Iota Draconis b[1] Hypatia
Artist's concept of Iota Draconis b (foreground) orbiting its parent star (center).
Discovery
Discovered byFrink et al.
Discovery dateJanuary 8, 2002
Doppler Spectroscopy
Orbital characteristics[2]
1.453±0.026 AU
Eccentricity0.7010+0.0016
−0.0017
1.398643 ± 0.000035 a (510.854 ± 0.013 d)
Inclination46+27
−19
87+64
−60
2455590.17±0.13
89.90±0.30
Semi-amplitude307.6 (± 2.3)
StarIota Draconis
Physical characteristics
Mass16.4+9.3
−4.0 MJ[2]

    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]

    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.[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, 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.[3]

    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]

    References

    1. ↑ Butler, R. P.; Wright, J. T.; Marcy, G. W.; Fischer, D. A.; Vogt, S. S.; Tinney, C. G.; Jones, H. R. A.; Carter, B. D.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701. S2CID 119067572. Archived from the original on 2019-12-07. Retrieved 2009-03-11.
    2. 1 2 3 4 Hill, Michelle L.; Kane, Stephen R.; Campante, Tiago L.; Li, Zhexing; Dalba, Paul A.; Brandt, Timothy D.; White, Timothy R.; Pope, Benjamin J. S.; Stassun, Keivan G.; Fulton, Benjamin J.; Corsaro, Enrico; Li, Tanda; Joel Ong, J. M.; Bedding, Timothy R.; Bossini, Diego; Buzasi, Derek L.; Chaplin, William J.; Cunha, Margarida S.; Garcia, Rafael A.; Breton, Sylvain N.; Hon, Marc; Huber, Daniel; Jiang, Chen; Kayhan, Cenk; Kuszlewicz, James S.; Mathur, Savita; Serenelli, Aldo; Stello, Dennis (2021), "Asteroseismology of iota Draconis and Discovery of an Additional Long-period Companion", The Astronomical Journal, 162 (5): 211, arXiv:2107.13583, Bibcode:2021AJ....162..211H, doi:10.3847/1538-3881/ac1b31, S2CID 236493583
    3. 1 2 Frink; Mitchell, David S.; Quirrenbach, Andreas; Fischer, Debra A.; Marcy, Geoffrey W.; Butler, R. Paul (2002). "Discovery of a Substellar Companion to the K2 III Giant Iota Draconis". The Astrophysical Journal. 576 (1): 478–484. Bibcode:2002ApJ...576..478F. CiteSeerX 10.1.1.6.5332. doi:10.1086/341629. S2CID 12778096.
    4. ↑ Safonova, M.; Murthy, J.; Shchekinov, Yu. A. (2014). "Age Aspects of Habitability". International Journal of Astrobiology. 15 (2): 93–105. arXiv:1404.0641. Bibcode:2016IJAsB..15...93S. doi:10.1017/S1473550415000208. S2CID 20205600.
    5. ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
    6. ↑ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
    7. ↑ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
    8. ↑ "NameExoWorlds The Process". Archived from the original on 2015-08-15. Retrieved 2015-09-05.
    9. ↑ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
    10. ↑ "NameExoWorlds The Approved Names". Archived from the original on 2018-02-01. Retrieved 2016-01-02.
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