References of "Gillon, Michaël"
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See detailThe HARPS search for southern extra-solar planets: XLIII. A compact system of four super-Earth planets orbiting HD 215152
Delisle, J.-B.; Ségransan, D.; Dumusque, X. et al

in Astronomy and Astrophysics (2018), 614

We report the discovery of four super-Earth planets around HD 215152, with orbital periods of 5.76, 7.28, 10.86, and 25.2 d, and minimum masses of 1.8, 1.7, 2.8, and 2.9 M· respectively. This discovery is ... [more ▼]

We report the discovery of four super-Earth planets around HD 215152, with orbital periods of 5.76, 7.28, 10.86, and 25.2 d, and minimum masses of 1.8, 1.7, 2.8, and 2.9 M· respectively. This discovery is based on 373 high-quality radial velocity measurements taken by HARPS over 13 yr. Given the low masses of the planets, the signal-to-noise ratio is not sufficient to constrain the planet eccentricities. However, a preliminary dynamical analysis suggests that eccentricities should be typically lower than about 0.03 for the system to remain stable. With two pairs of planets with a period ratio lower than 1.5, with short orbital periods, low masses, and low eccentricities, HD 215152 is similar to the very compact multi-planet systems found by Kepler, which is very rare in radial-velocity surveys. This discovery proves that these systems can be reached with the radial-velocity technique, but characterizing them requires a huge amount of observations. © 2018 ESO. [less ▲]

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See detailThe nature of the TRAPPIST-1 exoplanets
Grimm, S. L.; Demory, B.-O.; Gillon, Michaël ULiege et al

in Astronomy and Astrophysics (2018), 613

Context. The TRAPPIST-1 system hosts seven Earth-sized, temperate exoplanets orbiting an ultra-cool dwarf star. As such, it represents a remarkable setting to study the formation and evolution of ... [more ▼]

Context. The TRAPPIST-1 system hosts seven Earth-sized, temperate exoplanets orbiting an ultra-cool dwarf star. As such, it represents a remarkable setting to study the formation and evolution of terrestrial planets that formed in the same protoplanetary disk. While the sizes of the TRAPPIST-1 planets are all known to better than 5% precision, their densities have significant uncertainties (between 28% and 95%) because of poor constraints on the planet's masses. Aims. The goal of this paper is to improve our knowledge of the TRAPPIST-1 planetary masses and densities using transit-timing variations (TTVs). The complexity of the TTV inversion problem is known to be particularly acute in multi-planetary systems (convergence issues, degeneracies and size of the parameter space), especially for resonant chain systems such as TRAPPIST-1. Methods. To overcome these challenges, we have used a novel method that employs a genetic algorithm coupled to a full N-body integrator that we applied to a set of 284 individual transit timings. This approach enables us to efficiently explore the parameter space and to derive reliable masses and densities from TTVs for all seven planets. Results. Our new masses result in a five- to eight-fold improvement on the planetary density uncertainties, with precisions ranging from 5% to 12%. These updated values provide new insights into the bulk structure of the TRAPPIST-1 planets. We find that TRAPPIST-1 c and e likely have largely rocky interiors, while planets b, d, f, g, and h require envelopes of volatiles in the form of thick atmospheres, oceans, or ice, in most cases with water mass fractions less than 5%. © ESO 2018. [less ▲]

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See detailAtmospheric reconnaissance of the habitable-zone Earth-sized planets orbiting TRAPPIST-1
De Wit, J.; Wakeford, H. R.; Lewis, N. K. et al

in Nature Astronomy (2018), 2(3), 214-219

Seven temperate Earth-sized exoplanets readily amenable for atmospheric studies transit the nearby ultracool dwarf star TRAPPIST-1 (refs 1,2 ). Their atmospheric regime is unknown and could range from ... [more ▼]

