# An Ultra-Hot Neptune in the Neptune desert

**Authors:** James S. Jenkins, Matías R. Díaz, Nicolás T. Kurtovic, Néstor Espinoza, Jose I. Vines, Pablo A. Peña Rojas, Rafael Brahm, Pascal Torres, Pía Cortés-Zuleta, Maritza G. Soto, Eric D. Lopez, George W. King, Peter J. Wheatley, Joshua N. Winn, David R. Ciardi, George Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Jon M. Jenkins  
**arXiv:** [2009.12832](https://arxiv.org/abs/2009.12832)  
**Date:** 2020-09-27  
**Summary page:** https://www.summarizepaper.com/en/paper/2009.12832v2/

## Key points

- A team of researchers discovered an ultra-hot Neptune planet in the "hot Neptune desert"
- The planet has a radius of 4.6 Earth radii and a mass of 29 Earth masses
- It was discovered using data from the Transiting Exoplanet Survey Satellite (TESS)
- The planet orbits a bright Sun-like star every 0.79 days and has a mean density similar to that of Neptune
- Thermal evolution models suggest it has a hydrogen/helium-rich envelope constituting 9.0^(+2.7)_(-2.9)% of its total mass
- The existence of such planets challenges current theories about how planets form and evolve, as low-mass planets are believed to be unable to retain any hydrogen/helium envelope in the face of strong stellar irradiation
- The brightness (Vmag=9.8) of the host star will facilitate follow-up observations of the planet's atmosphere which may provide insights into how such planets form and evolve under extreme conditions, shedding light on planetary formation and evolution in our universe

## Summary

A team of researchers has reported the discovery of an ultra-hot Neptune planet firmly in the "hot Neptune desert". This planet has a radius of 4.6 Earth radii and a mass of 29 Earth masses, and was discovered using data from the Transiting Exoplanet Survey Satellite (TESS). It orbits a bright Sun-like star every 0.79 days and has a mean density similar to that of Neptune. Thermal evolution models suggest that it has a hydrogen/helium-rich envelope constituting 9.0^(+2.7)_(-2.9)% of its total mass. The existence of such planets in the "hot Neptune desert" has been interpreted as low-mass planets' inability to retain any hydrogen/helium envelope in the face of strong stellar irradiation; however, this newly discovered ultra-hot Neptune's ability to retain its envelope at an equilibrium temperature around 2000 K is unclear. This discovery challenges current theories about how planets form and evolve and raises questions about how this ultra-hot Neptune managed to maintain its envelope despite being subjected to intense radiation from its host star. The brightness (Vmag=9.8) of the host star will facilitate follow-up observations of the planet's atmosphere which may provide insights into how such planets form and evolve under extreme conditions, shedding light on planetary formation and evolution in our universe.