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Michael Gillon - One of the best experts on this subject based on the ideXlab platform.
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WASP-94 A and B planets: hot-Jupiter cousins in a twin-star system
Astronomy & Astrophysics, 2014Co-Authors: M. Neveu-vanmalle, Michael Gillon, Didier Queloz, David R. Anderson, Corinne Charbonnel, A. Collier Cameron, Laetitia Delrez, Coel Hellier, Emmanuel Jehin, Monika LendlAbstract:We report the discovery of two hot-Jupiter planets, each Orbiting one of the stars of a wide binary system. WASP-94A (2MASS 20550794-3408079) is an F8 type star hosting a transiting planet with a radius of 1.72 +/- 0.06 R_Jup, a mass of 0.452 +/- 0.034 M_Jup, and an Orbital period of 3.95 days. The Rossiter-McLaughlin effect is clearly detected, and the measured projected spin-Orbit angle indicates that the planet occupies a Retrograde Orbit. WASP-94B (2MASS 20550915-3408078) is an F9 stellar companion at an angular separation of 15" (projected separation 2700 au), hosting a gas giant with a minimum mass of 0.618 +/- 0.028 M_Jup with a period of 2.008 days, detected by Doppler measurements. The Orbital planes of the two planets are inclined relative to each other, indicating that at least one of them is inclined relative to the plane of the stellar binary. These hot Jupiters in a binary system bring new insights into the formation of close-in giant planets and the role of stellar multiplicity.
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wasp 17b an ultra low density planet in a probable Retrograde Orbit
The Astrophysical Journal, 2010Co-Authors: D R Anderson, C Hellier, Michael Gillon, A H M J Triaud, B Smalley, Leslie Hebb, Collier A Cameron, P F L Maxted, D QuelozAbstract:We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses, but 1.5-2 Jupiter radii, giving a density of 6%-14% that of Jupiter. WASP-17b is in a 3.7 day Orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a Retrograde Orbit (λ –150°), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularization of an eccentric Orbit, such as the highly eccentric Orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current Orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
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wasp 17b an ultra low density planet in a probable Retrograde Orbit
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: D R Anderson, C Hellier, Michael Gillon, A H M J Triaud, B Smalley, Leslie Hebb, Collier A Cameron, P F L Maxted, D QuelozAbstract:We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses but 1.5-2 Jupiter radii, giving a density of 6-14 per cent that of Jupiter. WASP-17b is in a 3.7-day Orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a Retrograde Orbit (lambda ~ -150 deg), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularisation of an eccentric Orbit, such as the highly eccentric Orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current Orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
D Queloz - One of the best experts on this subject based on the ideXlab platform.
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wasp 17b an ultra low density planet in a probable Retrograde Orbit
The Astrophysical Journal, 2010Co-Authors: D R Anderson, C Hellier, Michael Gillon, A H M J Triaud, B Smalley, Leslie Hebb, Collier A Cameron, P F L Maxted, D QuelozAbstract:We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses, but 1.5-2 Jupiter radii, giving a density of 6%-14% that of Jupiter. WASP-17b is in a 3.7 day Orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a Retrograde Orbit (λ –150°), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularization of an eccentric Orbit, such as the highly eccentric Orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current Orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
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wasp 17b an ultra low density planet in a probable Retrograde Orbit
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: D R Anderson, C Hellier, Michael Gillon, A H M J Triaud, B Smalley, Leslie Hebb, Collier A Cameron, P F L Maxted, D QuelozAbstract:We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses but 1.5-2 Jupiter radii, giving a density of 6-14 per cent that of Jupiter. WASP-17b is in a 3.7-day Orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a Retrograde Orbit (lambda ~ -150 deg), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularisation of an eccentric Orbit, such as the highly eccentric Orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current Orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
Joshua N. Winn - One of the best experts on this subject based on the ideXlab platform.
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a low stellar obliquity for wasp 47 a compact multiplanet system with a hot jupiter and an ultra short period planet
The Astrophysical Journal, 2015Co-Authors: Roberto Sanchisojeda, Joshua N. Winn, Fei Dai, Andrew W Howard, Howard Isaacson, Geoffrey W Marcy, Erik A Petigura, Evan Sinukoff, Lauren M Weiss, Simon AlbrechtAbstract:We have detected the Rossiter–Mclaughlin effect during a transit of WASP-47b, the only known hot Jupiter with close planetary companions. By combining our spectroscopic observations with Kepler photometry, we show that the projected stellar obliquity is λ = 0° ± 24°. We can firmly exclude a Retrograde Orbit for WASP-47b, and rule out strongly misaligned prograde Orbits. Low obliquities have also been found for most of the other compact multiplanet systems that have been investigated. The Kepler-56 system, with two close-in gas giants transiting their subgiant host star with an obliquity of at least 45o, remains the only clear counterexample.
