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Francis O'Donovan

Francis O'Donovan
Hospital IQ · Data Science

PhD

About

43
Publications
3,036
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2,803
Citations
Additional affiliations
September 2002 - August 2007
California Institute of Technology
Position
  • Research Assistant

Publications

Publications (43)
Article
Full-text available
An increasing portion of modern socializing takes place via online social networks. Members of these communities often play distinct roles that can be deduced from observations of users' online activities. One such activity is the sharing of multimedia, the popularity of which can vary dramatically. Here we discuss our initial analysis of anonymize...
Article
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We analyze light curves obtained by the Trans-atlantic Exoplanet Survey (TrES) for a field centered on the L1495 dark cloud in Taurus. The Spitzer Taurus Legacy Survey catalog identifies 179 bona fide Taurus members within the TrES field; 48 of the known Taurus members are detected by TrES, as well as 26 candidate members identified by the Spitzer...
Article
Full-text available
We present a novel automated methodology to detect and classify periodic variable stars in a large data base of photometric time series. The methods are based on multivariate Bayesian statistics and use a multistage approach. We applied our method to the ground-based data of the Trans-Atlantic Exoplanet Survey (TrES) Lyr1 field, which is also obser...
Article
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We report the discovery of TrES-5, a massive hot Jupiter that transits the star GSC 03949-00967 every 1.48 days. From spectroscopy of the star we estimate a stellar effective temperature of$5171 +/- 36 K, and from high-precision B, R and I photometry of the transit we constrain the ratio of the semi-major axis and the stellar radius to be 6.07 +/-...
Article
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Accurate absolute properties have been determined for the eclipsing triple star CO And (F8+F8) based on extensive differential photometry obtained by three robotic observatories and CfA spectroscopy. The eclipsing binary star orbit is circular with a period of 3.655 days. The triple nature of this system is revealed by more than a century of timing...
Article
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We use the Spitzer Space Telescope to estimate the dayside thermal emission of the exoplanet TrES-3 integrated in the 3.6, 4.5, 5.8, and 8.0 μm bandpasses of the Infrared Array Camera (IRAC) instrument. We observe two secondary eclipses and find relative eclipse depths of 0.00346 ± 0.00035, 0.00372 ± 0.00054, 0.00449 ± 0.00097, and 0.00475 ± 0.0004...
Article
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We present here the results of our observations of TrES-2 using the Infrared Array Camera on Spitzer. We monitored this transiting system during two secondary eclipses, when the planetary emission is blocked by the star. The resulting decrease in flux is 0.127% ± 0.021%, 0.230% ± 0.024%, 0.199% ± 0.054%, and 0.359% ± 0.060% at 3.6 μm, 4.5 μm, 5.8 μ...
Article
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We have derived masses and radii for both components in five short-period single-lined eclipsing binary stars discovered by the TrES wide-angle photometric survey for transiting planets. All these systems consist of a visible F-star primary and an unseen M-star secondary (M_A > 0.8 M_sun, M_B < 0.45 M_sun). The spectroscopic orbital solution combin...
Article
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Spectroscopic and eclipsing binary systems offer the best means for determining accurate physical properties of stars, including their masses and radii. The data available for low-mass stars have yielded firm evidence that stellar structure models predict smaller radii and higher effective temperatures than observed, but the number of systems with...
Article
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We report new spectroscopic and photometric observations of the parent stars of the recently discovered transiting planets TrES-3 and TrES-4. A detailed abundance analysis based on high-resolution spectra yields [Fe/H] = –0.19 ± 0.08, T eff = 5650 ± 75 K, and log g = 4.4 ± 0.1 for TrES-3, and [Fe/H] = +0.14 ± 0.09, T eff = 6200 ± 75 K, and log g =...
Conference Paper
The Trans-atlantic Exoplanet Survey (TrES) attempts to find planetary transits among bright stars. The two telescope used are the 10cm Sleuth Telescope (Palomar Observatory, California) and the 10cm Planet Search Survey Telescope (PSST) at Lowell Observatory, Arizona. The survey area covers 5.7 degrees by 5.7 degrees and is centered on the star 16...
Article
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We summarise the results of a) a Keck/HIRES Doppler search for planets orbiting metal-poor dwarfs, and b) a new spectroscopic and photometric analysis of the transiting planet systems TrES-3 and TrES-4. These two experiments have allowed us to address important issues related to the correlation between planet frequencies and properties and the meta...
Article
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We monitored the Doppler shift of the G0 V star TrES-2 throughout a transit of its giant planet. The anomalous Doppler shift due to stellar rotation (the Rossiter-McLaughlin effect) is discernible in the data, with a signal-to-noise ratio of 2.9, even though the star is a slow rotator. By modeling this effect we find that the planet’s trajectory ac...
Article
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We present precise z-band photometric time series spanning times of transit of the two exoplanets recently discovered by the SuperWASP collaboration. We find planetary radii of 1.44 ± 0.08 and 1.04 ± 0.06 RJ for WASP-1b and WASP-2b, respectively. These error estimates include both random errors in the photometry and also the uncertainty in the stel...
Article
