APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
I think many of us were thinking the same thing! <g>ronavoig wrote:At first glimpse it reminded me of a Calabi–Yau manifold.
As with virtually every other object in the sky, The Vela Pulsar spends about 20% of the time being tracked on Fermi's LAT camera's detector.Chris Peterson wrote:
Ah... I misread things and took this to be where the camera points in the sky. So I'll agree that any particular source (in this case the Vela pulsar) is unlikely to ever be in exactly the same place on the focal plane. I don't think that's remotely the point of the image, however. What it illustrates, if anything, is how much time this object spends on the camera's detector despite the complex path it follows over the sky.
However, I don't know quite how one could possibly deduce that fact simply from the complex path the Vela Pulsar follows over the detector (even if one knew the time interval involved).http://en.wikipedia.org/wiki/Fermi_LAT#Large_Area_Telescope_.28LAT.29 wrote:
The LAT's field of view is large, about 20% of the sky.
It certainly does that.neufer wrote:What this APOD illustrates, IMO, is the complex elegant path this bright object makes on the wide field LAT camera's detector over a long period of time. (Not unlike: http://apod.nasa.gov/apod/ap120121.html )
Ronhttp://en.wikipedia.org/wiki/Vela_Pulsar wrote: <<The Vela Pulsar (PSR B0833-45 or PSR J0835-4510) is a radio, optical, X-ray and gamma-emitting pulsar associated with Vela Supernova Remnant, in the constellation of Vela. The association of the Vela pulsar with the Vela Supernova Remnant, made by astronomers at the University of Sydney in 1968, was direct observational proof that supernovae form neutron stars.
It has a period of 89 ms (the shortest known at the time of its discovery) and the remnant from the supernova explosion is estimated to be travelling at 1,200 km/s. It has the third brightest optical component of all known pulsars (V = 23.6 mag) which pulses twice for every single radio pulse. The Vela pulsar is the brightest persistent object in the high energy gamma ray sky.
In early 1970, Curtis proposed the presence of a planetary companion to explain certain variations observed in the pulsar's timing. The putative object would have a mass of about 0.01 Solar masses (i.e., 10 times the mass of Jupiter) and orbit the parent star at a distance of 0.3 Astronomical Units.>>
Art "Gesamtkunstwerk" Neuendorfferhttp://en.wikipedia.org/wiki/Vela_X-1 wrote: <<Vela X-1 is a pulsing, eclipsing high-mass X-ray binary (HMXB) system, associated with the Uhuru source 4U 0900-40 and the supergiant star HD 77581. The X-ray emission of the neutron star is caused by the capture and accretion of matter from the stellar wind of the supergiant companion.
The orbital period of the system is 8.964 days, with the neutron star being eclipsed for about two days of each orbit by HD 77581. The spin period of the neutron star is about 283 seconds, and gives rise to strong X-ray pulsations. The mass of the pulsar is estimated to be at least 1.88±0.13 solar masses. Long term monitoring of the spin period shows small random increases and decreases over time similar to a random walk. The accreting matter causes the random spin period changes.
Vela X-1 should not be confused with the isolated radio pulsar, Vela X, which is a very different kind of object. Vela X is associated with a very strong 100 MeV gamma-ray source, which corresponds to a rather weak Uhuru X-ray source, 4U 0833-45.>>
I googled "Calabi-Yau manifold". Goodness! I've never read a wikipedia article that managed to confuse me so thoroughly! Or rather, I've never run into so many impossible words in an article that is supposedly in English. Or what about K3 surfaces, Kähler manifolds, canonical bundle, Calabi conjecture and Ricci flat metrics? Wanna know what a compact n-dimensional Kähler manifold M is? Easy as a pie! http://en.wikipedia.org/wiki/Calabi–Yau_manifold wrote:Beyond wrote:Well, then i am one of the few. I have never heard of a Calabi-Yau manifold.
Still confused? Don't worry, here's a further explanation:The canonical bundle of M is trivial.
M has a holomorphic n-form that vanishes nowhere.
The structure group of M can be reduced from U(n) to SU(n).
M has a Kähler metric with global holonomy contained in SU(n).
These conditions imply that the first integral Chern class c1(M) of M vanishes, but the converse is not true. The simplest examples where this happens are hyperelliptic surfaces, finite quotients of a complex torus of complex dimension 2, which have vanishing first integral Chern class but the canonical bundle is not trivial.
right up to, and including, the quintic Calabi–Yau three-fold (3D projection). 
Actually, as I understand it, it is exactly like a spirograph, or like the epicycles that astronomers used prior to Galileo when they assumed the Earth was the center of the universe.tnzkka wrote:Beautifully asymmetric. No spirograph-drawing seen.
