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Name an exoplanet and its star - Romania participates in the IAU100 NameExoWorlds campaign

on 29 August 2019

Romanians are invited to name the exoplanet XO-1 b and the star it orbits, XO-1. The campaign is taking place within the framework of the 100th anniversary of the International Astronomical Union (IAU), with around 100 countries in the world participating. The call for suggesting names for these two objects reserved to Romania is open to everyone until 5 October 2019. The proposals can be submitted by an individual or a group (school class or astronomy club).

12 valid name proposals will be selected and then voted upon between 12 – 31 October 2019. The top result, together with the next two back-up names, will be sent to the IAU International Committee, and the final names will be made public on 15 December 2019.

Over the past two decades, astronomers have discovered thousands of planets around other stars than our Sun. These planets outside of our Solar System are called “exoplanets” and some can be rocky like the Earth, whilst others are gas giants like Jupiter.

Founded in 1919, the IAU brings together more than 13.500 professional astronomers from 107 countries worldwide. The IAU is the international authority responsible for assigning scientific designations and names to celestial bodies. On its centennial anniversary, it is offering everyone the possibility to name an exoplanet and its star. The IAU assigned an exoplanetary system, containing one star and one planet, to each country. Romania was assigned the system with the XO-1 star and its planet, XO-1 b, located at 536 light years, in the Corona Borealis constellation.

2019 08 NameExoWorlds Image A

The map of constellations near the XO-1 star. The location of the star in the Corona Borealis constellation is marked in red. Illustration credit: EXOKyoto

The star is very similar to our own Sun, both in its yellow colour (given by its surface temperature), as well as dimension, mass and total luminosity. Despite these physical resemblances, the XO-1 star is 1 billion years of age, over four times younger than our Sun.

As far as we know to date, the planet XO-1 b is the only planet orbiting the XO-1 star. It was discovered in 2006 by a team of amateur and professional astronomers, led by Peter R. McCullough. A year on the XO-1 b planet lasts almost 4 Earth days and its average radius is 1,21 larger than Jupiter’s. Spectroscopic observations have revealed that the atmosphere of XO-1 b is rich in H2/He, containing water, molecules carrying NH3 and HCN and it has cloud patches.

2019 08 NameExoWorlds Image B

The orbit of the XO-1 b planet around the XO-1 star. In this planetary system, the extrasolar planet XO-1 b orbits its star once every 3.9 days, at an orbital distance 0.05 AU (7300376.1 km). Illustration credit: EXOKyoto

2019 08 NameExoWorlds Image C

The habitable zone of the XO-1 star, calculated based on the SEAU (Solar Equivalent Astronomical Unit). Illustration credit: EXOKyoto

Until 5 October, proposals can be submitted by individuals or groups such as school classes or astronomy clubs from Romania. Each proposal must contain two names  — one for the XO-1 star and one for the XO-1 b planet — and it must also have a short explanation for the names.

12 valid proposals will be chosen and submitted to a vote between 12 and 31 October 2019 (the vote will not be open to individuals, but groups such as school classes and astronomy clubs). The top result, together with the next two back-up names, will be further sent to the IAU International Committee and the final name will be made public on 15 December 2019.

In order to be considered valid, the name proposals for the star and planet must respect a series of rules, which can be accessed on the website of the Astronomical Institute of the Romanian Academy (IAAR) and on the IAU website.

The suggested names must:

  • Have a maximum of 16 characters and a minimum of 4;
  • Be made of one word, if possible;
  • Be easy to pronounce (in any language);
  • Not be offensive;
  • Not be similar to already existing names.

More details about how the names should be and places to check existing names are available here.

It is not permitted to suggest:

  • Names of pets;
  • Names of commercial nature or protected by copyright or trademark;
  • Names of individuals, places or events principally known for political, military or religious activities;
  • Names of individuals that died less than a century ago;
  • The same name for the star and planet.

The full list of criteria is available here and here. Only name proposals that are fully compliant with these rules will be taken into account.

The name suggestions together with a short explanation (maximum 200 characters) can be sent using this form until 5 October.

The process must respect intellectual property rights. The suggested names have to be free to use in the public domain, internationally, permanently and with no restrictions. The IAU will credit the organisation or individuals that have suggested the names.

Further details about the campaign in Romania can be accessed on the website of the Astronomical Institute of the Romanian Academy, while details about the global campaign are available on the IAU website.

President of the National Committee:
Dumitru Pricopi
E-mail: dpricopi at

Credit main image:
IAU/L. Calçada