithium (Li) and Beryllium (Be). But today, we have other heavier elements such as Iron (Fe) and lots of others. So, how was those elements created? Well, the most likely thing that can create heavier elements are stars. When stars die, they can explode and send a lot of gas out in the Universe. That gas, can then create new stars, but those new stars will contain of heavier elements than the star before. This leads to heavier and heavier elements for every generation of stars.

When knowing this, you can perhaps see why this star is different. It seems like it doesn't have heavier elements. That's why people are saying that it might be a really old star, perhaps the oldest one we've found so far. It is also located withing our galaxy, which contains a lot of gas. So, this is a new, interesting discovery! What else that is interesting is that this will be a new challenge for astronomers to understand. Earlier models for how stars are formed need some heavier elements to contribute to its formation. So this star should not have been formed according to the understanding we have so far. Very interesting indeed!

Swedish links:
ESO Swedish - Stjärnan som inte borde finnas
Sveriges radio - Mystisk stjärna funnen i Vintergatan

English link:
ESO English - The Star That Should Not Exist