Shakespeare got it!

Hamlet:
O God, I could be bounded in a nutshell, and count myself a
king of infinite space

My Dissertation, Decisions Decisions! - X-ray Binaries

Recently I was given the suggested list of topics for my dissertation. However none of them took my fancy, so started my search for another topic. I thought about Active Galactic Nuclei(AGN) as it is the topic for which I would like to study for my Ph.D. Alas it had been done last year and they strongly recommend against something that was done in the previous couple of years.

So I was trying to think of a reasonably exciting topic and hopefully something with some sort of relation to AGN. In my lab work this week we where talking about Binary systems (I've got to update some predictions of when there gonna eclipse) this got me thinking about X-ray Binaries. So I've had a little bit of look around for some paper and books -still in the process of reading them. They're pretty interesting and accretion powered just like AGN which is a win win.

Heres a bit of background on binary star systems their when 2 stars orbit a common centre of mass(around each other) in an X-ray binary system one of the stars is a compact object(neutron star or a black hole). As the compact object has a strong gravitational field is can sometimes take some of the matter from is 'companion' star this produces X-rays hence there name.

So here's what I know so far. X-ray binaries come in two types - when companion star is high or low mass. In the high mass case the companion is massive enough to resist the compact objects gravitational pull however due to its high mass it also burns much hotter and this drives off some matter(this is known as stellar wind), which is then collected by the compact object. These systems tend to undergo pulsations in X-ray observations and there companion star tends to dominate the optical emissions.

The second type is when the low mass companion star can not resist the pull of the compact object. In this situation the matter of the companion closest to the compact object pulled towards it more than the matter on the other side. This creates a distortion and allows some of the matter to pass point at which the companion can pull it back -this is called a Lagrangian point. Once passed the Lagrangian point the matter heads straight for the compact object- This is called Roche-lobe overflow. It can't fall directly in as angular momentum must be conserved so the matter forms a disk around the compact object-this is also true for the former case.

Once in the accretion disk the material loses angular momentum as it does this it gets closer to the compact object before in the inner regions it falls into it. It is from the inner regions of the which the X-rays are emitted.

The energy gained in accretion is gravitational potential energy. Its really just a fancy way of saying the energy given to matter when its pulled on by other matter and as gravity gets stronger the closer the masses. The more massive the object pulling the matter in and the closer the matter gets to the object the more energy is released. So as the compact objects are very very massive the matter falling into them gains a huge amount of energy.

Thats no all I've learned but its getting pretty late and this post has gotten quite long so I'll leave it here for now.

Close to 1

In a quantum mechanics lecture last year, the subject of relative values came up. My lecturer said that a certain value was close to 1 then said in this example it was 2. To which one of the other students seemed quite confused and remarked about how he(my lecturer) had just said it was close to 1 to which my lecturer replied 2 is close to 1 it's not like it's a 1,000 or a 1,000,000. A bit of background my lecturer like pretty much all the lecturers at keele is an astronomer so he deals with very large numbers most of the time.

Now it might sound like the student was being very silly but thinking back at it there are an infinite number of values between 1 and 2 but you could say that about any value. I just thought it was interesting to think about the scales of numbers and how to say some value is close to another depends heavily on the context.

Definition of a Planet

A Planet must...

• Obit around a Star
• Be sufficiently large that it's self gravity can overcome rigid body forces (it's nearly round).
• Have cleared the area around it's orbit from debris

It is the last bullet point that means Pluto is not a planet.

Source

Galactic Punctuation and Collisions

VV340 (also known as Arp 340 or UGC 9618) is a pair of interacting gas rich spiral galaxies in the Bootes constellation. Located ~450 million light years from Earth.

It is classified as Luminous Infrared Galaxy (LIRG). LIRGs produce high amounts of IR radiation and can emit from tens to hundreds times more energy than typical galaxies. Actively growing supermassive black holes (AGN) or an intense period of star formation are normally attributed to be the cause of this energy production.

Spitzer data shows that the majority of the IR emissions is coming from the edge on galaxy (VV340 North), and coupled with data from Chandra there is strong evidence for a growing supermassive black hole (SMBH) at its centre obscured by the rest of the galaxy - however only a small proportion of the IR radiation is emitted from SMBH region. However in the UV and short wavelength optical emissions from GALEX and Hubble observations, show that VV340 South to be the brighter suggesting that it has a much higher level of star formation.

Colliding galaxies like this are a premonition of our own Milkyway's future. As we are predicted to be on a collision course with Andromeda. But before anyone starts preaching the apocalypse it's not going to happen for another 3 to 5 billion years. So where safe! Galactic cannibalism is not rare! In fact there are 2 BHs in Andromeda's nucleus. The second BH may well be from a galactic collision.

Juno

The Space mission not the film about the pregnant girl with Michael Cera playing his usual role. Set sail last friday as part of NASA's new frontiers program, it will take about five years to get to Jupiter where it will then spend a year orbiting the gas giant.

The main objectives of Juno are to peer into Jupiter's interior to determine how it formed and to map its atmosphere below the clouds to determine its global structure and motion. Also to be probed is Jupiter's magnetosphere by directly sampling charged particles and measuring the magnetic field while observing the auroras in the UV-region. It is suspected that in the inner atmosphere the hydrogen it contains is under such high pressure it becomes a fluid known as metallic hydrogen which is thought to be the source of Jupiter's magnetic field hopefully Juno will shed some light on this.

The name for Juno is very apt as in Greek-Roman mythology Jupiter drew a vail of clouds around him self to hide his mischief and it was Jupiter's wife Juno who peered though the clouds and exposed Jupiter. Hopefully the spacecraft will live up to it's name.

Lego figures of (From left to right) the gods Jupiter and Juno as well as astronomer Galileo Galilei made of aluminium have been sent along for the ride.

Maths/Physics tattoo

Is it sad that instantaneously knew this was the Maclaurin series for sine?


Note! the if you follow the link the guy says it's a Taylor series but its a Taylor series where that starting point is zero so it's a Maclaurin series