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NGTS -1b: A hot transiting an M -dwarf

Journal: Monthly Notices of the Royal Astronomical Society

Manuscript ID MN173244MJ

Manuscript type: Main Journal

Date Submitted by the Author: 13Sep2017

Complete List of Authors: Bayliss, Daniel; Observatoire Astronomique de l’Universit ́e de Gen`eve, Gillen, Edward; University of Cambridge, Cavendish Astrophysics Eigmüller, Philipp; Deutsches Zentrum für Luft und Raumfahrt, Institut für Planetenforschung McCormac, James; University of Warwick, Physics Alexander, Richard; University of Leicester, Physics & Astronomy; Armstrong, David; University of Warwick, Physics Booth, Rachel; Queen's University Belfast, Astrophysics Research Centre, School of Mathematics & Physics Bouchy, Francois; Observatoire Astronomique de l’Université de Genève, Département d'Astronomie Burleigh, Matthew Cabrera, Juan; DLR Casewell, Sarah Chaushev, Alexander; Department of Physics and Astronomy, Leicester Institute of Space and Earth Observation, University of Leicester, LE1 7RH Chazelas, Bruno Csizmadia, Szilard Erikson, Anders Faedi, Francesca; University of Warwick, Department of Physics Foxell, Emma; University of Warwick Department of Physics Gaensicke, Boris; University of Warwick, Department of Physics Goad, Michael; University of Leicester, Physics and Astronomy Grange, Andrew Guenther, Maximilian; University of Cambridge, Cavendish Laboratory Hodgkin, Simon; Cambridge University, Institute of Astronomy Jackman, James Jenkins, James; Universidad de Chile, Astronomy Lambert, Greg; University of Cambridge, Cavendish Astrophysics Louden, Tom; University of Warwick, Physics Metrailler, Lionel; Universite de Geneve Observatoire Astronomique Moyano, Maximiliano; Universidad Católica del Norte, Instituto de Astronomía Pollacco, Don; University of Warwick, Physics Poppenhaeger, Katja; Queen's University Belfast, Astrophysics Research Centre; HarvardSmithsonian Center for Astrophysics, Queloz, Didier; Universite de Geneve Observatoire Astronomique Raddi, Roberto; University of Warwick, Department of Physics Rauer, Heike; DLR Page 1 of 10

1 2 3 4 Raynard, Liam; Department of Physics and Astronomy, Leicester Institute 5 of Space and Earth Observation, University of Leicester, LE1 7RH Smith, Alexis 6 Soto, Martiza; Universidad de Chile Facultad de Ciencias Fisicas y 7 Matematicas 8 Thompson, Andrew; Queen's University Belfast School of Mathematics and 9 Physics, Astrophysics Research Centre 10 TitzWeider, Ruth; Deutsches Zentrumf für Luft und Raumfahrt, Institut 11 für Planetenforschung 12 Udry, Stephane; Geneva University, Astronomy (Geneva Observatory) 13 Walker, S.; warwick Watson, Christopher; Queen's University Belfast, Mathematics & Physics 14 West, Richard; University of Warwick, Department of Physics 15 Wheatley, P.J.; University of Warwick, Department of Physics 16 techniques: photometric < Astronomical instrumentation, methods, and 17 Keywords: 18 techniques, (:) planetary systems < Stars, stars: individual:... < Stars 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Page 2 of 10

