4U 1543-475 is a recurrent

X-ray transient X-ray emission occurs from many celestial objects. These emissions can have a pattern, occur intermittently, or as a transient astronomical event. In X-ray astronomy many sources have been discovered by placing an X-ray detector above the Earth's ...

located in the southern

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Lupus Lupus, technically known as systemic lupus erythematosus (SLE), is an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body. Symptoms vary among people and may be mild to severe. Comm ...

, the wolf. IL Lupi is its variable star designation. It has an apparent magnitude that fluctuates between 14.6 and 16.7, making it readily visible in large telescopes but not to the naked eye. The object is located relatively far at a distance of approximately 17,000

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s based on Gaia DR3

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

measurements. 4U 1543-475 was first observed by

Uhuru Uhuru (a Swahili word meaning ''freedom'') may refer to: People * Uhuru Hamiter (born 1973), American football player * Uhuru Kenyatta (born 1961), President of Kenya since 2013 Places *Uhuru (Tanzanian ward), an administrative ward in the Dodoma ...

in 1971. In 1976, 4U 1543-475's spectrum was observed. However, its status as a

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

binary had not been confirmed until 1984 by astronomer S. Kiamoto and colleagues. After subsequent observations, it was given the variable star designation IL Lupi in 1995. 4U 1543-475 erupted three times.

References

{{Stars of Lupus Lupus (constellation) Stellar black holes X-ray binaries Lupi, IL A-type main-sequence stars

See also

References