Haswell C.A.,Open University Milton Keynes |
Fossati L.,Open University Milton Keynes |
Ayres T.,University of Colorado at Boulder |
France K.,University of Colorado at Boulder |
And 14 more authors.
Astrophysical Journal | Year: 2012
Extended gas clouds have been previously detected surrounding the brightest known close-in transiting hot Jupiter exoplanets, HD 209458b and HD 189733b; we observed the distant but more extreme close-in hot Jupiter system, WASP-12, with Hubble Space Telescope (HST). Near-UV (NUV) transits up to three times deeper than the optical transit of WASP-12b reveal extensive diffuse gas, extending well beyond the Roche lobe. The distribution of absorbing gas varies between visits. The deepest NUV transits are at wavelength ranges with strong stellar photospheric absorption, implying that the absorbing gas may have temperature and composition similar to those of the stellar photosphere. Our spectra reveal significantly enhanced absorption (greater than 3σ below the median) at 200 individual wavelengths on each of two HST visits; 65 of these wavelengths are consistent between the two visits, using a strict criterion for velocity matching that excludes matches with velocity shifts exceeding 20 km s-1. Excess transit depths are robustly detected throughout the inner wings of the Mg II resonance lines independently on both HST visits. We detected absorption in Fe II λ2586, the heaviest species yet detected in an exoplanet transit. The Mg II line cores have zero flux, emission cores exhibited by every other observed star of similar age and spectral type are conspicuously absent. WASP-12 probably produces normal Mg II profiles, but the inner portions of these strong resonance lines are likely affected by extrinsic absorption. The required Mg+ column is an order of magnitude greater than expected from the interstellar medium, though we cannot completely dismiss that possibility. A more plausible source of absorption is gas lost by WASP-12b. We show that planetary mass loss can produce the required column. Our Visit2 NUV light curves show evidence for a stellar flare. We show that some of the possible transit detections in resonance lines of rare elements may be due instead to non-resonant transitions in common species. We present optical observations and update the transit ephemeris. © 2012. The American Astronomical Society. All rights reserved..
Bloom J.S.,University of California at Berkeley |
Bloom J.S.,Lawrence Berkeley National Laboratory |
Kasen D.,University of California at Berkeley |
Kasen D.,Lawrence Berkeley National Laboratory |
And 15 more authors.
Astrophysical Journal Letters | Year: 2012
While a white dwarf (WD) is, from a theoretical perspective, the most plausible primary star of a Type Ia supernova (SN Ia), many other candidates have not been formally ruled out. Shock energy deposited in the envelope of any exploding primary contributes to the early SN brightness and, since this radiation energy is degraded by expansion after the explosion, the diffusive luminosity depends on the initial primary radius. We present a new non-detection limit of the nearby SN Ia 2011fe, obtained at a time that appears to be just 4hr after explosion, allowing us to directly constrain the initial primary radius (Rp ). Coupled with the non-detection of a quiescent X-ray counterpart and the inferred synthesized 56Ni mass, we show that Rp ≲ 0.02 R ⊙ (a factor of five smaller than previously inferred), that the average density of the primary must be ρp > 104 g cm-3, and that the effective temperature must be less than a few × 105K. This rules out hydrogen-burning main-sequence stars and giants. Constructing the helium-burning and carbon-burning main sequences, we find that such objects are also excluded. By process of elimination, we find that only degeneracy-supported compact objects - WDs and neutron stars - are viable as the primary star of SN2011fe. With few caveats, we also restrict the companion (secondary) star radius to R c ≲ 0.1 R ⊙, excluding Roche-lobe overflowing red giant and main-sequence companions to high significance. © 2012 The American Astronomical Society. All rights reserved.
Brothwell R.D.,Queen's University of Belfast |
Watson C.A.,Queen's University of Belfast |
Hebrard G.,University Pierre and Marie Curie |
Hebrard G.,French National Center for Scientific Research |
And 47 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2013
We present Rossiter-McLaughlin observations of WASP-13b and WASP-32b and determine the sky-projected angle between the normal of the planetary orbit and the stellar rotation axis (λ). WASP-13b and WASP-32b both have prograde orbits and are consistent with alignment with measured sky-projected angles of λ =8°-12 +13 and λ = -2°-19 +17, respectively. Both WASP-13 and WASP-32 have Teff < 6250 K, and therefore, these systems support the general trend that aligned planetary systems are preferentially found orbiting cool host stars. A Lomb-Scargle periodogram analysis was carried out on archival Super WASP data for both systems. A statistically significant stellar rotation period detection (above 99.9 per cent confidence) was identified for the WASP-32 system with Prot = 11.6 ± 1.0 days. This rotation period is in agreement with the predicted stellar rotation period calculated from the stellar radius, R*, and vsin i if a stellar inclination of i* = 90° is assumed. With the determined rotation period, the true 3D angle between the stellar rotation axis and the planetary orbit, ψ, was found to be ψ = 11° ± 14°. We conclude with a discussion on the alignment of systems around cool host stars with Teff < 6150 K by calculating the tidal dissipation time-scale. We find that systems with short tidal dissipation time-scales are preferentially aligned and systems with long tidal dissipation time-scales have a broad range of obliquities. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Gomez Maqueo Chew Y.,University of Warwick |
Gomez Maqueo Chew Y.,Vanderbilt University |
Gomez Maqueo Chew Y.,National Autonomous University of Mexico |
Faedi F.,University of Warwick |
And 45 more authors.
