# WASP-11b/HAT-P-10b

Extrasolar planet Parent star Orbital elements List of extrasolar planets Size comparison of WASP-11b/HAT-P-10b with Jupiter. Star WASP-11/HAT-P-10[1] Constellation Perseus Right ascension (α) 03h 09m 28.55s[2] Declination (δ) +30° 40′ 24.9″[2] Apparent magnitude (mV) 11.89 Distance 408+20 −16[2] ly (125+6 −5[2] pc) Spectral type K3V[3] Semimajor axis (a) 0.0439+0.0006 −0.0009[2] AU Eccentricity (e) 0[2] Orbital period (P) 3.7224690 ± 0.0000067[2] d Inclination (i) 88.5 ± 0.6[2]° Time of transit (Tt) 2454729.90631 ± 0.00030[2] JD Semi-amplitude (K) 69.1 ± 3.5[2] m/s Mass (m) 0.460 ± 0.028[2] MJ Radius (r) 1.045+0.050 −0.033[2] RJ Density (ρ) 498 ± 64[2] kg m-3 Surface gravity (g) 10.5[2] m/s² Temperature (T) 1030+26 −19[2][note 1] K Discovery date April 1, 2008 (announced) September 26, 2008 (preprints) Discoverer(s) West et al. (SuperWASP) Bakos et al. (HATNet) Discovery method Transit Discovery site SAAO Discovery status Independently confirmed WASP-11b, HAT-P-10b Database references Extrasolar Planets Encyclopaedia data SIMBAD data
Artist's impression of WASP-11b/HAT-P-10b

WASP-11b/HAT-P-10b or WASP-11Ab/HAT-P-10Ab[4] is an extrasolar planet discovered in 2008. The discovery was announced (under the designation WASP-11b) by press release by the SuperWASP project in April 2008 along with planets WASP-6b through to WASP-15b, however at this stage more data was needed to confirm the parameters of the planets and the coordinates were not given.[5] On 26 September 2008, the HATNet Project's paper describing the planet which they designated HAT-P-10b appeared on the arXiv preprint server.[2] The SuperWASP team's paper appeared as a preprint on the Extrasolar Planets Encyclopaedia on the same day, confirming that the two objects (WASP-11b and HAT-P-10b) were in fact the same, and the teams agreed to use the combined designation.[1]

The planet has the third lowest insolation of the known transiting planets (only Gliese 436 b and HD 17156 b have lower insolation). The temperature implies it falls into the pL class of hot Jupiters: planets which lack significant quantities of titanium(II) oxide and vanadium(II) oxide in their atmospheres and do not have temperature inversions.[6] An alternative classification system for hot Jupiters is based on the equilibrium temperature and the planet's Safronov number.[note 2] In this scheme, for a given temperature, class I planets have high Safronov numbers and tend to be in orbit around cooler host stars, while class II planets have lower Safronov numbers.[7] In the case of WASP-11b/HAT-P-10b, the equilibrium temperature is 1030 K[note 1] and the Safronov number is 0.047±0.003, which means it is located close to the dividing line between the class I and class II planets.[2]

## Notes

1. ^ a b Assumes the planet has zero albedo. Its secondary transit of the planet behind its star has not yet been observed and so the temperature provided is a hypothetical "equilibrium temperature".
2. ^ The Safronov number is defined as $\textstyle \Theta = \frac{1}{2} \left(\frac{\mathrm{Planetary\ escape\ velocity}}{\mathrm{Orbital\ velocity}}\right)^2$