References of "Jehin, Emmanuel"
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See detailForbidden oxygen lines in comets at various heliocentric distances
Decock, Alice ULg; Jehin, Emmanuel ULg; Hutsemekers, Damien ULg et al

in Astronomy and Astrophysics (2013), 555

We present a study of the three forbidden oxygen lines [OI] located in the optical region - i.e., 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the two red lines) - in order to better understand ... [more ▼]

We present a study of the three forbidden oxygen lines [OI] located in the optical region - i.e., 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the two red lines) - in order to better understand the production of these atoms in cometary atmospheres. The analysis is based on 48 high-resolution and high signal-to-noise spectra collected with UVES at the ESO VLT between 2003 and 2011 referring to 12 comets of different origins observed at various heliocentric distances. The flux ratio of the green line to the sum of the two red lines is evaluated to determine the parent species of the oxygen atoms by comparison with theoretical models. This analysis confirms that, at about 1 AU, H[SUB]2[/SUB]O is the main parent molecule producing oxygen atoms. At heliocentric distances >2.5 AU, this ratio changes rapidly, an indication that other molecules are starting to contribute. The most abundant species after H[SUB]2[/SUB]O in the coma, CO and CO[SUB]2[/SUB], are good candidates, and the ratio is used to estimate their abundances. We found that the CO[SUB]2[/SUB] abundance relative to H[SUB]2[/SUB]O in comet C/2001 Q4 (NEAT) observed at 4 AU can be as high as ~70%. The intrinsic widths of the oxygen lines were also measured. The green line is on average about 1 km s[SUP]-1[/SUP] broader than the red lines, while the theory predicts that the red lines are broader. This might be due to the nature of the excitation source or to a contribution of CO[SUB]2[/SUB] as the parent molecule of the 5577.339 Å line. At 4 AU, we found that the width of the green and red lines in comet C/2001 Q4 are the same, which could be explained if CO[SUB]2[/SUB] becomes the main contributor to the three [OI] lines at high heliocentric distances. Based on observations made with ESO Telescope at the La Silla Paranal Observatory under programs ID 268.C-5570, 270.C-5043, 073.C-0525, 274.C-5015, 075.C-0355, 080.C-0615, 280.C-5053, 086.C-0958, and 087.C-0929. [less ▲]

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See detailComets C/2012 F6 (Lemmon), C/2013 E2 (Iwamoto), and 63P/Wild
Opitom, Cyrielle ULg; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Central Bureau Electronic Telegrams (2013), 3530

CBET 3530 available at Central Bureau for Astronomical Telegrams.

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See detailThe TRAPPIST survey of southern transiting planets – Physical properties of the WASP-36 planetary system
Delrez, Laetitia ULg; Gillon, Michaël ULg; Jehin, Emmanuel ULg et al

Poster (2013, April 29)

We present ten new transit light curves obtained with the TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) and Euler telescopes for the recently discovered planetary system WASP-36 (Smith ... [more ▼]

We present ten new transit light curves obtained with the TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) and Euler telescopes for the recently discovered planetary system WASP-36 (Smith et al. 2012). Thanks to this extensive data set, we are able to confirm and improve the parameters of the system. WASP-36 is a solar-mass G2 dwarf which hosts a giant planet on a 1.54 d orbit. With a mass of ~2.3 MJup and a radius of ~1.3 RJup, this planet is slightly denser than Jupiter. One of the most interesting properties of the system is its low stellar metallicity ([Fe/H] =-0.26+-0.10), as giant planets are actually known to be rare around such stars (e.g. Fischer & Valenti 2005). Furthermore, due to its small orbital distance and large radius, WASP-36b is an exquisite target for spectrophotometric emission measurements able to constrain the thermal and chemical properties of its atmosphere. [less ▲]

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See detailTRAPPIST-UCDTS: A prototype search for habitable planets transiting ultra-cool stars
Gillon, Michaël ULg; Jehin, Emmanuel ULg; Fumel, A. et al

in Saglia, Roberto (Ed.) European Physical Journal Web of Conferences (2013, April 01)

The ˜1000 nearest ultra-cool stars (spectral type M6 and latter) represent a unique opportunity for the search for life outside solar system. Due to their small luminosity, their habitable zone is 30-100 ... [more ▼]

