A transiting extrasolar giant planet around the star OGLE-TR-10
TL;DR: In this paper, a transiting extrasolar giant planet around the star OGLE-TR-10 (orbital period = 3.1 days), which was uncovered as a candidate by the OGLE team in their photometric survey towards the Galactic center, was reported.
Abstract: We report a transiting extrasolar giant planet around the star OGLE-TR-10 (orbital period = 3.1 days), which was uncovered as a candidate by the OGLE team in their photometric survey towards the Galactic center (Udalski et al, 2002a). We observed OGLE-TR-10 spectroscopically over a period of two years (2002-2004) using the HIRES instrument with an iodine cell on the Keck I telescope, and measured small radial velocity variations that are consistent with the presence of a planetary companion. This confirms the earlier identification of OGLE-TR-10b by our team and also recently by Bouchy et al (2004a) as a possible planet. Additionally, in this paper we are able to rule out a blend scenario as an alternative explanation. From an analysis combining all available radial velocity measurements with the OGLE light curve we find that OGLE-TR-10b has a mass of 0.57+/-0.12 MJup and a radius of 1.24+/-0.09 RJup. These parameters bear close resemblance to those of the first known transiting extrasolar planet, HD 209458b.
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TL;DR: In this paper, the authors present Spitzer Space Telescope infrared photometric time series of the transiting extrasolar planet system TrES-1, which represents the first direct detection of photons emitted by a planet orbiting another star.
Abstract: We present Spitzer Space Telescope infrared photometric time series of the transiting extrasolar planet system TrES-1. The data span a predicted time of secondary eclipse, corresponding to the passage of the planet behind the star. In both bands of our observations, we detect a flux decrement with a timing, amplitude, and duration as predicted by published parameters of the system. This signal represents the first direct detection of (i.e. the observation of photons emitted by) a planet orbiting another star. The observed eclipse depths (in units of relative flux) are 0.00066 ± 0.00013 at 4.5 µm and 0.00225±0.00036 at 8.0 µm. These estimates provide the first observational constraints on models of the thermal emission of hot Jupiters. Assuming that the planet emits as a blackbody, we estimate an effective temperature of Tp = 1060 ±50 K. Under the additional assumptions that the planet is in thermal equilibrium with the radiation from the star and emits isotropically, we find a Bond albedo of A = 0.31 ± 0.14. This would imply that the planet absorbs the majority of stellar radiation incident upon it, a conclusion of significant impact to atmospheric models of these objects. We also compare our data to a previously-published model of the planetary thermal emission, which predicts prominent spectral features in our observational bands due to water and carbon monoxide. This model adequately reproduces the observed planet-to-star flux ratio at 8.0 µm, however it significantly over-predicts the ratio at 4.5 µm. We also present an estimate of the timing of the secondary eclipse, which we use to place a
754 citations
TL;DR: In this article, the authors developed a simple method to determine the effect of red noise on photometric planetary transit detections, and showed that the detection threshold in the presence of systematics can be much higher than that with the assumption of white noise and obeys a different dependence on magnitude, orbital period and the parameters of the survey.
Abstract: Since the discovery of short-period exoplanets a decade ago, photometric surveys have been recognized as a feasible method to detect transiting hot Jupiters. Many transit surveys are now underway, with instruments ranging from 10-cm cameras to the Hubble Space Telescope. However, the results of these surveys have been much below the expected capacity, estimated in the dozens of detections per year.
One of the reasons is the presence of systematics (‘red noise’) in photometric time-series. In general, yield predictions assume uncorrelated noise (‘white noise’). In this paper, we show that the effect of red noise on the detection threshold and the expected yields cannot be neglected in typical ground-based surveys. We develop a simple method to determine the effect of red noise on photometric planetary transit detections. This method can be applied to determine detection thresholds for transit surveys. We show that the detection threshold in the presence of systematics can be much higher than that with the assumption of white noise, and obeys a different dependence on magnitude, orbital period and the parameters of the survey. Our method can also be used to estimate the significance level of a planetary transit candidate (to select promising candidates for spectroscopic follow-up).
