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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 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.; Bakos, G. et al

E-print/Working paper (2019)

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 HATNet survey which have also been observed by the Transiting Exoplanet Survey Satellite (TESS). HAT-P-69 b has a mass of 3.73 (+0.61/-0.59) Mjup and a radius of 1.626 (+0.032/-0.025) Rjup, and is in a prograde 4.79-day orbit around a star of mass 1.698+/-0.025 Msun and radius 1.854 (+0.043/-0.022) Rsun. HAT-P-70 b has a radius of 1.87 (+0.15/-0.10) Rjup and a mass constraint of <6.78 (3sigma) Mjup, and is in a retrograde 2.74-day orbit around a star of mass 1.890 (+0.010/-0.013) Msun and radius 1.858 (+0.119/-0.091) Rsun. 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 Tmag=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 0.45+/-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% G stars, 0.43+/-0.15% for F stars, and 0.32+/-0.12% for A stars. Thus, at this point, we cannot discern any statistically significant trend in the occurrence of hot Jupiters with stellar mass. [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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See detailLower atmosphere and pressure evolution on Pluto from ground-based stellar occultations, 1988-2016
Meza, E.; Sicardy, B.; Assafin, M. et al

in Astronomy and Astrophysics (2019), 625(A42), 21

Context. The tenuous nitrogen (N[SUB]2[/SUB]) atmosphere on Pluto undergoes strong seasonal effects due to high obliquity and orbital eccentricity, and has recently (July 2015) been observed by the New ... [more ▼]

Context. The tenuous nitrogen (N[SUB]2[/SUB]) atmosphere on Pluto undergoes strong seasonal effects due to high obliquity and orbital eccentricity, and has recently (July 2015) been observed by the New Horizons spacecraft. <BR /> Aims: The main goals of this study are (i) to construct a well calibrated record of the seasonal evolution of surface pressure on Pluto and (ii) to constrain the structure of the lower atmosphere using a central flash observed in 2015. <BR /> Methods: Eleven stellar occultations by Pluto observed between 2002 and 2016 are used to retrieve atmospheric profiles (density, pressure, temperature) between altitude levels of 5 and 380 km (i.e. pressures from 10 μbar to 10 nbar). <BR /> Results: (i) Pressure has suffered a monotonic increase from 1988 to 2016, that is compared to a seasonal volatile transport model, from which tight constraints on a combination of albedo and emissivity of N[SUB]2[/SUB] ice are derived. (ii) A central flash observed on 2015 June 29 is consistent with New Horizons REX profiles, provided that (a) large diurnal temperature variations (not expected by current models) occur over Sputnik Planitia; and/or (b) hazes with tangential optical depth of 0.3 are present at 4-7 km altitude levels; and/or (c) the nominal REX density values are overestimated by an implausibly large factor of 20%; and/or (d) higher terrains block part of the flash in the Charon facing hemisphere. [less ▲]

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See detailWASP-190b: Tomographic Discovery of a Transiting Hot Jupiter
Temple, L. Y.; Hellier, C.; Almleaky, Y. et al

in Astronomical Journal (2019), 157

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[/SUB]} = 6400 ± 100 K, M [SUB]*[/SUB] = 1.35 ± 0.05 M [SUB]⊙[/SUB ... [more ▼]

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[/SUB]} = 6400 ± 100 K, M [SUB]*[/SUB] = 1.35 ± 0.05 M [SUB]⊙[/SUB], and R [SUB]*[/SUB] = 1.6 ± 0.1 R [SUB]⊙[/SUB]. The planet has a radius of R [SUB]P[/SUB] = 1.15 ± 0.09 R [SUB]Jup[/SUB] and a mass of M [SUB]P[/SUB] = 1.0 ± 0.1 M [SUB]Jup[/SUB], 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. [less ▲]