Seven temperate Earth-sized exoplanets readily amenable for atmospheric studies transit the nearby ultracool dwarf star TRAPPIST-1 (refs 1,2 ). Their atmospheric regime is unknown and could range from extended primordial hydrogen-dominated to depleted atmospheres 3-6 . Hydrogen in particular is a powerful greenhouse gas that may prevent the habitability of inner planets while enabling the habitability of outer ones 6-8 . An atmosphere largely dominated by hydrogen, if cloud-free, should yield prominent spectroscopic signatures in the near-infrared detectable during transits. Observations of the innermost planets have ruled out such signatures 9 . However, the outermost planets are more likely to have sustained such a Neptune-like atmosphere 10, 11 . Here, we report observations for the four planets within or near the system's habitable zone, the circumstellar region where liquid water could exist on a planetary surface 12-14 . These planets do not exhibit prominent spectroscopic signatures at near-infrared wavelengths either, which rules out cloud-free hydrogen-dominated atmospheres for TRAPPIST-1 d, e and f, with significance of 8σ, 6σ and 4σ, respectively. Such an atmosphere is instead not excluded for planet g. As high-altitude clouds and hazes are not expected in hydrogen-dominated atmospheres around planets with such insolation 15, 16, these observations further support their terrestrial and potentially habitable nature. © 2018 The Author(s). [less ▲]

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See detailSPECULOOS: A network of robotic telescopes to hunt for terrestrial planets around the nearest ultracool dwarfs
Delrez, L.; Gillon, Michaël ULiege; Queloz, D. et al

in Proceedings of SPIE: The International Society for Optical Engineering (2018), 10700

We present here SPECULOOS, a new exoplanet transit search based on a network of 1m-class robotic telescopes targeting the ∼1200 ultracool (spectral type M7 and later) dwarfs bright enough in the infrared ... [more ▼]

We present here SPECULOOS, a new exoplanet transit search based on a network of 1m-class robotic telescopes targeting the ∼1200 ultracool (spectral type M7 and later) dwarfs bright enough in the infrared (K-mag ≤ 12.5) to possibly enable the atmospheric characterization of temperate terrestrial planets with next-generation facilities like the James Webb Space Telescope. The ultimate goals of the project are to reveal the frequency of temperate terrestrial planets around the lowest-mass stars and brown dwarfs, to probe the diversity of their bulk compositions, atmospheres and surface conditions, and to assess their potential habitability. © 2018 SPIE. [less ▲]

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See detailSearching for red worlds
Gillon, Michaël ULiege

in Nature Astronomy (2018), 2(4), 344

The SPECULOOS project aims to detect terrestrial exoplanets well suited for detailed atmospheric characterization, explains Principal Investigator Michaël Gillon. © 2018 The Author(s).

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See detailHigh-precision multiwavelength eclipse photometry of the ultra-hot gas giant exoplanetWASP-103 b
Delrez, L.; Madhusudhan, N.; Lendl, M. et al

in Monthly Notices of the Royal Astronomical Society (2018), 474(2), 2334-2351

We present 16 occultation and three transit light curves for the ultra-short period hot Jupiter WASP-103b, in addition to five new radial velocity measurements. We combine these observations with archival ... [more ▼]

We present 16 occultation and three transit light curves for the ultra-short period hot Jupiter WASP-103b, in addition to five new radial velocity measurements. We combine these observations with archival data and perform a global analysis of the resulting extensive data set, accounting for the contamination from a nearby star. We detect the thermal emission of the planet in both the z' and KS bands, the measured occultation depths being 699±110 ppm (6.4σ) and 3567-350 +400 ppm (10.2σ), respectively. We use these two measurements, together with recently published HST/WFC3 data, to derive joint constraints on the properties of WASP- 103b's dayside atmosphere. On one hand, we find that the z' band and WFC3 data are best fit by an isothermal atmosphere at 2900K or an atmosphere with a low H2O abundance. On the other hand, we find an unexpected excess in the KS band measured flux compared to these models, which requires confirmation with additional observations before any interpretation can be given. From our global data analysis, we also derive a broad-band optical transmission spectrum that shows a minimum around 700 nm and increasing values towards both shorter and longer wavelengths. This is in agreement with a previous study based on a large fraction of the archival transit light curves used in our analysis. The unusual profile of this transmission spectrum is poorly matched by theoretical spectra and is not confirmed by more recent observations at higher spectral resolution. Additional data, in both emission and transmission, are required to better constrain the atmospheric properties of WASP-103b. © 2017 The Author(s). [less ▲]

