WASP-11b

Lore & Background

The planet was initially announced by the SuperWASP project in April 2008 under the designation WASP-11b, alongside planets WASP-6b through WASP-15b, though at that stage more data was needed to confirm the parameters and coordinates were not given. Later, on 26 September 2008, the HATNet Project published a paper on the arXiv preprint server designating the object HAT-P-10b. The SuperWASP team's paper appeared as a preprint on the Extrasolar Planets Encyclopaedia the same day, confirming that the two objects were the same, and the teams agreed to use the combined designation.

At the time of discovery, the planet had the third lowest insolation among known transiting planets, after Gliese 436 b and HD 17156 b. Its equilibrium temperature of 1030 K places it in the pL class of hot Jupiters, meaning it lacks significant quantities of titanium(II) oxide and vanadium(II) oxide in its atmosphere and does not have a temperature inversion. An alternative classification system based on equilibrium temperature and Safronov number places it close to the dividing line between class I (high Safronov number, cooler host stars) and class II (lower Safronov number) planets, with a Safronov number of 0.047 ± 0.003.

The planet orbits in a binary star system; the second star, WASP-11 B, has a mass of 0.34 ± 0.05 solar masses and a temperature of 3483 ± 43 K.

Reader's Guide

WASP-11b/HAT-P-10b holds significance as one of the earliest transiting exoplanets discovered with a relatively low insolation, providing an early benchmark for studying cooler hot Jupiters. Its dual discovery by two independent surveys—SuperWASP and HATNet—illustrates the collaborative nature of exoplanet detection and the need for cross-confirmation of parameters. The planet's equilibrium temperature and Safronov number place it near a classification boundary, making it a useful test case for models of atmospheric composition and thermal structure. Its location in a binary star system adds further interest, as the companion star's properties are well characterized. The planet's pL classification indicates an atmosphere without significant titanium(II) oxide or vanadium(II) oxide and lacking a temperature inversion, contributing to the understanding of hot Jupiter atmospheric diversity. The agreement between the two teams to use a combined designation set a precedent for naming conventions in the field.

Did You Know?

• WASP-11b and HAT-P-10b were independently discovered and later confirmed to be the same planet.
• It had the third lowest insolation of known transiting planets at the time of its discovery.
• It orbits in a binary star system with a companion star of mass 0.34 ± 0.05 solar masses.