HD80606b. L’exoplanet – those planets that revolve around a star other than our sun – is nestled in the foreleg of the constellation Ursa Major, 190 light years from us. This gas giant, classified in the hot Jupiter categoryis nonetheless a needle – rather a microdust – in the haystack that is the Universe.
Yet it is towards this that the James Webb Space Telescope (JWST) should point its instruments towards October for one of its first observations. Leaving on December 25, the largest and most powerful telescope ever sent into space arrived a month later at its observation post, 1.5 million kilometers from Earth, and calibrated from its instruments before be fully operational. “Not before six months”, it was expected, at the time of the launch, to the European Space Agency (ESA).
With its infrared vision, the JWST could allow great advances, in particular to learn more about the habitability of exoplanets. That’s why Hubble’s big brother is interested in HD80606b. “Astronomers want to study its atmosphere to better understand the meteorological phenomena at play there,” says Bruno Guillet, teacher-researcher in applied physics at the University of Caen by day, amateur astronomer by night, from his garden.
The observation will give rise to a scientific article in which Bruno Guillet should be mentioned. Yes yes. Because the Caennais contributed to its success, on its own scale, with other amateurs from all over the world. Scientists will want to observe HD80606b during its transit, “when the exoplanet passes between us and its star”, explains Franck Marchis, Franco-American astronomerresearcher at Seti Institute and scientific director of Unistellar, a Marseille company who designs digital telescopes. With HD80606b, we know that the transit occurs every 111 days. “But the astronomers who wish to observe it needed more details to better prepare this observation and avoid directing the JWST two hours too early or too late, continues Bruno Guillet. In November, through Nasa Exoplanet Watch, a participatory science program of the American space agency, they asked amateur astronomers to observe a transit of HD80606b to specify its ephemeris, time its duration, etc. The Caennais answered present, with other amateurs from all over the world. “It was December 7 last,” he says.
An invaluable network of small telescopes present in the four corners of the globe
The perfect illustration of the more that amateur astronomers can bring, for Franck Marchis. “In many cases, it is also very useful to have a network of small telescopes, mobile and present everywhere on the globe, he says. It is the assurance of always having someone to observe an unprecedented event. And to pre-chew the task of professional telescopes. This is the whole purpose of Unistellar’s digital telescopes, which are perfect for citizen science. “All you have to do is enter the celestial coordinates of the object you want to observe for the telescope to automatically point in that direction,” continues Franck Marchis. You can be a complete neophyte and very quickly make fascinating observations. »
Since its launch in 2016, Unistellar has gradually built up a community of 5,000 enthusiasts, of which Bruno Guillet is one of the most active members. “Last year, this community made 413 observations of exoplanets, including one located more than 2,700 light-years away,” Unistellar said.
Again, the idea is to help scientists. In April 2018, NASA launched into orbit Tess, a space telescope too, devoted to the search for exoplanets. Not easy since the proximity of these planets to their star is so great that their light is completely drowned in it. “To do this, Tess detects and observes their transit, the moment when we will see the shadow of the celestial body take shape and the luminous intensity of its star decrease, facilitating its observation. But a single observation is not enough to certify that we have an exoplanet before our eyes. “We have to observe other of these transits, which Tess does not have time to do… unlike amateur astronomers, points out Franck Marchis. The space telescope has thus identified nearly 10,000 potential exponentials, including 5,000 confirmed later. Do the same for the other half. This meticulous work also indirectly benefits the JWST, since the telescope will be pointed at the most interesting exoplanets spotted by Tess.
Do not waste precious JWST time
Other similar contributions from amateurs to the success of the JWST could follow, believes Franck Marchis. One certainty: “The “telescope time” on James Webb will be very precious as the demand is strong, indicates Franck Marchis. No question of wasting time by pointing it, for example, two hours too early towards an exoplanet that has not yet begun its transit. »
While waiting for the needs to become clearer, amateur astronomers already have a lot to do with the participatory science programs in progress. Until early May, Unistellar is calling on its community to point its telescopes at comet C/2021 O3. coming of the Oort cloud, at 100,000 astronomical units from us (very, very far), “it is currently passing through our solar system and it is likely to be visible all May, indicates Franck Marchis. Not only should the spectacle be dazzling, but it will also be scientifically interesting to observe the behavior of the comet as it approaches our Sun. The data collected will be sent to the Seti Institute, which hopes to learn more about the internal composition of this comet.
In addition to exoplanets, the other big hobby of the Interstellar community – 395 observations last year – is the observation of asteroids. “At a precise moment, when they find themselves between us and their star, specifies Franck Marchis. From Earth, we can then see the shadow of the asteroid, which makes it possible to better determine its size and shape. Very useful information for the success of space missions. In particular that ofthe Lucy probe, which left on October 16 to visit an asteroid in the main belt (between Mars and Jupiter) – it will be there in 2025 – then seven Jupiter’s Trojan asteroids. “It will pass relatively quickly over these objects, so NASA needs as much information as possible to refine its trajectory, to know when to point this or that instrument on an interesting part of the asteroid”, says Franck Marchis.