1 2 3 MNRAS 000,1–10(2017) Preprint13September2017 CompiledusingMNRAS LATEX style file v3.0 4 5 6 7 NGTS-1b: A transiting an M-dwarf 8 9 10 1⋆ 2 3 4,5 11 Daniel Bayliss, Edward Gillen, Philipp Eigmuller,¨ James McCormac, 6 4,5 7 1 12 Richard D. Alexander, David J. Armstrong, Rachel S. Booth, Fran¸cois Bouchy, 13 Matthew R. Burleigh,6 Juan Cabrera,3 Sarah L. Casewell,6 Alexander Chaushev,6 14 1 3 3 4 15 Bruno Chazelas, Szilard Csizmadia, Anders Erikson, Francesca Faedi, 16 Emma Foxell,4 Boris T. G¨ansicke,4,5 Michael R. Goad,6 Andrew Grange,6 Max- 17 imilian N. Gunther,¨ 2 Simon T. Hodgkin,8 James Jackman,4 James S. Jenkins,9,10 18 2 4,5 1 11 19 Gregory Lambert, Tom Louden, Lionel Metrailler, Maximiliano Moyano, 20 Don Pollacco,4,5 Katja Poppenhaeger,7 ,2 Roberto Raddi,4 21 Heike Rauer,3 Liam Raynard,6 Alexis M. S. Smith,3 Maritza Soto,9 An- 22 7 3 1 4 23 drew P. G. Thompson, Ruth Titz-Weider, St´ephane Udry, Simon. R. Walker, 24 Christopher A. Watson,7 Richard G. West,4,5 Peter J. Wheatley,4,5 25 1Observatoire de Gen`eve, Universit´ede Gen`eve, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland 2 26 Astrophysics Group, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK 3Institute of Planetary Research, German Aerospace Center, Rutherfordstrasse 2, 12489 Berlin, Germany 27 4Dept. of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK 28 5Centre for and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK 29 6Department of Physics and Astronomy, Leicester Institute of Space and Earth Observation, University of Leicester, LE1 7RH, UK 7 30 Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, BT7 1NN Belfast, UK 8Institute of Astronomy, University of Cambridge, Madingley Rise, Cambridge CB3 0HA, UK 31 9Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago, Chile 32 10 Centro de Astrof´ısica y Tecnolog´ıas Afines (CATA), Casilla 36-D, Santiago, Chile. 33 11Instituto de Astronomia, Universidad Cat´olica del Norte, Casa Central, Angamos 0610, Antofagasta, Chile 34 35 36 Accepted XXX. Received YYY; in original form ZZZ 37 38 ABSTRACT 39 We present the discovery of NGTS-1b, a hot-Jupiter transiting an early M-dwarf T +71 P = 40 host ( eff, =3916 63 K) in a 2.647 d orbit discovered as part of the Next Gener- 41 ∗ − +0.066 ation Survey (NGTS). The has a mass of 0.812 0.075 MJ and radius 42 +0.61 − of 1.33 0.33 RJ , making it the largest and massive planet discovered transiting 43 any M-dwarf.− NGTS-1b is the third transiting found around an M-dwarf, 44 reinforcing the notion that close-in gas giants can form and migrate similar to the 45 known population of hot around solar type stars. The host shows no signs of activity, and the kinematics hint at the star being from the thick disk popu- 46 K = 47 lation. With a deep (2.5%) transit around a 11.9 host, NGTS-1b will be a strong candidate to probe giant planet composition around M-dwarfs via JWST transmission 48 spectroscopy. 49 50 Key words: techniques: photometric, stars: individual: NGTS-1, planetary systems 51 52 53 54 1 INTRODUCTION Escud´eet al. 2016) and Trappist-1 (Gillon et al. 2017). The interest primarily derives from the fact that the radius ra- 55 M-dwarf stars as planetary hosts are of high interest. Two tio (R Rstar) and mass ratio (M Mstar) for such systems important recent discoveries in the field of exoplanets relate P/ P/ 56 are much higher than equivalent systems with solar-type to orbiting M-dwarfs: Proxima Centauri (Anglada- 57 hosts, thus they can be easier to detect via transits and 58 radial velocities. The low intrinsic luminosity of M-dwarfs ⋆ also means that the habitable zone is very close to the host 59 E-mail: [email protected] 60 © 2017 The Authors Page 3 of 10

