Publications of Michaël Gillon
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See detailTOI-150b and TOI-163b: two transiting hot Jupiters, one eccentric and one inflated, revealed by TESS near and at the edge of the JWST CVZ
Kossakowski, Diana; Espinoza, Néstor; Brahm, Rafael et al

in Monthly Notices of the Royal Astronomical Society (2019), 490

We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite ... [more ▼]

We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through follow-up photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPIST-S), high- resolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package JULIET reveals that TOI-150b is a 1.254± 0.016 {R}_ {J}, massive (2.61^{+0.19}_{-0.12} {M}_ {J}) hot Jupiter in a 5.857-d orbit, while TOI-163b is an inflated (R_ {P} = 1.478^{+0.022}_{-0.029} R_ {J}, M_ {P} = 1.219± 0.11 {M}_ {J}) hot Jupiter on a P = 4.231-d orbit; both planets orbit F-type stars. A particularly interesting result is that TOI-150b shows an eccentric orbit (e=0.262^{+0.045}_{-0.037}), which is quite uncommon among hot Jupiters. We estimate that this is consistent, however, with the circularization time-scale, which is slightly larger than the age of the system. These two hot Jupiters are both prime candidates for further characterization - in particular, both are excellent candidates for determining spin-orbit alignments via the Rossiter-McLaughlin (RM) effect and for characterizing atmospheric thermal structures using secondary eclipse observations considering they are both located closely to the James Webb Space Telescope (JWST) Continuous Viewing Zone (CVZ). [less ▲]

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See detailNear-resonance in a System of Sub-Neptunes from TESS
Quinn, Samuel N.; Becker, Juliette C.; Rodriguez, Joseph E. et al

in Astronomical Journal (2019), 158

We report the Transiting Exoplanet Survey Satellite detection of a multi-planet system orbiting the V = 10.9 K0 dwarf TOI-125. We find evidence for up to five planets, with varying confidence. Three ... [more ▼]

We report the Transiting Exoplanet Survey Satellite detection of a multi-planet system orbiting the V = 10.9 K0 dwarf TOI-125. We find evidence for up to five planets, with varying confidence. Three transit signals with high signal-to-noise ratio correspond to sub-Neptune-sized planets (2.76, 2.79, and 2.94 R [SUB]⊕[/SUB]), and we statistically validate the planetary nature of the two inner planets (P [SUB] b [/SUB] = 4.65 days, P [SUB] c [/SUB] = 9.15 days). With only two transits observed, we report the outer object (P [SUB].03[/SUB] = 19.98 days) as a planet candidate with high signal-to-noise ratio. We also detect a candidate transiting super-Earth (1.4 R [SUB]⊕[/SUB]) with an orbital period of only 12.7 hr and a candidate Neptune-sized planet (4.2 R [SUB]⊕[/SUB]) with a period of 13.28 days, both at low signal-to-noise ratio. This system is amenable to mass determination via radial velocities and transit-timing variations, and provides an opportunity to study planets of similar size while controlling for age and environment. The ratio of orbital periods between TOI-125 b and c (P [SUB] c [/SUB]/P [SUB] b [/SUB] = 1.97) is slightly lower than an exact 2:1 commensurability and is atypical of multiple planet systems from Kepler, which show a preference for period ratios just wide of first-order period ratios. A dynamical analysis refines the allowed parameter space through stability arguments and suggests that despite the nearly commensurate periods, the system is unlikely to be in resonance. [less ▲]

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See detailWASP-169, WASP-171, WASP-175, and WASP-182: three hot Jupiters and one bloated sub-Saturn mass planet discovered by WASP-South
Nielsen, L. D.; Bouchy, F.; Turner, O. D. et al

in Monthly Notices of the Royal Astronomical Society (2019), 489(2), 2478-2487

We present the discovery of four new giant planets from the Wide Angle Search for Planets-South (WASP-South), three hot Jupiters and one bloated sub-Saturn mass planet: WASP-169b, WASP-171b, WASP-175b ... [more ▼]

We present the discovery of four new giant planets from the Wide Angle Search for Planets-South (WASP-South), three hot Jupiters and one bloated sub-Saturn mass planet: WASP-169b, WASP-171b, WASP-175b, and WASP-182b. Besides the discovery photometry from WASP-South we use radial velocity measurements from CORALIE and HARPS and follow-up photometry from EulerCam, TRAPPIST-North and -South, and SPECULOOS. WASP-169b is a low-density Jupiter (M=0.561 ± 0.061 {M_Jup}, R=1.304^{+0.150}_{-0.073} {R_Jup}) orbiting a V = 12.17 F8 subgiant in a 5.611 d orbit. WASP-171b is a typical hot Jupiter (M=1.084 ± 0.094 {M_Jup}, R=0.98^{+0.07}_{-0.04} {R_Jup}, P = 3.82 d) around a V = 13.05 G0 star. We find a linear drift in the radial velocities of WASP-171 spanning 3.5 yr, indicating the possibility of an additional outer planet or stellar companion. WASP-175b is an inflated hot Jupiter (M = 0.99 ± 0.13 M[SUB]Jup[/SUB], R = 1.208 ± 0.081 R[SUB]Jup[/SUB], P = 3.07 d) around a V = 12.04 F7 star, which possibly is part of a binary system with a star 7.9 arcsec away. WASP-182b is a bloated sub-Saturn mass planet (M = 0.148 ± 0.011 M[SUB]Jup[/SUB], R = 0.850 ± 0.030 R[SUB]Jup[/SUB]) around a metal-rich V = 11.98 G5 star ([Fe/H] = 0.27 ± 0.11). With an orbital period of P = 3.377 d, it sits right in the apex of the sub-Jovian desert, bordering the upper and lower edge of the desert in both the mass-period and radius-period plane. WASP-169b, WASP- 175b, and WASP-182b are promising targets for atmospheric characterization through transmission spectroscopy, with expected transmission signals of 121, 150, and 264 ppm, respectively. [less ▲]

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See detailSuperWASP dispositions and false positive catalogue
Schanche, N.; Collier Cameron, A.; Almenara, J. M. et al

in Monthly Notices of the Royal Astronomical Society (2019), 488

SuperWASP, the Northern hemisphere WASP observatory, has been observing the skies from La Palma since 2004. In that time, more than 50 planets have been discovered with data contributions from SuperWASP ... [more ▼]

SuperWASP, the Northern hemisphere WASP observatory, has been observing the skies from La Palma since 2004. In that time, more than 50 planets have been discovered with data contributions from SuperWASP. In the process of validating planets, many false-positive candidates have also been identified. The TESS telescope is set to begin observations of the northern sky in 2019. Similar to the WASP survey, the TESS pixel size is relatively large (13 arcsec for WASP and 21 arcsec for TESS), making it susceptible to many blended signals and false detections caused principally by grazing and blended stellar eclipsing binary systems. In order to reduce duplication of effort on targets, we present a catalogue of 1 041 Northern hemisphere SuperWASP targets that have been rejected as planetary transits through follow-up observation. [less ▲]

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See detailA basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea
Vernazza, Pierre; Jorda, Laurent; Ševeček, P. et al

in Nature Astronomy (2019)

(10) Hygiea is the fourth largest main belt asteroid and the only known asteroid whose surface composition appears similar to that of the dwarf planet (1) Ceres[SUP]1,2[/SUP], suggesting a similar origin ... [more ▼]

(10) Hygiea is the fourth largest main belt asteroid and the only known asteroid whose surface composition appears similar to that of the dwarf planet (1) Ceres[SUP]1,2[/SUP], suggesting a similar origin for these two objects. Hygiea suffered a giant impact more than 2 Gyr ago[SUP]3[/SUP] that is at the origin of one of the largest asteroid families. However, Hygeia has never been observed with sufficiently high resolution to resolve the details of its surface or to constrain its size and shape. Here, we report high-angular-resolution imaging observations of Hygiea with the VLT/SPHERE instrument ( 20 mas at 600 nm) that reveal a basin-free nearly spherical shape with a volume- equivalent radius of 217 ± 7 km, implying a density of 1,944 ± 250 kg m[SUP]-[/SUP][SUP]3[/SUP] to 1σ. In addition, we have determined a new rotation period for Hygiea of 13.8 h, which is half the currently accepted value. Numerical simulations of the family-forming event show that Hygiea's spherical shape and family can be explained by a collision with a large projectile (diameter 75-150 km). By comparing Hygiea's sphericity with that of other Solar System objects, it appears that Hygiea is nearly as spherical as Ceres, opening up the possibility for this object to be reclassified as a dwarf planet. [less ▲]

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See detailTwo New HATNet Hot Jupiters around A Stars and the First Glimpse at the Occurrence Rate of Hot Jupiters from TESS
Zhou, G.; Huang, C. X.; Bakos, G. Á. et al

in Astronomical Journal (2019), 158

Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their parent stars. We ... [more ▼]

Wide-field surveys for transiting planets are well suited to searching diverse stellar populations, enabling a better understanding of the link between the properties of planets and their parent stars. We report the discovery of HAT-P-69 b (TOI 625.01) and HAT-P-70 b (TOI 624.01), two new hot Jupiters around A stars from the Hungarian-made Automated Telescope Network (HATNet) survey that have also been observed by the Transiting Exoplanet Survey Satellite. HAT-P-69 b has a mass of {3.58}[SUB]-0.58[/SUB][SUP]+0.58[/SUP] M [SUB]Jup[/SUB] and a radius of {1.676}[SUB]-0.033[/SUB][SUP]+0.051[/SUP] R [SUB]Jup[/SUB] and resides in a prograde 4.79 day orbit. HAT-P-70 b has a radius of {1.87}[SUB]-0.10[/SUB][SUP]+0.15[/SUP] R [SUB]Jup[/SUB] and a mass constraint of < 6.78 (3σ ) M [SUB]Jup[/SUB] and resides in a retrograde 2.74 day orbit. We use the confirmation of these planets around relatively massive stars as an opportunity to explore the occurrence rate of hot Jupiters as a function of stellar mass. We define a sample of 47,126 main-sequence stars brighter than T [SUB]mag[/SUB] = 10 that yields 31 giant planet candidates, including 18 confirmed planets, 3 candidates, and 10 false positives. We find a net hot Jupiter occurrence rate of 0.41 ± 0.10% within this sample, consistent with the rate measured by Kepler for FGK stars. When divided into stellar mass bins, we find the occurrence rate to be 0.71 ± 0.31% for G stars, 0.43 ± 0.15% for F stars, and 0.26 ± 0.11% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass. Based on observations obtained with the Hungarian-made Automated Telescope Network. Based in part on observations obtained with the Tillinghast Reflector 1.5 m telescope and the 1.2 m telescope, both operated by the Smithsonian Astrophysical Observatory at the Fred Lawrence Whipple Observatory in Arizona. This work makes use of the Smithsonian Institution High Performance Cluster (SI/HPC). Based in part on observations made with the Southern African Large Telescope (SALT). [less ▲]

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See detailLatest news of SPECULOOS and TRAPPIST-1
Ducrot, Elsa ULiege; Gillon, Michaël ULiege

in EPSC-DPS Joint Meeting 2019 (2019, September 01)

This talk will present the latest news of the SPECULOOS photometric survey, its installation, operations and progress. And will then focus on its most valuable discovery for now, the TRAPPIST-1 (aka ... [more ▼]

This talk will present the latest news of the SPECULOOS photometric survey, its installation, operations and progress. And will then focus on its most valuable discovery for now, the TRAPPIST-1 (aka SPECULOOS-1) system. We will notably discuss the important results brought by the intensive multi-epoch multi-wavelengths photometric follow of this unique system. [less ▲]

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See detailWASP-180Ab: Doppler tomography of an hot Jupiter orbiting the primary star in a visual binary
Temple, L. Y.; Hellier, C.; Anderson, D. R. et al

in Monthly Notices of the Royal Astronomical Society (2019)

We report the discovery and characterisation of WASP-180Ab, a hot Jupiter confirmed by the detection of its Doppler shadow and by measuring its mass using radial velocities. We find the 0.9 ± 0.1 M[SUB ... [more ▼]

We report the discovery and characterisation of WASP-180Ab, a hot Jupiter confirmed by the detection of its Doppler shadow and by measuring its mass using radial velocities. We find the 0.9 ± 0.1 M[SUB]Jup[/SUB], 1.24 ± 0.04 R[SUB]Jup[/SUB] planet to be in a misaligned, retrograde orbit around an F7 star with T[SUB]eff[/SUB] = 6500 K and a moderate rotation speed of vsin i[SUB]⋆[/SUB] = 19.9 km s[SUP]-1[/SUP]. The host star is the primary of a V = 10.7 binary, where a secondary separated by ̃5″ (̃1200 AU) contributes ̃ 30% of the light. WASP-180Ab therefore adds to a small sample of transiting hot Jupiters known in binary systems. A 4.6-day modulation seen in the WASP data is likely to be the rotational modulation of the companion star, WASP-180B. [less ▲]

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See detailWASP-166b: a bloated super-Neptune transiting a V = 9 star
Hellier, Coel; Anderson, D. R.; Triaud, A. H. M. J. et al

in Monthly Notices of the Royal Astronomical Society (2019), 488

We report the discovery of WASP-166b, a super-Neptune planet with a mass of 0.1 M[SUB]Jup[/SUB] (1.9 M[SUB]Nep[/SUB]) and a bloated radius of 0.63 R[SUB]Jup[/SUB]. It transits a V = 9.36, F9V star in a 5 ... [more ▼]

We report the discovery of WASP-166b, a super-Neptune planet with a mass of 0.1 M[SUB]Jup[/SUB] (1.9 M[SUB]Nep[/SUB]) and a bloated radius of 0.63 R[SUB]Jup[/SUB]. It transits a V = 9.36, F9V star in a 5.44-d orbit that is aligned with the stellar rotation axis (sky-projected obliquity angle λ = 3 ± 5 deg). Variations in the radial-velocity measurements are likely the result of magnetic activity over a 12-d stellar rotation period. WASP-166b appears to be a rare object within the `Neptune desert'. [less ▲]

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See detailOn the hunt for Trappist-1 siblings
Queloz, Didier; Gillon, Michaël ULiege

in AAS/Division for Extreme Solar Systems Abstracts (2019, August 01)

The TRAPPIST-South 60cm telescope at La Silla (ESO) is famously known for its detection of the extraordinary TRAPPIST-1 planetary system. A discovery made during the prototype phase of our ultra-cool ... [more ▼]

The TRAPPIST-South 60cm telescope at La Silla (ESO) is famously known for its detection of the extraordinary TRAPPIST-1 planetary system. A discovery made during the prototype phase of our ultra-cool dwarf transit survey SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars). This talk will first report on the self-consistence transit occurrence analysis of all observations of 42 bright ultra-cool dwarfs made with TRAPPIST-South during a period ranging from 2011 to 2017. On the basis that, with the exception of the discovery of TRAPPIST-1 planets, we didn't detect any other significant transiting event, we concluded on a 10% lower limit for the occurrence of planets similar to TRAPPIST-1b in this sample. The outcome is very sensitive to the size and period of the planet considered. A comprehensive statistic will be presented. Finally, performance obtained with our recently commissioned SPECULOOS Southern facility installed at Paranal will be presented. The lower occurrence limit measured with TRAPPIST survey will be compared with early results from 6 months of continue SPECULOOS core survey operations <P /> [less ▲]

