They used the GRAVITY and MUSE instruments on the VLT to study the star system, and pin down the distance each star is from its partners, finding no evidence of a bright companion star in a wide orbit - as the black hole model predicted. 'We agreed that there were two sources of light in the system, so the question was whether they orbit each other closely, as in the stripped-star scenario, or are far apart from each other, as in the black hole scenario.' The researchers turned to the Very Large Telescope, and in particular the Interferometer on the VLT, known as the VLTAI, to gather detailed observations. 'We had reached the limit of the existing data, so we had to turn to a different observational strategy to decide between the two scenarios proposed by the two teams,' says KU Leuven researcher Abigail Frost, who led the new study This alternative scenario would require one of the stars to be 'stripped', meaning that, at an earlier time, it had lost a large fraction of its mass to the other star. She suggested that HR 6819 could also be a system with only two stars.Įach of the stars would be found in a very close 40-day orbit, with no black hole at all. Rivinius and his colleagues were convinced that the best explanation for the data they had was that HR 6819 was a triple system, with one star orbiting a black hole every 40 days and a second star in a much wider orbit.īut a study led by Julia Bodensteiner, then a PhD student at KU Leuven, Belgium, proposed a different explanation for the same data. 'Not only is it normal, but it should be that results are scrutinised,' he said, adding that it was 'even more so' important for results that 'make the headlines'.
Thomas Rivinius, a Chile-based ESO astronomer and lead author on the original black hole paper, was not surprised by the astronomy community's reception. There was no evidence of a distant orbiting star, as would be required by the black hole theory. They pointed the European Southern Observatory Very Large Telescope (ESO, VLT), and the VLT Interferometer at the star system, as this instrument can provide decisive data required to distinguish between the two explanations.Īll the evidence pointed to a 'vampire' star system, finding two stars in a very close orbit, with one ripping material from the other. However, a new study, by researchers from KU Leuven in Belgium, took new measurements of the system, to see which scenario was most likely to be true. The idea of a black hole just 1,000 light years away, within our stellar neighbourhood, hit the headlines at the time of the discovery and was presented as the main finding - with the other scenario not being widely reported. When it was discovered in 2020, two scenarios were proposed for the discovery of the unusual HR 6819 system, one with, and one without a black hole. The closest black hole system to the Earth, found about 1,000 light years away, doesn't actually contain a black hole, according to a new study.
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