An image of the star HL Tauri, which shows a blue circle of water vapour in the star's disc. Image: ALMA (ESO/NAOJ/NRAO)/S Facchini et al.
The new images from ALMA suggest water vapour plays a significant role in the formation of planets.
Astronomers have found what appears to be a vast amount of water surrounding a star – in the region where planets would typically form.
The researchers believe up to three times as much water as there is in the Earth’s oceans is surrounding the inner disc of HL Tauri, a star located 450 light-years away from Earth. The distance of this disc to the star presents favourable conditions for planets to form.
The images provide evidence to support the theory that water plays a significant role in the formation of planets. But the researchers behind this new discovery claim there had been no success in mapping how water is distributed around a star until now.
Using the Atacama Large Millimeter/submillimeter Array (ALMA), the researchers were able to spot the significant level of water and its distribution in different parts of the disc. The researchers claim ALMA is the only ground-based observatory that could make these observations.
Attempting to observe water using a ground-based telescope presents difficulties as water vapour in the Earth’s atmosphere degrades the astronomical signal. But ALMA – operated by the European Space Observatory (ESO) and international partners – is an array of telescopes in the Chilean Atacama Desert. The array is built in a high and dry environment, which helps to minimise the degradation from water vapour in the atmosphere.
The results and detail of the images have stunned the research team, as they were able to spot water in a gap in a disc surrounding the star. This gap could be where a planet is forming in real time and suggests that the water vapour could affect the chemical composition of forming planets.
“I had never imagined that we could capture an image of oceans of water vapour in the same region where a planet is likely forming,” said astronomer Dr Stefano Facchini who led the study. “Our recent images reveal a substantial quantity of water vapour at a range of distances from the star that include a gap where a planet could potentially be forming at the present time.”
The ESO said that insights into planet formation and the role water plays will become clearer in the future, as ALMA is in the process of being upgraded and the ESO’s Extremely Large Telescope is scheduled to be completed this decade.
Recently, ESO researchers spotted the brightest and fastest-growing quasar ever discovered, which appears to be as bright as 500trn suns and growing in mass by the equivalent of one sun every day.
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