Discovery [1] | |
---|---|
Discovered by | SPHERE consortium [2] |
Discovery date | 6 July 2017 |
Direct imaging | |
Designations | |
Najsakopajk [3] | |
Orbital characteristics | |
87+108 −31 au [4] | |
Inclination | 100+15 −6 deg [4] |
Physical characteristics | |
Atmospheric model: 0.92±0.04 RJ [4] Evolutionary model: 1.45±0.03 RJ [4] | |
Mass | 7.1±1.1 MJ [4] |
4.07±0.19 dex | |
Temperature | Atmospheric model: 1667+25 −24 K [4] Evolutionary model: 1282+26 −31 K [4] |
HIP 65426 b, formally named Najsakopajk, [3] is a super-Jupiter exoplanet orbiting the star HIP 65426. It was discovered on 6 July 2017 by the SPHERE consortium using the Spectro-Polarimetric High-Contrast Exoplanet Research (SPHERE) instrument belonging to the European Southern Observatory (ESO). [6] [7] It is 385 light-years from Earth. [8] It is the first planet discovered by ESO's SPHERE instrument. [9]
In August 2022, this planet and its host star were included among 20 systems to be named by the third NameExoWorlds project. [10] The approved names, proposed by a team from Mexico, were announced in June 2023. HIP 65426 b is named Najsakopajk and its host star is named Matza, after Zoque words for "Mother Earth" and "star". [3]
The exoplanet HIP 65426 b orbits its host star HIP 65426, an A2V star with apparent magnitude 7.01 and a mass of 1.96±0.04 M☉. [11] This planetary system is located in the constellation Centaurus. The planet is around 14 million years old. However, it is not associated with a debris disk, despite its young age, [7] [8] causing it to not fit current models for planetary formation. [12] It is around 92 AU from its parent star, with a possible dusty atmosphere. [13] It was discovered as part of the SHINE program, which aimed to find planetary systems around 600 new stars. [1]
In September 2022, HIP 65426 b became the first exoplanet directly observed by the James Webb Space Telescope. [14]
The spectrum taken in 2020 has indicated that HIP 65426 b is carbon-poor and oxygen-rich compared to Solar System gas giants. [5]
Spectral analysis of data from the James Webb Space Telescope revealed strong evidence of silicate clouds containing enstatite with no evidence of a dusty atmosphere. [15]
In August 2022, a pre-print of the 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 to , which provides a robust mass constraint of 7.1±1.1 MJ. The atmospheric fitting of both temperature and radius are in disagreement with evolutionary models. The team also constrained the semi-major axis and the inclination of the planet, but the new JWST astrometry of the planet did not significantly improve the orbit of the planet, especially the eccentricity remains unconstrained. [4]
HIP 65426 b is the first exoplanet to be imaged by JWST and the first exoplanet to be detected beyond 5 μm. The observations [16] 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 planets at 100 au for main-sequence stars, Neptune and Uranus-mass objects at 100-200 au for M-dwarfs and Saturn-mass objects at 10 au for M-dwarfs. For α Cen A JWST might be able to push the limit to a 5 R🜨 planet at 0.5 to 2.5 au. [4]
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