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See detailThe impact crater at the origin of the Julia family detected with VLT/SPHERE?
Vernazza, Pierre; Brož, M.; Drouard, A. et al

in Astronomy and Astrophysics (2018)

Context. The vast majority of the geophysical and geological constraints (e.g., internal structure, cratering history) for main belt asteroids have so far been obtained via dedicated interplanetary ... [more ▼]

Context. The vast majority of the geophysical and geological constraints (e.g., internal structure, cratering history) for main belt asteroids have so far been obtained via dedicated interplanetary missions (e.g., ESA Rosetta, NASA Dawn). The high angular resolution of SPHERE/ZIMPOL, the new-generation visible adaptive-optics camera at ESO VLT, implies that these science objectives can now be investigated from the ground for a large fraction of D 100 km main-belt asteroids. The sharp images acquired by this instrument can be used to constrain accurately the shape and thus volume of these bodies (hence density when combined with mass estimates) and to characterize the distribution and topography of D 30 km craters across their surfaces. Aims. Here, we evaluated - via several complementary approaches - the recently proposed hypothesis that S-type asteroid (89) Julia is the parent body of a small compact asteroid family that formed via a cratering collisional event. Methods. We observed (89) Julia with VLT/SPHERE/ZIMPOL throughout its rotation (these observations were taken as part of an ESO Large Program; ID: 199.C-0074), derived its 3D shape and performed a reconnaissance and characterization of the largest craters. We also performed numerical simulations to first confirm the existence of the Julia family and to determine its age as well as the size of the impact crater at its origin. Finally, we utilized the images/3D shape to attempt identifying the origin location of the small collisional family. Results. On the one hand, our VLT/SPHERE observations reveal the presence of a large crater (D~75 km) in Julia’s southern hemisphere. On the other hand, our numerical simulations suggest that (89) Julia was impacted 30 to 120 Myrs ago by a D~8km asteroid, thereby creating a D~60 km impact crater at the surface of Julia. Given the small size of the impactor, the obliquity of Julia and the particular orientation of the family in the (a,i) space, the imaged impact crater is likely the one at the origin of the family. Conclusions. New doors of ground-based asteroid exploration, namely geophysics and geology, are getting opened thanks to VLT/SPHERE’s unique capabilities. Also, the present work may represent the beginning of a new era of asteroid-family studies. In those fields (geophysics, geology and asteroid family studies), the future will only get brighter with the forthcoming arrival of 30-40m class telescopes (ELT, TMT, GMT). [less ▲]

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See detailHigh-precision multi-wavelength eclipse photometry of the ultra-hot gas giant exoplanet WASP-103 b
Delrez, L.; Madhusudhan, N.; Lendl, M. et al

in Monthly Notices of the Royal Astronomical Society (2017), 474(2), 2334-2351

We present sixteen occultation and three transit light curves for the ultra-short period hot Jupiter WASP-103 b, in addition to five new radial velocity measurements. We combine these observations with ... [more ▼]