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See detailGround-based follow-up observations of TRAPPIST-1 transits in the near-infrared
Burdanov, Artem ULiege; Lederer, S. M.; Gillon, Michaël ULiege et al

in Monthly Notices of the Royal Astronomical Society (2019), 487

The TRAPPIST-1 planetary system is a favourable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space ... [more ▼]

The TRAPPIST-1 planetary system is a favourable target for the atmospheric characterization of temperate earth-sized exoplanets by means of transmission spectroscopy with the forthcoming James Webb Space Telescope (JWST). A possible obstacle to this technique could come from the photospheric heterogeneity of the host star that could affect planetary signatures in the transit transmission spectra. To constrain further this possibility, we gathered an extensive photometric data set of 25 TRAPPIST-1 transits observed in the near-IR J band (1.2 μm) with the UKIRT and the AAT, and in the NB2090 band (2.1 μm) with the VLT during the period 2015-18. In our analysis of these data, we used a special strategy aiming to ensure uniformity in our measurements and robustness in our conclusions. We reach a photometric precision of 0.003 (RMS of the residuals), and we detect no significant temporal variations of transit depths of TRAPPIST-1 b, c, e, and g over the period of 3 yr. The few transit depths measured for planets d and f hint towards some level of variability, but more measurements will be required for confirmation. Our depth measurements for planets b and c disagree with the stellar contamination spectra originating from the possible existence of bright spots of temperature 4500 K. We report updated transmission spectra for the six inner planets of the system which are globally flat for planets b and g and some structures are seen for planets c, d, e, and f. [less ▲]

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See detailSearching for transiting cold Jupiters around bright stars with ASTEP South at Dome C, Antarctica
Crouzet, Nicolas; Mékarnia, Djamel; Guillot, Tristan et al

in Bulletin of the American Astronomical Society (2019, August 01)

Much of our understanding of gas giant exoplanets come from those transiting in front of bright stars at small orbital separations (P 3 days, a 0.05 au). These hot Jupiters are coupled to their host star ... [more ▼]

Much of our understanding of gas giant exoplanets come from those transiting in front of bright stars at small orbital separations (P 3 days, a 0.05 au). These hot Jupiters are coupled to their host star: stellar irradiation impacts the chemistry and temperature structure of their atmospheres and tidal interactions affects the orbital dynamics and may even impact the star itself. In contrast, gas giant exoplanets with long orbital periods and large separations (P > 30 days, a > 0.2 au) are much less coupled to their host star and provide ideal benchmarks to study gas giant planets in general. However, only a few transiting "cold Jupiters" orbiting bright stars are known to date. In the past years, we conducted the ASTEP experiment (Antarctica Search for Transiting ExoPlanets) to search and characterize transiting exoplanets from Dome C, Antarctica and to qualify this site for photometry in the visible. One instrument, ASTEP South, is a 10 cm diameter lens equipped with a CCD camera in a thermalised box pointing continuously towards the celestial South pole. We analysed four winters of data collected with this instrument and identified about 30 transit candidates around relatively bright stars (9 < V < 13) with orbital periods up to 80 days. We performed photometric follow-up with the Las Cumbres Observatory (LCO) 0.4m telescopes to investigate these signals. Most of these stars are also observed by TESS and their lightcurves can be extracted from the full frame images. In this poster, we present our set of candidates, the first results of the photometric follow-up, and discuss the use of TESS data to investigate these objects. [less ▲]

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See detailESA Voyage 2050 White Paper: Detecting life outside our solar system with a large high-contrast-imaging mission
Snellen, Ignas; Albrecht, Simon; Anglada-Escude, Guillem et al

E-print/Working paper (2019)

In this white paper, we recommend the European Space Agency plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as currently ... [more ▼]

In this white paper, we recommend the European Space Agency plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as currently under study by NASA. Such a mission will be needed to characterize a sizable sample of temperate Earth-like planets in the habitable zones of nearby Sun-like stars and to search for extraterrestrial biological activity. We provide an overview of relevant European expertise, and advocate ESA to start a technology development program towards detecting life outside the Solar system. <P /> [less ▲]

