Iota Draconis b
Extrasolar planet in the constellation Draco
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Iota Draconis b, properly named Hypatia (pronounced /haɪˈpeɪʃiə/ or /hɪˈpeɪʃə/), is an exoplanet orbiting the K-type giant star Iota Draconis about 101.2 light-years (31 parsecs, or nearly 2.932×1014 km) from Earth in the constellation Draco. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star.[4]
Artist's concept of Iota Draconis b (foreground) orbiting its parent star (center) | |
| Discovery | |
|---|---|
| Discovered by | Frink et al. |
| Discovery date | January 8, 2002 |
| Doppler Spectroscopy | |
| Orbital characteristics[2] | |
| 1.453±0.026 AU | |
| Eccentricity | 0.7010+0.0016 −0.0017 |
| 1.398643 ± 0.000035 a (510.854 ± 0.013 d) | |
| Inclination | 46+27 −19 |
| 87+64 −60 | |
| 2455590.17±0.13 | |
| 89.90±0.30 | |
| Semi-amplitude | 307.6 (± 2.3) |
| Star | Iota Draconis |
| Physical characteristics | |
| 1.1+0.22 −0.19 RJ[3] | |
| Mass | 16.4+9.3 −4.0 MJ[2] |
Physical characteristics
Mass
Iota Draconis b is a "super-Jupiter", a planet that has mass larger than that of the gas giants Jupiter and Saturn. It has an estimated minimum mass of around 11.82 MJ.[2]
In 2021, astrometric observations revealed the true mass of Iota Draconis b to be 16.4 MJ.[2]
Host star
The planet orbits a (K-type) giant star named Edasich (designated Iota Draconis). The star has exhausted the hydrogen supply in its core and is currently fusing helium. The star has a mass of 1.82 M☉ and a radius of around 12 R☉. It has a surface temperature of 4545 K and is around 800 million years old based on its evolution. Although much younger than the Sun, the higher mass of this star correlates to a faster evolution, leading to the host star having already departed from the main sequence. When on the main sequence, Edasich was probably a Class A star with surface temperature between 7,400 and 10,000K.[5] In comparison, the Sun is about 4.6 billion years old[6] and has a surface temperature of 5778 K.[7]
The star's apparent magnitude, a measure of how bright it appears from Earth, is 3.31. Therefore, Edasich can be seen with the naked eye.
Orbit
Iota Draconis b orbits its star with nearly 55 times the Sun's luminosity (55 L☉) every 511 days at an average distance of 1.275 AU (compared to Mars' orbital distance from the Sun, which is 1.52 AU) It has a very eccentric orbit, with an eccentricity of 0.7124.
Discovery
Discovered in 2002 during a radial velocity study of K-class giant stars, its eccentric orbit aided its detection, as giant stars have pulsations which can mimic the presence of a planet.[4]
Name
Following its discovery the planet was designated Iota Draconis b. In July 2014, the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.[8] The process involved public nomination and voting for the new names.[9] In December 2015, the IAU announced that the winning name for this planet was Hypatia.[10] The winning name was submitted by Hypatia, a student society of the Physics Faculty of the Universidad Complutense de Madrid, Spain. Hypatia was a famous Greek astronomer, mathematician, and philosopher.[11]