1 2 3 2 First Author 4 5 star and therefore it is much easier to detect potential hab- third found to transit an M-dwarf. In Section 2 6 itable planets around these stars, compared to their more we detail the observations that led to the discovery of this 7 massive counterparts. Finally, M-dwarfs are the most pop- planet, including the NGTS survey photometry, high preci- 8 ulous stars in the Galaxy ( 75%; Henry et al. 2006), and sion follow-up photometry, and high resolution spectroscopy. ∼ 9 hence understanding planet formation and planet frequency In Section 3 we analyse the observational data in conjunc- 10 around these low mass stars greatly enhances our knowledge tion with archival photometric data to precisely determine 11 of the full population of planets in the Galaxy. the physical characteristics of NGTS-1b. Finally, in Section4 However, observationally M-dwarfs present some signif- we discuss the results including the significance of this dis- 12 icant drawbacks when searching for exoplanets. Firstly, the covery in terms of planet formation scenarios around low 13 intrinsically low luminosity of M-dwarfs means that on aver- mass stars and the prospects for characterisation via JWST. 14 age they have much fainter apparent magnitudes than solar 15 type stars, making it hard to obtain high precision photome- 16 try or high precision measurements. Secondly, 17 the spectra of M-dwarfs are dominated by molecular lines 2 OBSERVATIONS 18 which do not allow the same precision radial velocity mea- The discovery of NGTS-1b was made using the NGTS 19 surements as are afforded by the unblended, sharp metal telescopes in conjunction with high precision photometric lines that can be found in solar-type spectra. Finally the follow-up from Eulercam and high precision spectroscopy 20 low effective temperatures of M-dwarfs means they have a 21 from HARPS. We detail all of these observations in this peak flux well outside the optical wavelength range where Section. 22 most photometry and spectroscopy is targeted. 23 Despite these difficulties there has been progress in iden- 24 tifying exoplanets orbiting M-dwarfs using dedicated facil- 2.1 NGTS Photometry 25 ities. Notably the Earth-sized GJ1132-b (Berta-Thompson 26 et al. 2015) and super-Earth GJ1214-b (Charbonneau et al. NGTS is a fully automated array of twelve 20 cm aperture Newtonian telescopes situated at the ESO Paranal Observa- 27 2009), detected with the M-Earth ground-based transit sur- vey (Nutzman & Charbonneau 2008), have been popular tory in Chile. Each telescope is coupled to an Andor Ikon-L 28 targets for atmospheric characterisation owing to the small Camera featuring a 2K 2K e2V deep-depleted CCD with × 29 radii and close proximity to Earth of their M-dwarf hosts. 13.5 µm pixels, which corresponds to an on-sky size of 4.97 ′′. 30 A large radial velocity program to monitor M-dwarfs, car- Telescopes are operated from independent Optical Mechan- 31 ried out by the HARPS consortium (Mayor et al. 2003a; ics, Inc. (OMI) mounts, allowing for excellent tracking and 32 Bonfils et al. 2005), has produced more than 10 confirmed freedom in scheduling observations. 33 exoplanets and recently two planets orbiting GJ 273 - po- NGTS-1 was observed on a single NGTS telescope over 34 tentially making this the closest known system with plan- a photometric campaign conducted between 2016 August 10 ets in the habitable zone after Proxima Centauri (Berdi˜nas and 2016 December 7. In total we obtained 118,498 10s ex- × 35 2016; Astudillo-Defru et al. 2017). The Kepler and K2 mis- posures in the NGTS bandpass (550 – 927 nm) over 100 us- ∼ 36 sions, while not designed to specifically target M-dwarfs, able nights. Raw data were reduced to calibrated fits frames 37 have discovered transiting planets around M-dwarfs in their via the NGTS reduction pipeline fully described in Wheatley 38 FOV: Kepler-138b (Rowe et al. 2014); K2-33b (David et al. (2017). Photometry was extracted via aperture photometry 39 2016). In addition to these programs the wide-field Next using the NGTS photometric pipeline, which is a customised 1 40 Generation Transit Survey (NGTS) survey is under-way. implementation of the CASUTools photometry package. To 41 NGTS is optimised to detect transits around K and early M- account for systematic effects in the data, an implementation of the SysRem algorithm (Tamuz et al. 2005) was applied to 42 dwarfs and is at the limit of photometric precision possible for ground-based observations (Wheatley 2017; McCormac the data. Again full details can be found in Wheatley (2017). 43 et al. 2017; Wheatley et al. 2013; Chazelas et al. 2012). Light curves were searched for transit-like signals using 44 Small planets (0.5–4 R ) appear to be common around ORION, an implementation of the box-fitting least squares 45 M-dwarfs (Dressing & Charbonneau⊕ 2013), and gas gi- (BLS) algorithm (Kov´acs et al. 2002). We identified a strong 46 ants are considerably rarer. Meyer et al. (2017) give the BLS signal for NGTS-1 at a period of 2.647298 0.000020 d. ± 47 frequency of planets with masses 1-10 MJ as 0.07 plan- We set out the transit feature identified in the NGTS 48 ets per M-dwarf. To date only two gas giant planets light curve, phase-folded to this period, in Figure 1, and 49 have been discovered transiting M-dwarfs - namely Kepler- provide the full light curve dataset in Table 1. Our previous yield simulations have evaluated the risk 50 45b (Mp=0.505 MJ , Rp=0.96 RJ Johnson et al. 2012) and HATS-6b (Mp=0.32 MJ ,Rp=1.00 RJ Hartman et al. 2015). of false positives mimicking a planetary transit such as 51 However, hot Jupiters are rare around solar type stars also - NGTS-1 (Gunther¨ et al. 2017a). In order to verify that this 52 from Kepler statistics the frequency of hot-Jupiter systems transit signal is consistent with a transiting planet, we ap- 53 around solar-type stars is 0.43 0.05 for P < 10 d (Fressin plied a series of vetting tests to the NGTS data. ± 54 et al. 2013). Coupled to this, transit surveys have not mon- Firstly, we checked the light curve for evidence of a sec- 55 itored large numbers of M-dwarfs compared with the solar- ondary eclipse near phase 0.5. Such a detection, at our pho- 56 type population. Thus a larger population of M-dwarfs needs tometric precision, would indicate an eclipsing stellar com- 57 to be monitored in order to ascertain if the frequency of hot-Jupiters around M-dwarfs significantly departs from the 58 solar-type frequency. 1 http://casu.ast.cam.ac.uk/surveys-projects/ 59 In this paper we report the discovery of NGTS-1b, the software-release 60 MNRAS 000, 1–10 (2017) Page 4 of 10

