G2HGE BONUS EPISODE : Kappa Iota and the Turix star
Hey, haven't you ever wondered where the neutron star Turix might be located ?
You remember Turix, right ? From lore that's not at all insignificant and obscure ?
March 18, 2185 : “Astronomers are excited tonight as the probe TR-15 Letus comes the closest any probe has ever come to a neutron star. The star in question is in a globular cluster approximately 18,000 light-years from Earth. Though it contains slightly more than two times the mass of Earth's sun, its radius is a tiny 15.8 kilometers, spinning at approximately 24% of the speed of light. The probe was sent to the star via the Kappa Iota Relay, a charted but rarely-used relay predating the Rachni War. The relay was abandoned due to the highly lethal radiation found on the other side, but the small doses that pass through the relay are manageable for a shielded probe. Control of the radiation emission and reception of Letus's signal is made possible by the infamous Dark Switches, a set of previously unknown control functions the Protheans installed on mass effect relays.”
May 26, 2185 : “The astronomical team that launched the TR-15 Letus probe is being blasted by the scientific community for falsifying results about the neutron star Turix. "The data they were posting was too good to be true", said Dr. Aurana T'Meles, who reviewed their work. "When they claimed to have sent the probe through the relay leading to Turix, we all wondered how and why the Protheans could have built a corresponding relay so close to such an energetic star. Then came questions about isolating the probe's signals from the radiation, claims of unprecedented dark energy control -- I would almost go so far as to use the word 'hoax'". Letus team lead Dr. Akil Carinii apologized for what he called "sloppy record-keeping" but insisted his findings were authentic. "The galactic community has but scratched the surface of all the functions of mass relays", he said, "and my team will continue to try to solve their mysteries".”
Key takeaways :
Turix is a very energetic neutron star ;
It is in a globular cluster ;
It is 18,000 light-years from Earth ;
There is a relay close to Turix ;
Its twin is the Kappa Iota relay, which has been accessible since before the Rachni Wars (i.e. since any date between 580 BCE and 1 CE) but has been rarely used because of all the radiation on the other side, seemingly filtering through when the relay is active.
What if we tried to place it on a map ?
Our solar system is estimated to be between 12 and 22 parsecs from the galactic plane, i.e. between 39 and 72 light-years ; on the map we'll be using, the unit is the thousand of light-years, so we can assume, for our purposes, that Sol is flush on the galactic plane.
Sol is also about 26,000 light-years from the Galactic Center ; the Milky Way as a whole is approximately 100,000 light-years across and about 1000 light-years thick at the spiral arms (more at the bar in the center). Most of the stars of the Milky Way are situated in or around the galactic plane, but not all of them.
If Turix is about 18,000 light-years from Earth, we have to calculate where it might fall both on the galactic plane but also above and below.
If Turix is on the galactic plane itself, at its closest it would be merely 8000 light-years from the Galactic Center (in conjunction with it relative to Earth) while at its furthest it would be at 44,000 light-years from the Galactic Center (in opposition to it relative to Earth).
But what if it's above or below the plane ? Well, you know who to call… our good friend Pythagoras.
(That's right, who said geometry had no real-world uses ?)
We can assume that wherever Turix is relative to the galactic plane, it is one of the vertices (T) of a right triangle with another vertex being where the Sol system (S) is ; the third and right angle of that triangle being the intersection of the line passing through both T and the galactic plane that is also the shortest distance between both, i.e. a line perpendicular to the galactic plane. This vertex we'll call G.
We'll call that side of the triangle between T and G a, the side of the triangle between G and S b, and the side of the triangle between S and T c, the hypotenuse. We know that c = 18,000 light-years, and that a will be anywhere between 0 and 500 light-years (half the thickness of the galaxy) ; but if we want to place Turix on a map showing the flattened galaxy, as in the Galaxy Map, we need the length of b. As we want to calculate a possible range, we'll assume a = 500 light-years, which will be the maximal distance of Turix from the galactic plane.
Given that our triangle is a right triangle, we can calculate the length of any side as long as we have the other two, using the Pythagorean theorem : a^2 + b^2 = c^2 ; therefore, b^2 = c^2 - a^2, and b will be equal to the square root of the difference of c^2 and a^2.
c^2 = 18,000 x 18,000 = 324,000,000
a^2 = 500 x 500 = 250,000
b^2 = c^2 - a^2 = 324,000,000 - 250,000 = 323,750,000
b = √323,750,000 = 17,993.05 (and then some)
In practice, what does this mean for us ?