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See detailDust properties of double-tailed active asteroid (6478) Gault
Moreno, F.; Jehin, Emmanuel ULiege; Licandro, J. et al

in Astronomy and Astrophysics (2019), 624(L14), 11

Context. Asteroid (6478) Gault was discovered to exhibit a comet-like tail in observations from December 2018, becoming a new member of the so-called active asteroid population in the main asteroid belt ... [more ▼]

Context. Asteroid (6478) Gault was discovered to exhibit a comet-like tail in observations from December 2018, becoming a new member of the so-called active asteroid population in the main asteroid belt. <BR /> Aims: We seek to investigate the grain properties of the dust ejected from asteroid (6478) Gault and to give insight into the activity mechanism(s). <BR /> Methods: We use a Monte Carlo dust tail brightness code to retrieve the dates of dust ejection, the physical properties of the grains, and the total dust mass losses during each event. The code takes into account the brightness contribution of the asteroid itself. The model is applied to a large data set of images spanning the period from 2019 January 11 to 2019 March 13. In addition, we carried out both short- and long-term photometric measurements of the asteroid. <BR /> Results: It is shown that, to date, asteroid (6478) Gault has experienced two episodes of impulsive dust ejection, which took place around 2018 November 5 and 2019 January 2. These two episodes released at least 1.4 × 10[SUP]7[/SUP] kg and 1.6 × 10[SUP]6[/SUP] kg of dust, respectively, at escape speeds. The size distribution, consisting of particles in the 1 μm-1 cm radius range, follows a broken power law with bending points near 15 μm and 870 μm. On the other hand, the photometric series indicate a nearly constant magnitude over several 5-7.3 h periods, which is a possible effect of the masking of a rotational light curve by the dust. <BR /> Conclusions: The dust particles forming Gault's tails were released from the asteroid at escape speeds, but the specific ejection mechanism is unclear until photometry of the dust-free asteroid are conducted to assess whether this was related to rotational disruption or to other possible causes. [less ▲]

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See detailThe shape of (7) Iris as evidence of an ancient large impact?
Hanuš, J.; Marsset, M.; Vernazza, P. et al

in Astronomy and Astrophysics (2019), 624(A121), 17

Context. Asteroid (7) Iris is an ideal target for disk-resolved imaging owing to its brightness (V 7-8) and large angular size of 0.33'' during its apparitions. Iris is believed to belong to the category ... [more ▼]

Context. Asteroid (7) Iris is an ideal target for disk-resolved imaging owing to its brightness (V 7-8) and large angular size of 0.33'' during its apparitions. Iris is believed to belong to the category of large unfragmented asteroids that avoided internal differentiation, implying that its current shape and topography may record the first few 100 Myr of the solar system's collisional evolution. <BR /> Aims: We recovered information about the shape and surface topography of Iris from disk-resolved VLT/SPHERE/ZIMPOL images acquired in the frame of our ESO large program. <BR /> Methods: We used the All-Data Asteroid Modeling (ADAM) shape reconstruction algorithm to model the 3D shape of Iris, using optical disk-integrated data and disk-resolved images from SPHERE and earlier AO systems as inputs. We analyzed the SPHERE images and our model to infer the asteroid's global shape and the morphology of its main craters. <BR /> Results: We present the 3D shape, volume-equivalent diameter D[SUB]eq[/SUB] = 214 ± 5 km, and bulk density ρ = 2.7 ± 0.3 g cm[SUP]-3[/SUP] of Iris. Its shape appears to be consistent with that of an oblate spheroid with a large equatorial excavation. We identified eight putative surface features 20-40 km in diameter detected at several epochs, which we interpret as impact craters, and several additional crater candidates. Craters on Iris have depth-to-diameter ratios that are similar to those of analogous 10 km craters on Vesta. <BR /> Conclusions: The bulk density of Iris is consistent with that of its meteoritic analog based on spectroscopic observations, namely LL ordinary chondrites. Considering the absence of a collisional family related to Iris and the number of large craters on its surface, we suggest that its equatorial depression may be the remnant of an ancient (at least 3 Gyr) impact. Iris's shape further opens the possibility that large planetesimals formed as almost perfect oblate spheroids. Finally, we attribute the difference in crater morphology between Iris and Vesta to their different surface gravities, and the absence of a substantial impact-induced regolith on Iris. The reduced images are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A121">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/624/A121</A>Based on observations made with ESO Telescopes at the Paranal Observatory under programme ID 199.C-0074 (PI: P. Vernazza) and 086.C-0785 (PI: B. Carry). [less ▲]

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See detailHigh resolution optical spectroscopy of the N2-rich comet C/2016 R2 (PanSTARRS)
Opitom, C.; Hutsemekers, Damien ULiege; Jehin, Emmanuel ULiege et al

in Astronomy and Astrophysics (2019), 624

Context. Early observations of comet C/2016 R2 (PanSTARRS) have shown that the composition of this comet is very peculiar. Radio observations have revealed a CO-rich and HCN-poor comet and an optical coma ... [more ▼]

Context. Early observations of comet C/2016 R2 (PanSTARRS) have shown that the composition of this comet is very peculiar. Radio observations have revealed a CO-rich and HCN-poor comet and an optical coma dominated by strong emission bands of CO[SUP]+[/SUP] and, more surprisingly, N[SUB]2[/SUB][SUP]+[/SUP]. <BR /> Aims: The strong detection of N[SUB]2[/SUB][SUP]+[/SUP] in the coma of C/2016 R2 provided an ideal opportunity to measure the [SUP]14[/SUP]N/[SUP]15[/SUP]N isotopic ratio directly from N[SUB]2[/SUB][SUP]+[/SUP] for the first time, and to estimate the N[SUB]2[/SUB]/CO ratio, which is an important diagnostic to constrain formation models of planetesimals, in addition to the more general study of coma composition. <BR /> Methods: We obtained high resolution spectra of the comet in February 2018 when it was at 2.8 au from the Sun. We used the UVES spectrograph of the European Southern Observatory Very Large Telescope, complemented with narrowband images obtained with the TRAPPIST telescopes. <BR /> Results: We detect strong emissions from the N[SUB]2[/SUB][SUP]+[/SUP] and CO[SUP]+[/SUP] ions, but also CO[SUB]2[/SUB][SUP]+[/SUP], emission lines from the CH radical, and much fainter emissions of the CN, C[SUB]2[/SUB], and C[SUB]3[/SUB] radicals that were not detected in previous observations of this comet. We do not detect OH or H[SUB]2[/SUB]O[SUP]+[/SUP], and we derive an upper limit of the H[SUB]2[/SUB]O[SUP]+[/SUP]/CO[SUP]+[/SUP] ratio of 0.4, implying that the comet has a low water abundance. We measure a N[SUB]2[/SUB][SUP]+[/SUP]/CO[SUP]+[/SUP] ratio of 0.06 ± 0.01. The non-detection of NH[SUB]2[/SUB] indicates that most of the nitrogen content of the comet is in N[SUB]2[/SUB]. Together with the high N[SUB]2[/SUB][SUP]+[/SUP]/CO[SUP]+[/SUP] ratio, this could indicate a low formation temperature of the comet or that the comet is a fragment of a large differentiated Kuiper Belt object. The CO[SUB]2[/SUB][SUP]+[/SUP]/CO[SUP]+[/SUP] ratio is 1.1 ± 0.3. We do not detect [SUP]14[/SUP]N[SUP]15[/SUP]N[SUP]+[/SUP] lines and can only put a lower limit on the [SUP]14[/SUP]N/[SUP]15[/SUP]N ratio (measured from N[SUB]2[/SUB][SUP]+[/SUP]) of about 100, which is compatible with measurements of the same isotopic ratio for NH[SUB]2[/SUB] and CN in other comets. Finally, in addition to the [OI] and [CI] forbidden lines, we detect for the first time the forbidden nitrogen lines [NI] doublet at 519.79 and 520.03 nm in the coma of a comet. [less ▲]

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See detailClosing the gap between Earth-based and interplanetary mission observations: Vesta seen by VLT/SPHERE
Fétick, R. J. L.; Jorda, L.; Vernazza, P. et al

in Astronomy and Astrophysics (2019), 623

Context. Over the past decades, several interplanetary missions have studied small bodies in situ, leading to major advances in our understanding of their geological and geophysical properties. These ... [more ▼]

Context. Over the past decades, several interplanetary missions have studied small bodies in situ, leading to major advances in our understanding of their geological and geophysical properties. These missions, however, have had a limited number of targets. Among them, the NASA Dawn mission has characterised in detail the topography and albedo variegation across the surface of asteroid (4) Vesta down to a spatial resolution of 20 m pixel[SUP]-1[/SUP] scale. <BR /> Aims: Here our aim was to determine how much topographic and albedo information can be retrieved from the ground with VLT/SPHERE in the case of Vesta, having a former space mission (Dawn) providing us with the ground truth that can be used as a benchmark. <BR /> Methods: We observed Vesta with VLT/SPHERE/ZIMPOL as part of our ESO large programme (ID 199.C-0074) at six different epochs, and deconvolved the collected images with a parametric point spread function (PSF). We then compared our images with synthetic views of Vesta generated from the 3D shape model of the Dawn mission, on which we projected Vesta's albedo information. <BR /> Results: We show that the deconvolution of the VLT/SPHERE images with a parametric PSF allows the retrieval of the main topographic and albedo features present across the surface of Vesta down to a spatial resolution of 20-30 km. Contour extraction shows an accuracy of 1 pixel (3.6 mas). The present study provides the very first quantitative estimate of the accuracy of ground-based adaptive-optics imaging observations of asteroid surfaces. <BR /> Conclusions: In the case of Vesta, the upcoming generation of 30-40 m telescopes (ELT, TMT, GMT) should in principle be able to resolve all of the main features present across its surface, including the troughs and the north-south crater dichotomy, provided that they operate at the diffraction limit. Reduced images of Table A.1 are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/623/A6">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/623/A6</A>Based on observations made with ESO Telescopes at the Paranal Observatory under programme ID 199.C-0074 (PI: P. Vernazza). [less ▲]

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See detailDiscovery of three new transiting hot Jupiters: WASP-161 b, WASP-163 b and WASP-170 b
Barkaoui, K.; Burdanov, Artem ULiege; Hellier, C. et al

in Astronomical Journal (2019), 157(2),

We present the discovery by the WASP-South transit survey of three new transiting hot Jupiters, WASP-161 b, WASP-163 b and WASP-170 b. Follow-up radial velocities obtained with the Euler/CORALIE ... [more ▼]

We present the discovery by the WASP-South transit survey of three new transiting hot Jupiters, WASP-161 b, WASP-163 b and WASP-170 b. Follow-up radial velocities obtained with the Euler/CORALIE spectrograph and high-precision 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 and radius of $2.5\pm 0.2$$M_{Jup}$ and $1.14\pm 0.06$ $R_{Jup}$ respectively. WASP-163\,b has an orbital period of 1.609 days, a mass of $1.9\pm0.2$ $M_{Jup}$, and a radius of $1.2\pm0.1$ $R_{Jup}$. Its host star is a $V=12.5$ G8-type dwarf. WASP-170\,b is on a 2.344 days orbit around a G1V-type star of magnitude $V=12.8$. It has a mass of $1.7\pm0.2$ $M_{Jup}$ and a radius of $1.14\pm0.09$ $R_{Jup}$. Given their irradiations ($\sim10^9$ erg.s$^{-1}$.cm$^{-2}$) and masses, the three new planets sizes are in good agreement with classical structure models of irradiated giant planets. [less ▲]

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See detailL'observatoire SPECULOOS-Sud
Jehin, Emmanuel ULiege; Gillon, Michaël ULiege

in Ciel (Le) (2019), (Février), 75-90

Après quatre années de préparation et deux années de travail sur le site, l’observatoire SPECULOOS Sud a été installé avec succès dans l’enceinte de l’observatoire européen austral (ESO) de Paranal. C’est ... [more ▼]

