Iota Draconis b, formally 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. It was the first planet discovered orbiting a giant star.[3]

Iota Draconis b[1]

Artist's concept of Iota Draconis b (foreground) orbiting its parent star (center).
Discovery
Discovered by	Frink et al.
Discovery date	January 8, 2002
Detection method	Doppler Spectroscopy
Orbital characteristics[2]
Semi-major axis	1.453±0.026 AU
Eccentricity	0.7010+0.0016 −0.0017
Orbital period (sidereal)	1.398643 ± 0.000035 a (510.854 ± 0.013 d)
Inclination	46+27 −19
Longitude of ascending node	87+64 −60
Time of periastron	2455590.17±0.13
Argument of periastron	89.90±0.30
Semi-amplitude	307.6 (± 2.3)
Star	Iota Draconis
Physical characteristics
Mean radius	~12 REarth[citation needed]
Mass	16.4+9.3 −4.0 MJ[2]
Temperature	598 K (325 °C; 617 °F)[citation needed]

Physical characteristics

Mass, radius and temperature

Iota Draconis b is a "super-Jupiter", a planet that has mass larger than that of the gas giants Jupiter and Saturn. It has a blackbody temperature of 598 K (325 °C; 617 °F).^{[citation needed]} It has an estimated minimum mass of around 11.82 M_J[2] and a potential radius of around 12 R_Earth based on its mass,^{[citation needed]} since it is more massive than Jupiter.

In 2021, astrometric observations revealed the true mass of Iota Draconis b to be 16.4 M_J.[2]

Host star

The planet orbits a (K-type) giant star named 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, Iota Draconis was probably a Class A star with surface temperature between 7,400 and 10,000K.[4] In comparison, the Sun is about 4.6 billion years old[5] and has a surface temperature of 5778 K.[6]

The star's apparent magnitude, a measure of how bright it appears from Earth, is 3.31. Therefore, Iota Draconis 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.

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.[7] The process involved public nomination and voting for the new names.[8] In December 2015, the IAU announced that the winning name for this planet was Hypatia.[9] 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.[10]

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.[3]

References

External links

• SolStation: Edasich/Iota Draconis

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[de] Hypatia (Exoplanet)

[es] Hypatia (planeta)