A young double star with parallel gas jets
In the vicinity of Rho Ophiuchi, the young double star system WL20 shows something unusual: both stars emit parallel gas jets while they are surrounded by dense discs of gas and dust.
The ALMA telescope network of the European Southern Observatory ESO in Chile and the James Webb Space Telescope JWST have observed an unusual, young binary star system in the constellation of the Serpent Bearer: The two stars of WL20 are surrounded by dense discs of gas and dust and both emit two jets of gas via their poles. The jets propagate parallel to each other. WL20 is located around 400 light years away from us and was discovered purely by chance. Although WL20 had been known as an object for a long time, the star appeared to be significantly younger than the rest of the star cluster around Rho Ophiuchi, which did not fit the picture. To investigate this, a group led by Mary Bersony from the Californian Space Science Institute took a closer look at WL20. An observation was not actually planned, but as there was still observation time available with the JWST, WL20 was targeted once on suspicion.
In the subsequent analysis, the team used archive data from ALMA and utilised the new measurements from the JWST. The combined data then clearly showed that the supposedly younger star is in fact a binary star. The data from ALMA also revealed that both components are surrounded by an accretion disc, each with a diameter of around 100 astronomical units (100 AU, corresponding to 100 times the distance from the Earth to the Sun). The data from the JWST, which had been recorded with the MIRI instrument, then provided clear evidence of jets being ejected from both stars parallel to each other. Such behaviour has never been observed before.
Source: U.S. NSF/ NSF NRAO/B. Saxton; NASA/JPL-Caltech/Harvard-Smithsonian CfA; CC BY 3.0
The system of WL20 sheds light on how binary stars evolve. It is quite conceivable that planets could one day form in the two accretion discs. The knowledge gained here can then also be transferred to other binary stars.
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