The ˜1000 nearest ultra-cool stars (spectral type M6 and latter) represent a unique opportunity for the search for life outside solar system. Due to their small luminosity, their habitable zone is 30-100 times closer than for the Sun, the corresponding orbital periods ranging from one to a few days. Thanks to this proximity, the transits of a habitable planet are much more probable and frequent than for an Earth-Sun analog, while their tiny size (˜1 Jupiter radius) leads to transits deep enough for a ground-based detection, even for sub-Earth size planets. Furthermore, a habitable planet transiting one of these nearby ultra-cool star would be amenable for a thorough atmospheric characterization, including the detection of possible biosignatures, notably with the near-to-come JWST. Motivated by these reasons, we have set up the concept of a ground-based survey optimized for detecting planets of Earth-size and below transiting the nearest Southern ultra-cool stars. To assess thoroughly the actual potential of this future survey, we are currently conducting a prototype mini-survey using the TRAPPIST robotic 60cm telescope located at La Silla ESO Observatory (Chile). We summarize here the preliminary results of this mini-survey that fully validate our concept. [less ▲]

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See detailWASP-64b and WASP-72b: two new transiting highly irradiated giant planets
Gillon, Michaël ULg; Anderson, D. R.; Collier-Cameron, A. et al

in Astronomy and Astrophysics (2013), 552

We report the discovery by the WASP transit survey of two new highly irradiated giant planets. WASP-64 b is slightly more massive (1.271 ± 0.068 MJup) and larger (1.271 ± 0.039 RJup) than Jupiter, and is ... [more ▼]

We report the discovery by the WASP transit survey of two new highly irradiated giant planets. WASP-64 b is slightly more massive (1.271 ± 0.068 MJup) and larger (1.271 ± 0.039 RJup) than Jupiter, and is in very-short (a = 0.02648 ± 0.00024 AU, P = 1.5732918 ± 0.0000015 days) circular orbit around a V = 12.3 G7-type dwarf (1.004 ± 0.028 Msun, 1.058 ± 0.025 Rsun, Teff = 5500 ± 150 K). Its size is typical of hot Jupiters with similar masses. WASP-72 b has also a mass a bit higher than Jupiter's (1.461-0.056+0.059 MJup) and orbits very close (0.03708 ± 0.00050 AU, P = 2.2167421 ± 0.0000081 days) to a bright (V = 9.6) and moderately evolved F7-type star (1.386 ± 0.055 Msun, 1.98 ± 0.24 Rsun, Teff = 6250 ± 100 K). Despite its extreme irradiation (~5.5 × 109 erg s-1 cm-2), WASP-72 b has a moderate size (1.27 ± 0.20 RJup) that could suggest a significant enrichment in heavy elements. Nevertheless, the errors on its physical parameters are still too high to draw any strong inference on its internal structure or its possible peculiarity. [less ▲]

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See detailL’eau dans l’univers
Jehin, Emmanuel ULg; Javaux, Emmanuelle ULg; Magain, Pierre ULg et al

Conference given outside the academic context (2013)

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See detailSearching for water in the atmosphere of the hot Saturn WASP-49b
Delrez, Laetitia ULg; Lendl, M.; Gillon, Michaël ULg et al

Poster (2013, March 11)

At the forefront of comparative exoplanetology, the atmospheric characterization of transiting exoplanets is revealing the intimate nature of these 'new worlds'. In this exciting context, we present here ... [more ▼]

At the forefront of comparative exoplanetology, the atmospheric characterization of transiting exoplanets is revealing the intimate nature of these 'new worlds'. In this exciting context, we present here some preliminary results of our VLT program that consisted in monitoring three transits of the new 'hot Saturn' WASP-49b (Lendl et al. 2012) with the FORS instrument in Multi-Object Spectroscopic mode (MXU). [less ▲]

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See detailComets C/2012 F6 (Lemmon) and C/2011 L4 (Panstarrs)
Opitom, Cyrielle ULg; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Central Bureau Electronic Telegrams (2013), 3433

CBET 3433 available at Central Bureau for Astronomical Telegrams.