We present sixteen occultation and three transit light curves for the ultra-short period hot Jupiter WASP-103 b, in addition to five new radial velocity measurements. We combine these observations with archival data and perform a global analysis of the resulting extensive dataset, accounting for the contamination from a nearby star. We detect the thermal emission of the planet in both the $z'$ and $K_{\mathrm{S}}$-bands, the measured occultation depths being 699$\pm$110 ppm (6.4-$\sigma$) and $3567_{-350}^{+400}$ ppm (10.2-$\sigma$), respectively. We use these two measurements together with recently published HST/WFC3 data to derive joint constraints on the properties of WASP-103 b's dayside atmosphere. On one hand, we find that the $z'$-band and WFC3 data are best fit by an isothermal atmosphere at 2900 K or an atmosphere with a low H$_2$O abundance. On the other hand, we find an unexpected excess in the $K_{\mathrm{S}}$-band measured flux compared to these models, which requires confirmation with additional observations before any interpretation can be given. From our global data analysis, we also derive a broad-band optical transmission spectrum that shows a minimum around 700 nm and increasing values towards both shorter and longer wavelengths. This is in agreement with a previous study based on a large fraction of the archival transit light curves used in our analysis. The unusual profile of this transmission spectrum is poorly matched by theoretical spectra and is not confirmed by more recent observations at higher spectral resolution. Additional data, both in emission and transmission, are required to better constrain the atmospheric properties of WASP-103 b. [less ▲]

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See detailSPECULOOS exoplanet search and its prototype on TRAPPIST
Burdanov, Artem ULiege; Delrez, Laetitia; Gillon, Michaël ULiege et al

in Deeg, Hans; Belmonte, Juan Antonio (Eds.) Handbook of Exoplanets (2017)

One of the most significant goals of modern science is establishing whether life exists around other suns. The most direct path towards its achievement is the detection and atmospheric characterization of ... [more ▼]

One of the most significant goals of modern science is establishing whether life exists around other suns. The most direct path towards its achievement is the detection and atmospheric characterization of terrestrial exoplanets with potentially habitable surface conditions. The nearest ultracool dwarfs (UCDs), i.e. very-low-mass stars and brown dwarfs with effective temperatures lower than 2700 K, represent a unique opportunity to reach this goal within the next decade. The potential of the transit method for detecting potentially habitable Earth-sized planets around these objects is drastically increased compared to Earth-Sun analogs. Furthermore, only a terrestrial planet transiting a nearby UCD would be amenable for a thorough atmospheric characterization, including the search for possible biosignatures, with near-future facilities such as the James Webb Space Telescope. In this chapter, we first describe the physical properties of UCDs as well as the unique potential they offer for the detection of potentially habitable Earth-sized planets suitable for atmospheric characterization. Then, we present the SPECULOOS ground-based transit survey, that will search for Earth-sized planets transiting the nearest UCDs, as well as its prototype survey on the TRAPPIST telescopes. We conclude by discussing the prospects offered by the recent detection by this prototype survey of a system of seven temperate Earth-sized planets transiting a nearby UCD, TRAPPIST-1. [less ▲]

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See detailThe Science Case for an Extended Spitzer Mission
Yee, Jennifer C.; Fazio, Giovanni G.; Benjamin, Robert et al

E-print/Working paper (2017)

Although the final observations of the Spitzer Warm Mission are currently scheduled for March 2019, it can continue operations through the end of the decade with no loss of photometric precision. As we ... [more ▼]

Although the final observations of the Spitzer Warm Mission are currently scheduled for March 2019, it can continue operations through the end of the decade with no loss of photometric precision. As we will show, there is a strong science case for extending the current Warm Mission to December 2020. Spitzer has already made major impacts in the fields of exoplanets (including microlensing events), characterizing near Earth objects, enhancing our knowledge of nearby stars and brown dwarfs, understanding the properties and structure of our Milky Way galaxy, and deep wide-field extragalactic surveys to study galaxy birth and evolution. By extending Spitzer through 2020, it can continue to make ground-breaking discoveries in those fields, and provide crucial support to the NASA flagship missions JWST and WFIRST, as well as the upcoming TESS mission, and it will complement ground-based observations by LSST and the new large telescopes of the next decade. This scientific program addresses NASA's Science Mission Directive's objectives in astrophysics, which include discovering how the universe works, exploring how it began and evolved, and searching for life on planets around other stars. [less ▲]

