Iota Draconis b, formally named Hypatia (pronounced /hˈpʃiə/ or /hɪˈpʃə/), 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.[4]

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
1.1+0.22
−0.19
 RJ
[3]
Mass16.4+9.3
−4.0
 MJ
[2]

Physical characteristics

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Mass

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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

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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

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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

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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

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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]

References

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  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. ^ a b c d 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. ^ Campante, Tiago L.; Li, Tanda; Ong, J. M. Joel; Corsaro, Enrico; Cunha, Margarida S.; Bedding, Timothy R.; Bossini, Diego; Breton, Sylvain N.; Buzasi, Derek L.; Chaplin, William J.; Deal, Morgan; García, Rafael A.; Hill, Michelle L.; Hon, Marc; Huber, Daniel; Jiang, Chen; Kane, Stephen R.; Kayhan, Cenk; Kuszlewicz, James S.; Lillo-Box, Jorge; Mathur, Savita; Monteiro, Mário J. P. F. G.; Pereira, Filipe; Santos, Nuno C.; Serenelli, Aldo; Stello, Dennis (2023), "Revisiting the Red Giant Branch Hosts KOI-3886 and ι Draconis. Detailed Asteroseismic Modeling and Consolidated Stellar Parameters", The Astronomical Journal, 165 (5): 214, arXiv:2304.01570, Bibcode:2023AJ....165..214C, doi:10.3847/1538-3881/acc9c1, S2CID 257921759
  4. ^ a b 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.
  5. ^ 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.
  6. ^ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
  7. ^ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
  8. ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
  9. ^ "NameExoWorlds The Process". Archived from the original on 2015-08-15. Retrieved 2015-09-05.
  10. ^ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
  11. ^ "NameExoWorlds The Approved Names". Archived from the original on 2018-02-01. Retrieved 2016-01-02.
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