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See detailWASP-54b, WASP-56b and WASP-57b: Three new sub-Jupiter mass planets from SuperWASP
Faedi, F.; Pollacco, D.; Barros, S. C. C. et al

in Astronomy and Astrophysics (2013), 551

We present three newly discovered sub-Jupiter mass planets from the SuperWASP survey: WASP-54b is a heavily bloated planet of mass 0.636+0.025-0.024RJ. It orbits a F9 star, evolving off the main sequence ... [more ▼]

We present three newly discovered sub-Jupiter mass planets from the SuperWASP survey: WASP-54b is a heavily bloated planet of mass 0.636+0.025-0.024RJ. It orbits a F9 star, evolving off the main sequence, every 3.69 days. Our MCMC fit of the system yields a slightly eccentric orbit (e = 0.067+0.033-0.025) for WASP-54b. We investigated further the veracity of our detection of the eccentric orbit for WASP-54b, and we find that it could be real. However, given the brightness of WASP-54 V = 10.42 mag, we encourage observations of a secondary eclipse to draw robust conclusions on both the orbital eccentricity and the thermal structure of the planet. WASP-56b and WASP-57b have masses of 0.571+0.034-0.035MJ and 0.672+0.049-0.046MJ, respectively; and radii of 1.092+0.035-0.033RJ for WASP-56b and 0.916+0.017-0.014RJ for WASP-57b. They orbit main sequence stars of spectral type G6 every 4.67 and 2.84 days, respectively. WASP-56b and WASP-57b show no radius anomaly and a high density possibly implying a large core of heavy elements; possibly as high as ~50 M⊕ in the case of WASP-57b. However,the composition of the deep interior of exoplanets remains still undetermined. Thus, more exoplanet discoveries such as the ones presented in this paper, are needed to understand and constrain giant planets' physical properties. [less ▲]

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See detailWASP-80b: a gas giant transiting a cool dwarf
Triaud, A. H. M. J.; Anderson, D. R.; Collier Cameron, A. et al

in Astronomy and Astrophysics (2013), 551

We report the discovery of a planet transiting the star <ASTROBJ>WASP-80</ASTROBJ> (<ASTROBJ>1SWASP J201240.26-020838.2</ASTROBJ>; <ASTROBJ>2MASS J20124017-0208391</ASTROBJ>; <ASTROBJ>TYC 5165-481-1 ... [more ▼]

We report the discovery of a planet transiting the star <ASTROBJ>WASP-80</ASTROBJ> (<ASTROBJ>1SWASP J201240.26-020838.2</ASTROBJ>; <ASTROBJ>2MASS J20124017-0208391</ASTROBJ>; <ASTROBJ>TYC 5165-481-1</ASTROBJ>; <ASTROBJ>BPM 80815</ASTROBJ>; V = 11.9, K = 8.4). Our analysis shows this is a 0.55 ± 0.04 M[SUB]jup[/SUB], 0.95 ± 0.03 R[SUB]jup[/SUB] gas giant on a circular 3.07 day orbit around a star with a spectral type between K7V and M0V. This system produces one of the largest transit depths so far reported, making it a worthwhile target for transmission spectroscopy. We find a large discrepancy between the vsini[SUB]⋆[/SUB] inferred from stellar line broadening and the observed amplitude of the Rossiter-McLaughlin effect. This can be understood either by an orbital plane nearly perpendicular to the stellar spin or by an additional, unaccounted for source of broadening. Using WASP-South photometric observations, from Sutherland (South Africa), confirmed with the 60 cm TRAPPIST robotic telescope, EulerCam, and the CORALIE spectrograph on the Swiss 1.2 m Euler Telescope, and HARPS on the ESO 3.6 m (Prog ID 089.C-0151), all three located at La Silla Observatory, Chile.Radial velocity and photometric data are available in electronic form at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">cdsarc.u-strasbg.fr</A>(<A href="http://130.79.128.5">130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A80">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A80</A> [less ▲]

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See detailWASP-77 Ab: A Transiting Hot Jupiter Planet in a Wide Binary System
Maxted, P. F. L.; Anderson, D. R.; Collier Cameron, A. et al

in Publications of the Astronomical Society of the Pacific (2013), 125

We report the discovery of a transiting planet with an orbital period of 1.36 days orbiting the brighter component of the visual binary star BD 07 436. The host star, WASP-77 A, is a moderately bright G8 ... [more ▼]