We apply our method to the OGLE planetary transit search, and show that it provides a reliable description of the actual detection threshold with real correlated noise. We point out in what way the presence of red noise could be at least partly responsible for the dearth of transiting planet detections from existing surveys, and examine some possible adaptations in survey planning and strategy. Finally, we estimate the photometric stability necessary to the detection of transiting ‘hot Neptunes’.
595 citations
TL;DR: In this article, a self-consistent and uniform analysis of transit light curves and the observable properties of the host stars is presented, which can be used to interpret the ensemble properties of transiting exoplanets because of widely different methodologies applied in individual cases.
Abstract: We present refined values for the physical parameters of transiting exoplanets, based on a self-consistent and uniform analysis of transit light curves and the observable properties of the host stars. Previously it has been difficult to interpret the ensemble properties of transiting exoplanets because of the widely different methodologies that have been applied in individual cases. Furthermore, previous studies often ignored an important constraint on the mean stellar density that can be derived directly from the light curve. The main contributions of this work are (1) a critical compilation and error assessment of all reported values for the effective temperature and metallicity of the host stars, (2) the application of a consistent methodology and treatment of errors in modeling the transit light curves, and (3) more accurate estimates of the stellar mass and radius based on stellar evolution models, incorporating the photometric constraint on the stellar density. We use our results to revisit some previously proposed patterns and correlations within the ensemble. We confirm the mass-period correlation and find evidence for a new pattern within the scatter about this correlation: planets around metal-poor stars are more massive than those around metal-rich stars at a given orbital period. Likewise, we confirm the proposed dichotomy of planets according to their Safronov number, and we find evidence that the systems with small Safronov numbers are more metal-rich on average. Finally, we confirm the trend that led to the suggestion that higher metallicity stars harbor planets with a greater heavy-element content.
533 citations
TL;DR: In this article, a scaling law of R ∝ M 0.267 − 0.272 for super-Earths was obtained for a class of planets with one to ten times the mass of the Earth.
506 citations
TL;DR: In this article, a new transiting hot Jupiter orbiting the star HD189733b has been discovered, with an orbital period of 2.219 days, and presents the largest photometric depth in the light curve observed to date.
Abstract: Among the 160 known exoplanets, mainly detected in large radial-velocity surveys, only 8 have a characterization of their actual mass and radius thanks to the two complementary methods of detection: radial velocities and photometric transit. We started in March 2004 an exoplanet-search programme biased toward high-metallicity stars which are more frequently host extra-solar planets. This survey aims to detect close-in giant planets, which are most likely to transit their host star. For this programme, high-precision radial velocities are measured with the ELODIE fiber-fed spectrograph on the 1.93-m telescope, and high-precision photometry is obtained with the CCD Camera on the 1.20-m telescope, both at the Haute-Provence Observatory. We report here the discovery of a new transiting hot Jupiter orbiting the star HD189733. The planetary nature of this object is confirmed by the observation of both the spectroscopic and photometric transits. The exoplanet HD189733b, with an orbital period of 2.219 days, has one of the shortest orbital periods detected by radial velocities, and presents the largest photometric depth in the light curve (~ 3%) observed to date. We estimate for the planet a mass of 1.15 +- 0.04 Mjup and a radius of 1.26 +- 0.03 RJup. Considering that HD189733 has the same visual magnitude as the well known exoplanet host star HD209458, further ground-based and space-based follow-up observations are very promising and will permit a characterization of the atmosphere and exosphere of this giant exoplanet.
497 citations
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TL;DR: In this paper, exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening are presented for the HST observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207+-0.0003.
Abstract: We present exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening. In the limit that the planet radius is less than a tenth of the stellar radius, we show that the exact lightcurve can be well approximated by assuming the region of the star blocked by the planet has constant surface brightness. We apply these results to the HST observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207+-0.0003. These formulae give a fast and accurate means of computing lightcurves using limb-darkening coefficients from model atmospheres which should aid in the detection, simulation, and parameter fitting of planetary transits.
2,370 citations
TL;DR: In this paper, the exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening were presented, and the authors applied these results to the Hubble Space Telescope observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207 ± 0.0003.
