(ORDO NEWS) — Hadar (also known as Agena) is a star that is visible from the Southern Hemisphere. It is the second largest star in the constellation Centaurus – otherwise known as Beta Centauri – and the 10th brightest star in the night sky.
However, as is often the case with many other bright stars, Hadar reveals unexpected details about herself if you look at her more closely: she is actually a group consisting of three different stars. Hadar itself is a pair of spectral type B stars, and next to it, at a distance of 210 distances from Earth to the Sun, lies the star Hadar-B.
Both Hadar stars are expected to explode as supernovae one day, but until now, scientists have not been able to accurately determine the size of these stars. One of the possible options for their future fate is to turn into large white dwarfs after they have burned all their “stellar fuel”.
Discovery of Multiple Stars
No one knows exactly where the name “Hadar” came from, but astronomer David Darling points out that the name “Agena” means the “tribe” of Centaurus, the constellation to which this star belongs.
The brightness of this star – its apparent magnitude is 0.61 – makes it one of the landmarks that can be used to locate the Southern Cross, the famous constellation of the Southern Hemisphere, which is often used in the creation of flags, insignia and other symbols of several countries of the world.
Using telescopes to observe, astronomers eventually realized that Hadar was made up of several stars. Hadar A, according to astronomer Jim Keiller, is two twin stars moving in a common orbit with an orbital period of 357 days.
They are, on average, three astronomical units apart, but this distance varies from 0.5 to 5.5 AU. It is believed that the mass of each of these stars is 14.7 solar masses.
Hadar B is located at a distance of about 1.3 arc seconds from the above star system in the night sky; and if we talk about true distances, then it is at a distance of at least 210 AU. from the Hadar A system, and makes one complete revolution around the center of mass of this system in about 600 years, writes astronomer David Darling.
Is a supernova coming?
Whether twin stars in the Hadar system will one day go supernova remains debatable, despite what astronomers believe is the most likely fate for such binary stars.
“The twin stars of the Hadar A system are about 12 million years old, and due to rapid expansion, these stars will first turn into red giants, and only then flare up as supernovae,” writes Darling.
Keiler notes that the measured masses of these stars vary depending on which system of units is used in the measurements. Interferometry data show that the masses of stars are between 10.7 and 10.3 solar masses, well below the mass threshold required for them to go supernova at the end of their life cycle.
“If this is the case, then these stars could avoid destruction and end up as massive white dwarfs. Only time or additional research can tell us more about this,” concludes Keiler.
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