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See detailTrappist Lightcurves of Main-Belt Asteroids 31 Euphrosyne, 41 Daphne and 89 Julia
Ferrais, Marin ULiege; Jehin, Emmanuel ULiege; Manfroid, Jean ULiege et al

in Minor Planet Bulletin (2019), 46

Densely sampled lightcurves of three large main-belt asteroids were obtained with the TRAPPIST-South (TS) and TRAPPIST-North (TN) telescopes from 2017 September to 2018 July. We found their synodic ... [more ▼]

Densely sampled lightcurves of three large main-belt asteroids were obtained with the TRAPPIST-South (TS) and TRAPPIST-North (TN) telescopes from 2017 September to 2018 July. We found their synodic rotation periods and amplitudes to be: 31 Euphrosyne, 5.5312 ± 0.0007 h and 0.07 mag; 41 Daphne, 5.9912 ± 0.0028 h and 0.18 mag; and 89 Julia, 11.3844 ± 0.0002 h and 0.19 mag. All data have been submitted to the ALCDEF database. [less ▲]

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See detailA super-Earth and two sub-Neptunes transiting the nearby and quiet M dwarf TOI-270
Günther, Maximilian N.; Pozuelos Romero, Francisco José ULiege; Dittmann, Jason A. et al

in Nature Astronomy (2019)

One of the primary goals of exoplanetary science is to detect small, temperate planets passing (transiting) in front of bright and quiet host stars. This enables the characterization of planetary sizes ... [more ▼]

One of the primary goals of exoplanetary science is to detect small, temperate planets passing (transiting) in front of bright and quiet host stars. This enables the characterization of planetary sizes, orbits, bulk compositions, atmospheres and formation histories. These studies are facilitated by small and cool M dwarf host stars. Here we report the Transiting Exoplanet Survey Satellite (TESS)[SUP]1[/SUP] discovery of three small planets transiting one of the nearest and brightest M dwarf hosts observed to date, TOI-270 (TIC 259377017, with K-magnitude 8.3, and 22.5 parsecs away from Earth). The M3V-type star is transited by the super-Earth-sized planet TOI-270 b (1.247[SUB]-0.083[/SUB][SUP]+0.089[/SUP]R[SUB]⊕[/SUB]) and the sub- Neptune-sized planets TOI-270 c (2.42 ± 0.13 R[SUB]⊕[/SUB]) and TOI-270 d (2.13 ± 0.12 R[SUB]⊕[/SUB]). The planets orbit close to a mean-motion resonant chain, with periods (3.36 days, 5.66 days and 11.38 days, respectively) near ratios of small integers (5:3 and 2:1). TOI-270 is a prime target for future studies because (1) its near-resonance allows the detection of transit timing variations, enabling precise mass measurements and dynamical studies; (2) its brightness enables independent radial-velocity mass measurements; (3) the outer planets are ideal for atmospheric characterization via transmission spectroscopy; and (4) the quietness of the star enables future searches for habitable zone planets. Altogether, very few systems with small, temperate exoplanets are as suitable for such complementary and detailed characterization as TOI-270. [less ▲]

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See detailNGTS-4b: A sub-Neptune Transiting in the Desert
West, Richard G.; Gillen, Edward; Bayliss, Daniel et al

in Monthly Notices of the Royal Astronomical Society (2019), 486

We report the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34d orbit. NGTS-4b has a mass M=$20.6\pm3.0$M_E and radius R=$3.18\pm0.26$R_E, which places it ... [more ▼]

