A screenshot from the NASA announcement of Kepler-16 b showing Luke Skywalker on Tatooine
NASA, headed by the Kepler team recently announced the discovery of Kepler-16b, an exoplanet which orbits two binary stars. Something seem oddly familiar? Let’s just say it makes perfect sense to have John Knoll there (visual effects supervisor of Industrial Light & Magic, a division of Lucasfilm Ltd.)
There has recently been a lot of talk in the media about the discovery of new Super-Earths (ESO, BBC). The Kepler team has also announced that they will be revealing new discoveries tomorrow. In this post I thought I might write about the Super-Earths Kepler has found so far.
Super-Earths are a class of exoplanets with masses between 1-10 times the mass of Earth. The study of Super-Earths are of great interest as there is no planet in this mass and size regime in our solar system.
Kepler-10 b – The smallest Super-Earth
Kepler-10 b is the smallest Super-Earth discovered to date with a Radius of 1.4 Earth radii. It is also the first rocky planet found by the Kepler spacecraft and also the first terrestrial planet found outside our solar system. Here is a video by NASA about this exoplanet:
Kepler-11 – A planetary system with multiple Super-Earths
The Kepler-11 planetary system has 4 Super-Earths (so far) and is the most compact exoplanet system discovered to date. Kepler-11 is a remarkable planetary system whose architecture and dynamics provide clues to its formation. More information on this in the discovery paper.
Kepler-9 d – Thought to be a Super-Earth
Kepler-9 d is thought to be a Super-Earth. I say “thought to be” as current spectroscopic observations are still insufficient to establish its mass. The discoverers of the planet led by Torres, G say:
Based on several realistic estimates of this frequency, we conclude with very high confidence that this small signal is due to a super-Earth-size planet (Kepler-9 d) in a multiple system, rather than a false positive.
Secret companion found via Transit Timing Variations
Worth mentioning here is last weeks news of the discovery of Kepler-19 b. What made this discovery so special wasn’t so much the exoplanet Kepler-19 b but that a companion of this planet, Kepler-19 c was found using transit timing variations (mentioned in my post here). In short, transit timing variations deals with inferring the presence of one or more planets due to timing variations in the expected transit time. For this to be possible, very high quality data is needed, something Kepler provides. Although Kepler-19 is not a Super-Earth it is likely that the transit timing variations technique will discover more Super-Earths in the future.
The Kepler-10 planetary system with Exoplanet 10 c in the foreground. Image credit: NASA/Ames/JPL-Caltech
Validated Exoplanets:
Are a celestial object with a high likelihood of being an exoplanet, but has not been confirmed as no measurements of mass have been done.
Confirmed Exoplanets:
The exoplanet has a confirmed mass usually from radial velocity measurements or transit timing variations. When talking about the number of exoplanet discovered to date one talks about confirmed exoplanets.
This is an explanation of the terminology used by astronomers working on data from the Kepler satellite.
The Kepler satellite was launched in March 2009 and has since June 2009 been sending data down to Earth. It has been pointing at only one portion of the sky the entire time looking for variations in the brightness of stars. The image below shows the field of view of Kepler.
Kepler Field of View. 42 CCDs each with 2200 × 1024 pixels are used in order to get a large field of view. Credit: NASA
When an exoplanet passes infront of a star a small portion of the light is blocked out. Studying how the light is being dimmed gives astronomers a wealth of information about exoplanet candidates. I say candidates as a dip in the light curve alone is not enough to confirm the existence of an exoplanet. Binary and variable stars are examples of what is known as false candidates.
Observational exoplanet astronomer studying the atmospheres of exoplanets. Interested in public outreach and conveying my interest in astronomy to others.
Credit: STSCI
