stz3140.pdf (2.71 MB)
NGTS-8b and NGTS-9b: two non-inflated hot-Jupiters
journal contributionposted on 2020-04-23, 13:03 authored by Jean C Costes, Christopher A Watson, Claudia Belardi, Ian P Braker, Matthew R Burleigh, Sarah L Casewell, Philipp Eigmüller, Maximilian N Günther, James AG Jackman, Louise D Nielsen, Maritza G Soto, Oliver Turner, David R Anderson, Daniel Bayliss, François Bouchy, Joshua T Briegal, Edward M Bryant, Juan Cabrera, Alexander Chaushev, Szilard Csizmadia, Anders Erikson, Samuel Gill, Edward Gillen, Michael R Goad, Matthew J Hooton, James S Jenkins, James McCormac, Maximiliano Moyano, Didier Queloz, Heike Rauer, Liam Raynard, Alexis MS Smith, Andrew PG Thompson, Rosanna H Tilbrook, Stephane Udry, Jose I Vines, Richard G West, Peter J Wheatley
We report the discovery, by the Next Generation Transit Survey (NGTS), of two hot-Jupiters NGTS-8b and NGTS-9b. These orbit a V = 13.68 K0V star (Teff = 5241 +/- 50 K) with a period of 2.49970 days, and a V = 12.80 F8V star (Teff = 6330 +/- 130 K) in 4.43527 days, respectively. The transits were independently verified by follow-up photometric observations with the SAAO 1.0-m and Euler telescopes, and we report on the planetary parameters using HARPS, FEROS and CORALIE radial velocities. NGTS-8b has a mass, 0.93 +0.04 -0.03 MJ and a radius, 1.09 +/- 0.03 RJ similar to Jupiter, resulting in a density of 0.89 +0.08 -0.07 g cm-3. This is in contrast to NGTS-9b, which has a mass of 2.90 +/- 0.17 MJ and a radius of 1.07 +/- 0.06 RJ , resulting in a much greater density of 2.93 +0.53 -0.49 g cm-3. Statistically, the planetary parameters put both objects in the regime where they would be expected to exhibit larger than predicted radii. However, we find that their radii are in agreement with predictions by theoretical non-inflated models.
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.
CitationMonthly Notices of the Royal Astronomical Society, Volume 491, Issue 2, January 2020, Pages 2834–2844, https://doi.org/10.1093/mnras/stz3140
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