We report the discovery of NGTS-4b, a sub-Neptune-sized planet transiting a 13th magnitude K-dwarf in a 1.34d orbit. NGTS-4b has a mass M=$20.6\pm3.0$M_E and radius R=$3.18\pm0.26$R_E, which places it well within the so-called "Neptunian Desert". The mean density of the planet ($3.45\pm0.95$g/cm^3) is consistent with a composition of 100% H$_2$O or a rocky core with a volatile envelope. NGTS-4b is likely to suffer significant mass loss due to relatively strong EUV/X-ray irradiation. Its survival in the Neptunian desert may be due to an unusually high core mass, or it may have avoided the most intense X-ray irradiation by migrating after the initial activity of its host star had subsided. With a transit depth of $0.13\pm0.02$%, NGTS-4b represents the shallowest transiting system ever discovered from the ground, and is the smallest planet discovered in a wide-field ground-based photometric survey. [less ▲]

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See detailThe L 98-59 System: Three Transiting, Terrestrial-size Planets Orbiting a Nearby M Dwarf
Kostov, Veselin B.; Schlieder, Joshua E.; Barclay, Thomas et al

in Astronomical Journal (2019), 158

We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-size planets transiting L 98-59 (TOI-175, TIC 307210830)—a bright M dwarf at a distance of 10.6 pc. Using the Gaia ... [more ▼]

We report the Transiting Exoplanet Survey Satellite (TESS) discovery of three terrestrial-size planets transiting L 98-59 (TOI-175, TIC 307210830)—a bright M dwarf at a distance of 10.6 pc. Using the Gaia- measured distance and broadband photometry, we find that the host star is an M3 dwarf. Combined with the TESS transits from three sectors, the corresponding stellar parameters yield planet radii ranging from 0.8 R [SUB]⊕[/SUB] to 1.6 R [SUB]⊕[/SUB]. All three planets have short orbital periods, ranging from 2.25 to 7.45 days with the outer pair just wide of a 2:1 period resonance. Diagnostic tests produced by the TESS Data Validation Report and the vetting package DAVE rule out common false- positive sources. These analyses, along with dedicated follow-up and the multiplicity of the system, lend confidence that the observed signals are caused by planets transiting L 98-59 and are not associated with other sources in the field. The L 98-59 system is interesting for a number of reasons: the host star is bright (V = 11.7 mag, K = 7.1 mag) and the planets are prime targets for further follow-up observations including precision radial-velocity mass measurements and future transit spectroscopy with the James Webb Space Telescope; the near-resonant configuration makes the system a laboratory to study planetary system dynamical evolution; and three planets of relatively similar size in the same system present an opportunity to study terrestrial planets where other variables (age, metallicity, etc.) can be held constant. L 98-59 will be observed in four more TESS sectors, which will provide a wealth of information on the three currently known planets and have the potential to reveal additional planets in the system. [less ▲]

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See detailThe Ultracool SpeXtroscopic Survey. I. Volume-Limited Spectroscopic Sample and Luminosity Function of M7$-$L5 Ultracool Dwarfs
Bardalez Gagliuffi, Daniella C.; Burgasser, Adam J.; Schmidt, Sarah J. et al

E-print/Working paper (2019)

We present a volume-limited, spectroscopically-verified sample of M7$-$L5 ultracool dwarfs within 25\,pc. The sample contains 410 sources, of which $93\%$ have trigonometric distance measurements ($80 ... [more ▼]

We present a volume-limited, spectroscopically-verified sample of M7$-$L5 ultracool dwarfs within 25\,pc. The sample contains 410 sources, of which $93\%$ have trigonometric distance measurements ($80\%$ from \textit{Gaia} DR2), and $81\%$ have low-resolution ($R\sim120$), near- infrared (NIR) spectroscopy. We also present an additional list of 60 sources which may be M7$-$L5 dwarfs within 25\,pc when distance or spectral type uncertainties are taken into account. The spectra provide NIR spectral and gravity classifications, and we use these to identify young sources, red and blue $J-K_S$ color outliers, and spectral binaries. We measure very low gravity and intermediate gravity fractions of $2.1^{+0.9}_{-0.8}\%$ and $7.8^{+1.7}_{-1.5}\%$, respectively; fractions of red and blue color outliers of $1.4^{+0.6}_{-0.5}$\% and $3.6^{+1.0}_{-0.9}$\%, respectively; and a spectral binary fraction of $1.6^{+0.5}_{-0.5}\%$. We present an updated luminosity function for M7$-$L5 dwarfs continuous across the hydrogen burning limit that agrees with previous studies. We estimate our completeness to range between $69-80\%$ when compared to an isotropic model. However, we find that the literature late-M sample is severely incomplete compared to L dwarfs, with completeness of $62^{+8}_{-7}\%$ and $83^{+10}_{-9}\%$, respectively. This incompleteness can be addressed with astrometric- based searches of ultracool dwarfs with \textit{Gaia} to identify objects previously missed by color- and magnitude-limited surveys. [less ▲]

