A first look at the giant star Mira and its companion Melo makes it possible to understand the interrelationship between them
Although the giant star Mira has been known to scientists for about 400 years, astronomers had to wait for the Hubble Space Telescope to view the first images of the cold red giant and its companion, the hot little star. The clear image in the ultraviolet frequencies of the stars that make up the binary star system allows scientists a better understanding of the interrelationship between the two stars.
The distance between Mira and the star that accompanies it is indeed about 70 times greater than the distance between the Earth and the Sun, but when viewed from Earth, at the angle of view at which the star orbiting Mira is seen, the visible interval between them is only 0.6 seconds (a second - one-sixtieth of a degree) - as if watching in a ten-penny coin that is seven kilometers away. In observations from Earth it was difficult to see this distance.
Using the European Space Agency's Faint Object Camera, which is mounted on the Hubble Space Telescope, scientists were able to view images in both the visible light and ultraviolet regions of the two separate stars in the Mira system. Hubble was able to photograph in ultraviolet light a prominent spot of light coming out of Mira towards the companion star. This blob may be material being gravitationally pulled from a star towards the small star. Another possibility is that it is matter in the upper atmosphere of Mira, which is heated by the presence of the companion star.
The visible light images show that Mira has an asymmetrical shape, similar to a soccer ball (which is elliptical and not round like our soccer ball). The dramatic changes in its shape are apparently caused by the strange orbit of the companion star, or by unexplained events occurring on the surface of the large star. Using Hubble's images, astronomers were able to measure the size of the giant star, whose diameter is 700 times that of the Sun.
If Mira, with a diameter of about 500 million km, was placed in the center of our solar system - it would extend far beyond the orbit of Mars, reaching up to two-thirds of the distance to Jupiter. The planets Mercury, Venus, Earth and Mars would reside in the heart of that planet.
Mira, also known as Umericon Seti in the Stos system, is a prototype for a certain type of star known as "Mira-type variables". Mira was once a star like the Sun, but today it is in the final stages of its life - a cold red giant subject to large changes in brightness. The cycle of the change in brightness from pale to brighter and back to pale is 332 days. The star throws a huge amount of gas and dust into space in a kind of "wind resource".
Mira's companion is a white dwarf surrounded by matter thrown by Mira's spirit. Mira, 400 light-years away, is the wind-blown double star closest to Earth. Separating the spectrum of Mira and its companion - something that astronomers tried to do in the past in an indirect way - is an important step in understanding the physical processes of the flight of the wind in a binary star system.
Mira was discovered on August 13, 1596 by the Dutch astronomer David Fabricius, who recognized it as a nova - a star that erupts all at once and then dies down and disappears - due to its changing brightness. He happened to Mira, which means "the wonderful one". Only then did the astronomers realize that they were observing a variable star for the first time.
The behavior of variable stars is monitored by astronomy enthusiasts all over the world. The Israeli Astronomical Society also has a division for variable stars. Observing them requires expensive and long observation time, so the professional astronomers rarely observe them.
