Credit: ESO/S. Ramstedt (Uppsala University, Sweden) & W. Vlemmings (Chalmers University of Technology, Sweden)
Studying red giant stars
tells astronomers about the future of the Sun — and about how previous
generations of stars spread the elements needed for life across the
Universe. One of the most famous red giants in the sky is called Mira A,
part of the binary system Mira which lies about 400 light-years from Earth. In this image ALMA reveals Mira’s secret life.
Mira
A is an old star, already starting to throw out the products of its
life’s work into space for recycling. Mira A’s companion, known as Mira B, orbits it at twice the distance from the Sun to Neptune.
Mira
A is known to have a slow wind which gently moulds the surrounding
material. ALMA has now confirmed that Mira’s companion is a very
different kind of star, with a very different wind. Mira B is a hot,
dense white dwarf with a fierce and fast stellar wind.
New
observations show how the winds from the two stars have created a
fascinating, beautiful and complex nebula. The remarkable heart-shaped
bubble at the centre is created by Mira B’s energetic wind inside Mira
A’s more relaxed outflow. The heart, which formed some time in the last
400 years or so, and the rest of the gas surrounding the pair show that
they have long been building this strange and beautiful environment
together.
By looking at stars like Mira A and Mira B scientists
hope to discover how our galaxy’s double stars differ from single stars
in how they give back what they have created to the Milky Way’s stellar
ecosystem. Despite their distance from one another, Mira A and its
companion have had a strong effect on one another and demonstrate how
double stars can influence their environments and leave clues for
scientists to decipher.
Other old and dying stars also have
bizarre surroundings, as astronomers have seen using both ALMA and other
telescopes. But it’s not always clear whether the stars are single,
like the Sun, or double, like Mira. Mira A, its mysterious partner and
their heart-shaped bubble are all part of this story.
The new observations of Mira A and its partner are presented in this paper.
Source: ESO - Picture of the Week
