Nav: Home

Five planets revealed after 20 years of observation

April 17, 2019

Over 4000 exoplanets have been discovered since the first one in 1995, but the vast majority of them orbit their stars with relatively short periods of revolution. Indeed, to confirm the presence of a planet, it is necessary to wait until it has made one or more revolutions around its star. This can take from a few days for the closest to the star to decades for the furthest away: Jupiter for example takes 11 years to go around the Sun. Only a telescope dedicated to the search for exoplanets can carry out such measurements over such long periods of time, which is the case of the EULER telescope of the Geneva University (UNIGE), Switzerland, located at the Silla Observatory in Chile. These planets with long periods of revolution are of particular interest to astronomers because they are part of a poorly known but unavoidable population to explain the formation and evolution of planets. An article published by the journal Astronomy & Astrophysics.

"It took 20 years and many more observers,» comments Emily Rickman, first author of the study and researcher in the Astronomy Department of the UNIGE Faculty of Science. "This result would have been impossible without the availability and reliability of the CORALIE spectrograph installed on the EULER telescope, a unique instrument in the world." Since 1995, when the first exoplanet was discovered, about 4000 planets have been found. The vast majority of them are massive planets close to their stars which are the easiest to detect relying on the current technology. However, planets with long periods of revolution are of great interest to astronomers. Being farther away from their stars, they can be observed using direct imaging techniques. Indeed, to date, almost all planets have been discovered using the two main indirect methods: radial velocities, which measure the gravitational influence of a planet on its star, and transits, which detect the mini eclipse caused by a planet passing in front of its star.

Planets directly observed

The EULER telescope is a telescope that depends only on the UNIGE Astronomy Department and is mainly dedicated to the study of exoplanets. Since its commissioning in 1998 it has been equipped with the CORALIE spectrograph which allows to measure radial velocities with an accuracy of a few meters per second, allowing for the detection of planets which mass is as small as Neptune's. "As early as 1998, a planetary monitoring programme was set up and carried out scrupulously by the many UNIGE observers who took turn every two weeks in La Silla for 20 years", says Emily Rickman. The result is remarkable: five new planets have been discovered and the orbits of four others known have been precisely defined. All these planets have periods of revolution between 15.6 and 40.4 years, with masses ranging approximately from 3 to 27 times that of Jupiter. This study contributes to increasing the list of 26 planets with a rotation period greater than 15 years, "but above all, it provides us with new targets for direct imaging!", concludes the Geneva researcher.
-end-


Université de Genève

Related Planets Articles:

Planets around a black hole?
Theoreticians in two different fields defied the common knowledge that planets orbit stars like the Sun.
The rare molecule weighing in on the birth of planets
Astronomers using one of the most advanced radio telescopes have discovered a rare molecule in the dust and gas disc around a young star -- and it may provide an answer to one of the conundrums facing astronomers.
How many Earth-like planets are around sun-like stars?
A new study provides the most accurate estimate of the frequency that planets that are similar to Earth in size and in distance from their host star occur around stars similar to our Sun.
Dead planets can 'broadcast' for up to a billion years
Astronomers are planning to hunt for cores of exoplanets around white dwarf stars by 'tuning in' to the radio waves that they emit.
The sun follows the rhythm of the planets
One of the big questions in solar physics is why the sun's activity follows a regular cycle of 11 years.
Five planets revealed after 20 years of observation
To confirm the presence of a planet, it is necessary to wait until it has made one or more revolutions around its star.
Icy giant planets in the laboratory
Giant planets like Neptune may contain much less free hydrogen than previously assumed.
New NASA mission could find more than 1,000 planets
A NASA telescope that will give humans the largest, deepest, clearest picture of the universe since the Hubble Space Telescope could find as many as 1,400 new planets outside Earth's solar system, new research suggests.
Giant planets around young star raise questions about how planets form
Researchers have identified a young star with four Jupiter and Saturn-sized planets in orbit around it, the first time that so many massive planets have been detected in such a young system.
The stuff that planets are made of
UZH researchers have analyzed the composition and structure of faraway exoplanets using statistical tools.
More Planets News and Planets Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Accessing Better Health
Essential health care is a right, not a privilege ... or is it? This hour, TED speakers explore how we can give everyone access to a healthier way of life, despite who you are or where you live. Guests include physician Raj Panjabi, former NYC health commissioner Mary Bassett, researcher Michael Hendryx, and neuroscientist Rachel Wurzman.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab