SS 433 is one of the most exotic star systems observed. It is located in the

Milky Way galaxy The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...

, and is an eclipsing

X-ray binary X-ray binaries are a class of binary stars that are luminous in X-rays. The X-rays are produced by matter falling from one component, called the ''donor'' (usually a relatively normal star), to the other component, called the ''accretor'', whi ...

system, with the primary being a stellar-mass black hole. The spectrum of the secondary

companion star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in w ...

suggests that it is a late

A-type star An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...

. SS 433 is the first discovered

microquasar A microquasar, the smaller version of a quasar, is a compact region surrounding a stellar black hole with a mass several times that of its companion star. The matter being pulled from the companion star forms an accretion disk around the black hole ...

. It is at the centre of the supernova remnant W50. SS 433's designation comes from the initials of two astronomers at Case Western Reserve University: Nicholas Sanduleak and Charles Bruce Stephenson. It was the 433rd entry in their 1977 catalog of stars with strong emission lines.SS 433
David Darling, entry in ''The Internet Encyclopedia of Science'', accessed on line September 14, 2007. Its emission lines were studied by Mordehai Milgrom in 1979.

Location

SS 433, also known as V1343 Aquilae, located at 5.5 kpc in the galactic plane (''l= 39.7° and b= -2.2°'')

System

The compact central object is consuming the companion star which rapidly loses mass into an

accretion disc An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is typically a star. Friction, uneven irradiance, magnetohydrodynamic effects, and other ...

formed around the central object. The accretion disc is subject to extreme heating as it spirals into the primary and this heating causes the accretion disc to give off intense X-rays and opposing jets of hot hydrogen along the axis of rotation, above and below the plane of the accretion disc. The material in the jets travels at 26% of the

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit ...

. The companion star presumably had lower mass than the original primary object and was therefore longer lived. Estimates for its mass range from 3 to 30 solar masses. The primary and secondary orbit each other at a very close distance in stellar terms, with an orbital period of 13.082 days. Their orbit is very slightly eccentric, and it is slowly increasing at a rate of about seconds per second, or about 3 seconds per year.

Observational data

The jets from the primary are emitted perpendicular to its accretion disk. The jets and disk

precess Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...

around an axis inclined about 79° to a line between Earth and SS 433. The angle between the jets and the axis is around 20°, and the precessional period is around 162.5 days. Precession means that the jets sometimes point more towards the Earth, and sometimes more away, producing both blue and red Doppler shifts in the observed visible spectrum. Also, the precession means that the jets corkscrew through space in an expanding helical spray. As they impact the surrounding W50 supernova remnant clouds, they distort it into an elongated shape. PIA24574-SS433-ULXray-20210709

Observations in 2004 by the

Very Long Baseline Array The Very Long Baseline Array (VLBA) is a system of ten radio telescopes which are operated remotely from their Array Operations Center located in Socorro, New Mexico, as a part of the National Radio Astronomy Observatory (NRAO). These ten radi ...

for 42 consecutive days gave new data and understanding of the action of the jets. It appears that the jets are sometimes impacting material shortly after being created and thus brightening. The material the jets are impacting appears to be replaced some of the time, but not always, leading to variations in the brightening of the jets. The spectrum of SS 433 is affected not just by Doppler shifts but also by relativity: when the effects of the Doppler shift are subtracted, there is a residual redshift which corresponds to a velocity of about 12,000

kilometers The kilometre ( SI symbol: km; or ), spelt kilometer in American English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for ). It is now the measurement unit used for ex ...

per second. This does not represent an actual velocity of the system away from the Earth; rather, it is due to

time dilation In physics and relativity, time dilation is the difference in the elapsed time as measured by two clocks. It is either due to a relative velocity between them ( special relativistic "kinetic" time dilation) or to a difference in gravitational ...

, which makes moving clocks appear to stationary observers to be ticking more slowly. In this case, the relativistically moving excited atoms in the jets appear to vibrate more slowly and their radiation thus appears red-shifted. In September 2018, A. U. Abeysekara et al. published in ''

Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...

'' details of investigations using the High-Altitude Water Cherenkov Gamma-Ray (HAWC) Observatory in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. They reported teraelectronvolt γ-ray observations exceeding 25 TeV of the SS 433/W50 system that spatially resolve the lobes, and consistent with a single population of electrons with energies extending to at least hundreds of teraelectronvolts in a magnetic field of about 16 micro

gauss Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...

.Scientists discover new nursery for superpowered photons
Space Daily, 2018-10-04

In popular culture

In '' SNL'' Season 4 (1979), Father Guido Sarducci mentions SS 433. In the ''Seven Wonders of The World'' documentary series, Arthur C. Clarke mentions SS 443 as one of his "seven wonders of the universe".

Location

System

Observational data

In popular culture

See also

References

Further reading