We report the discovery of a transiting planet with an orbital period of 1.36 days orbiting the brighter component of the visual binary star BD 07 436. The host star, WASP-77 A, is a moderately bright G8 V star (V=10.3) with a metallicity close to solar ([Fe/H] = 0.0 ± 0.1). The companion star, WASP-77 B, is a K-dwarf approximately 2 mag fainter at a separation of approximately 3″. The spectrum of WASP-77 A shows emission in the cores of the Caii H and K lines, indicative of moderate chromospheric activity. The Wide Angle Search for Planets (WASP) light curves show photometric variability with a period of 15.3 days and an amplitude of about 0.3% that is probably due to the magnetic activity of the host star. We use an analysis of the combined photometric and spectroscopic data to derive the mass and radius of the planet (1.76 ± 0.06 M[SUB]Jup[/SUB], 1.21 ± 0.02 R[SUB]Jup[/SUB]). The age of WASP-77 A estimated from its rotation rate (˜1 Gyr) agrees with the age estimated in a similar way for WASP-77 B (˜0.6 Gyr) but is in poor agreement with the age inferred by comparing its effective temperature and density to stellar models (˜8 Gyr). Follow-up observations of WASP-77 Ab will make a useful contribution to our understanding of the influence of binarity and host star activity on the properties of hot Jupiters. [less ▲]

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See detailSpitzer Transits of the Super-Earth GJ1214b and Implications for Its Atmosphere
Fraine, Jonathan D.; Deming, Drake; Gillon, Michaël ULg et al

in Astrophysical Journal (2013), 765(2), 127

We observed the transiting super-Earth exoplanet GJ1214b using Warm Spitzer at 4.5 microns wavelength during a 20-day quasi-continuous sequence in May 2011. The goals of our long observation were to ... [more ▼]

We observed the transiting super-Earth exoplanet GJ1214b using Warm Spitzer at 4.5 microns wavelength during a 20-day quasi-continuous sequence in May 2011. The goals of our long observation were to accurately define the infrared transit radius of this nearby super-Earth, to search for the secondary eclipse, and to search for other transiting planets in the habitable zone of GJ1214. We here report results from the transit monitoring of GJ1214b, including a re-analysis of previous transit observations by Desert et al. (2011). In total, we analyse 14 transits of GJ1214b at 4.5 microns, 3 transits at 3.6 microns, and 7 new ground-based transits in the I+z band. Our new Spitzer data by themselves eliminate cloudless solar composition atmospheres for GJ1214b, and methane-rich models from Howe & Burrows (2012). Using our new Spitzer measurements to anchor the observed transit radii of GJ1214b at long wavelengths, and adding new measurements in I+z, we evaluate models from Benneke & Seager (2012) and Howe & Burrows (2012) using a chi-squared analysis. We find that the best-fit model exhibits an increase in transit radius at short wavelengths due to Rayleigh scattering. Pure water atmospheres are also possible. However, a flat line (no atmosphere detected) remains among the best of the statistically acceptable models, and better than pure water atmospheres. We explore the effect of systematic differences among results from different observational groups, and we find that the Howe & Burrows (2012) tholin-haze model remains the best fit, even when systematic differences among observers are considered. [less ▲]

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See detailThe EBLM Project I-Physical and orbital parameters, including spin-orbit angles, of two low-mass eclipsing binaries on opposite sides of the Brown Dwarf limit
Triaud, Amaury H. M. J.; Hebb, Leslie; Anderson, David R. et al

in Astronomy and Astrophysics (2013), 549

This paper introduces a series of papers aiming to study the dozens of low mass eclipsing binaries (EBLM), with F, G, K primaries, that have been discovered in the course of the WASP survey. Our objects ... [more ▼]

This paper introduces a series of papers aiming to study the dozens of low mass eclipsing binaries (EBLM), with F, G, K primaries, that have been discovered in the course of the WASP survey. Our objects are mostly single-line binaries whose eclipses have been detected by WASP and were initially followed up as potential planetary transit candidates. These have bright primaries, which facilitates spectroscopic observations during transit and allows the study of the spin-orbit distribution of F, G, K+M eclipsing binaries through the Rossiter-McLaughlin effect. Here we report on the spin-orbit angle of WASP-30b, a transiting brown dwarf, and improve its orbital parameters. We also present the mass, radius, spin-orbit angle and orbital parameters of a new eclipsing binary, J1219-39b (1SWAPJ121921.03-395125.6, TYC 7760-484-1), which, with a mass of 95 +/- 2 Mjup, is close to the limit between brown dwarfs and stars. We find that both objects orbit in planes that appear aligned with their primaries' equatorial planes. Neither primaries are synchronous. J1219-39b has a modestly eccentric orbit and is in agreement with the theoretical mass--radius relationship, whereas WASP-30b lies above it. [less ▲]