It means that, on the Galaxy Map, Turix would be anywhere between 17,993.05 and 18,000 light-years from Earth. As these are effectively indistinguishable on a map of that scale, that means Turix could be any point on a circle on the Galaxy Map whose center is the Sol system and whose radius is 18,000 light-years.
And maybe we can refine it further with history ! Since Turix was accessible prior to the Rachni Wars, then it can only have been accessible from one of the clusters which had been opened before !
LET'S BREAK OUT THE MAP !!!!!!!!!!
A few notes :
the Sol system is at the center of the red circle where Turix can be. I stress again that Turix can only be on the circle itself, not within it.
the three clusters within the circle who cannot not have been accessible on the eve of the Rachni Wars are the Annos Basin (salarian home cluster), the Aethon Cluster (volus home cluster) and the Horsehead Nebula (the only way for the salarians to access the rachni home cluster). The connections between these clusters and other clusters outside of that range are shown with full red lines ; the Aethon Cluster is not connected to anything because its only canon connection is to the Apien Crest, which wouldn't have been accessible before the Rachni Wars ; in other words, we do not know how the Aethon Cluster connects to the Citadel, and what other clusters (or neutron stars) may branch off it.
The clusters which may or may not have been accessible prior to the Rachni Wars are also shown, but with a dotted red line connecting them to surefire clusters. In practice, we only see clusters branching off the Horse Head Nebula, because while the Annos Basin and the Aethon Cluster must have additional connections, we just don't know them.
The territory with green borders is the presumed territory of the Salarian Union (+ hanar space, included and not set apart because we don't know when first contact was made with the hanar).
Within the red circle, there are two zones with parallel black lines the closer you get to the Galactic Center : the outermost black arc is the Five Kiloparsec Ring, an area of intense star formation around the galactic core too dangerous to travel. The innermost black arc is the 4-kpc limit, which is usually considered the radius of the deadly galactic core itself, and the inner limit of the so-called Life Zone in the galaxy (i.e. the zone where life could develop at all) ; beyond that, closer to the core, life is impossible. Note that the map suggests that salarian territory partly extends into these zones.
The dotted parts of the red circle are the furthest from the Citadel and the other accessible clusters prior to the Rachni Wars, meaning Turix is far less likely to be there.
At this point, the only thing we can be certain of is that Turix cannot be outside the red circle ; and moreover, that it cannot be in the central region of the map (the Galactic Core) as it is inaccessible. The closest to the Galactic Core it can be, historically speaking, is within the green region that's likely to be Salarian Union space.
Ah, fuck, I forgot to include the Serpent Nebula and the Apien Crest, which were both active (if unconnected) prior to the Rachni Wars, and which might both plausibly lead to Turix. Be right back.
Note that I am not connecting the Apien Crest to either the Serpent Nebula or the Aethon Cluster, since (for some reason) the turians were off doing their own thing until c.700 CE, i.e. four hundred years after the end of the Rachni Wars (and, uh, seven hundred years after their start).
This means, of course, that the turians had their own parallel mini relay network before c.700 CE.
Could Turix have been part of it ?
I'm not gonna lie, "Turix" sounds really turixturian, so I think the odds are pretty significant. Let's consider the circumstantial evidence :
"Turix" sounds turian ;
"Letus", the name of the probe going through the relay, sounds turian, i.e. Latinish ;
"Akil Carinii", the name of the lead researcher in charge of the probe, is 100% a turian-sounding name.
So it really sounds like a turian affair, suggesting turians first accessed and then ran away from Turix. But again, it could be circumstantial : maybe the star's name was a string of numbers, but Akil Carinii decided to name it Turix after his boyfriend or girlfriend or kid or pet pyjak or something.
Anyway, we can't know anything else.
Case closed !
Turix is in a globular cluster, which can be found anywhere in the galactic halo, i.e. a spheroid region with a radius of about 100 kpc i.e. 326,156.38 light-years. This is significant, because now Turix couldn't just be anywhere on a circle centered on Earth 36,000 light-years across, but anywhere within the corresponding sphere.
GASP !
Okay, hold your horses : globular clusters congregate around the galactic core but above and below the galaxy's disk (where we are), i.e. far from the galactic plane.
A neutron star is what's left after a massive, dying star has exploded into a supernova — the dead, ultra-dense heart of the star. A neutron star is the extremely heavy remains of a star whose escape velocity (i.e. the minimum speed an object must reach to escape the gravity of an astronomical body) is nonetheless lower than the speed of light ; otherwise, what you have is a black hole.
