Siwarha is the small companion reported orbiting Betelgeuse, a modest star orbiting so close to the red supergiant that it is almost lost in its glare.
At a glance
| type | white star (class A) |
|---|---|
| distance from the Sun | 548 light-years (168 pc) |
| its light left it | 548 years ago |
| luminosity | 6 × the Sun |
| radius | 1.5 × the Sun |
| surface temperature | 8,000 K |
Read off the piece’s own catalogue, the same values it draws with.
About Siwarha
Betelgeuse brightens and fades on a long, slow rhythm on top of its faster pulsations, and astronomers had argued that a companion pulling on it could explain that long cycle. A small star circling close in, well within the space that the supergiant’s outer layers and dust can reach, was the favoured explanation.
A team using speckle imaging, which freezes the blurring of the atmosphere with very short exposures, then reported a faint point of light next to Betelgeuse at about the place and time the prediction expected. The companion was named Siwarha. It is far fainter than Betelgeuse, which made the detection one of the hardest in the bright sky.
If it is real, it is a young, lightweight star, and its future is short: friction with the supergiant’s extended envelope is expected to drag it inward until Betelgeuse swallows it, long before the supergiant itself explodes.
What you see in the piece
Fly to Betelgeuse and Siwarha is a small white point almost touching the swollen red disc, outshone by it in every direction.
Measured or modelled
Siwarha is a recent report and is still being confirmed: the detection sits at the edge of what the instruments can do, and astronomers are waiting for the companion to return to its widest separation to check it. Its type, size and temperature on the card are estimates, not measurements.
Questions
Does Betelgeuse have a companion star?
A small companion, named Siwarha, has been reported close to Betelgeuse. It fits the supergiant’s long brightness cycle but is still awaiting confirmation.
What kind of star is Siwarha?
It is thought to be a white star (class A), much smaller than Betelgeuse, at 548 light-years (168 pc) from the Sun.