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Alignment of the stellar spin with the Orbits of a three-planet system
Nature, 2012Co-Authors: Roberto Sanchis-ojeda, Joshua N. Winn, Matthew J. Holman, Daniel C. Fabrycky, Thomas Barclay, Bruce D. Clarke, Eric B. Ford, Jonathan J. Fortney, John C. Geary, Andrew W HowardAbstract:The Sun’s equator and the planets’ Orbital planes are nearly aligned, which is presumably a consequence of their formation from a single spinning gaseous disk. For exoplanetary systems this well-aligned configuration is not guaranteed: dynamical interactions may tilt planetary Orbits, or stars may be misaligned with the protoplanetary disk through chaotic accretion^ 1 , magnetic interactions^ 2 or torques from neighbouring stars. Indeed, isolated ‘hot Jupiters’ are often misaligned and even Orbiting Retrograde^ 3 , 4 . Here we report an analysis of transits of planets over starspots^ 5 , 6 , 7 on the Sun-like star Kepler-30 (ref. 8 ), and show that the Orbits of its three planets are aligned with the stellar equator. Furthermore, the Orbits are aligned with one another to within a few degrees. This configuration is similar to that of our Solar System, and contrasts with the isolated hot Jupiters. The orderly alignment seen in the Kepler-30 system suggests that high obliquities are confined to systems that experienced disruptive dynamical interactions. Should this be corroborated by observations of other coplanar multi-planet systems, then star–disk misalignments would be ruled out as the explanation for the high obliquities of hot Jupiters, and dynamical interactions would be implicated as the origin of hot Jupiters. In our Solar System, the Sun's equator and the planets' Orbital planes are almost in alignment. This probably reflects the way they formed, from a single spinning disk of gas. Many exoplanet systems do not display this arrangement, however, and isolated 'hot Jupiters' are often misaligned and even have a Retrograde Orbit. This paper reports an exoplanet system that features alignments similar to those in the Solar System. Analysis of planetary transits across starspots on the Sun-like star Kepler-30 shows that the Orbits of its three planets are aligned with the stellar equator. These findings support the suggestion that high Orbital tilts (obliquities) are confined to systems that have experienced dynamic interactions of the type that produce hot Jupiters and potentially rule out star–disk misalignments as a cause. An analysis of transits of planets over starspots on the Sun-like star Kepler-30 shows that the Orbits of the three planets are aligned with the stellar equator; this configuration is similar to that of our Solar System, and suggests that high obliquities are confined to systems that experienced disruptive dynamical interactions.
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Confirmation of a Retrograde Orbit for Exoplanet Wasp-17b
The Astrophysical Journal, 2010Co-Authors: Daniel Bayliss, Joshua N. Winn, Rosemary A. Mardling, Penny D. SackettAbstract:We present high-precision radial velocity observations of WASP-17 throughout the transit of its close-in giant planet, using the MIKE spectrograph on the 6.5 m Magellan Telescope at Las Campanas Observatory. By modeling the Rossiter-McLaughlin effect, we find the sky-projected spin-Orbit angle to be λ = 167.4 ± 11.2 deg. This independently confirms the previous finding that WASP-17b is on a Retrograde Orbit, suggesting it underwent migration via a mechanism other than just the gravitational interaction between the planet and the disk. Interestingly, our result for λ differs by 45 ± 13 deg from the previously announced value, and we also find that the spectroscopic transit occurs 15 ± 5 minutes earlier than expected, based on the published ephemeris. The discrepancy in the ephemeris highlights the need for contemporaneous spectroscopic and photometric transit observations whenever possible.
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confirmation of a Retrograde Orbit for exoplanet wasp 17b
arXiv: Earth and Planetary Astrophysics, 2010Co-Authors: Daniel Bayliss, Joshua N. Winn, Rosemary A. Mardling, Penny D. SackettAbstract:We present high-precision radial velocity observations of WASP-17 throughout the transit of its close-in giant planet, using the MIKE spectrograph on the 6.5m Magellan Telescope at Las Campanas Observatory. By modeling the Rossiter-McLaughlin effect, we find the sky-projected spin-Orbit angle to be lambda = 167.4 \pm 11.2 deg. This independently confirms the previous finding that WASP-17b is on a Retrograde Orbit, suggesting it underwent migration via a mechanism other than just the gravitational interaction between the planet and the disk. Interestingly, our result for lambda differs by 45 \pm 13 deg from the previously announced value, and we also find that the spectroscopic transit occurs 15 \pm 5 min earlier than expected, based on the published ephemeris. The discrepancy in the ephemeris highlights the need for contemporaneous spectroscopic and photometric transit observations whenever possible.
D R Anderson - One of the best experts on this subject based on the ideXlab platform.
