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NGTS-5b: a highly inflated planet offering insights into the sub-Jovian desert

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posted on 2019-05-13, 11:34 authored by P Eigmüller, A Chaushev, E Gillen, A Smith, LD Nielsen, O Turner, S Czismadia, B Smalley, D Bayliss, C Belardi, F Bouchy, MR Burleigh, J Cabrera, SL Casewell, B Chazelas, BF Cooke, A Erikson, BT Gänsicke, MN Günther, MR Goad, A Grange, JAG Jackman, JS Jenkins, J McCormac, M Moyano, D Pollacco, K Poppenhaeger, D Queloz, L Raynard, H Rauer, S Udry, SR Walker, CA Watson, RG West, PJ Wheatley
Context: Planetary population analysis gives us insight into formation and evolution processes. For short-period planets, the subJovian desert has been discussed in recent years with regard to the planet population in the mass/period and radius/period parameter space without taking stellar parameters into account. The Next Generation Transit Survey (NGTS) is optimised for detecting planets in this regime, which allows for further analysis of the sub-Jovian desert. Aims: With high-precision photometric surveys (e.g. with NGTS and TESS), which aim to detect short period planets especially around M/K-type host stars, stellar parameters need to be accounted for when empirical data are compared to model predictions. Presenting a newly discovered planet at the boundary of the sub-Jovian desert, we analyse its bulk properties and use it to show the properties of exoplanets that border the sub-Jovian desert. Methods: Using NGTS light curve and spectroscopic follow-up observations, we confirm the planetary nature of planet NGTS-5b and determine its mass. Using exoplanet archives, we set the planet in context with other discoveries. Results: NGTS-5b is a short-period planet with an orbital period of 3.3569866 +- 0.0000026 days. With a mass of 0.229 +- 0.037 MJup and a radius of 1.136 +- 0.023 RJup, it is highly inflated. Its mass places it at the upper boundary of the sub-Jovian desert. Because the host is a K2 dwarf, we need to account for the stellar parameters when NGTS-5b is analysed with regard to planet populations. Conclusions: With red-sensitive surveys (e.g. with NGTS and TESS), we expect many more planets around late-type stars to be detected. An empirical analysis of the sub-Jovian desert should therefore take stellar parameters into account.


This work is based on data collected under the NGTS project at the ESO La Silla Paranal Observatory. The NGTS facility is operated by the consortium institutes with support from the UK Science and Technology Facilities Council (STFC) project ST/M001962/1. This paper uses observations made at the South African Astronomical Observatory (SAAO). The contributions at the University of Warwick by PJW, RGW, DLP, DJA, BTG and TL have been supported by STFC through consolidated grants ST/L000733/1 and ST/P000495/1. Contributions at the University of Geneva by DB, FB, BC, LM, and SU were carried out within the framework of the National Centre for Competence in Research "PlanetS" supported by the Swiss National Science Foundation (SNSF). The contributions at the University of Leicester by MRG and MRB have been supported by STFC through consolidated grant ST/N000757/1. CAW acknowledges support from the STFC grant ST/P000312/1. EG gratefully acknowledges support from Winton Philanthropies in the form of a Winton Exoplanet Fellowship. MNG is supported by the STFC award reference 1490409 as well as the Isaac Newton Studentship. JSJ acknowledges support by Fondecyt grant 1161218 and partial support by CATABasal (PB06, CONICYT). DJA gratefully acknowledges support from the STFC via an Ernest Rutherford Fellowship (ST/R00384X/1). PE, ACh, and HR acknowledge the support of the DFG priority program SPP 1992 "Exploring the Diversity of Extrasolar Planets" (RA 714/13-1). LD acknowledges support from the Gruber Foundation Fellowship. The research leading to these results has received funding from the European Research Council under the FP/2007-2013 ERC Grant Agreement number 336480 and from the ARC grant for Concerted Research Actions, financed by the Wallonia-Brussels Federation. This work was also partially supported by a grant from the Simons Foundation (PI Queloz, ID 327127). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.c



Astronomy and Astrophysics, 2019, 625, A142

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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