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Finding a planet has a 10 years orbit in a few months
To discover and confirm the presence of a planet around stars other than the Sun, astronomers wait until it has completed three orbits. However, this very effective technique has its drawbacks since it cannot confirm the presence of planets at relatively long periods (it is ideally suited for periods of a few days to a few months). To overcome this obstacle, a team of astronomers under the direction of the University of Geneva (UNIGE) have developed a method that makes it possible to ensure the presence of a planet in a few months, even if it takes 10 years to circle its star: this new method is described for the first time in the journal Astronomy & Astrophysics.
[...] By analysing data from the space telescope K2, one star showed a significant long-duration temporary decrease of luminosity, the signature of a possible transit, in other words, the passage of a planet in front of its star. "We had to analyse hundreds of light curves" explains the astronomer, to find one where such a transit was unequivocal.
[...] [Lead researcher] Helen Giles consulted recent data from the Gaïa mission to determine the diameter of the star referenced as EPIC248847494 and its distance, 1500 light-years away from the planet Earth. With that knowledge and the fact that the transit lasted 53 hours, she found that the planet is located at 4.5 times the distance from the Sun to the Earth, and that consequently it takes about 10 years to orbit once. The key question left to answer was whether it was a planet and not a star. The Euler telescope of the UNIGE in Chile would provide the answer. By measuring the radial velocity of the star, which makes it possible to deduce the mass of the planet, she was able to show that the mass of the object is less than 13 times that of Jupiter -- well below the minimum mass of a star (at least 80 times the mass of Jupiter).
The longest period transiting planet candidate from K2
(Score: 1, Interesting) by Anonymous Coward on Wednesday July 25 2018, @12:40PM (2 children)
a 53 hr window of discovery every 10 years gives a 53/10/365.25/24= 0.06% chance.
wondering ...
how much of the sky we're able to monitor at sufficient resolutions to catch the buggers that get between us and their host so that we would notice dips within a 53 hr window (of which there are 10*365.25*24/53=~1654 in a 10 year period.)
also .. (math) what the chance of an occultation facing us would be -- say if we were pretend detecting jupiter or saturn from alpha centauri.
also .. this well prepared lady/team seems to have won some sort of cosmic lottery granting her/them a science first! but were the chances greater or lesser than her/them winning a terrestrial lottery? (if we were detecting jupiter from alpha centauri)
greatly appreciative of anyone who'd turn my wonderings into better questions!
(Score: 3, Informative) by takyon on Wednesday July 25 2018, @01:32PM (1 child)
NASA's TESS Mission Set to Launch on Wednesday, April 18 [soylentnews.org]
TESS is studying at least 500,000 stars. Some of its observation sectors overlap [wikipedia.org], allowing for continuous observation of up to 351 days during the first 2 years of the mission, while other sectors are only viewed for 27 days.
Only the plan for the first 2 years is known. In principle, TESS could last for decades and change up how/what it views as the mission is extended. I suspect it will observe a lot more than 500k stars. Compare to Kepler [wikipedia.org] which apparently observed about 150k stars in a much smaller field of view. TESS covers 85% of the sky with at least 27 days of viewing in its first 2 years.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Thursday July 26 2018, @11:29AM
Hey thanks for telling me about TESS!