WASP-19b
WASP-19b, formally named Banksia, is an exoplanet, notable for possessing one of the shortest orbital periods of any known planetary body: 0.79 days or approximately 18.932 hours. It has a mass close to that of Jupiter (1.15 Jupiter masses), but by comparison has a much larger radius (1.31 times that of Jupiter, or 0.13 Solar radii); making it nearly the size of a low-mass star. It orbits the star WASP-19 in the Vela constellation. At the time of discovery it was the shortest period hot Jupiter discovered as planets with shorter orbital periods had a rocky, or metallic composition.
Size comparison of WASP-19b with Jupiter. | |
| Discovery | |
|---|---|
| Discovered by | Hebb et al. (SuperWASP) |
| Discovery date | December 10, 2009 |
| Transit | |
| Designations | |
| Banksia | |
| Orbital characteristics | |
| 0.01655 ± 0.00013 AU (2,476,000 ± 19,000 km) | |
| Eccentricity | 0.0046+0.0044 −0.0028 |
| 0.79 ± 0.0000003 d (18.9600000 ± 7.2×10−6 h; 68,256.000 ± 0.026 s) | |
| Inclination | 79.4±0.4 |
| Star | WASP-19 |
| Physical characteristics | |
Mean radius | 1.386±0.032 RJ |
| Mass | 1.168±0.023 MJ |
Mean density | 680 kg/m3 (1,150 lb/cu yd) |
| Albedo | <0.26 0.16±0.04 |
| Temperature | 2350+168 −314 2240±40 |
A study in 2012, utilizing the Rossiter–McLaughlin effect, determined the planetary orbit is well aligned with the equatorial plane of the star, misalignment equal to -15±11°.
In 2013, secondary eclipse and orbital phases were barely observed from the data gathered with ASTEP telescope, making it the first detection of such kind through ground-based observations. This was possible due to the large size of the planet and its small semi-major axis.
In 2019 the planet was observed with TESS and the eclipse of the planet was measured. The broad variations caused by the changing aspect of the heated face of the planet were measured. The study deduced that the dayside has a temperature of 2240 ± 40 K (1967 ± 40 °C) and that the planet reflects 16 ± 4 percent of the light that falls on it. The last value is relatively high compared to other planets.
Despite the short orbital period, orbital decay of WASP-19b was not detected as of 2019.