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See detailThe Structure of Chariklo’s Rings from Stellar Occultations
Bérard, D.; Sicardy, B.; Camargo, J. I. B. et al

in Astronomical Journal (2017), 154

Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned ... [more ▼]

Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo’s system in order to better characterize the physical properties of the ring and main body. Here, we use 12 successful occulations by Chariklo observed between 2014 and 2016. They provide ring profiles (physical width, opacity, edge structure) and constraints on the radii and pole position. Our new observations are currently consistent with the circular ring solution and pole position, to within the ±3.3 km formal uncertainty for the ring radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal significant width variations from ∼5 to 7.5 km. The width of the fainter ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and outer edges of C1R are consistent with infinitely sharp boundaries, with typical upper limits of one kilometer for the transition zone between the ring and empty space. No constraint on the sharpness of C2R’s edges is available. A 1σ upper limit of ∼20 m is derived for the equivalent width of narrow (physical width < 4 km) rings up to distances of 12,000 km, counted in the ring plane. [less ▲]

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See detailExoplanetary Transits
Gillon, Michaël ULiege

Scientific conference (2017, September 15)

Exoplanetary Transits

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See detailTemporal Evolution of the High-energy Irradiation and Water Content of TRAPPIST-1 Exoplanets
Bourrier, V.; de Wit, J.; Bolmont, E. et al

in Astronomical Journal (2017), 154

The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could harbor liquid water on their surfaces. Ultraviolet observations are essential to measuring their high ... [more ▼]

The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could harbor liquid water on their surfaces. Ultraviolet observations are essential to measuring their high-energy irradiation and searching for photodissociated water escaping from their putative atmospheres. Our new observations of the TRAPPIST-1 Lyα line during the transit of TRAPPIST-1c show an evolution of the star emission over three months, preventing us from assessing the presence of an extended hydrogen exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape. However, TRAPPIST-1e to h might have lost less than three Earth oceans if hydrodynamic escape stopped once they entered the habitable zone (HZ). We caution that these estimates remain limited by the large uncertainty on the planet masses. They likely represent upper limits on the actual water loss because our assumptions maximize the X-rays to ultraviolet-driven escape, while photodissociation in the upper atmospheres should be the limiting process. Late-stage outgassing could also have contributed significant amounts of water for the outer, more massive planets after they entered the HZ. While our results suggest that the outer planets are the best candidates to search for water with the JWST, they also highlight the need for theoretical studies and complementary observations in all wavelength domains to determine the nature of the TRAPPIST-1 planets and their potential habitability. [less ▲]

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See detailThe discoveries of WASP-91b, WASP-105b and WASP-107b: Two warm Jupiters and a planet in the transition region between ice giants and gas giants
Anderson, D. R.; Collier Cameron, A.; Delrez, L. et al

in Astronomy and Astrophysics (2017), 604

We report the discoveries of three transiting exoplanets. WASP-91b is a warm Jupiter (1.34 M[SUB]Jup[/SUB], 1.03 R[SUB]Jup[/SUB]) in a 2.8-day orbit around a metal-rich K3 star. WASP-105b is a warm ... [more ▼]