Après quatre années de préparation et deux années de travail sur le site, l’observatoire SPECULOOS Sud a été installé avec succès dans l’enceinte de l’observatoire européen austral (ESO) de Paranal. C’est la veille de la Saint Nicolas, une date de circonstance, que l’observatoire a été inauguré en présence des autorités de l’université de Liège et de l’ensemble de l’équipe SPECULOOS1 rassemblant des chercheurs de nombreux pays et dirigée à Liège par le chercheur liégeois Michaël Gillon. Après cette « First Light » symbolique pour montrer que les télescopes sont opérationnels, ces nouveaux chasseurs d’exoplanètes débuteront officiellement leurs observations scientifiques en janvier 2019. [less ▲]

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See detailThe homogeneous internal structure of CM-like asteroid (41) Daphne
Carry, B.; Vachier, F.; Berthier, J. et al

in Astronomy and Astrophysics (2019), 623(A132),

Context. CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been ... [more ▼]

Context. CM-like asteroids (Ch and Cgh classes) are a major population within the broader C-complex, encompassing about 10% of the mass of the main asteroid belt. Their internal structure has been predicted to be homogeneous, based on their compositional similarity as inferred from spectroscopy (Vernazza et al., 2016, AJ 152, 154) and numerical modeling of their early thermal evolution (Bland & Travis, 2017, Sci. Adv. 3, e1602514). Aims. Here we aim to test this hypothesis by deriving the density of the CM-like asteroid (41) Daphne from detailed modeling of its shape and the orbit of its small satellite. Methods. We observed Daphne and its satellite within our imaging survey with the Very Large Telescope extreme adaptive-optics SPHERE/ZIMPOL camera (ID 199.C-0074, PI P. Vernazza) and complemented this data set with earlier Keck/NIRC2 and VLT/NACO observations. We analyzed the dynamics of the satellite with our Genoid meta-heuristic algorithm. Combining our high-angular resolution images with optical lightcurves and stellar occultations, we determine the spin period, orientation, and 3-D shape, using our ADAM shape modeling algorithm. Results. The satellite orbits Daphne on an equatorial, quasi-circular, prograde orbit, like the satellites of many other large main-belt asteroids. The shape model of Daphne reveals several large flat areas that could be large impact craters. The mass determined from this orbit combined with the volume computed from the shape model implies a density for Daphne of 1.77+/-0.26 g/cm3 (3 {\sigma}). This density is consistent with a primordial CM-like homogeneous internal structure with some level of macroporosity (~17%). Conclusions. Based on our analysis of the density of Daphne and 75 other Ch/Cgh-type asteroids gathered from the literature, we conclude that the primordial internal structure of the CM parent bodies was homogeneous. [less ▲]

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See detailNew transiting hot Jupiters discovered by WASP-South, Euler/CORALIE, and TRAPPIST-South
Hellier, Coel; Anderson, D. R.; Bouchy, F. et al

in Monthly Notices of the Royal Astronomical Society (2019), 482

We report the discovery of eight hot-Jupiter exoplanets from the WASP-South transit survey. WASP-144b has a mass of 0.44 M[SUB]Jup[/SUB], a radius of 0.85 R[SUB]Jup[/SUB], and is in a 2.27-d orbit around ... [more ▼]

