O n t h e T r a c k o f M o d e r n P h y s i c s Crab Nebula testifies the Supernova explosion in 1054AD, noted in Europe, China and by Indians in New Mexico Left: 12 C nucleus. Right: a strange matter droplet with A=12. down up strange Strange quark droplets are a possible form of hadronic matter, containing approximately equal (and potentially very large) numbers of up, down, and strange quarks inside a single hadronic bag. RX J1856 in Optical Light This optical image of RX J portrays a crowded region of star formation. In comparison, the Chandra X-ray image shows that RX J1856 outshines all of the other sources in the field, indicating it is both extremely hot and very small. Credit: European Southern Observatory Very Large Telescope Confined quarks Free quarks The Grand Canyon is 30 km wide. A neutron star is about 20 km in diameter, and a quark star is about 12 km in diameter. (Illustration: CXC/D. Berry) Chandra X-ray observation of RX J (or the C58 pulsar), the remnants of a supernova noted on Earth in AD 1181, reveal that the neutron star in the core has a temperature much lower than expected. This suggests that a new state of nuclear matter might exist inside the star. Credits:NASA/CXC/CfA/P.Slane et al. Is the black hole really black? And how heavy is it? And how is it made inside? Astronomers still discuss if a real black hole has been discovered. Sign-down these numbers and check from time to time on internet, if they are really BLACK: X-ray transient XTE J SS433 MilkyWay Star Cygnus X1 and HDE Seyfert-1 galaxy NGC 4593 Seyfert galaxy MCG Galaxy NGC 4486 Quasars - quasi-stellar radio sources, discovered in 1961, now believed to be super-massive (billion of M☺) black holes in centers of distant galaxies. The ionized gas quickly falling inside the hole emits powerful radio- waves. Pulsars - quickly rotating neutron stars which flares the magnetic field around the space. The first pulsar CP (1.3 s period of rotation) was discovered in the constellation of Cygnus (“Swan”) in 1967 by graduate student Jocelyn Bell Burnell but the Nobel prize went to her supervisor. Black holes are probably quite colorful: quickly rotating ionized gas, imploding towards the center contains heavy atoms, like iron, and its emission lines are strongly shifted by the Doppler effect. Fig. Krzysztof Karwasz "Cygnus." Wikipedia. Evolution of stars depend on their mass. Those above 8 Solar masses, at the end of the life, were all the termonuclear fuel is burn into iron, first collapse, and then explode into supernova. A part of the mass is expelled and the remnants form a core of about 20 km diameter made of neutrons. The expelled material contains heavy elements and can be re-cycled, to form a system, like the Solar one. European Southern Observatory: Credits: NASA Goddard Space Flight Center Cygnus Loop in X-rays Crab Nebula in X-rays Remnants of supernovae are sources of radio signals and also of X-ray radiation. The neutron ball is similar to a giant atomic nucleus with Z= With such a big compression, neutrons start to "crowd-up", following the Pauli's rule, which does not allow them to be in the same quantum state. It is energetically useful to replace some neutrons with protons, or even by isolated quarks. It seems (A.R. Bodmer 1971, E. Witten 1984) that the state of the matter with a lowest possible energy level is a mixture of the "normal" u and d quarks with strange quarks s. It is solely the big mass of the s quark (30 times more than that of u) which protects us from falling the nucleus of 58 Fe, for example, to a quark state. See aslo: