# HIP 65426 b

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Gas giant exoplanet orbiting HIP 65426

HIP 65426 b / Najsakopajk HIP 65426 b is on the lower left of the image, with the circle representing what Neptune's orbit would look like around the star HIP 65426, represented by a small cross. Discovery[1] Discovered by SPHERE consortium[2] Discovery date 6 July 2017 Detection method Direct imaging Designations Alternative names Najsakopajk[3] Orbital characteristics Semi-major axis 87+108 −31 AU[4] Inclination 100°+15° −6°[4] Physical characteristics Mean radius 1.44±0.03 RJ[4] Mass 7.1±1.2 MJ[4] Surface gravity 3.93+0.07 −0.09 dex[4] Temperature 1,283+25 −31 K[4]

**HIP 65426 b**, formally named **Najsakopajk**,[3] is a [super-Jupiter](/source/Super-Jupiter) [exoplanet](/source/Exoplanet) orbiting the [star](/source/Star) HIP 65426. It was discovered on 6 July 2017 by the SPHERE consortium using the [Spectro-Polarimetric High-Contrast Exoplanet Research](/source/Spectro-Polarimetric_High-Contrast_Exoplanet_Research) (SPHERE) instrument belonging to the [European Southern Observatory](/source/European_Southern_Observatory) (ESO),[5][6] being the first confirmed planet discovered by the SPHERE instrument.[7][a] It is 385 [light-years](/source/Light-year) from Earth in the [Centaurus](/source/Centaurus) constellation.[9]

## Nomenclature

HIP 65426 b is a designation inherited from the host star's name, HIP 65426, following the [exoplanet naming convention](/source/Exoplanet_naming_convention), where exoplanets receive lowercase letters. The designation HIP 65426 has its origin on the [Hipparcos catalogue](/source/Hipparcos_catalogue).[10]

In August 2022, this planet and its host star were included among 20 systems to be named by the third [NameExoWorlds](/source/NameExoWorlds) project.[11] The approved names, proposed by a team from [Mexico](/source/Mexico), were announced in June 2023. HIP 65426 b is named **Najsakopajk** and its host star is named **Matza**, after [Zoque](/source/Zoque_languages) words for "Mother Earth" and "star".[3]

## Overview

The exoplanet HIP 65426 b orbits its host star HIP 65426, an [A-type main-sequence star](/source/A-type_main-sequence_star) with [apparent magnitude](/source/Apparent_magnitude) 7.01, with a mass of 1.96±0.04 [*M*☉](/source/Solar_mass), a radius of 1.77±0.05 [*R*☉](/source/Solar_radius) and an [effective temperature](/source/Effective_temperature) of 8,840 [K](/source/Kelvin) (8,570 °C).[12] This planetary system is located in the constellation [Centaurus](/source/Centaurus). The planet is around 14 million years old, much younger than the [Solar System](/source/Solar_System) which is 4.5 billion years old, but is not associated with a debris disk, despite its young age,[6][9] causing it to not fit [current models for planetary formation](/source/Planet_formation).[13] It is around 92 [AU](/source/Astronomical_Unit) from its parent star, with a possible dusty [atmosphere](/source/Atmosphere).[14] It was discovered as part of the SHINE program, which aimed to find [planetary systems](/source/Planetary_system) around 600 new stars.[1]

In September 2022, HIP 65426 b became the first exoplanet directly observed by the [James Webb Space Telescope](/source/James_Webb_Space_Telescope).[15]

## Planetary atmosphere

The spectrum taken in 2020 has indicated that HIP 65426 b is carbon-poor and oxygen-rich compared to Solar System gas giants.[16]

Spectral analysis of data from the James Webb Space Telescope revealed strong evidence of silicate clouds containing [enstatite](/source/Enstatite) with no evidence of a dusty atmosphere.[17]

## James Webb Space Telescope observations

In August 2022, a [pre-print](/source/Preprint) of the [James Webb Space Telescope](/source/James_Webb_Space_Telescope) (JWST) observations was published. The JWST direct imaging observations between 2-16 μm of HIP 65426 b tightly constrained its [bolometric luminosity](/source/Luminosity) to log ⁡ ( L b o l / L s u n ) = − 4.23 ± 0.08 {\displaystyle \log(L_{bol}/L_{sun})=-4.23\pm 0.08} , which provides a robust mass constraint of 7.1±1.2 [*M*J](/source/Jupiter_mass). Evolutionary models suggest a radius 45% larger than that of Jupiter and an [effective temperature](/source/Effective_temperature) of 1,283 [K](/source/Kelvin) (1,010 °C). Atmospheric models suggest lower radii down to 0.9 RJ and higher temperatures, but these results are unreliable. The team also constrained the [semi-major axis](/source/Semi-major_and_semi-minor_axes) and the [inclination](/source/Orbital_inclination) of the planet, but the new JWST astrometry of the planet did not significantly improve the orbit of the planet, especially the [eccentricity](/source/Orbital_eccentricity) remains unconstrained.[4]

HIP 65426 b is the first exoplanet to be imaged by JWST and the first to be detected in [wavelengths](/source/Wavelength) beyond 5 μm. The observations demonstrate that the James Webb Space Telescope will exceed its nominal predicted performance by a factor of 10 and that it will be able to image 0.3 [MJ](/source/Jupiter_mass) planets at 100 [au](/source/Astronomical_unit) for [main-sequence stars](/source/Main_sequence), [Neptune](/source/Neptune) and [Uranus](/source/Uranus)-mass objects at 100-200 au for [M-dwarfs](/source/Red_dwarf) and [Saturn](/source/Saturn)-mass objects at 10 au for M-dwarfs. For [α Cen A](/source/Alpha_Centauri) JWST might be able to push the limit to a 5 [R🜨](/source/Earth_radius) planet at 0.5 to 2.5 au.[4]

HIP 65426 star map

HIP 65426 b viewed by the [James Webb Space Telescope](/source/James_Webb_Space_Telescope) (August 2022)

## See also

- [Lists of exoplanets](/source/Lists_of_exoplanets)

- [List of exoplanets discovered in 2017](/source/List_of_exoplanets_discovered_in_2017)

## References

1. ^ [***a***](#cite_ref-Chauvin2017_1-0) [***b***](#cite_ref-Chauvin2017_1-1) Chauvin, G.; Desidera, S.; Lagrange, A. -M.; Vigan, A.; Gratton, R.; Langlois, M.; Bonnefoy, M.; Beuzit, J. -L.; Feldt, M.; Mouillet, D.; Meyer, M.; Cheetham, A.; Biller, B.; Boccaletti, A.; d'Orazi, V.; Galicher, R.; Hagelberg, J.; Maire, A. -L.; Mesa, D.; Olofsson, J.; Samland, M.; Schmidt, T. O. B.; Sissa, E.; Bonavita, M.; Charnay, B.; Cudel, M.; Daemgen, S.; Delorme, P.; Janin-Potiron, P.; et al. (2017). "Discovery of a warm, dusty giant planet around HIP 65426". *Astronomy and Astrophysics*. **605**: L9. [arXiv](/source/ArXiv_(identifier)):[1707.01413](https://arxiv.org/abs/1707.01413). [Bibcode](/source/Bibcode_(identifier)):[2017A&A...605L...9C](https://ui.adsabs.harvard.edu/abs/2017A&A...605L...9C). [doi](/source/Doi_(identifier)):[10.1051/0004-6361/201731152](https://doi.org/10.1051%2F0004-6361%2F201731152). [S2CID](/source/S2CID_(identifier)) [102344893](https://api.semanticscholar.org/CorpusID:102344893).

1. **[^](#cite_ref-2)** ["Odd planetary system around fast-spinning star doesn't quite fit existing models of planet formation"](https://sphere.osug.fr/spip.php?rubrique7). *www.sphere.osug.fr*. Retrieved 2017-07-06.

1. ^ [***a***](#cite_ref-NEW2022_3-0) [***b***](#cite_ref-NEW2022_3-1) [***c***](#cite_ref-NEW2022_3-2) ["2022 Approved Names"](https://www.nameexoworlds.iau.org/2022approved-names). *nameexoworlds.iau.org*. [IAU](/source/International_Astronomical_Union). Retrieved 7 June 2023.

1. ^ [***a***](#cite_ref-Carter_et_al_4-0) [***b***](#cite_ref-Carter_et_al_4-1) [***c***](#cite_ref-Carter_et_al_4-2) [***d***](#cite_ref-Carter_et_al_4-3) [***e***](#cite_ref-Carter_et_al_4-4) [***f***](#cite_ref-Carter_et_al_4-5) [***g***](#cite_ref-Carter_et_al_4-6) [***h***](#cite_ref-Carter_et_al_4-7) Carter, Aarynn L.; Hinkley, Sasha; Kammerer, Jens; Skemer, Andrew; Biller, Beth A.; Leisenring, Jarron M.; Millar-Blanchaer, Maxwell A.; Petrus, Simon; Stone, Jordan M.; Ward-Duong, Kimberly; Wang, Jason J.; Girard, Julien H.; Hines, Dean C.; Perrin, Marshall D.; Pueyo, Laurent (2023-07-06). ["The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems I: High Contrast Imaging of the Exoplanet HIP 65426 b from 2-16 μm"](https://doi.org/10.3847%2F2041-8213%2Facd93e). *The Astrophysical Journal Letters*. **951** (1): L20. [arXiv](/source/ArXiv_(identifier)):[2208.14990](https://arxiv.org/abs/2208.14990). [Bibcode](/source/Bibcode_(identifier)):[2023ApJ...951L..20C](https://ui.adsabs.harvard.edu/abs/2023ApJ...951L..20C). [doi](/source/Doi_(identifier)):[10.3847/2041-8213/acd93e](https://doi.org/10.3847%2F2041-8213%2Facd93e).

1. **[^](#cite_ref-Independent_5-0)** ["Scientists have found a planet that means everything they thought about planets isn't true"](http://www.independent.co.uk/news/science/planets-hip-65426b-scientists-stars-solar-systems-sun-a7830556.html). *The Independent*. 2017-07-08. Retrieved 2019-08-02.

1. ^ [***a***](#cite_ref-scinews_6-0) [***b***](#cite_ref-scinews_6-1) ["Astronomers Directly Image Super-Jupiter around HIP 65426 | Astronomy | Sci-News.com"](http://www.sci-news.com/astronomy/super-jupiter-hip-65426-05023.html). *Breaking Science News | Sci-News.com*. Retrieved 2019-08-02.

1. **[^](#cite_ref-7)** ["ESO's SPHERE Unveils its First Exoplanet"](https://www.eso.org/public/announcements/ann17041/). *www.eso.org*. Retrieved 2017-07-07.

1. **[^](#cite_ref-8)** Oransky, Ivan (14 April 2022). ["Triple sunrise, triple sunset: Science paper retracted when it turns out a planet is a star"](https://retractionwatch.com/2022/04/14/triple-sunrise-triple-sunset-science-paper-retracted-when-it-turns-out-a-planet-is-a-star/#more-124683). *Retraction Watch*. Retrieved 25 April 2022.

1. ^ [***a***](#cite_ref-nasa_10-0) [***b***](#cite_ref-nasa_10-1) ["Holiday Special: Eight nights of Exoplanet Light"](https://exoplanets.nasa.gov/news/1477/holiday-special-eight-nights-of-exoplanet-light/). *Exoplanet Exploration: Planets Beyond our Solar System*. NASA. Retrieved 2019-08-03.