We report the discovery of eight hot-Jupiter exoplanets from the WASP-South transit survey. WASP-144b has a mass of 0.44 M[SUB]Jup[/SUB], a radius of 0.85 R[SUB]Jup[/SUB], and is in a 2.27-d orbit around a V = 12.9, K2 star which shows a 21-d rotational modulation. WASP-145Ab is a 0.89 M[SUB]Jup[/SUB] planet in a 1.77-d orbit with a grazing transit. The host is a V = 11.5, K2 star with a companion 5 arcsec away and 1.4 mag fainter. WASP-158b is a relatively massive planet at 2.8 M[SUB]Jup[/SUB] with a radius of 1.1 R[SUB]Jup[/SUB] and a 3.66-d orbit. It transits a V = 12.1, F6 star. WASP-159b is a bloated hot Jupiter (1.4 R[SUB]Jup[/SUB] and 0.55 M[SUB]Jup[/SUB]) in a 3.8-d orbit around a V = 12.9, F9 star. WASP-162b is a massive planet in a relatively long and highly eccentric orbit (5.2 M[SUB]Jup[/SUB], P = 9.6 d, e = 0.43). It transits a V = 12.2, K0 star. WASP-168b is a bloated hot Jupiter (0.42 M[SUB]Jup[/SUB]; 1.5 R[SUB]Jup[/SUB]) in a 4.15-d orbit with a grazing transit. The host is a V = 12.1, F9 star. WASP-172b is a bloated hot Jupiter (0.5 M[SUB]Jup[/SUB]; 1.6 R[SUB]Jup[/SUB]) in a 5.48-d orbit around a V = 11.0, F1 star. WASP-173Ab is a massive planet (3.7 M[SUB]Jup[/SUB]) with a 1.2 R[SUB]Jup[/SUB] radius in a circular orbit with a period of 1.39 d. The host is a V = 11.3, G3 star, being the brighter component of the double-star system WDS23366 - 3437, with a companion 6 arcsec away and 0.8 mag fainter. One of the two stars shows a rotational modulation of 7.9 d. [less ▲]

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See detailAnalytic methods for the Abel transform of exponential functions describing planetary and cometary atmospheres.
Hubert, Benoît ULiege; Munhoven, Guy ULiege; Opitom, Cyrielle et al

Poster (2018, December 11)

Remote sensing of planetary and cometary atmosphere is one of the most important source of data and knowledge of the gas layers surrounding the celestial objects of our solar system, including our own ... [more ▼]

Remote sensing of planetary and cometary atmosphere is one of the most important source of data and knowledge of the gas layers surrounding the celestial objects of our solar system, including our own planet. Most of the instruments used up to now and that will be used in a near future study the emission of radiations directly produced by the atmosphere. Under optically thin conditions, this observation method provides the local volume emission rate (VER) originating from the atmosphere, integrated along the full line of sight (l.o.s.) of the instrument. Under a spherical or cylindrical symmetry assumption, the l.o.s. integration of the VER takes the form of the Abel transform of the vertical VER profile. The simplest analytical functions representing VER profiles in real planetary and cometary atmosphere include an exponential function of the altitude (or radial distance), giving the isothermal profile for a planet and the Haser model for a coma. The Abel transform of these functions can be computed analytically using combinations of special functions. Retrieving the vertical (radial) profile of the VER does however require to invert the observed Abel transform to account for possible departures from these idealized analytical expressions, so that indefinite integrals defined from the Abel integral (which we will call indefinite Abel transforms) are needed (or numerical integrations need to be performed). In this study, we present a new method to produce a workable series development allowing accurate computation of the indefinite Abel transforms that appear in the study of optically thin emissions of planetary and cometary atmospheres. Indeed, taking the Taylor series development of the exponential function to reduce the problem to a series of indefinite Abel transforms of polynomial functions (which can be carried analytically) does not work. It leads to the computation of the difference of large, nearly equal numbers, which cannot be done accurately. Our method rather relies on an appropriate series development of the Jacobian of the Abel transform. We show that the computation can be done reliably up to near machine precision, and that accuracy control can be enforced for tailored applications. Possible applications are considered, that include the study of comas and of the upper atmosphere of Mars and the Earth [less ▲]

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See detailThe SPECULOOS Southern Observatory Begins its Hunt for Rocky Planets
Jehin, Emmanuel ULiege; Gillon, Michaël ULiege; Queloz, D. et al

in Messenger (2018), 174

The SPECULOOS Southern Observatory (SSO), a new facility of four 1- metre robotic telescopes, began scientific operations at Cerro Paranal on 1 January 2019. The main goal of the SPECULOOS project is to ... [more ▼]

The SPECULOOS Southern Observatory (SSO), a new facility of four 1- metre robotic telescopes, began scientific operations at Cerro Paranal on 1 January 2019. The main goal of the SPECULOOS project is to explore approximately 1000 of the smallest (≤ 0.15 R[SUB]⊙[/SUB]), brightest (K[SUB]mag[/SUB] ≤ 12.5), and nearest (d ≤ 40 pc) very low mass stars and brown dwarfs. It aims to discover transiting temperate terrestrial planets well-suited for detailed atmospheric characterisation with future giant telescopes like ESO’s Extremely Large Telescope (ELT) and the NASA James Webb Telescope (JWST). The SSO is the core facility of SPECULOOS. The exquisite astronomical conditions at Cerro Paranal will enable SPECULOOS to detect exoplanets as small as Mars. Here, we briefly describe SPECULOOS, and present the features and performance of the SSO facility. [less ▲]

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See detailThe discovery of WASP-134b, WASP-134c, WASP-137b, WASP-143b and WASP-146b: three hot Jupiters and a pair of warm Jupiters orbiting Solar-type stars
Anderson, D. R.; Bouchy, F.; Brown, D. J. A. et al

E-print/Working paper (2018)

We report the discovery by WASP of five planets orbiting moderately bright ($V$ = 11.0-12.9) Solar-type stars. WASP-137b, WASP-143b and WASP-146b are typical hot Jupiters in orbits of 3-4 d and with ... [more ▼]

We report the discovery by WASP of five planets orbiting moderately bright ($V$ = 11.0-12.9) Solar-type stars. WASP-137b, WASP-143b and WASP-146b are typical hot Jupiters in orbits of 3-4 d and with masses in the range 0.68--1.11 $M_{\rm Jup}$. WASP-134 is a metal-rich ([Fe/H] = +0.40 $\pm$ 0.07]) G4 star orbited by two warm Jupiters: WASP-134b ($M_{\rm pl}$ = 1.41 $M_{\rm Jup}$; $P = 10.1$ d; $e = 0.15 \pm 0.01$; $T_{\rm eql}$ = 950 K) and WASP-134c ($M_{\rm pl} \sin i$ = 0.70 $M_{\rm Jup}$; $P = 70.0$ d; $e = 0.17 \pm 0.09$; $T_{\rm eql}$ = 500 K). From observations of the Rossiter-McLaughlin effect of WASP-134b, we find its orbit to be misaligned with the spin of its star ($\lambda = -44 \pm 10^\circ$). WASP-134 is a rare example of a system with a short-period giant planet and a nearby giant companion. In-situ formation or disc migration seem more likely explanations for such systems than does high-eccentricity migration. [less ▲]

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See detailActivity induced variation in spin-orbit angles as derived from Rossiter-McLaughlin measurements
Oshagh, M.; Triaud, A. H. M. J.; Burdanov, Artem ULiege et al

in Astronomy and Astrophysics (2018), 619(150),

One of the most powerful methods used to estimate sky-projected spin-orbit angles of exoplanetary systems is through a spectroscopic transit observation known as the Rossiter-McLaughlin (RM) effect. So ... [more ▼]