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1 2 3 NGTS-1b 5 4 5 Table 3. Radial Velocities for NGTS-1 6 7 HJD RV RVerr FWHM contrast BIS (-2450000) (kms 1) (kms 1) (kms 1) (kms 1) 8 − − − − 9 7780.712430 97.310 0.023 3.783 10.7 -0.080 7784.657148 97.032 0.013 3.718 11.3 -0.011 10 7785.598834 97.218 0.011 3.730 11.3 -0.011 11 7786.618897 97.268 0.013 3.671 11.1 -0.044 12 7789.645749 97.121 0.015 3.737 11.1 -0.035 13 7790.641250 97.106 0.017 3.735 10.7 -0.012 14 7791.655373 97.336 0.015 3.693 10.5 -0.006 15 16 T M error ellipses in eff–radius space and radius– Ks space are Table 4. Stellar Properties for NGTS-1 17 orthogonal. We use this mass estimate only to check our final 18 value. Property Value Source 19 (ii) We modelled the spectral energy distribution (SED) Astrometric Properties 20 of NGTS-1 (Figure 4) using the method described in Gillen R.A. 05h30m51s.45 2MASS et al. (2017). Briefly, we convolved the BT-SETTL and Dec 36 37 50. 83 2MASS 21 − ◦ ′ ′′ PHOENIX v2 model (Allard et al. 2011) with 2MASSI.D. J05305145-3637508 2MASS 22 1 the available bandpasses (see Table 4) and interpolated in µR.A. (mas y− ) 32.9 2.0 UCAC4 1 − ± 23 T µDec. (mas y− ) 39.6 1.8 UCAC4 eff–log g space (fixing [M/H]=0) within a Markov chain − ± 24 Monte Carlo (MCMC) and placed the following priors: Photometric Properties 25 a uniform (but not uninformative) prior on the radius: V (mag) 15.524 0.083 APASS R R ± 26 0.4 Rs 0.7 , which brackets plausible radius es- B (mag) 16.912 0.077 APASS ⊙ ≤ ≤ ⊙ T ± 27 timates given the expected eff range; a Gaussian prior on g (mag) 16.288 0.000 APASS ± log g: log g = 4.7 0.2, which is estimated from the predictions r (mag) 14.999 0.006 APASS 28 ± ± of the PARSEC v1.2 stellar evolution models given our Teff, i (mag) 14.328 0.022 APASS 29 ± M and R estimates (with the uncertainty further inflated); a GGAIA mag 14.702 0.001 Gaia ( ) ± 30 Gaussian prior on A : A = 0.0 0.1 (positive values allowed NGTS (mag) 14.320 0.02 This work V V ± 31 ± J (mag) 12.702 0.024 2MASS only) following initial tests implying a low-to-negligible red- ± T H (mag) 12.058 0.022 2MASS 32 dening; uninformative priors on the eff and distance; and ± K (mag) 11.936 0.027 2MASS 33 an uninformative prior on the uncertainties, which are fit ± W1 (mag) 11.800 0.023 WISE 34 for within the MCMC. Combining the results from the BT- ± + W2 (mag) 11.779 0.022 WISE T = 71 ± 35 SETTL and PHOENIX models gives eff 3916 63 K and +37 − 36 distance d = 224 pc. Derived Properties 44 + − T (K) 3916 71 SED fitting 37 (iii) We then used our SED modelling results and eff 63 M = M H 0− HARPSSpectrum the Ks – mass relation of B16 to determine Ms 38 +0.023 [ / ] 1 0.617 M . We note that this is in agreement with the vsini (kms− ) < 1.0 HARPS Spectrum 0.062 1 39 − ⊙ γRV (kms ) 97.1808 0.0070 HARPS Spectrum M15 value. − ± 40 log g 4.71 0.23 ER ±+ . T M 0.617 0 023 41 We adopt, as our final stellar parameters, the eff and Ms ( ) 0.062 ER ⊙ − distance estimates from our SED modelling, the radius esti- Rs (R ) 0.573 0.033 ER 42 ⊙ 3 ±+0.85 mate from M15, and the mass estimate from B16; these are ρ (gcm− ) 4.45 2.35 43 −+37 reported in Table 4. Distance (pc) 224 44 SED fitting 44 − 45 2MASS (Skrutskie et al. 2006); UCAC4 (Zacharias et al. 2013); APASS (Henden & Munari 2014); WISE (Wright et al. 2010); 46 3.2 Global Modelling Gaia (Gaia Collaboration et al. 2016) 47 ER = empirical relations using Benedict et al. (2016) 48 Using the photometric and radial velocity data set out in and Mann et al. (2015) 49 Section 2, in addition to the stellar parameters set out in 50 Section 3.1, we globally model the system in order to deter- mine the stellar and planetary parameters for the NGTS-1b GP-EBOP explores the posterior parameter space using an 51 system. We use the GP-EBOP transiting planet and eclips- affine-invariant MCMC. 52 ing binary model. GP-EBOP is fully described in Gillen et al. One difficulty in modelling this system is that the tran- 53 (2017), where it is applied to eclipsing binaries and a tran- sit is grazing, which is relatively likely given the radius ratio +0.100 54 siting , and we further note its tested ability between the planet and the star (0.239 0.054). Such a con- 55 to model transiting planets, e.g. Pepper et al. (2017). In figuration results in a strong degeneracy− between the impact 56 GP-EBOP, the full light curve is modelled as a Gaussian parameter (b) and the planetary radius (Rp). To help break 57 process, whose mean function is a transit model. The radial this degeneracy we construct a prior on the radius of the 58 velocity data are modelled simultaneously with the available planet based on the existing population of hot Jupiters. To photometry and incorporates a jitter term to allow for stellar a first approximation the two measurable quantities that 59 activity variations and instrumental systematics in the data. influence the radius of hot Jupiters are mass (Hatzes & 60 MNRAS 000, 1–10 (2017) Page 7 of 10

