A previously inconspicuous star system in the constellation arrow is on the best way to merge. Researchers have calculated a not too distant period for this.
- The inconspicuous star system V Sge in the constellation arrow ( Sagitta ) will merge
- This explosive event will be very bright in the night sky
- Researchers expect the merger and the so-called merger burst for the current century
In the inconspicuous constellation arrow (Sagitta) there is an at least as inconspicuous star called V Sagittae (V Sge) . It is difficult to see even in medium-sized telescopes - so far. But researchers have found that this could change in the future.
But from the front: The star V Sagittae is a star system of the "cataclysmic variable" (CV) class. It consists of a white dwarf and a normal star orbiting this white dwarf. The star loses mass that gradually falls on the white star. However, V Sge shines a hundred times brighter than any other cataclysmic variable known to date; the star has 3.9 times more mass than the white dwarf. "In all other known CVs, the white dwarf is more massive than the normal star orbiting it," explains Bradley E. Schaefer from Louisiana State University (LSU). "That is why V Sge is absolutely unique."
Star system V Sge in the constellation arrow stands before the end
The lifespan of this unique star system is, however, numbered: "We now have a strong forecast for the future of V Sge," explains Schaefer. "The star will quickly become brighter in the coming decades." Around the year 2083, the star would give its mass to the white dwarf in "unbelievably high installments", in the final days of this "death spiral" it should lose its entire mass to the white dwarf, according to Schaefer.
Then the star V Sge will briefly become the brightest star in the Milky Way, researchers around Schaefer have calculated. He would then shine "as bright as Sirius, possibly as bright as Venus" in the night sky. "It will be brighter than the brightest nova ever made about a century ago or Kepler's supernova in 1604," explains Schaefer. The giant star Betelgeuse in the constellation Orion could explode in the future *.
Star system V Sge is in a "death spiral"
observing Tip
If you want to search for the arrow constellation in the starry sky yourself, you will find it between the constellations Adler (Aquila) and Schwan (Cygnus).
In order to reach this conclusion, the astronomers Schaefer, Juhan Frank and Manos Chatzopoulos, who are all located in the Physics and Astronomy department at the LSU, looked at old sky photos that go back to 1890. According to their own information, they found from measurements that the star system V Sge became systematically brighter over time. "V Sge gains exponentially in luminosity," says Frank. This increase in brightness can only come from the fact that the mass that the star loses to its companion, the white dwarf, also increases exponentially.
"The fate of the star V Sge is sealed," explains Schaefer. The star's death spiral will peak when most of the normal star falls on the white dwarf. Then the brightness of the star system V Sge will almost reach the brightness of a supernova, Schaefer continues.
Star system V Sge is said to merge later this century
This explosive event - the so-called merger burst - will be seen very brightly in the sky for more than a month, according to the astronomers. The white dwarf and its companion ultimately merge into one star. The astronomers expect the final merging of the two stars around 2083. "The inaccuracy is plus and minus 16 years," explains Frank. "The merger will take place between 2067 and 2099, most likely around the middle of this period," emphasizes Frank.
By Tanja Banner
* fr.de is part of the nationwide Ippen-Digital central editorial office.
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