Pulsars

The pulsar is a topic I have often heard about and was always curious about the major facts of their existence. Most documentaries I've watched have covered some of the main concepts of pulsars: rotating neutron stars that have cones of radiation emitting from it's magnetic poles. However I haven't really dug deeper into the other observations made about them. Are there more than one type of pulsar/ neutron star? What exactly classifies a neutron star? Are there any in our galaxy? What would happen to objects near it?
So let's dive in then and look some of this up.
Starting from the beginning of the topic, the neutron star. A neutron star is an extremely dense, usually very small (average so far is about 20 km diameter), core of a star left over from a supernova. It's remnants are the matter that was unable to escape the intense gravity at the core during the supernova (usually around 2-3 solar masses). This matter collapses down so much that protons and electrons combine to for neutrons. Neutron star, makes sense. Since a neutron star has such a small radius comparatively to it's former star self, the rotational speed of the neutron star is extremely high. The concept of a neutron star was proposed in 1934 and was confirmed in 1967 through the discovery of a pulsar. They emit electromagnetic  radiation and they usually appear white in the visible spectrum since they generally emit photons across the spectrum.
Most of the neutron stars discovered have been in the form of a pulsar which is a rotating, highly magnetized version of a neutron star. The rotation is determined by the cone of radiation crossing the path of the earth. We can use it's blinking of the cones from the poles to see the rotational period of the pulsar. Usually many pulsars spin extremely fast upon creation but gradually lose their energy and begin to slow down. The average speed of a pulsar we can observe today range from one second to 30 seconds. However there are others that are much faster than this still. The crab nebula has a pulsar at it's center that has a rotational period of about 30 rotations a second. This pulsar is one of the more famous ones since it is the result of one of the few witnessed supernovas by mankind; it happened in 1054 AD and was observed by Chinese and European astronomers during the day!

http://www.jb.man.ac.uk/pulsar/Education/Sounds/crab.au

The Crab Nebula picture (Optical and X-ray composite) and a link to the sounds representing the radio-waves detected from the pulsar.


There are multiple categories of pulsars relating to the way in which they power their electromagnetic emissions.
Rotation powered pulsars are pulsars that transform rotational energy into electromagnetic emissions and lose energy in the system this way.
Accretion powered pulsars are pulsars that are usually in a binary system with another star and fuel the emissions through matter taken from the neighboring star and merging it with it's own mass. Pulsars that are this type usually emit in the X-ray portion of the spectrum.
Magnetars are the third type which gain the power for emission through the decay of it's own intense magnetic field. Magnetars are usually the shortest lived of pulsars, halting it's emissions over the course of around 10,000 years.
Since pulsars slow their rotation gradually overtime, not allowing the electromagnetic radiation to pass by earth, they become "dormant" as we can no longer observe them. The time it takes for this to happen is usually 10-100million years after it's creation. Over the time of the Universe's existence, it is believed that 99% of all pulsars are now dormant.
 Pulsars are generally located in most areas of space including our own galaxy. Currently we know of 2000 neutron stars in our galaxy alone. The closest one to us is 130 parsecs away.
Interaction with a neutron star can be quite devastating. In Binary systems, they are known to eventually steal mass from it's partner star and use that to fuel it's emissions. If the second star is large enough and becomes a neutron star itself, if they remain in orbit together, it is theorized that the two neutron stars can eventually collide and form a black hole.
There have been cases of planets being discovered around pulsars as well. One such case, located in the Milky Way, theorizes that the planet orbiting the pulsar is now a crystalline carbon planet, a diamond planet. The theories push that the planet was originally a star in a binary system with the pulsar. When the star moved into a closer orbit with the pulsar, the pulsar began stealing it's mass until it took away 99.9% of its mass leaving it a cold fusion-less planet known as a white dwarf. Measurements indicate that it's density is high enough that the mostly carbon composition of the planet is most likely in a crystalline state. According to the article, this planet is an object that helps challenge the definitions of what is a star and what is a planet.

Artistic rendition of the pulsar with the orbiting white dwarf. The rotational period of the star is about 10,000 revolutions per minute and the white dwarf orbits around the pulsar once every 2 hours and 10 minutes.

As for other planets orbiting the pulsar before it became one, they would need to survive the supernova that creates the pulsar to remain part of the system afterwards. In most cases, regular rocky and gaseous planets would be blasted away by a supernova and would not remain.
One thing I had trouble finding was the effects of the x-ray and other electromagnetic emissions on other bodies such as planets and stars or even other systems. I figure they would be extremely detrimental towards life, but for the stability of other star systems, if they were close enough, would the constant bursts be enough to destabilize orbits?


Sources:
http://www.cosmosmagazine.com/news/planet-made-diamond-found-milky-way/
http://www.astrophysicsspectator.com/topics/milkyway/RadioPulsarDistribution.html
http://imagine.gsfc.nasa.gov/docs/science/know_l2/pulsars.html
http://imagine.gsfc.nasa.gov/docs/science/know_l1/pulsars.html
http://en.wikipedia.org/wiki/Pulsar
http://en.wikipedia.org/wiki/Neutron_star
http://www.jb.man.ac.uk/pulsar/Education/Sounds/sounds.html

Astronomers

Late to the party but hopefully I'll be able to get used to this.

Starting off, we were asked to talk about what we think an astronomer does when we started off this quarter. This post may be a little late, but I'll use my mindset from January.
From what I knew on the topic, I figured that an astronomer was responsible for the identification and categorization of the entire night sky. This would involve observing each item able to be observed as well as being able to distinguish its individual features from other objects in the sky so as to not confuse things like a single star and a galaxy. Even with all the time we have spent watching the sky as a species, there are enough things in the night sky that still need observance or reevaluation.
Since technologies have become more and more refined, and with the placement of telescopes in space, our ability to distinguish bodies in the night sky has improved dramatically. This allowed for the discovery of exoplanets, different types of stars, the timeline of the life of a star, distances more vast then anticipated, as well as our position and level of uniqueness in this vast universe. Through more observation I figured with current technologies, it would just be a matter of time before the universe was categorized for the most part and that not many more advancements were needed in the field of observation. An improper thought in the field of physics; the idea that we are close to done. 
It is interesting to think that not too long ago (over written history) we believed that our Milky Way galaxy was believed to be the entire observable universe.
Through what I've learned from the course thus far, I know more about how much telescopes have improved over the last decade as well as how they can improve even more so in the future. With this improvement however, there are still objects out there that are still extremely difficult to observe due to the distances they are from us and the amount of photons we receive from them being such a small amount. I've also learned how important the different parts of the electromagnetic spectrum are for determining features of distant objects from temperature to composition.
I am still curious about the creation of new stars from supernova of older stars. Since heavy elements are made throughout the lifetime of a star, and even heavier elements through supernova, I wonder what happens to those elements in the ejected cloud and whether they always end up in planets or asteroids, or can end up just becoming a cloud of atoms. Or are their cases where the heavier elements will end up in a star and stop it from reaching a point where it can reach fusion levels by interacting with the hydrogen to make new compounds.