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1 2 3 NGTS-1b 7 4 5 Table 5. Fitted and derived parameters of the models applied to ecc + ρ prior and ecc + ρ & ρpl priors. 6 ∗ ∗ 7

8 Parameter Symbol Unit Value ecc + ρ prior ecc + ρ & ρpl priors 9 ∗ ∗ 10 11 Transit parameters +0.0108 Sum of radii Rs + Rp a 0.139 0.034 0.1021 12 ( )/ ± 0.0087 +0.68 +−0.100 Radius ratio Rp Rs 0.76 0.239 13 / 0.47 0.054 − −+ . Orbital inclination 0 61 i ◦ 82.8 2.3 85.27 0.73 14 ± − P days 2.647297 0.000021 2.647298 0.000020 15 ± ± Time of transit centre Tcentre BJD 2457720.65939 0.00067 2457720.65940 0.00062 ± ± 16 √e cos ω 0.01 0.11 0.001 0.098 ± − ± 17 √e sin ω 0.05 0.12 0.02 0.12 18 ± ± Linear LDC u 0.40 0.14 0.46 0.13 19 NGTS ± ± Non-linear LDC u 0.14 0.23 0.12 0.2 NGTS′ ± ± 20 Linear LDC u 0.30 0.11 0.322 0.083 Euler ± ± 21 Non-linear LDC u 0.21 0.24 0.21 0.18 Euler′ ± ± 22

