Some planetary systems are not alike. A number of different configurations have been spotted in the big, wide galaxy, some vastly different from our home system. The fictional world of Tatooine is an example of an extrasolar planet that is not one, but two stars.
For the first time, astronomy has been able to detect the tiny pull that an exoplanet exerts on one of its host stars, giving us a new tool to probe and explore these exotic worlds.
The discovery of the exoplanet is not new. The discovery of its name was made in 2011.
It was hailed as the first confirmed, unambiguous detection of an exoplanet going around two stars. Astronomers have looked at it a lot, and we know a lot about it.
If you want to try something new in astronomy, using a well-characterized and well-studied target is a good way to find out if techniques work.
The team led by Amaury Triaud of the University of Birmingham wanted to see if they could detect the planetary system through the wobble of one of the stars.
10 years ago, NASA's Kepler satellite used the transit method to discover the 16b.
The most unexpected discovery was made by the system. We turned our telescope to show the validity of our radial-velocity methods.
Two of the most popular methods are looking for exoplanets. A space-based telescope will look for faint dips in starlight that indicate an exoplanet is passing between a star and us.
The radial-velocity method is the second most fruitful method because it relies on the complexity of a planetary system. Stars are not stationary objects with planets around them. Each planet exerts its own influence on the star, causing it to wobble a bit like a discus thrower. The Sun is influenced by Jupiter.
The observed light is changed by this motion. When the star moves closer to the red end of the spectrum, the wavelengths compress and shift towards the blue end of the spectrum. Astronomers can use these changes to find an exoplanet.
This was only performed on single stars. Since they have larger motions through space, the detection of the smaller tug of the planets is more difficult.
The team targeted a system with one bright star and one much fainter star in order to circumvent problems that arose from trying to disentangle the spectrum of two bright stars. It worked. The brighter of the two stars had a radial velocity signal detected by the 1.93-meter telescope at the Haute-Provence Observatory.
We can learn a lot from this. One of the key properties of an exoplanet is its mass, which can be measured with the help of radial velocity measurements.
The team found that the mass of Jupiter is around a third of that of the moon.
This information could help us figure out how circumbinary worlds form, which is difficult to explain with current planet formation models. A disk of dust and gas left over from the star's own formation is thought to form planets around other stars.
It is difficult to understand how circumbinary planets can exist. The presence of two stars prevents dust from agglomerating into planets, a process called accretion.
The planet may have formed far from the two stars, where their influence is weaker, and then moved inwards in a process called disk-driven migration.
This problem may be solved by more detailed information about the kinds of exoplanets in circumbinary. The team hopes that their work will lead to future discoveries.
The research has been published.
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