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See detailSpitzer 3.6 micron and 4.5 micron full-orbit lightcurves of WASP-18
Maxted, P. F. L.; Anderson, D. R.; Doyle, A. P. et al

in Monthly Notices of the Royal Astronomical Society (2013), 428(3), 2645-2660

We present new lightcurves of the massive hot Jupiter system WASP-18 obtained with the Spitzer spacecraft covering the entire orbit at 3.6 micron and 4.5 micron. These lightcurves are used to measure the ... [more ▼]

We present new lightcurves of the massive hot Jupiter system WASP-18 obtained with the Spitzer spacecraft covering the entire orbit at 3.6 micron and 4.5 micron. These lightcurves are used to measure the amplitude, shape and phase of the thermal phase effect for WASP-18b. We find that our results for the thermal phase effect are limited to an accuracy of about 0.01% by systematic noise sources of unknown origin. At this level of accuracy we find that the thermal phase effect has a peak-to-peak amplitude approximately equal to the secondary eclipse depth, has a sinusoidal shape and that the maximum brightness occurs at the same phase as mid-occultation to within about 5 degrees at 3.6 micron and to within about 10 degrees at 4.5 micron. The shape and amplitude of the thermal phase curve imply very low levels of heat redistribution within the atmosphere of the planet. We also perform a separate analysis to determine the system geometry by fitting a lightcurve model to the data covering the occultation and the transit. The secondary eclipse depths we measure at 3.6 micron and 4.5 micron are in good agreement with previous measurements and imply a very low albedo for WASP-18b. The parameters of the system (masses, radii, etc.) derived from our analysis are in also good agreement with those from previous studies, but with improved precision. We use new high-resolution imaging and published limits on the rate of change of the mean radial velocity to check for the presence of any faint companion stars that may affect our results. We find that there is unlikely to be any significant contribution to the flux at Spitzer wavelengths from a stellar companion to WASP-18. We find that there is no evidence for variations in the times of eclipse from a linear ephemeris greater than about 100 seconds over 3 years. [less ▲]

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See detailTransiting exoplanets from the CoRoT space mission XXI. CoRoT-19b: A low density planet orbiting an old inactive F9V-star
Guenther, E. W.; Diaz, R. F.; Gazzano, J-C et al

in Astronomy and Astrophysics (2012), 537

Observations of transiting extrasolar planets are of key importance to our understanding of planets because their mass, radius, and mass density can be determined. The CoRoT space mission allows us to ... [more ▼]

Observations of transiting extrasolar planets are of key importance to our understanding of planets because their mass, radius, and mass density can be determined. The CoRoT space mission allows us to achieve a very high photometric accuracy. By combining CoRoT data with high-precision radial velocity measurements, we derive precise planetary radii and masses. We report the discovery of CoRoT-19b, a gas-giant planet transiting an old, inactive F9V-type star with a period of four days. After excluding alternative physical configurations mimicking a planetary transit signal, we determine the radius and mass of the planet by combining CoRoT photometry with high-resolution spectroscopy obtained with the echelle spectrographs SOPHIE, HARPS, FIES, and SANDIFORD. To improve the precision of its ephemeris and the epoch, we observed additional transits with the TRAPPIST and Euler telescopes. Using HARPS spectra obtained during the transit, we then determine the projected angle between the spin of the star and the orbit of the planet. We find that the host star of CoRoT-19b is an inactive F9V-type star close to the end of its main-sequence life. The host star has a mass M*=1.21+/-0.05 Msun and radius R*=1.65+/-0.04 Rsun. The planet has a mass of Mp=1.11+/-0.06 Mjup and radius of Rp=1.29+/-0.03 Rjup. The resulting bulk density is only rho=0.71+/-0.06 gcm-3, which is much lower than that for Jupiter. The exoplanet CoRoT-19b is an example of a giant planet of almost the same mass as Jupiter but a 30% larger radius. [less ▲]

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See detailAlbedo and atmospheric constraints of dwarf planet Makemake from a stellar occultation
Ortiz, J. L.; Sicardy, B.; Braga-Ribas, F. et al

in Nature (2012), 491

Pluto and Eris are icy dwarf planets with nearly identical sizes, comparable densities and similar surface compositions as revealed by spectroscopic studies. Pluto possesses an atmosphere whereas Eris ... [more ▼]