23 Out-of-transit variability parameters

+ . + . 24 Amplitude % 0 00033 0 00035 ANGTS 0.00228 0.00027 0.00228 0.00028 +− . +− . 25 Timescale l days . 0 29 . 0 29 NGTS 2 76 0.46 2 76 0.45 − − 26 White noise term σ 1.180 0.016 1.181 0.017 NGTS ± ± + . + . Amplitude A % . 0 056 . 0 179 27 Euler 0 035 0.025 0 065 0.050 +− . +− . Timescale days 0 61 0 50 28 lEuler 2.32 0.83 2.48 0.82 − − White noise term σ 1.16 0.13 1.17 0.13 29 Euler ± ± 30 31 Radial velocity parameters + . Systemic velocity km s 1 0 0071 32 Vsys − 97.1801 0.0078 97.1809 0.0070 − ± Primary RV semi-amplitude K km s 1 0.166 0.012 0.166 0.011 33 pri − ± ± + . + . HARPS White noise term σ km s 1 . 0 0116 . 0 0101 34 HARPS − 0 0080 0.0057 0 0071 0.0049 − − 35

36 * LDC = limb darkening coefficient 37 38 1 Table 6. Planetary Properties for NGTS-1b (97.1808 0.0070 kms− ), and the estimated distance of 39 +37 ± U V W 224 44 pc, we calculate the ( LSR, LSR, LSR) galac- 40 Property Value tic− motion for NGTS-1 to be (11.3 8.3, 57.2 1.6, 1 ± − ± 41 P (days) 2.647298 0.000020 79.7 7.6)kms− . This suggests that NGTS-1 is a mem- ± − ± TC (HJD) 2457720.6593965 0.00062 ber of the thick disk population, and may therefore be 42 ± T (hours) 1.23 0.04 a very old system. The major uncertainty in obtaining 43 14 ± a R 12.2 0.7 the galactic motion is the uncertainty in the distance to 44 / ∗ ±+0.13 b 0.9948 0.088 NGTS-1. It will be interesting to confirm the motion after 1 − 45 K (ms− ) 166 11 ±+ . the second GAIA data release (Gaia Collaboration et al. e 0.016 0 023 46 0.012 2016), which will provide a much more precise distance for . +−0.066 47 Mp (MJ ) 0 812 0.075 +−0.61 NGTS-1. Rp (RJ ) 1.33 0.33 48 3 −+0.59 ρp (gcm− ) 0.42 0.28 49 −+0.0047 a (AU) 0.0326 0.0045 − 50 Teq (K) 790 20 1 2 ± 7 51 Flux (ergs− cm− ) (8.89 0.70 10 ± ) × 52 4 DISCUSSION 53 NGTS-1b is a Jupiter-mass planet orbiting an M0-dwarf star at a significant flux level within the current NGTS point- 54 in a 2.647298 0.000020 d period. As such, it is just the third spread function. ± 55 transiting gas giant to be discovered around an M-dwarf, and = +0.066 = +0.61 56 with Mp 0.812 0.075 MJ and Rp 1.33 0.33 RJ it is easily the largest and highest− mass planet known− transiting an M- 57 3.5 Kinematics dwarf. The two previously discovered examples are Kepler- 58 1 Using the proper motion (R.A.: 32.9 2.0 masy− , 45b (Mp=0.505MJ , Rp=0.96RJ Johnson et al. 2012) and 59 1 − ± Dec.: 39.6 1.8 masy− ), the absolute radial velocity HATS-6b (Mp=0.32MJ , Rp=1.00RJ Hartman et al. 2015). 60 − ± MNRAS 000, 1–10 (2017) Page 9 of 10

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