Almost two years after the International Astronomical Union (IAU) General Assembly introduced the category of dwarf planets, the IAU, as promised, has decided on a name for transneptunian dwarf planets similar to Pluto. The name plutoid was proposed by the members of the IAU Committee on Small Body Nomenclature (CSBN), accepted by the Board of Division III, by the IAU Working Group for Planetary System Nomenclature (WGPSN) and approved by the IAU Executive Committee at its recent meeting in Oslo, Norway.
Plutoids are celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit. The two known and named plutoids are Pluto and Eris. It is expected that more plutoids will be named as science progresses and new discoveries are made.
The dwarf planet Ceres is not a plutoid as it is located in the asteroid belt between Mars and Jupiter. Current scientific knowledge lends credence to the belief that Ceres is the only object of its kind. Therefore, a separate category of Ceres-like dwarf planets will not be proposed at this time.
The IAU has been responsible for naming planetary bodies and their satellites since the early 1900s. The IAU CSBN, who originally proposed the term plutoid, is responsible for naming small bodies (except satellites of the major planets) in the Solar System. The CSBN will be working with the IAU WGPSN to determine the names of new plutoids to ensure that no dwarf planet shares the name of another small Solar System body. The WGPSN oversees the assignment of names to surface features on bodies in the Solar System. These two committees have previously worked together to accept the names of dwarf planet Eris and its satellite Dysnomia.
In Oslo, members of the IAU also discussed the timing involved with the naming of new plutoids. Again, following the advice of the Division III Board and the two Working Groups, it was decided that, for naming purposes, any Solar System body having (a) a semimajor axis greater than that of Neptune, and (b) an absolute magnitude brighter than H = +1 magnitude will be considered to be a plutoid, and be named by the WGPSN and the CSBN. Name(s) proposed by the discovery team(s) will be given deference. If further investigations show that the object is not massive enough and does not qualify as a plutoid, it will keep its name but change category.
In French plutoid is plutoïde, in Spanish plutoide.
Source: International Astronomical Union
Related stories:
COROT's exoplanet hunt update
Two new exoplanets and an unknown celestial object are the latest findings of the COROT mission. These discoveries mean that the mission has now found a total of four new exoplanets.
The star, the dwarf and the planet
Astronomers have detected a new faint companion to the star HD 3651, already known to host a planet. This companion, a brown dwarf, is the faintest known companion of an exoplanet host star imaged directly and one of the faintest T dwarfs detected in the Solar neighbourhood so far. The detection yields important information on the conditions under which planets form.
IAU names dwarf planet Eris
The International Astronomical Union announces the names Eris for the dwarf planet provisionally named 2003 UB 313 and Dysnomia for its moon.
Astronomers React to Pluto's Planetary 'Demotion'
Several Johns Hopkins University astronomers described a decision Thursday to strip Pluto of its planetary status as a "muddled" ruling that is unlikely to settle ongoing debates over how to define a planet and whether the term should apply to Pluto. In an informal poll, only one astronomer was pleased to hear about Pluto’s new status.
The Final IAU Resolution on the definition of 'planet' ready for voting
At the second session of the 2006 International Astronomical Union (IAU) General Assembly, which will be held 14:00 CEST (08:00 EDT) Thursday 24 August, members of the IAU will vote on the Resolutions presented below. There will be separate sequential votes on Resolution 5A and Resolution 5B. Similarly, there will be separate votes on Resolutions 6A and 6B.
The IAU draft definition of 'planet' and 'plutons'
The world’s astronomers, under the auspices of the International Astronomical Union (IAU), have concluded two years of work defining the difference between “planets” and the smaller “solar system bodies” such as comets and asteroids. If the definition is approved by the astronomers gathered 14-25 August 2006 at the IAU General Assembly in Prague, our Solar System will include 12 planets, with more to come: eight classical planets that dominate the system, three planets in a new and growing category of “plutons” – Pluto-like objects – and Ceres. Pluto remains a planet and is the prototype for the new category of “plutons.”
A new era in search for 'sister Earths'?
Research presented at a recent astronomical conference is being hailed as ushering in a new era in the search for Earth-like planets by showing that they are more numerous than previously thought and that scientists can now analyze their atmospheres for elements that might be conducive to life.
The UN declares 2009 the International Year of Astronomy
Early this morning, the United Nations 62nd General Assembly proclaimed 2009 the International Year of Astronomy. The Resolution was submitted by Italy, Galileo Galilei's home country. The International Year of Astronomy 2009 is an initiative of the International Astronomical Union and UNESCO.
