Denys Wilkinson Building Keble Road

Oxford, United Kingdom

Denys Wilkinson Building Keble Road

Oxford, United Kingdom

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Smith D.J.B.,University of Hertfordshire | Hardcastle M.J.,University of the Western Cape | Hardcastle M.J.,University of Canterbury | Jarvis M.J.,Denys Wilkinson Building Keble Road | And 23 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2013

We use galaxies from the Herschel-ATLAS (H-ATLAS) survey, and a suite of ancillary simulations based on an isothermal dust model, to study our ability to determine the effective dust temperature, luminosity and emissivity index of 250 μm selected galaxies in the local Universe (z < 0.5). As well as simple far-infrared spectral energy distribution (SED) fitting of individual galaxies based on X2 minimization, we attempt to derive the best global isothermal properties of 13 826 galaxies with reliable optical counterparts and spectroscopic redshifts. Using our simulations, we highlight the fact that applying traditional SED fitting techniques to noisy observational data in the Herschel Space Observatory bands introduces artificial anticorrelation between derived values of dust temperature and emissivity index. This is true even for galaxies with the most robust statistical detections in our sample, making the results of such fitting difficult to interpret.We apply a method to determine the best-fitting global values of isothermal effective temperature and emissivity index for z < 0.5 galaxies in H-ATLAS, deriving Teff = 22.3 ± 0.1K and β = 1.98 ± 0.02 (or Teff = 23.5 ± 0.1K and β = 1.82 ± 0.02 if we attempt to correct for bias by assuming that Teff and βeff are independent and normally distributed). We use our technique to test for an evolving emissivity index, finding only weak evidence. The median dust luminosity of our sample is log10(Ldust/L⊙) = 10.72 ± 0.05, which (unlike Teff) shows little dependence on the choice of β used in our analysis, including whether it is variable or fixed. In addition, we use a further suite of simulations based on a fixed emissivity index isothermal model to emphasize the importance of the H-ATLAS PACS data for deriving dust temperatures at these redshifts, even though they are considerably less sensitive than the SPIRE data. Finally, we show that the majority of galaxies detected by H-ATLAS are normal star-forming galaxies, though with a substantial minority (~31 per cent) falling in the Luminous Infrared Galaxy category. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


Ollivier M.,University Paris - Sud | Gillon M.,University of Liège | Santerne A.,French National Center for Scientific Research | Wuchterl G.,Thuringer Landessternwarte | And 60 more authors.
Astronomy and Astrophysics | Year: 2012

Aims. We report the discovery of CoRoT-16b, a low density hot jupiter that orbits a faint G5V star (mV = 15.63) in 5.3523 ± 0.0002 days with slight eccentricity. A fit of the data with no a priori assumptions on the orbit leads to an eccentricity of 0.33 ± 0.1. We discuss this value and also derive the mass and radius of the planet. Methods. We analyse the photometric transit curve of CoRoT-16 given by the CoRoT satellite, and radial velocity data from the HARPS and HIRES spectrometers. A combined analysis using a Markov chain Monte Carlo algorithm is used to get the system parameters. Results. CoRoT-16b is a 0.535-0.083/+0.085 M J, 1.17-0.14/+0.16 R J hot Jupiter with a density of 0.44-0.14/+0.21 g cm -3. Despite its short orbital distance (0.0618 ± 0.0015 AU) and the age of the parent star (6.73 ± 2.8 Gyr), the planet orbit exhibits significantly non-zero eccentricity. This is very uncommon for this type of objects as tidal effects tend to circularise the orbit. This value is discussed taking into account the characteristics of the star and the observation accuracy. © 2012 ESO.