One of the most powerful methods used to estimate sky-projected spin-orbit angles of exoplanetary systems is through a spectroscopic transit observation known as the Rossiter-McLaughlin (RM) effect. So far mostly single RM observations have been used to estimate the spin-orbit angle, and thus there have been no studies regarding the variation of estimated spin-orbit angle from transit to transit. Stellar activity can alter the shape of photometric transit light curves and in a similar way they can deform the RM signal. In this paper we discuss several RM observations, obtained using the HARPS spectrograph, of known transiting planets that all transit extremely active stars, and by analyzing them individually we assess the variation in the estimated spin-orbit angle. Our results reveal that the estimated spin-orbit angle can vary significantly (up to 42 degrees) from transit to transit, due to variation in the configuration of stellar active regions over different nights. This finding is almost two times larger than the expected variation predicted from simulations. We could not identify any meaningful correlation between the variation of estimated spin-orbit angles and the stellar magnetic activity indicators. We also investigated two possible approaches to mitigate the stellar activity influence on RM observations. The first strategy was based on obtaining several RM observations and folding them to reduce the stellar activity noise. Our results demonstrated that this is a feasible and robust way to overcome this issue. The second approach is based on acquiring simultaneous high-precision short-cadence photometric transit light curves using TRAPPIST/SPECULOOS telescopes, which provide more information about the stellar active region's properties and allow a better RM modeling. [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

E-print/Working paper (2018)

We report the discovery of WASP-166b, a super-Neptune planet with a mass of 0.1 Mjup and a bloated radius of 0.63 Rjup. It transits a V = 9.36, F9V star in a 5.44-d orbit that is aligned with the stellar ... [more ▼]

We report the discovery of WASP-166b, a super-Neptune planet with a mass of 0.1 Mjup and a bloated radius of 0.63 Rjup. It transits a V = 9.36, F9V star in a 5.44-d orbit that is aligned with the stellar rotation (lambda = -3 +/- 5 degrees). WASP-166b appears to be a rare object within the `Neptune desert'. The planet's low surface gravity and bright host star make it a promising target for atmospheric characterisation. There are variations in the radial-velocity measurements that might result from stellar magnetic activity. [less ▲]

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See detail(16) Psyche: A mesosiderite-like asteroid?
Viikinkoski, M.; Vernazza, P.; Hanuš, J. et al

in Astronomy and Astrophysics (2018), 619

Context. Asteroid (16) Psyche is the target of the NASA Psyche mission. It is considered one of the few main-belt bodies that could be an exposed proto-planetary metallic core and that would thus be ... [more ▼]

Context. Asteroid (16) Psyche is the target of the NASA Psyche mission. It is considered one of the few main-belt bodies that could be an exposed proto-planetary metallic core and that would thus be related to iron meteorites. Such an association is however challenged by both its near- and mid-infrared spectral properties and the reported estimates of its density. <BR /> Aims: Here, we aim to refine the density of (16) Psyche to set further constraints on its bulk composition and determine its potential meteoritic analog. <BR /> Methods: We observed (16) Psyche with ESO VLT/SPHERE/ZIMPOL as part of our large program (ID 199.C-0074). We used the high angular resolution of these observations to refine Psyche's three-dimensional (3D) shape model and subsequently its density when combined with the most recent mass estimates. In addition, we searched for potential companions around the asteroid. <BR /> Results: We derived a bulk density of 3.99 ± 0.26 g cm[SUP]-3[/SUP] for Psyche. While such density is incompatible at the 3-sigma level with any iron meteorites (˜7.8 g cm[SUP]-3[/SUP]), it appears fully consistent with that of stony-iron meteorites such as mesosiderites (density ˜4.25 g cm[SUP]-3[/SUP]). In addition, we found no satellite in our images and set an upper limit on the diameter of any non-detected satellite of 1460 ± 200 m at 150 km from Psyche (0.2% × R[SUB]Hill[/SUB], the Hill radius) and 800 ± 200 m at 2000 km (3% × R[SUB]Hill[/SUB]). <BR /> Conclusions: Considering that the visible and near-infrared spectral properties of mesosiderites are similar to those of Psyche, there is merit to a long-published initial hypothesis that Psyche could be a plausible candidate parent body for mesosiderites. Based on observations made with 1) ESO Telescopes at the La Silla Paranal Observatory under programs 086.C-0785 (PI Carry) and 199.C-0074 (PI Vernazza); and 2) the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.Tables A1 and A2 and reduced images are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr/">http://cdsarc.u-strasbg.fr</A> (ftp://130.79.128.5) or via <A href="http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/619/L3">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/L3</A> [less ▲]

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