White Dwarf Caught Destroying a Large Asteroid

 

A Ceres-like asteroid is slowly disintegrating as it orbits a white dwarf star. Astronomers have spotted telltales signs of such an object using data from the Kepler K2 mission. It is the first planetary object detected transiting a white dwarf. Within about a million years the object will be destroyed, leaving a thin dusting of metals on the surface of the white dwarf.

During observations of the white dwarf WD 1145+017, astronomers noticed  the presence of several planetary pieces in orbit.   The total mass of debris is thought to be around the size of the asteroid Ceres in our solar system's main asteroid belt.

These small planetary husks, all having orbits of between 4.5 to 4.9 hours, are too small to be seen by themselves; but their presence became known when the researchers detected huge dust clouds trailing them in their orbits. Follow-up observations by ground-based observatories were used to decipher what elements are inside the debris.

read the complete article here

Rare Binary White Dwarfs Discovered

I just read this killer article in the Daily Galaxy about white dwarf stars. To be precise a binary pair of white dwarfs that are orbiting each other once every 39 minutes! Oh wait, it gets weirder. In a few million years they will collide and merge to create a single star! Ok I hear the comments. So, you have a rare event here, but what is so strange about 2 stars colliding to make one?

To answer that we really should take a moment to figure out just what a white dwarf star really is. The Daily Galaxy article really does it best:

• White Dwarfs are among the oldest objects in the galaxy and are the remnants of the earliest phases of star formation. No bigger than the Earth, they are formed when a star like our Sun ends its life.

And weirder still:

• Out of the 100 billion stars in the Milky Way, only a handful of merging white dwarf systems are known to exist. The latest discovery will be the first of the group to merge AND be reborn.

That's right, two dead remains of long dead stars will combine to make a brand new star, not a bunch of junk from two dead stars... But you thought that it can't get any weirder? Oh my...we have only scratched the surface. Check this:

• The two white dwarfs orbit each other at a distance of 140,000 miles -- less than the distance from the Earth to the Moon. (Their orbital speeds reach upwards) of 270 miles per second or 1 million miles per hour!

Ok, now this is important.... in the normal stream of events, when two white dwarfs collide, the produce a super-nova. But and this is a big but...(ok, I know, I could have gone there but give me a little credit for not being juvenile 24/7) for a supernova to happen the mass must reach about 40% more than the mass of our sun. Now the binary system has one viable star which masses 17 percent of Sol and the second companion white dwarf weighs 43 percent. Now my high school math tells me that comes out to somewhere 60% or so. Instead of going boom, the new what....zombie star?... will begin fusing helium (which is the main element in the two dwarfs) and enter onto main sequence again, like a normal star.

Astronomers discovered the largest diamond of all times in space.

I found this article an interesting intellectual exercise. Why? Well, anyone that has studied even basic astronomy has heard about white dwarf stars and how they are formed, and what their makeup is like in latter stages of their life. Basically what I found interesting is that I understood the sequences of a star like our own or slightly larger going off main sequence. Going through it red giant stage and collapsing back to a white or brown dwarf. The cause is mostly running out of hydrogen and burning helium into carbon. (gross oversimplification, I know. ) Intellectually you know that this carbon has to be under extreme compression....but I just never went to the next logical step. What exactly is this compressed carbon....well in Pravda online (I know.... first time I ever ran across a straight science article here....one never knows) I saw a title that I just had to read. Astronomers discover largest diamond in space! Here are some excerpts, click on the article title to read complete story.

Astronomers discovered the largest diamond of all times in space. The weight is estimated at ten billion trillion trillion carats or five million trillion trillion pounds). The space diamond is virtually an enormous chunk of crystallized carbon, 4,000 kilometers in diameter. The stone is located at a distance of 50 light years from Earth, in the Constellation Centaurus. The "diamond" also known as BPM 37093, is actually a crystallized 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 and is coated by a thin layer of hydrogen and helium gases.