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See detailThree hot-Jupiters on the upper edge of the mass-radius distribution: WASP-177, WASP-181, and WASP-183
Turner, Oliver D.; Anderson, D. R.; Barkaoui, K. et al

in Monthly Notices of the Royal Astronomical Society (2019), 485

We present the discovery of three transiting planets from the WASP survey, two hot-Jupiters: WASP-177 b (˜0.5 M[SUB]Jup[/SUB], ˜1.6 R[SUB]Jup[/SUB]) in a 3.07-d orbit of a V = 12.6 K2 star, WASP-183 b (˜0 ... [more ▼]

We present the discovery of three transiting planets from the WASP survey, two hot-Jupiters: WASP-177 b (˜0.5 M[SUB]Jup[/SUB], ˜1.6 R[SUB]Jup[/SUB]) in a 3.07-d orbit of a V = 12.6 K2 star, WASP-183 b (˜0.5 M[SUB]Jup[/SUB], ˜1.5 R[SUB]Jup[/SUB]) in a 4.11-d orbit of a V = 12.8 G9/K0 star; and one hot-Saturn planet WASP-181 b (˜0.3 M[SUB]Jup[/SUB], ˜1.2 R[SUB]Jup[/SUB]) in a 4.52-d orbit of a V = 12.9 G2 star. Each planet is close to the upper bound of mass-radius space and has a scaled semimajor axis, a/R[SUB]*[/SUB], between 9.6 and 12.1. These lie in the transition between systems that tend to be in orbits that are well aligned with their host-star's spin and those that show a higher dispersion. [less ▲]

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See detailQatar Exoplanet Survey: Qatar-8b, 9b, and 10b—A Hot Saturn and Two Hot Jupiters
Alsubai, Khalid; Tsvetanov, Zlatan I.; Pyrzas, Stylianos et al

in Astronomical Journal (2019), 157(6), 10

In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey. Qatar-8b is a hot Saturn, with M [SUB]P[/SUB] = 0.37 M [SUB]J[/SUB] and R [SUB]P[/SUB] = 1.3 R [SUB]J[/SUB], orbiting ... [more ▼]

In this paper we present three new extrasolar planets from the Qatar Exoplanet Survey. Qatar-8b is a hot Saturn, with M [SUB]P[/SUB] = 0.37 M [SUB]J[/SUB] and R [SUB]P[/SUB] = 1.3 R [SUB]J[/SUB], orbiting a solar-like star every P [SUB]orb[/SUB] = 3.7 days. Qatar-9b is a hot Jupiter with a mass of M [SUB]P[/SUB] = 1.2 M [SUB]J[/SUB] and a radius of R [SUB]P[/SUB] = 1 R [SUB]J[/SUB], in an orbit of P [SUB]orb[/SUB] = 1.5 days around a low mass, M [SUB]⋆[/SUB] = 0.7 M [SUB]⊙[/SUB], mid-K main-sequence star. Finally, Qatar-10b is a hot, T [SUB]eq[/SUB] ∼ 2000 K, sub-Jupiter mass planet, M [SUB]P[/SUB] = 0.7 M [SUB]J[/SUB], with a radius of R [SUB]P[/SUB] = 1.54 R [SUB]J[/SUB] and an orbital period of P [SUB]orb[/SUB] = 1.6 days, placing it on the edge of the sub-Jupiter desert. [less ▲]

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