1. **[^](#cite_ref-11)** ["Details on Acronym: HIP"](https://cds.unistra.fr/cgi-bin/Dic-Simbad?HIP). *[SIMBAD](/source/SIMBAD)*. Retrieved 2025-01-08.

1. **[^](#cite_ref-12)** ["List of ExoWorlds 2022"](https://www.nameexoworlds.iau.org/2022exoworlds). *nameexoworlds.iau.org*. [IAU](/source/International_Astronomical_Union). 8 August 2022. Retrieved 27 August 2022.

1. **[^](#cite_ref-13)** ["The Extrasolar Planet Encyclopaedia — HIP 65426 b"](http://exoplanet.eu/catalog/hip_65426_b--6586/). *[Extrasolar Planets Encyclopaedia](/source/Extrasolar_Planets_Encyclopaedia)*. [Paris Observatory](/source/Paris_Observatory).

1. **[^](#cite_ref-14)** ["Odd planetary system around fast-spinning star doesn't quite fit existing models of planet formation"](https://phys.org/news/2017-07-discovery-exoplanet-spherevlt.html). *phys.org*. Retrieved 2019-08-03.

1. **[^](#cite_ref-15)** Johnson-Groh, Mara; July 12, 2017 (12 July 2017). ["New exoplanet challenges formation models"](https://astronomy.com/news/2017/07/fast-spinning-exoplanet-system-deeper). *Astronomy.com*. Retrieved 2019-08-03.{{[cite web](https://en.wikipedia.org/wiki/Template:Cite_web)}}: CS1 maint: numeric names: authors list ([link](https://en.wikipedia.org/wiki/Category:CS1_maint:_numeric_names:_authors_list))

1. **[^](#cite_ref-16)** Fisher, Alise (2022-09-01). ["NASA's Webb Takes Its First-Ever Direct Image of Distant World"](https://blogs.nasa.gov/webb/2022/09/01/nasas-webb-takes-its-first-ever-direct-image-of-distant-world/?linkId=179637235). *NASA Blogs*. [NASA](/source/NASA). Retrieved 2022-09-01.

1. **[^](#cite_ref-Petrus2020_17-0)** Petrus, S.; Bonnefoy, M.; Chauvin, G.; Charnay, B.; Marleau, G.-D.; Gratton, R.; Lagrange, A.-M.; Rameau, J.; Mordasini, C.; Nowak, M.; Delorme, P.; Boccaletti, A.; Carlotti, A.; Houllé, M.; Vigan, A.; Allard, F.; Desidera, S.; d'Orazi, V.; Hoeijmakers, H. J.; Wyttenbach, A.; Lavie, B. (2021), "Medium-resolution spectrum of the exoplanet HIP 65426 B", *Astronomy & Astrophysics*, **648**: A59, [arXiv](/source/ArXiv_(identifier)):[2012.02798](https://arxiv.org/abs/2012.02798), [Bibcode](/source/Bibcode_(identifier)):[2021A&A...648A..59P](https://ui.adsabs.harvard.edu/abs/2021A&A...648A..59P), [doi](/source/Doi_(identifier)):[10.1051/0004-6361/202038914](https://doi.org/10.1051%2F0004-6361%2F202038914), [S2CID](/source/S2CID_(identifier)) [227347064](https://api.semanticscholar.org/CorpusID:227347064)

1. **[^](#cite_ref-18)** Wang 王, Ji 吉 (2023-11-01). ["Spectral Retrieval with JWST Photometric data: a Case Study for HIP 65426 b"](https://doi.org/10.3847%2F1538-3881%2Facfca0). *The Astronomical Journal*. **166** (5): 203. [arXiv](/source/ArXiv_(identifier)):[2310.00089](https://arxiv.org/abs/2310.00089). [Bibcode](/source/Bibcode_(identifier)):[2023AJ....166..203W](https://ui.adsabs.harvard.edu/abs/2023AJ....166..203W). [doi](/source/Doi_(identifier)):[10.3847/1538-3881/acfca0](https://doi.org/10.3847%2F1538-3881%2Facfca0). [ISSN](/source/ISSN_(identifier)) [0004-6256](https://search.worldcat.org/issn/0004-6256).