Astronomy and Astrophysics | Year: 2013
We report the discovery of two transiting hot Jupiters, WASP-65b (Mpl = 1.55 ± 0.16 MJ; Rpl = 1.11 ± 0.06 RJ), and WASP-75b (Mpl = 1.07 ± 0.05 MJ; Rpl = 1.27 ± 0.05 RJ). They orbit their host star every ?2.311, and ?2.484 days, respectively. The planet host WASP-65 is a G6 star (Teff = 5600 K, [Fe/H] = ?0.07 ± 0.07, age 8 Gyr); WASP-75 is an F9 star (Teff = 6100 K, [Fe/H] = 0.07 ± 0.09, age ? 3 Gyr).WASP-65b is one of the densest known exoplanets in the mass range 0.1 and 2.0 MJ (?pl = 1.13 ± 0.08 ?J), a mass range where a large fraction of planets are found to be inflated with respect to theoretical planet models. WASP-65b is one of only a handful of planets with masses of ?1.5 MJ, a mass regime surprisingly underrepresented among the currently known hot Jupiters. The radius of WASP-75b is slightly inflated (10%) as compared to theoretical planet models with no core, and has a density similar to that of Saturn (?pl = 0.52 ± 0.06 ?J). © ESO 2013.
Lohr M.E.,Open University Milton Keynes |
Norton A.J.,Open University Milton Keynes |
Gillen E.,University of Oxford |
Busuttil R.,Open University Milton Keynes |
And 6 more authors.
Astronomy and Astrophysics | Year: 2015
Our discovery of 1SWASP J093010.78+533859.5 as a probable doubly eclipsing quadruple system, containing a contact binary with P ~ 0.23 d and a detached binary with P ~ 1.31 d, was announced in 2013. Subsequently, Koo and collaborators confirmed the detached binary spectroscopically, and identified a fifth set of static spectral lines at its location, corresponding to an additional noneclipsing component of the system. Here we present new spectroscopic and photometric observations, allowing confirmation of the contact binary and improved modelling of all four eclipsing components. The detached binary is found to contain components of masses 0.837 ± 0.008 and 0.674 ± 0.007 M, with radii of 0.832 ± 0.018 and 0.669 ± 0.018 R and effective temperatures of 5185+25-20 and 4325+20-15 K, respectively; the contact system has masses 0.86±0.02 and 0.341±0.011 M, radii of 0.79±0.04 and 0.52±0.05 R, respectively, and a common effective temperature of 4700 ± 50 K. The fifth star is of similar temperature and spectral type to the primaries in the two binaries. Long-term photometric observations indicate the presence of a spot on one component of the detached binary, moving at an apparent rate of approximately one rotation every two years. Both binaries have consistent system velocities around -11 to -12 km s-1, which match the average radial velocity of the fifth star; consistent distance estimates for both subsystems of d = 78 ± 3 and d = 73 ± 4 pc are also found, and, with some further assumptions, of d = 83 ± 9 pc for the fifth star. These findings strongly support the claim that both binaries - and very probably all five stars - are gravitationally bound in a single system. The consistent angles of inclination found for the two binaries (88.2 ± 0.3°and 86 ± 4°) may also indicate that they originally formed by fragmentation (around 9-10 Gyr ago) from a single protostellar disk, and subsequently remained in the same orbital plane. © ESO, 2015.
Holmes S.,Open University Milton Keynes |
Kolb U.,Open University Milton Keynes |
Haswell C.A.,Open University Milton Keynes |
Burwitz V.,Max Planck Institute for Extraterrestrial Physics |
And 5 more authors.
Publications of the Astronomical Society of the Pacific | Year: 2011
We introduce PIRATE, a new remotely operable telescope facility for use in research and education, constructed from off-the-shelf hardware, operated by The Open University. We focus on the PIRATE Mark 1 operational phase, in which PIRATE was equipped with a widely used 0.35 m Schmidt-Cassegrain system (now replaced with a 0.425 m corrected Dall-Kirkham astrograph). Situated at the Observatori Astronòmic de Mallorca, PIRATE is currently used to follow up potential transiting extrasolar planet candidates produced by the Super WASP North experiment, as well as to hunt for novae in M31 and other nearby galaxies. It is operated by a mixture of commercially available software and proprietary software developed at the Open University. We discuss problems associated with performing precision time-series photometry when using a German Equatorial Mount, investigating the overall performance of such off-the-shelf solutions in both research and teaching applications. We conclude that PIRATE is a cost-effective research facility, and it also provides exciting prospects for undergraduate astronomy. PIRATE has broken new ground in offering practical astronomy education to distance-learning students in their own homes. © 2011. The Astronomical Society of the Pacific.
Mas L.,Observatori Astronomic de Mallorca
Monografies de la Societat d'Historia Natural de les Balears | Year: 2010
It is important to make clear the difference between astronomy in popular culture (science) and the call popular astronomy, in many cases based on direct observation of natural phenomena but also in false beliefs and superstitions. In this article, and from a scientific point of view, we try to explain why a proverb or belief, or at least suggest a possible explanation. For his part, when speaking of popular astronomy, documents and publications consulted are concerned above all to make a compilation and as much, we find a brief explanation of its meaning or consequences.