The GAPS programme with HARPS-N at TNG

Abstract

Context. The measurement of the orbital obliquity of hot Jupiters with different physical characteristics can provide clues to the mechanisms of migration and orbital evolution of this particular class of giant exoplanets. Aims. We aim to derive the degree of alignment between planetary orbit and stellar spin angular momentum vectors and look for possible links with other orbital and fundamental physical parameters of the star-planet system. We focus on the characterisation of five transiting planetary systems (HAT-P-3, HAT-P-12, HAT-P-22, WASP-39, and WASP-60) and the determination of their sky-projected planet orbital obliquity through the measurement of the Rossiter–McLaughlin effect. Methods. We used HARPS-N high-precision radial velocity measurements, gathered during transit events, to measure the Rossiter–McLaughlin effect in the target systems and determine the sky-projected angle between the planetary orbital plane and stellar equator. The characterisation of stellar atmospheric parameters was performed by exploiting the HARPS-N spectra, using line equivalent width ratios and spectral synthesis methods. Photometric parameters of the five transiting exoplanets were re-analysed through 17 new light curves, obtained with an array of medium-class telescopes, and other light curves from the literature. Survey-time-series photometric data were analysed for determining the rotation periods of the five stars and their spin inclination. Results. From the analysis of the Rossiter–McLaughlin effect we derived a sky-projected obliquity of λ = 21.2° ± 8.7°, λ = −54°−13°+41°, λ = −2.1° ± 3.0°, λ = 0° ± 11°, and λ = −129° ± 17° for HAT-P-3 b, HAT-P-12 b, HAT-P-22 b, WASP-39 b, and WASP-60 b, respectively. The latter value indicates that WASP-60 b is moving on a retrograde orbit. These values represent the first measurements of λ for the five exoplanetary systems under study. The stellar activity of HAT-P-22 indicates a rotation period of 28.7 ± 0.4 days, which allowed us to estimate the true misalignment angle of HAT-P-22 b, ψ = 24° ± 18°. The revision of the physical parameters of the five exoplanetary systems returned values that are fully compatible with those existing in the literature. The exception to this is the WASP-60 system, for which, based on higher quality spectroscopic and photometric data, we found a more massive and younger star and a larger and hotter planet.

LRG-BEASTS: Transmission Spectroscopy and Retrieval Analysis of the Highly Inflated Saturn-mass Planet WASP-39b

“…This result implies that stellar activity is not the reason behind the supersolar metallicity atmosphere we derive for WASP-39b. This is also in agreement with the star being inactive as determined through a lack of photometric variation (Faedi et al 2011;Fischer et al 2016) and weak Ca II H and K emission (log R HK = −4.97 ± 0.06; Mancini et al 2018). As noted throughout this work, there have been significantly different water abundances, and hence metallicities, reported for WASP-39b in the literature.…”

Deciphering the atmosphere of HAT-P-12b: solving discrepant results

“…The orbital period agrees with that published by Mallonn et al (2015), with slightly improved precision, and it shows a difference of about 1 σ to the work of Hartman et al (2009). In Table 5 we compare our values with the most recent literature values of HAT-P-12b (Mancini et al 2018), and our results are in agreement. Moreover, the equilibrium temperature estimated here agrees with the upper limit on the brightness temperature derived by Todorov et al (2013) if for simplicity we assume the planet to radiate as a blackbody.…”

“…Now, we aim for a homogeneous reanalysis of both the ground-based and the space-based data. We consider the orbital parameter values derived in this work ( References a/R k = R p /R i (deg) Hartman et al (2009) 11.76 ± 0.18 0.1406 ± 0.0013 89.0 ± 0.4 Lee et al (2012) 11.74 ± 0.17 0.1370 ± 0.0019 89.9 ± 0.1 Sada et al (2012) 11.22 ± 0.57 0.1404 ± 0.0026 88.5 ± 1.0 Line et al (2013) 11.60 ± 0.39 0.1370 ± 0.0011 88.7 ± 0.6 Mallonn et al (2015) 11.72 ± 0.12 0.13779 ± 0.00079 88.98 ± 0.29 Sing et al (2016) 11.19 ± 0.22 0.13596 ± 0.00059 88.10 ± 0.27 Mancini et al (2018) 11.93 ± 0.28 0.13898 ±0.00069 89.10 ± 0.24 This work 11.68 ± 0.12 0.13847± 0.00054 88.83 ± 0.19 multaneously fit detrending function. The wavelength-dependent limb-darkening coefficients of the four-parameter LDL were fixed to the theoretical values from Claret & Bloemen (2011).…”

Optical to Near-infrared Transmission Spectrum of the Warm Sub-Saturn HAT-P-12b

“…When performing a periodogram analysis of individual seasonal datasets, we do not retrieve any frequencies that produce amplitudes larger than the seasonal standard deviations. In particular, we do not detect a variability signal with a period near the estimated rotational period of the star (P rot ∼ 44 days; Mancini et al 2018). Such a periodicity in the photometry would be indicative of rotational modulation of weak features on the stellar surface.…”

“…the stellar surface. Analyses of stellar spectra from the Keck High Resolution Echelle Spectrometer (HIRES) and more recently from the High Accuracy Radial Velocity Planet Searcher (HARPS) instrument also indicate low stellar activity as determined by the Ca II H and K lines: log(R HK ) = −5.104 (Knutson et al 2010) and log(R HK ) = −4.9 (Mancini et al 2018). In addition, none of the transit light curves analyzed in this work show evidence for occulted spots.…”