Abstract: We present exact analytic formulae for the eclipse of a star described by quadratic or nonlinear limb darkening. In the limit that the planet radius is less than a tenth of the stellar radius, we show that the exact light curve can be well approximated by assuming the region of the star blocked by the planet has constant surface brightness. We apply these results to the Hubble Space Telescope observations of HD 209458, showing that the ratio of the planetary to stellar radii is 0.1207 ± 0.0003. These formulae give a fast and accurate means of computing light curves using limb-darkening coefficients from model atmospheres that should aid in the detection, simulation, and parameter fitting of planetary transits.
2,253 citations
01 Jun 1994
TL;DR: The high-resolution echelle spectrometer (HIRES) as discussed by the authors is a standard in-plane spectrograph with grating post dispersion, which is permanently located at a Nasmyth focus.
Abstract: We describe the high resolution echelle spectrometer (HIRES) now in operation on the Keck Telescope. HIRES, which is permanently located at a Nasmyth focus, is a standard in-plane echelle spectrometer with grating post dispersion. The collimated beam diameter is 12', and the echelle is a 1 x 3 mosaic, 12' by 48' in total size, of 52.6 gr mmMIN1, R-2.8 echelles. The cross disperser is a 2 x 1 mosaic, 24' by 16 ' in size. The camera is of a unique new design: a large (30' aperture) f/1.0, all spherical, all fused silica, catadioptric system with superachromatic performance. It spans the entire chromatic range from 0.3 (mu) to beyond 1.1 (mu) , delivering 12.6-micron (rms) images, averaged over all colors and field angles, without refocus. The detector is a thinned, backside-illuminated, Tektronix 2048 x 2048 CCD with 24-micron pixels, which spans the spectral region from 0.3 (mu) to 1.1 (mu) with very high overall quantum efficiency. The limiting spectral resolution of HIRES is 67,000 with the present CCD pixel size. The overall 'throughput' (resolution x slit width) product achieved by HIRES is 39,000 arcseconds. Peak overall efficiency for the spectrograph (not including telescope and slit losses) is 13% at 6000 angstrom. Some first-light science activities, including quasar absorption line spectra, beryllium abundances in metal-poor stars, lithium abundances in brown-dwarf candidates, and asteroseismology are discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
1,703 citations
TL;DR: High-precision, high-cadence photometric measurements of the star HD 209458 are reported, which is known from radial velocity measurements to have a planetary-mass companion in a close orbit and the detailed shape of the transit curve due to both the limb darkening of thestar and the finite size of the planet is clearly evident.
Abstract: We report high-precision, high-cadence photometric measurements of the star HD 209458, which is known from radial velocity measurements to have a planetary-mass companion in a close orbit. We detect two separate transit events at times that are consistent with the radial velocity measurements. In both cases, the detailed shape of the transit curve due to both the limb darkening of the star and the finite size of the planet is clearly evident. Assuming stellar parameters of 1.1 R⊙ and 1.1 M⊙, we find that the data are best interpreted as a gas giant with a radius of 1.27 ± 0.02 RJup in an orbit with an inclination of 871 ± 02. We present values for the planetary surface gravity, escape velocity, and average density and discuss the numerous observations that are warranted now that a planet is known to transit the disk of its parent star.
1,494 citations
TL;DR: Doppler measurements from Keck exhibit a sinusoidal periodicity in the velocities of the G0 dwarf HD 209458, having a semiamplitude of 81 m s-1 and a period of 3.5239 days, which is indicative of a "51 Peg-like" planet with a minimum mass (Msini) of 0.62 MJup and a semimajor axis of0.046 AU.
Abstract: Doppler measurements from Keck exhibit a sinusoidal periodicity in the velocities of the G0 dwarf HD 209458, having a semiamplitude of 81 m s 21 and a period of 3.5239 days, which is indicative of a “51 Peg‐like” planet with a minimum mass ( ) of 0.62 MJup and a semimajor axis of 0.046 AU. Follow-up photometry reveals M sin i a drop of 0.017 mag at the predicted time (within the errors) of transit by the companion based on the velocities. This is the first extrasolar planet observed to transit its star. The radius of the planet derived from the magnitude of the dimming is 1.42 RJup, which is consistent with models of irradiated Jupiter-mass planets. The transit implies that , leading to a true mass of 0.62 MJup for the planet. The resulting mean density of 0.27 g cm 23 sin i 1 0.993 implies that the companion is a gas giant. Subject headings: planetary systems — stars: individual (HD 209458)
940 citations