Scorpius X-1

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Scorpius X-1 data
Constellation Scorpio
Position ( equinox : J2000.0 )
Right ascension 16h 19m 55.1s
declination −15 ° 38 '25 "
X-ray source
Type Low - mass X-ray binary star
Catalog names 4U 1617-15
Double star system
distance 9100 ± 1000 light years
Period of circulation 18.8955 hours
Optical / stellar component: V818 Scorpii
Spectral class B0 to O7
Apparent brightness 12.2 mag
Dimensions 0.42 solar masses
Compact component
Type Neutron star
Dimensions approx. 1.4 solar masses

Scorpius X-1 (abbreviated Sco X-1 ) is an X-ray source located approximately 9,000 light years from Earth. It was the first X-ray source to be discovered outside the solar system and is the brightest X-ray source in the sky after the sun. Scorpius X-1 was discovered in 1962 by a team led by Riccardo Giacconi ; Giacconi received the Nobel Prize in 2002 for this discovery and his achievements in X-ray astronomy.


On June 12, 1962, an Aerobee high-altitude research rocket with an X-ray detector as a payload was launched for the first time . The stated goal, an X-ray of the moon , could not be achieved - today we know that the signal was too weak for the instruments of the time, so that an "X-ray photo" of the moon was only possible in 1990 with ROSAT - but instead a bright object became found in the constellation Scorpio , which was named Scorpius X-1.


Scorpius X-1 is a binary star system. The main component is a neutron star , the immense gravity of which pulls matter away from its smaller companion, which collects in an accretion disk . The matter is strongly accelerated by the gravitational field when it falls and releases the energy gained when it hits the surface of the neutron star. Since the material in the accretion disk is in the form of plasma , it is subject to the forces of the magnetic field of the neutron star, whose magnetic field strength can reach up to 10 11  Tesla or 10 15  Gauss . The ionized material follows the magnetic field lines and therefore crashes at the magnetic poles onto the surface of the neutron star. Due to the great gravitational potential, the material reaches speeds of up to 100,000 km / s, which is 30% of the speed of light . The impact area has a small area of ​​a few kilometers in diameter and temperatures of 100 million Kelvin are reached there. Most of the energy is emitted from there as X-rays. The observed radiation intensity of Scorpius X-1 shows that the neutron star emits energies close to its Eddington limit . This means that if the luminosity increases further, the associated radiation pressure becomes so high that the collapsing material is pushed outwards. At the same time, the energy supply is cut off, so that the luminosity drops below the Eddington limit and the material can flow in again. This process can be repeated periodically

Individual evidence