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Maxted, P. F. L.

Publications and source records attributed to Maxted, P. F. L..

5 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Exploiting timing capabilities of the CHEOPS mission with warm-Jupiter planets

ABSTRACT We present 17 transit light curves of seven known warm-Jupiters observed with the CHaracterising ExOPlanet Satellite (CHEOPS). The light curves have been collected as part of the CHEOPS Guaranteed Time Observation (GTO) program that searches for transit-timing variation (TTV) of warm-Jupiters induced by a possible external perturber to shed light on the evolution path of such planetary systems. We describe the CHEOPS observation process, from the planning to the data analysis. In this work, we focused on the timing performance of CHEOPS, the impact of the sampling of the transit phases, and the improvement we can obtain by combining multiple transits together. We reached the highest precision on the transit time of about 13–16 s for the brightest target (WASP-38, G = 9.2) in our sample. From the combined analysis of multiple transits of fainter targets with G ≥ 11, we obtained a timing precision of ∼2 min. Additional observations with CHEOPS, covering a longer temporal baseline, will further improve the precision on the transit times and will allow us to detect possible TTV signals induced by an external perturber.

Borsato, L. (ORCID:0000000300669268)↗
DOE OSTI2021

The EBLM project – VIII. First results for M-dwarf mass, radius, and effective temperature measurements using CHEOPS light curves

ABSTRACT The accuracy of theoretical mass, radius, and effective temperature values for M-dwarf stars is an active topic of debate. Differences between observed and theoretical values have raised the possibility that current theoretical stellar structure and evolution models are inaccurate towards the low-mass end of the main sequence. To explore this issue, we use the CHEOPS satellite to obtain high-precision light curves of eclipsing binaries with low-mass stellar companions. We use these light curves combined with the spectroscopic orbit for the solar-type companion to measure the mass, radius, and effective temperature of the M-dwarf star. Here, we present the analysis of three eclipsing binaries. We use the pycheops data analysis software to fit the observed transit and eclipse events of each system. Two of our systems were also observed by the TESS satellite – we similarly analyse these light curves for comparison. We find consistent results between CHEOPS and TESS, presenting three stellar radii and two stellar effective temperature values of low-mass stellar objects. These initial results from our on-going observing programme with CHEOPS show that we can expect to have ∼24 new mass, radius, and effective temperature measurements for very low-mass stars within the next few years.

Swayne, M. I.↗
DOE OSTI2019

WASP-190b: Tomographic Discovery of a Transiting Hot Jupiter

We report the discovery of WASP-190b, an exoplanet on a 5.37 day orbit around a mildly evolved F6 IV-V star with V = 11.7, T{sub eff} = 6400 ± 100 K, M {sub *} = 1.35 ± 0.05 M {sub ⊙}, and R {sub *} = 1.6 ± 0.1 R {sub ⊙}. The planet has a radius of R {sub P} = 1.15 ± 0.09 R {sub Jup} and a mass of M {sub P} = 1.0 ± 0.1 M {sub Jup}, making it a mildly inflated hot Jupiter. It is the first hot Jupiter confirmed via Doppler tomography with an orbital period of >5 days. The orbit is also marginally misaligned with respect to the stellar rotation, with λ = 21° ± 6° measured using Doppler tomography.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Discovery of Three New Transiting Hot Jupiters: WASP-161 b, WASP-163 b, and WASP-170 b

We present the discovery of three new transiting hot Jupiters by the WASP-South project, WASP-161 b, WASP-163 b, and WASP-170 b. Follow-up radial velocities obtained with the Euler/CORALIE spectrograph and transit light curves obtained with the TRAPPIST-North, TRAPPIST-South, SPECULOOS-South, NITES, and Euler telescopes have enabled us to determine the masses and radii for these transiting exoplanets. WASP-161 b completes an orbit around its V = 11.1 F6V-type host star in 5.406 days, and has a mass M {sub p} = 2.5 ± 0.2M {sub Jup} and radius R {sub p} = 1.14 ± 0.06 R {sub Jup}. WASP-163 b orbits around its host star (spectral type G8V and the magnitude V = 12.5) every 1.609 days, and has a mass of M {sub P} = 1.9 ± 0.2 M {sub Jup} and a radius of R {sub p} = 1.2 ± 0.1 R {sub Jup}. WASP-170 b has a mass of 1.7 ± 0.2 M {sub Jup} and a radius of 1.14 ± 0.09 R {sub Jup} and is on a 2.344 day orbit around a G1V-type star of magnitude V = 12.8. Given their irradiations (∼10{sup 9} erg s{sup −1} cm{sup −2}) and masses, the three new planets’ sizes are in good agreement with classical models of irradiated giant planets.

79 ASTRONOMY AND ASTROPHYSICS↗