SS 433

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SS 433
artist impression of SS 433
artist impression of SS 433
Position
Epoch :  J2000.0    Equinox :  J2000.0
Constellation Aquila
Right ascension 19 h 11 m 49.6 s
declination 2045857.6+ 4 ° 58 ′ 57.6 ″
Double star system
Type Massive X-ray binary star, microquasar
distance approx. 16,000 ly
Period of circulation 13 d
Apparent brightness (V-band) approx. 14.2 mag
Optical / stellar component
Spectral class A3 to A7
Dimensions 21 M ☉
Compact component
Type Black hole
Dimensions 16 M ☉ + 3 M ☉ (gas ring)
History and other names
discovery 1976, Ariel V.
Designations V1343 Aquilae • A1909 + 04 • 4U 1908 + 05 • INTREF 969

SS 433 is the astronomical name of an exotic binary star system in the constellation Aquila . It is the first known microquasar .

SS 433 was discovered in 1976 by the X-ray satellite Ariel V while scanning the sky for strong X-ray sources along the galactic plane . It was one of ten unknown sources and was first listed under the name A1909 + 04. After this source in the optical region, an object (the center of 16,000 light-years away bizarre Super Nova remnant could be assigned to W50), was found in studies of the star 1977 that its spectrum of strong H-α - emission lines has. Thereupon it was included in a catalog of such stars by the astronomers C. Bruce Stephenson and Nicholas Sanduleak as number 433 and thus got its name (SS 433).

Further research in the following years showed that the star not only emits X-rays, but also strong and rapidly changing radio waves. It also has some special features in the optical area. Its emission lines shift considerably with a period of 164 days, which could only be explained by gas moving at relativistic speed . This gas (and thus also the emission lines) comes only indirectly from the visible star. It flows from this into an accretion disk ( surrounding the invisible heavy companion) and is thrown away (similar to a quasar ) by two opposing jets at 26% the speed of light . The periodic shifts of the emission lines come from the precession motion of the jets. The binary star system is therefore also called a microquasar. The massive main star belongs to the spectral class A3 to A7 and completely fills its maximum possible volume ( Roche volume ). Due to its mass, its companion could only be a neutron star or a black hole , which was not initially clear due to uncertainties in determining the mass.

Recent studies of the star's spectrum and its static and variable components by the European Southern Observatory ESO showed that the binary star system is probably surrounded by a gas ring. Furthermore, the total mass of the system with 40 solar masses could be determined from these data, whereby due to the mass ratios even after subtracting three solar masses for the accretion disk, only a black hole is possible as a companion of the star, which orbits it in 13 days. The total apparent magnitude of the system is 14.2 mag.

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