We report the discoveries of three transiting exoplanets. WASP-91b is a warm Jupiter (1.34 M[SUB]Jup[/SUB], 1.03 R[SUB]Jup[/SUB]) in a 2.8-day orbit around a metal-rich K3 star. WASP-105b is a warm Jupiter (1.8 M[SUB]Jup[/SUB], 0.96 R[SUB]Jup[/SUB]) in a 7.9-day orbit around a metal-rich K2 star. WASP-107b is a warm super-Neptune/sub-Saturn (0.12 M[SUB]Jup[/SUB], 0.94 R[SUB]Jup[/SUB]) in a 5.7-day orbit around a solar-metallicity K6 star. Considering that giant planets seem to be more common around stars of higher metallicity and stars of higher mass, it is notable that the hosts are all metal-rich, late-type stars. With orbital separations that place both WASP-105b and WASP-107b in the weak-tide regime, measurements of the alignment between the planets' orbital axes and their stars' spin axes may help us to understand the inward migration of short-period, giant planets. The mass of WASP-107b (2.2 M[SUB]Nep[/SUB], 0.40 M[SUB]Sat[/SUB]) places it in the transition region between the ice giants and gas giants of the Solar System. Its radius of 0.94 R[SUB]Jup[/SUB] suggests that it is a low-mass gas giant with a H/He-dominated composition. The planet thus sets a lower limit of 2.2 M[SUB]Nep[/SUB] on the planetary mass above which large gaseous envelopes can be accreted and retained by proto-planets on their way to becoming gas giants. We may discover whether WASP-107b more closely resembles an ice giant or a gas giant by measuring its atmospheric metallicity via transmission spectroscopy, for which WASP-107b is a very good target. Based on observations made with: the WASP-South photometric survey instrument, the 0.6-m TRAPPIST robotic imager, and the EulerCam camera and the CORALIE spectrograph mounted on the 1.2-m Euler-Swiss telescope.The photometric time-series and radial-velocity data used in this work are only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A110">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/A110</A> [less ▲]

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See detailThe EBLM project. III. A Saturn-size low-mass star at the hydrogen-burning limit
von Boetticher, Alexander; Triaud, Amaury H. M. J.; Queloz, Didier et al

in Astronomy and Astrophysics (2017), 604

We report the discovery of an eclipsing binary system with mass-ratio q ˜ 0.07. After identifying a periodic photometric signal received by WASP, we obtained CORALIE spectroscopic radial velocities and ... [more ▼]

We report the discovery of an eclipsing binary system with mass-ratio q ˜ 0.07. After identifying a periodic photometric signal received by WASP, we obtained CORALIE spectroscopic radial velocities and follow-up light curves with the Euler and TRAPPIST telescopes. From a joint fit of these data we determine that EBLM J0555-57 consists of a sun-like primary star that is eclipsed by a low-mass companion, on a weakly eccentric 7.8-day orbit. Using a mass estimate for the primary star derived from stellar models, we determine a companion mass of 85 ± 4 M[SUB]Jup[/SUB] (0.081 M[SUB]⊙[/SUB]) and a radius of 0.84[SUP]+ 0.14[/SUP][SUB]-0.04[/SUB]R[SUB]Jup[/SUB] (0.084 R[SUB]⊙[/SUB]) that is comparable to that of Saturn. EBLM J0555-57Ab has a surface gravity log g[SUB]2[/SUB] =5.50[SUP]+ 0.03[/SUP][SUB]-0.13[/SUB] and is one of the densest non-stellar-remnant objects currently known. These measurements are consistent with models of low-mass stars. The photometry tables and radial velocities are only available at the CDS and on demand via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/L6">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/604/L6</A> [less ▲]

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See detailGround-based monitoring of comet 67P/Churyumov–Gerasimenko gas activity throughout the Rosetta mission
Opitom, C.; Snodgrass, C.; Fitzsimmons, A. et al

in Monthly Notices of the Royal Astronomical Society (2017), 469

Simultaneously to the ESA Rosetta mission, a world-wide ground-based campaign provided measurements of the large scale activity of comet 67P/Churyumov-Gerasimenko through measurement of optically active ... [more ▼]

Simultaneously to the ESA Rosetta mission, a world-wide ground-based campaign provided measurements of the large scale activity of comet 67P/Churyumov-Gerasimenko through measurement of optically active gas species and imaging of the overall dust coma. We present more than 2 yr of observations performed with the FORS2 low-resolution spectrograph at the VLT, TRAPPIST and ACAM at the WHT. We focus on the evolution of the CN production as a tracer of the comet activity. We find that it is asymmetric with respect to perihelion and different from that of the dust. The CN emission is detected for the first time at 1.34 au pre-perihelion and production rates then increase steeply to peak about 2 weeks after perihelion at (1.00 ± 0.10) × 10[SUP]25[/SUP] molecules s[SUP]-1[/SUP], while the post-perihelion decrease is more shallow. The evolution of the comet activity is strongly influenced by seasonal effects with enhanced CN production when the Southern hemisphere is illuminated. [less ▲]

