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Dutch ‘big data’ telescope finds exoplanets

Astronomers at Leiden University have discovered the first planets using a new instrument: the planet hunter MASCARA. This instrument, developed at Leiden Observatory, looks specifically for planet transitions around the brightest stars in the sky, which surprisingly enough have so far have hardly been looked for.

MASCARA (Multi-site All-Sky CAmeRA) is a relatively simple piece of equipment made up of five cameras with wide angle lenses that can photograph the whole sky in one go. The first MASCARA station is on Las Palmas in the Canary Islands; it has been taking photos of the sky every six seconds since early 2015.  The luminosity of more than 50,000 stars has since been determined.  'The crux is in the datastream that the camera generates - around 15 terabytes a month - which has to be processed straight away,' according to lead author Geert Jan Talens, PhD candidate in Leiden.  'MASCARA is actually more a kind of "big data" telescope.'

Two planets discovered

'In this enormous number of photos we are looking at which stars regularly shine a little weaker because a planet transits in front of them, as seen from the Earth.' The first two planets that the team discovered using this method - MASCARA 1b and MASCARA 2b - are very unusual in several ways. 'More than a thousand stars have been discovered with planet transitions, but most of them are very distant which means they are also very weak,' fellow research Gilles Otten comments. 'MASCARA 2b is the second brightest star to exhibit a planet transition of a giant planet. Last month the brightest star was discovered, but the KELT-9 transit survey snatched the discovery from under our very noses. The Kelt ster is only 2% brighter than the MASCARA  star.'


MASCARA's five cameras (Credit: MASCARA/Snellen)

Bigger than Jupiter

The MASCARA giant planets are much bigger than Jupiter and they orbit in just a few days around stars that are mugh larger and hotter than our Sun. 'We can now start to study planets that are located in extreme conditions,' explains Ignas Snellen (Leiden Observatory), head of the MASCARA project. 'The brightness of the stars also makes it possible to carry out all kinds of follow-up research, such as characterising the atmospheres in much more detail than we can do for other planets.' 

Second station

The MASCARA project will be expanded to include a second station, in the southern hemisphere. The telescope is now at the La Silla observatory of the European Southern Observatory (ESO) in the North of Chile, and will shortly start making observations. 

One of the roughly 25,000 photos that MASCARA makes of the sky every night. The red lines join the constellation of the Swan, in he yellow circle there is the MASCARA-2 star, where the Dutch team has now discovered a planet. In clear weather the star can be seen with a telescope. (Credit: MASCARA/Snellen)
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