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thermal emission at 4 5 and 8 micron of wasp 17b an extremely large planet in a slightly eccentric Orbit
arXiv: Earth and Planetary Astrophysics, 2011Co-Authors: D R Anderson, C Hellier, Collier A Cameron, A M S Smith, A A Lanotte, Travis Barman, Christopher J Campo, M Gillon, Joseph Harrington, P F L MaxtedAbstract:We report the detection of thermal emission at 4.5 and 8 micron from the planet WASP-17b. We used Spitzer to measure the system brightness at each wavelength during two occultations of the planet by its host star. By combining the resulting light curves with existing transit light curves and radial velocity measurements in a simultaneous analysis, we find the radius of WASP-17b to be 2.0 Rjup, which is 0.2 Rjup larger than any other known planet and 0.7 Rjup larger than predicted by the standard cooling theory of irradiated gas giant planets. We find the Retrograde Orbit of WASP-17b to be slightly eccentric, with 0.0012 < e < 0.070 (3 sigma). Such a low eccentricity suggests that, under current models, tidal heating alone could not have bloated the planet to its current size, so the radius of WASP-17b is currently unexplained. From the measured planet-star flux-density ratios we infer 4.5 and 8 micron brightness temperatures of 1881 +/- 50 K and 1580 +/- 150 K, respectively, consistent with a low-albedo planet that efficiently redistributes heat from its day side to its night side.
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wasp 17b an ultra low density planet in a probable Retrograde Orbit
The Astrophysical Journal, 2010Co-Authors: D R Anderson, C Hellier, Michael Gillon, A H M J Triaud, B Smalley, Leslie Hebb, Collier A Cameron, P F L Maxted, D QuelozAbstract:We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses, but 1.5-2 Jupiter radii, giving a density of 6%-14% that of Jupiter. WASP-17b is in a 3.7 day Orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a Retrograde Orbit (λ –150°), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularization of an eccentric Orbit, such as the highly eccentric Orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current Orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
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wasp 17b an ultra low density planet in a probable Retrograde Orbit
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: D R Anderson, C Hellier, Michael Gillon, A H M J Triaud, B Smalley, Leslie Hebb, Collier A Cameron, P F L Maxted, D QuelozAbstract:We report the discovery of the transiting giant planet WASP-17b, the least-dense planet currently known. It is 1.6 Saturn masses but 1.5-2 Jupiter radii, giving a density of 6-14 per cent that of Jupiter. WASP-17b is in a 3.7-day Orbit around a sub-solar metallicity, V = 11.6, F6 star. Preliminary detection of the Rossiter-McLaughlin effect suggests that WASP-17b is in a Retrograde Orbit (lambda ~ -150 deg), indicative of a violent history involving planet-planet or star-planet scattering. WASP-17b's bloated radius could be due to tidal heating resulting from recent or ongoing tidal circularisation of an eccentric Orbit, such as the highly eccentric Orbits that typically result from scattering interactions. It will thus be important to determine more precisely the current Orbital eccentricity by further high-precision radial velocity measurements or by timing the secondary eclipse, both to reduce the uncertainty on the planet's radius and to test tidal-heating models. Owing to its low surface gravity, WASP-17b's atmosphere has the largest scale height of any known planet, making it a good target for transmission spectroscopy.
Felix J Lockman - One of the best experts on this subject based on the ideXlab platform.
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high velocity cloud complex h a satellite of the milky way in a Retrograde Orbit
The Astrophysical Journal, 2003Co-Authors: Felix J LockmanAbstract:Observations with the Green Bank Telescope of 21 cm H I emission from the high-velocity cloud complex H suggest that it is interacting with the Milky Way. A model in which the cloud is a satellite of the Galaxy in an inclined, Retrograde circular Orbit reproduces both the cloud's average velocity and its velocity gradient with latitude. The model places complex H at R = 33 ± 9 kpc from the Galactic center on a Retrograde Orbit inclined ≈45° to the Galactic plane. At this location, it has a mass in H I of greater than 6 × 106 M☉ and dimensions of at least 10 × 5 kpc. Some of the diffuse H I associated with the cloud has apparently been decelerated by interaction with Galactic gas. Complex H has similarities to the dwarf irregular galaxy Leo A and to some compact high-velocity clouds, and it has an internal structure nearly identical to parts of the Magellanic Stream, with a pressure P/k ≈ 100 cm-3 K.
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high velocity cloud complex h a satellite of the milky way in a Retrograde Orbit
arXiv: Astrophysics, 2003Co-Authors: Felix J LockmanAbstract:Observations with the Green Bank Telescope of 21cm HI emission from the high-velocity cloud Complex H suggest that it is interacting with the Milky Way. A model in which the cloud is a satellite of the Galaxy in an inclined, Retrograde circular Orbit reproduces both the cloud's average velocity and its velocity gradient with latitude. The model places Complex H at approximately 33 kpc from the Galactic Center on a Retrograde Orbit inclined about 45 degrees to the Galactic plane. At this location it has an HI mass > 6 10^6 Msun and dimensions of at least 10 by 5 kpc. Some of the diffuse HI associated with the cloud has apparently been decelerated by interaction with Galactic gas. Complex H has similarities to the dwarf irregular galaxy Leo A and to some compact high-velocity clouds, and has an internal structure nearly identical to parts of the Magellanic Stream, with a pressure P/k about 100 cm^{-3} K.