Pluto and Eris are icy dwarf planets with nearly identical sizes, comparable densities and similar surface compositions as revealed by spectroscopic studies. Pluto possesses an atmosphere whereas Eris does not; the difference probably arises from their differing distances from the Sun, and explains their different albedos. Makemake is another icy dwarf planet with a spectrum similar to Eris and Pluto, and is currently at a distance to the Sun intermediate between the two. Although Makemake's size (1,420+/-60km) and albedo are roughly known, there has been no constraint on its density and there were expectations that it could have a Pluto-like atmosphere. Here we report the results from a stellar occultation by Makemake on 2011 April 23. Our preferred solution that fits the occultation chords corresponds to a body with projected axes of 1,430+/-9km (1σ) and 1,502+/-45km, implying a V-band geometric albedo p[SUB]V[/SUB] = 0.77+/-0.03. This albedo is larger than that of Pluto, but smaller than that of Eris. The disappearances and reappearances of the star were abrupt, showing that Makemake has no global Pluto-like atmosphere at an upper limit of 4-12nanobar (1σ) for the surface pressure, although a localized atmosphere is possible. A density of 1.7+/-0.3gcm[SUP]-3[/SUP] is inferred from the data. [less ▲]

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See detailCharon's Size And Orbit From Double Stellar Occultations
Sicardy, Bruno; Braga-Ribas, F.; Widemann, T. et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2012, October 01)

Stellar occultations of a same star by both Pluto and Charon (double events) yield instantaneous relative positions of the two bodies projected in the plane of the sky, at 10km-level accuracy. Assuming a ... [more ▼]

Stellar occultations of a same star by both Pluto and Charon (double events) yield instantaneous relative positions of the two bodies projected in the plane of the sky, at 10km-level accuracy. Assuming a given pole orientation for Charon's orbit, double events provide the satellite plutocentric distance r at a given orbital longitude L (counted from the ascending node on J2000 mean equator), and finally, constraints on its orbit. A double event observed on 22 June 2008 provides r=19,564+/-14 km at L=153.483+/-0.071 deg. (Sicardy et al. 2011), while another double event observed on 4 June 2011 yields: r=19,586+/-15 km at L = 343.211+/-0.072 deg. (all error bars at 1-sigma level). These two positions are consistent with a circular orbit for Charon, with a semi-major axis of a=19,575+\-10 km. This can be compared to the circular orbit found by Buie et al. (2012), based on Hubble Space Telescope data, with a=19,573+/-2 km. The 4 June 2011 stellar occultation provides 3 chords across Charon, from which a radius of Rc= 602.4+/-1.6 km is derived. This value can be compared to that obtained from the 11 July 2005 occultation: Rc= 606.0+/-1.5 km (Person et al. 2006) and Rc= 603.6+/-1.4 km (Sicardy et al. 2006). A third double event, observed on 23 June 2011 is under ongoing analysis, and will be presented. Buie et al. (2012), AJ 144, 15-34 (2012) Person et al, AJ 132, 1575-1580 (2006) Sicardy et al., Nature 439, 52-54 (2006) Sicardy et al., AJ 141, 67-83 (2011) B.S. thanks ANR "Beyond Neptune II". L.A.Y. acknowledges support by NASA, New Horizons and National Geographic grants. We thank B. Barnard, M.J. Brucker, J. Daily, C. Erikson, W. Fukunaga, C. Harlinten, C. Livermore, C. Nance, J.R. Regester, L. Salas, P. Tamblyn, R. Westhoff for help in the observations. [less ▲]

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See detailSpitzer Transits Of The Super-Earth Gj1214b And Implications For Its Atmosphere
Fraine, Jonathan D.; Deming, D.; Gillon, Michaël ULg et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2012, October 01)

We observed the transiting super-Earth exoplanet GJ1214b using Warm Spitzer at 4.5 μm wavelength during a 20-day quasi-continuous sequence in May 2011. The goals of our long observation were to accurately ... [more ▼]