## Notes

1. **[^](#cite_ref-9)** [HD 131399 Ab](/source/HD_131399) was claimed to be detected earlier via SPHERE, but it was later shown to be an unrelated background object.[8]

v t e Constellation of Centaurus List of stars in Centaurus Centaurus in Chinese astronomy Stars Bayer α A (Rigil Kentaurus) B (Toliman) C (Proxima Centauri) β (Hadar) γ δ ε ζ (Leepwal) η θ (Menkent) ι (Kulou) κ λ μ ν (Heng) ξ1 ξ2 ο1 ο2 π ρ σ τ υ1 υ2 φ χ ψ x1 x2 C3 D E F G H J K M N Q Flamsteed 1 (i) 2 (g) 3 (k) 4 (h) Variable R T V Y RR SV SX BV DY UY V346 V553 V744 V752 V761 (a) V763 (C1) V766 V779 (Krzemiński's star) V803 V810 V816 (Przybylski's Star) V831 V842 V885 V886 V863 V1032 V1369 V1400 V1935 HR 4460 (A) 4466 (C2) 4499 4522 4523 4537 (j) 4546 (B) 4721 4748 (u) 4796 4817 (l) 4831 (w) 4874 (p) 4888 (e) 4889 (n) 4940 (f) 4979 4989 5006 (r) 5041 (m) 5089 (d) 5174 (z) 5222 (y) 5224 5241 5297 5358 (v) 5371 5471 (b) 5485 (c1) 5489 (c2) HD 97413 98176 100453 101581 101930 102117 (Uklun) 103197 107914 108236 109749 110113 113538 113766 114386 114729 115600 116434 (Matza) 117207 117618 (Dofida) 117939 120411 121228 121504 124448 (Popper's Star) 125072 125595 131399 Other 2MASS J1126−5003 2M1207 Gaia BH2 HD 131399 Ab PSR B1259−63 PSR J1311−3430 TOI-763 WASP-15 (Nyamien) WASP-41 WASP-42 WASP-167/KELT-13 Exoplanets 2M1207b b Centauri b HD 101930 b HD 102117 b (Leklsullun) HD 103197 b HD 109749 b HD 113538 b c HD 114386 b HD 114729 b HD 117207 b HD 117618 b (Noifasui) HD 121504 b HIP 65426 b (Najsakopajk) HIP 67522 b NGTS-13b Proxima Centauri b c d WASP-15b (Asye) Star clusters NGC 3766 4230 4507 5281 5286 5316 5460 5617 5662 Other IC 2944 ω Centauri Scorpius–Centaurus association Stock 16 Nebulae NGC 3918 5307 Other Boomerang Nebula Fleming 1 G292.0+1.8 G306.3-0.9 Gum 41 IC 2944 IRAS 13208−6020 RCW 79 RCW 86 Southern Crab Nebula SuWt 2 Galaxies NGC 3557 3568 3749 3783 4444 4603 4622 4650A 4683 4696 4706 4709 4729 4730 4743 4744 4909 4930 4945 4976 5011 A 5026 5064 5082 5090 5091 5102 5114 5121 5128 (Centaurus A) 5161 5206 5253 5266 5291 5398 5408 5419 5483 5516 Other ESO 269-57 ESO 325-4 ESO 383-76 ESO 444-46 Fourcade-Figueroa Object IC 3370 IC 4214 IC 4329A IRAS 13224−3809 J1144−4308 LEDA 677373 PKS 1144−379 PKS 1353−341 PKS 1424−418 Galaxy clusters Abell S740 Centaurus Cluster Shapley Supercluster Astronomical events GW190521 SN 185 SN 1895B (Z) SN 1972E SN 1986G J1407b SN 2019so Category

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