What is a star?

Stars are massive, luminous balls of hot gas (plasma), which are held together by gravity. Although they look small, they are actually large bright objects. Our closest star is our Sun. Other stars look so small because they are very far away – the next nearest star, Alpha Centauri, is 4.3 light years away; this is approximately 41,000,000,000,000 km from us!

Stars come in an amazing range of different sizes and colours, which can tell us a lot about what type of star they are. They exist because of a balance between gravity trying to make the star shrink and all the heat from the middle trying to make it grow.

Stars “live” for many, many millions of years, but often change only very slowly during most of that time. However, exciting things can happen when they are born or when they run out of nuclear fuel and die.

To explore more about stars, how they form, their life cycle and how stars are classified, please follow the link to “Stars” section on the website of the National School’s Observatory 

Image courtesy of NASA Solar Dynamics Observatory Team
wasp exoplanet
Credit: University of Keele/David A. Hardy

What is an Exoplanet?

The planets in our own solar system orbit around our star, the Sun. Planets that orbit around other stars are called extra solar planets or exoplanets for short. They are very difficult to see directly with telescopes as an exoplanet is hidden by the brightness of the host star.

Astronomers use other means for detecting and studying these distant worlds, in particular by looking at the gravitational effects the exoplanets have on the host stars themselves.

To explore more about exoplanets, when they were first discovered and how they are now observed, please follow the link to “Exoplanets” section on the website of the National School’s Observatory

gas giant exoplanet
Artist impression of a gas giant exoplanet like WASP-13b (NASA).
extrasolar planet

WASP-13 and WASP-13b

The star and exoplanet given to the UK to name are WASP-13 and WASP-13b respectfully. Their current scientific designation arises from the fact they were discovered and investigated by the Wide-Angle Search for Planets international consortium.

WASP-13 is a star in the Lynx constellation. It is similar to our Sun, in terms of metallicity and mass, although it is hotter and most likely older. The star is 747 light years from Earth.

WASP-13b is an exoplanet in the orbit of WASP-13. The planet is about a third of the mass of Jupiter, but with a radius 22% bigger than that gas giant planet. WASP-13 orbits very close to its host star at a distance equivalent to 5% of the distance between the Sun and Earth. It does one full orbit in only four days.

This exoplanet was discovered and reported upon in 2009 by an international team lead by British astronomers.


MASS: 0.72 x Sun MASS: 0.36 x Jupiter
RADIUS: 1.37 x Sun RADIUS: 1.22 x Jupiter
AGE: approx. 8.5 billion years ORBITAL PERIOD: 4.4 days
TEMPERATURE: approx. 5900K ORBITAL RADIUS: 0.05362 AU (approx. 8 million km)


The Wide Angle Search for Planets website run by the University of Keele has some amazing further information about WASP-13 and WASP-13b.

Also see the interactive animations at the NASA Exoplanet Catalog website

If you want to explore more of the science into the UK’s chosen Exoworld system, Wikipedia is a good place to start for both WASP-13  and WASP-13b