We observed the transiting super-Earth exoplanet GJ1214b using Warm Spitzer at 4.5 μm wavelength during a 20-day quasi-continuous sequence in May 2011. The goals of our long observation were to accurately define the infrared transit radius of this nearby super-Earth, to search for the secondary eclipse, and to search for other transiting planets in the habitable zone of GJ1214. We here report results from the transit monitoring of GJ1214b, including a re-analysis of previous transit observations by Desert et al. (2011). In total, we analyze 14 transits of GJ1214b at 4.5 μm, 3 transits at 3.6 μm, and 7 new ground-based transits in the I+z band. Our new Spitzer data by themselves eliminate cloudless solar composition atmospheres for GJ1214b, and methane-rich models from Howe & Burrows (2012). Using our new Spitzer measurements to anchor the observed transit radii of GJ1214b at long wavelengths, and adding new measurements in I+z, we evaluate models from Benneke & Seager (2012) and Howe & Burrows (2012) using a χ2 analysis. We find that the best-fit model exhibits an increase in transit radius at short wavelength due to Rayleigh scattering. Pure water atmospheres are also possible. However, a flat line (no atmosphere detected) remains among the best of the statistically acceptable models, and better than pure water atmospheres. We explore the effect of systematic differences among results from different observational groups, and we find that the flat line model is the least sensitive to systematic error. [less ▲]

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See detailStellar Occultations by Large TNOs on 2012: The February 3rd by (208996) 2003 AZ84, and the February 17th by (50000) Quaoar
Braga Ribas, Felipe; Sicardy, B.; Ortiz, J. L. et al

in AAS/Division for Planetary Sciences Meeting Abstracts (2012, October 01)

On February 2012, two stellar occultation's by large Trans-neptunian Objects (TNO's) were observed by our group. On the 3rd, an event by (208996) 2003 AZ84 was recorded from Mont Abu Observatory and IUCAA ... [more ▼]

On February 2012, two stellar occultation's by large Trans-neptunian Objects (TNO's) were observed by our group. On the 3rd, an event by (208996) 2003 AZ84 was recorded from Mont Abu Observatory and IUCAA Girawali Observatory in India and from Weizmann Observatory in Israel. On the 17th, a stellar occultation by (50000) Quaoar was observed from south France and Switzerland. Both occultations are the second observed by our group for each object, and will be used to improve the results obtained on the previous events. The occultation by 2003 AZ84 is the first multi-chord event recorded for this object. From the single chord event on January 8th 2011, Braga-Ribas et al. 2011 obtained a lower limit of 573 +/- 21 km. From the 2012 occultation the longest chord has a size of 662 +/- 50 km. The other chords will permit to determine the size and shape of the TNO, and derive other physical parameters, such as the geometric albedo. The Quaoar occultation was observed from south of France (Observatoire de la Côte d'Azur, TAROT telescope and Valensole) and from Gnosca, Switzerland. Unfortunately, all three sites in France are almost at the same Quaoar's latitude, so in practice, we have two chords that can be used to fit Quaoar's limb. The resulting fit will be compared with the results obtained by Braga-Ribas et al. 2011. Braga-Ribas F., Sicardy B., et al. 2011, EPSC-DPS2011, 1060.Ribas F., Sicardy B., et al. 2011, EPSC-DPS2011, 1060. [less ▲]

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See detailAn upper limit for the water outgassing rate of the main-belt comet 176P/LINEAR observed with Herschel/HIFI
de Val-Borro, M.; Rezac, L.; Hartogh, P. et al

in Astronomy and Astrophysics (2012), 546

176P/LINEAR is a member of the new cometary class known as main-belt comets (MBCs). It displayed cometary activity shortly during its 2005 perihelion passage, which may be driven by the sublimation of ... [more ▼]

176P/LINEAR is a member of the new cometary class known as main-belt comets (MBCs). It displayed cometary activity shortly during its 2005 perihelion passage, which may be driven by the sublimation of subsurface ices. We have therefore searched for emission of the H[SUB]2[/SUB]O 1[SUB]10[/SUB]-1[SUB]01[/SUB] ground state rotational line at 557 GHz toward 176P/LINEAR with the Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory on UT 8.78 August 2011, about 40 days after its most recent perihelion passage, when the object was at a heliocentric distance of 2.58 AU. No H[SUB]2[/SUB]O line emission was detected in our observations, from which we derive sensitive 3-σ upper limits for the water production rate and column density of <4 × 10[SUP]25[/SUP] mol s[SUP]-1[/SUP] and of <3 × 10[SUP]10[/SUP] cm[SUP]-2[/SUP], respectively. From the peak brightness measured during the object's active period in 2005, this upper limit is lower than predicted by the relation between production rates and visual magnitudes observed for a sample of comets at this heliocentric distance. Thus, 176P/LINEAR was most likely less active at the time of our observation than during its previous perihelion passage. The retrieved upper limit is lower than most values derived for the H[SUB]2[/SUB]O production rate from the spectroscopic search for CN emission in MBCs. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. [less ▲]

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