Neutron stars are formed out of main-sequence stars whose initial mass is at least 8 times the mass of the sun, but no more than 40 times the sun's mass (i.e. the bigger B-type and the smaller O-type stars), subsequently increasing as they go through a supergiant phase until the core collapses into a neutron star and the rest of the star explodes into a Type II supernova.
Current models state that a neutron star's maximum mass before it becomes a black hole would be between 2.2 and 2.4 times the mass of the sun.
Turix is a neutron star with several known properties :
Mass : Slightly more than twice Sol's mass
Radius : 15.8 kilometers
It spins ; and it does so at about 24% of light speed.
First of all, we should note Turix is very large and very heavy for a neutron star. As a point of comparison, the pulsar PSR J0740+6620 is as heavy as 2.17 Sol's and a diameter of 24 km (i.e. a radius of 12 km) — and it is one of the most massive neutron stars ever recorded. But Turix is bizarrely large ; it would decrease its density, which might be a problem as neutron stars only exist if they're so dense the atoms of the old star core decay into rows upon rows of tightly-packed neutrons, who'd rather not be this close together, thank you very much. If the star isn't dense enough, the neutrons decay ! But that's clearly not the case here, given how mind-bogglingly massive Turix is.
(Watch me as I completely ignore what's likely to be a dev's mistake and/or comparative lack of scientific information given they only had the information that was on hand in ye year of yore 2010. They probably extrapolated what a really massive neutron star would be like out of what data was available at the time.)
EDIT : A look at the second page of the paper here suggests the radius, while extreme, is perfectly fine for a neutron star ! I stand humbled and corrected.
Moreover, what about that spin ? 24% of the speed of light is 71,950,189.92 m/s, or about 71,950.19 km per second. This means Turix would spin almost over four thousand times per second ! This isn't just a neutron star, but a millisecond pulsar !
Would you believe me if I told you that, in all likelihood, Turix is in fact a real neutron star, the fastest-spinning pulsar known at present in the globular cluster Terzan 5 approximately 18,000 light-years from Earth, spinning at approximately 24% of the speed of light ?
(I bet you didn't expect that plot twist !)
Turix's human name is PSR J1748−2446ad.
As for the Terzan 5 globular cluster, it lies toward the Galactic Center in the direction of Sagittarius and is found in the galactic bulge (i.e. the thickest, central part of the Milky Way), practically on the galactic plane and between Sol and the Galactic Center. In other words, it is…
ABOUT HERE !
Okay. Alright. I want to stress : there is no way on Earth that the dev (Hepler) who sat down to type out the CDN stories in 2010 for ME2 had come up with the regional division of the Milky Way we see crop up for the first time in ME3, and there is no way in hell he had worked out Terzan 5's location and the borders of the regions of the galaxy at the same time. This can't not be a coincidence.
Nonetheless, it's a wonderfully inspiring one.
Because it does look like Turix and the cluster it's at the center of (as an ultra-heavy neutron star, Turix would have naturally migrated to the center of its globular cluster due to mass segregation) is a landmark, a marker that serves as one of the cornerstones of salarian territory.
This would suggest that Turix and Terzan 5 are accessible either from the Serpent Nebula, the Annos Basin, or the Horse Head Nebula. Personally, I'd be a fan of Terzan 5 being accessible from the Annos Basin because the salarian home cluster's got a dearth of branching clusters, but there's no way to know.
(Worth pointing out : while the news story stresses that probes have a hard time getting close to a neutron star, Turix and its whereabouts seem uniquely inhospitable given that radiation filters through the Kappa Iota relay when it's active, to such an extent probes need to be shielded to even approach that relay. But in other circumstances, it is possible to mine "the asteroid debris that orbit neutron stars and pulsars" with the "extensive use of robotics, telepresence, and shielding to survive the incredible radiation from the dead star", alongside the "well-funded collection ships" called "Inferno-class" starships — it is is dangerous and very expensive, but it is possible, whereas even getting close to the relay leading to Turix was something of an (alleged) scientific breakthrough. We can presume the radiation off Turix is so massive because of the pulsar itself, all the densely-packed stars in Terzan 5, and the horrific radiation that's par for the course for the galactic core.)
And there you have it — an additional cluster on the galaxy map*.
* : Not like it's useful for anything anyway.