Rouan D.,University Paris Diderot | Parviainen H.,Institute of Astrophysics of Canarias | Parviainen H.,University of La Laguna | Moutou C.,Laboratoire Dastrophysique Of Marseille | And 45 more authors.
Astronomy and Astrophysics | Year: 2012

We report the detection of CoRoT-23b, a hot Jupiter transiting in front of its host star with a period of 3.6314 ± 0.0001 days. This planet was discovered thanks to photometric data secured with the CoRoT satellite, combined with spectroscopic radial velocity (RV) measurements. A photometric search for possible background eclipsing binaries conducted at CFHT and OGS concluded with a very low risk of false positives. The usual techniques of combining RV and transit data simultaneously were used to derive stellar and planetary parameters. The planet has a mass of Mp = 2.8 ± 0.3 M Jup, a radius of Rpl= 1.05 ± 0.13RJup, a density of ≈ 3 g cm-3. RV data also clearly reveal a nonzero eccentricity of e = 0.16 ± 0.02. The planet orbits a mature G0 main sequence star of V = 15.5 mag, with a mass M* = 1.14 ± 0.08 M⊙, a radius R*= 1. 61 ± 0.18 R⊙ and quasi-solarabundances. The age of the system is evaluated to be 7 Gyr, not far from the transition to subgiant, in agreement with the rather large stellar radius. The two features of a significant eccentricity of the orbit and of a fairly high density are fairly uncommon for a hot Jupiter. The high density is, however, consistent with a model of contraction of a planet at this mass, given the age of the system. On the other hand, at such an age, circularization is expected to be completed. In fact, we show that for this planetary mass and orbital distance, any initial eccentricity should not totally vanish after 7 Gyr, as long as the tidal quality factor Qp is more than a few 105, a value that is the lower bound of the usually expected range. Even if CoRoT-23b features a density and an eccentricity that are atypical of a hot Jupiter, it is thus not an enigmatic object. © 2012 ESO.


Erikson A.,German Aerospace Center | Santerne A.,French National Center for Scientific Research | Renner S.,German Aerospace Center | Renner S.,Lille University of Science and Technology | And 66 more authors.
Astronomy and Astrophysics | Year: 2012

Context. The space mission CoRoT is devoted to the analysis of stellar variability and the photometric detection of extrasolar planets. Aims. We present the list of planetary transit candidates detected in the first short run observed by CoRoT that targeted SRc01, towards the Galactic center in the direction of Aquila, which lasted from April to May 2007. Methods. Among the acquired data, we analyzed those for 1269 sources in the chromatic bands and 5705 in the monochromatic band. Instrumental noise and the stellar variability were treated with several detrending tools, to which several transit-search algorithms were subsequently applied. Results. Fifty-one sources were classified as planetary transit candidates and 26 were followed up with ground-based observations. Until now, no planet has been detected in the CoRoT data from the SRc01 field. © 2012 ESO.


Deleuil M.,Laboratoire Dastrophysique Of Marseille | Bonomo A.S.,Laboratoire Dastrophysique Of Marseille | Ferraz-Mello S.,University of Sao Paulo | Erikson A.,German Aerospace Center | And 47 more authors.
Astronomy and Astrophysics | Year: 2012

We report the discovery by the CoRoT space mission of a new giant planet, CoRoT-20b. The planet has a mass of 4.24 ± 0.23 MJup and a radius of 0.84 ± 0.04 RJup. With a mean density of 8.87 ± 1.10 g cm-3, it is among the most compact planets known so far. Evolutionary models for the planet suggest a mass of heavy elements of the order of 800 M⊕ if embedded in a central core, requiring a revision either of the planet formation models or both planet evolution and structure models. We note however that smaller amounts of heavy elements are expected by more realistic models in which they are mixed throughout the envelope. The planet orbits a G-type star with an orbital period of 9.24 days and an eccentricity of 0.56.The star's projected rotational velocity is vsini = 4.5 ± 1.0 km s-1, corresponding to a spin period of 11.5 ± 3.1 days if its axis of rotation is perpendicular to the orbital plane. In the framework of Darwinian theories and neglecting stellar magnetic breaking, we calculate the tidal evolution of the system and show that CoRoT-20b is presently one of the very few Darwin-stable planets that is evolving toward a triple synchronous state with equality of the orbital, planetary and stellar spin periods. © 2012 ESO.