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See detailProbing the atmosphere of a sub-Jovian planet orbiting a cool dwarf
Sedaghati, Elyar; Boffin, Henri M. J.; Delrez, Laetitia et al

in Monthly Notices of the Royal Astronomical Society (2017), 468

We derive the 0.01 $\mu$m binned transmission spectrum, between 0.74 and 1.0 $\mu$m, of WASP-80b from low resolution spectra obtained with the FORS2 instrument attached to ESO's Very Large Telescope. The ... [more ▼]

We derive the 0.01 $\mu$m binned transmission spectrum, between 0.74 and 1.0 $\mu$m, of WASP-80b from low resolution spectra obtained with the FORS2 instrument attached to ESO's Very Large Telescope. The combination of the fact that WASP-80 is an active star, together with instrumental and telluric factors, introduces correlated noise in the observed transit light curves, which we treat quantitatively using Gaussian Processes. Comparison of our results together with those from previous studies, to theoretically calculated models reveals an equilibrium temperature in agreement with the previously measured value of 825K, and a sub-solar metallicity, as well as an atmosphere depleted of molecular species with absorption bands in the IR ($\gg 5\sigma$). Our transmission spectrum alone shows evidence for additional absorption from the potassium core and wing, whereby its presence is detected from analysis of narrow 0.003 $\mu$m bin light curves ($\gg 5\sigma$). Further observations with visible and near-UV filters will be required to expand this spectrum and provide more in-depth knowledge of the atmosphere. These detections are only made possible through an instrument-dependent baseline model and a careful analysis of systematics in the data. [less ▲]

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See detailMonitoring of comets activity and composition with the TRAPPIST-North telescope
Moulane, Youssef ULiege; Benkhaldoun, Zouhair; Jehin, Emmanuel ULiege et al

in Journal of Physics. Conference Series (2017, July), 869

TRAPPIST-North (TRAnsiting Planets and PlanetesImals Small Telescope) is a 60-cm robotic telescope that was installed in May 2016 at the Oukaimeden Observatory. The project is led by the University of ... [more ▼]

TRAPPIST-North (TRAnsiting Planets and PlanetesImals Small Telescope) is a 60-cm robotic telescope that was installed in May 2016 at the Oukaimeden Observatory. The project is led by the University of Liège (Belgium) and the Caddi Ayad University of Marrakech (Morocco). This telescope is a twin of the TRAPPIST-South telescope, which was installed at the ESO La Silla Observatory in 2010. The TRAPPIST telescopes are dedicated to the detection and characterization of planets orbiting stars other than our Sun (exoplanets) and the study of comets and other small bodies in our solar system. For the comets research, these telescopes have very sensitive CCD cameras with complete sets of narrow band filters to measure the production rates of several gases (OH, NH, CN, C3 and C2) and the dust. With TRAPPIST-North we can also observe comets that would not be visible in the southern hemisphere. Therfore, with these two telescopes, we can now observe continuously the comets around their orbit. We project to study individually the evolution of the activity, chemical composition, dust properties, and coma morphology of several comets per year and of different origins (New comets and Jupiter Family comets) over a wide range of heliocentric distances, and on both sides of perihelion. We measure the production rates of each daughter molecules using a Haser model, in addition to the Afρ parameter to estimate the dust production in the coma. In this work, we present the first measurements of the production rates of comet C/2013 X1 (PANSTARRS) observed with TN in June 2016, and the measurements of comet C/2013 V5 (Oukaimeden) observed in 2014 with TRAPPIST-South. [less ▲]

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