Csizmadia S.,German Aerospace Center | Moutou C.,Laboratoire Dastrophysique Of Marseille | Deleuil M.,Laboratoire Dastrophysique Of Marseille | Cabrera J.,German Aerospace Center | And 55 more authors.
Astronomy and Astrophysics | Year: 2011

We report on the discovery of a hot Jupiter-type exoplanet, CoRoT-17b, detected by the CoRoT satellite. It has a mass of 2.43 ± 0.30 M Jup and a radius of 1.02 ± 0.07 RJup, while its mean density is 2.82 ± 0.38 g/cm3. CoRoT-17b is in a circular orbit with a period of 3.7681 ± 0.0003 days. The host star is an old (10.7 ± 1.0 Gyr) main-sequence star, which makes it an intriguing object for planetary evolution studies. The planet's internal composition is not well constrained and can range from pure H/He to one that can contain ∼380 earth masses of heavier elements. © 2011 ESO.


Tingley B.,Institute of Astrophysics of Canarias | Tingley B.,University of La Laguna | Endl M.,University of Texas at Austin | Gazzano J.-C.,Laboratoire Dastrophysique Of Marseille | And 55 more authors.
Astronomy and Astrophysics | Year: 2011

In this paper, the CoRoT ExoplanetScience Team announces its 14th discovery. Herein, we discuss the observations and analyses that allowed us to derive the parameters of this system: a hot Jupiter with a mass of 7.6 ± 0.6 Jupiter masses orbiting a solar-type star (F9V) with a period of only 1.5 d, less than 5 stellar radii from its parent star. It is unusual for such a massive planet to have such a small orbit: only one other known higher mass exoplanet orbits with a shorter period. © ESO 2011.


Bouchy F.,University Pierre and Marie Curie | Bouchy F.,French National Center for Scientific Research | Deleuil M.,Laboratoire Dastrophysique Of Marseille | Guillot T.,University of Nice Sophia Antipolis | And 51 more authors.
Astronomy and Astrophysics | Year: 2011

We report the discovery by the CoRoT space mission of a transiting brown dwarf orbiting a F7V star with an orbital period of 3.06 days. CoRoT-15b has a radius of 1.12+0.30 -0.15 RJup and a mass of 63.3 ± 4.1 MJup, and is thus the second transiting companion lying in the theoretical mass domain of brown dwarfs. CoRoT-15b is either very young or inflated compared to standard evolution models, a situation similar to that of M-dwarf stars orbiting close to solar-typestars. Spectroscopic constraints and an analysis of the lightcurve imply a spin period in the range 2.9-3.1 days for the central star, which is compatible with a double-synchronisation of the system. © ESO, 2010. © 2010 ESO.


Cabrera J.,German Aerospace Center | Cabrera J.,University of Paris Descartes | Bruntt H.,University Paris Diderot | Ollivier M.,CNRS Paris Institute of Astrophysics | And 49 more authors.
Astronomy and Astrophysics | Year: 2010

We announce the discovery of the transiting planet CoRoT-13b. Ground-based follow-up in CFHT and IAC80 confirmed CoRoT's observations. The mass of the planet was measured with the HARPS spectrograph and the properties of the host star were obtained analyzing HIRES spectra from the Keck telescope. It is a hot Jupiter-like planet with an orbital period of 4.04 days, 1.3 Jupiter masses, 0.9 Jupiter radii, and a density of 2.34 g cm-3. It orbits a G0V star with Teff = 5 945 K, M*= 1.09 M⊙, R*= 1.01 R⊙, solar metallicity, a lithium content of + 1.45 dex, and an estimated age of between 0.12 and 3.15 Gyr. The lithium abundance of the star is consistent with its effective temperature, activity level, and age range derived from the stellar analysis. The density of the planet is extreme for its mass, implies that heavy elements are present with a mass of between about 140 and 300 M⊕. © 2010 ESO.

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