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We describe the discovery of a 0.68+0.52 M☉ eclipsing binary (EB) with an 8.4 day orbital period, found through a systematic search of 10 fields of the Trans-atlantic Exoplanet Survey (TrES). Such long-period low-mass EBs constitute critical test cases for resolving the long-standing discrepancy between the theoretical and observational mass-radius...
Article
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We report the detection of a transiting Jupiter-sized planet orbiting a relatively bright (V = 11.79) K0 V star. We detected the transit light-curve signature in the course of the TrES multisite transiting planet survey and confirmed the planetary nature of the companion via multicolor photometry and precise radial velocity measurements. We designa...
Article
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Of the nearby transiting exoplanets that are amenable to detailed study, TrES-2 is both the most massive and the one with the largest impact parameter. We present z-band photometry of three transits of TrES-2. We improve on the estimates of the planetary, stellar, and orbital parameters, in conjunction with the spectroscopic analysis of the host st...
Article
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Driven by the incomplete understanding of the formation of gas giant extrasolar planets and of their mass-radius relationship, several ground-based, wide-field photometric campaigns are searching the skies for new transiting extrasolar gas giants. As part of the Trans-atlantic Exoplanet Survey (TrES), in 2003/2004 we monitored approximately 30,000...
Article
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We describe a newly discovered detached M dwarf eclipsing binary system. This system was first observed by the TrES network during a long-term photometry campaign of 54 nights. Analysis of the folded light curve indicates two very similar components orbiting each other with a period of 1.12079 ± 0.00001 days. Spectroscopic observations with the Hob...
Article
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We report on a spectroscopic determination of the atmospheric parameters and chemical abundance of the parent star of the recently discovered transiting planet TrES-2. A detailed LTE analysis of a set of Fe I and Fe II lines from our Keck spectra yields Teff = 5850 ± 50 K, log g = 4.4 ± 0.1, and [Fe/H] = -0.15 ± 0.10. Several independent checks (e....
Article
Full-text available
We present RIz photometry of four consecutive transits of the newly discovered exoplanet XO-1b. We improve on the estimates of the transit parameters, finding the planetary radius to be RP = 1.184RJ, and the stellar radius to be R = 0.928 R☉, assuming a stellar mass of M = (1.00 ± 0.03) M☉. The uncertainties in the planetary and stellar radii are d...
Article
Full-text available
Ground-based wide-field surveys for nearby transiting gas giants are yielding far fewer true planets than astrophysical false positives, some of which are difficult to reject. Recent experience has highlighted the need for careful analysis to eliminate astronomical systems in which light from a faint eclipsing binary is blended with that from a bri...
Article
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Wide-field searches for transiting extrasolar giant planets face the difficult challenge of separating true transit events from the numerous false positives caused by isolated or blended eclipsing binary systems. We describe here the investigation of GSC 01944-02289, a very promising candidate for a transiting brown dwarf detected by the Trans-Atla...
Article
Full-text available
We announce the discovery of the second transiting hot Jupiter discovered by the Trans-atlantic Exoplanet Survey. The planet, which we dub TrES-2, orbits the nearby star GSC 03549-02811 every 2.47063 days. From high-resolution spectra, we determine that the star has Teff = 5960 ± 100 K and log g = 4.4 ± 0.2, implying a spectral type of G0 V and a m...
Article
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We report g, V, and r photometric time series of HD 149026 spanning predicted times of transit of the Saturn-mass planetary companion, which was recently discovered by Sato and collaborators. We present a joint analysis of our observations and the previously reported photometry and radial velocities of the central star. We refine the estimate of th...
Article
Full-text available
We describe the discovery of a massive transiting hot Jupiter with a very short orbital period (1.30619 days), which we name TrES-3. From spectroscopy of the host star GSC 03089-00929, we measure Teff = 5720 ± 150 K, log g = 4.6 ± 0.3, and v sin i < 2 km s-1 and derive a stellar mass of 0.90 ± 0.15 M☉. We estimate a planetary mass of 1.92 ± 0.23 MJ...
Article
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We report the discovery of TrES-4, a hot Jupiter that transits the star GSC 02620-00648 every 3.55 days. From high-resolution spectroscopy of the star, we estimate a stellar effective temperature of Teff = 6100 ± 150 K, and from high-precision z and B photometry of the transit we constrain the ratio of the semimajor axis a and the stellar radius R*...
Article
Full-text available
We estimate the strength of the bandpass-integrated thermal emission from the extrasolar planet TrES-4 at 3.6, 4.5, 5.8, and 8.0 micron using the Infrared Array Camera (IRAC) on the Spitzer Space Telescope. We find relative eclipse depths of 0.137 +/- 0.011%, 0.148 +/- 0.016%, 0.261 +/- 0.059%, and 0.318 +/- 0.044% in these four bandpasses, respect...
Article
Our discovery of the transiting exoplanet TrES-3 presents an opportunity to study the atmosphere of a gas giant with an orbital period of only 31 hours, the shortest period of the known transiting exoplanets observable with Spitzer. The radius of TrES-3 is larger than permitted by current models of the structure of these highly irradiated short per...
Article
Full-text available
Aims. Our objective is to elucidate the physical process that causes the observed observed-minus-calculated (O-C) behavior in the M4.5/ M4.5 binary CM Dra and to test for any evidence of a third body around the CM Dra system. Methods. New eclipse minimum timings of CM Dra were obtained between the years 2000 and 2007. The O-C times of the system...
Article
Full-text available
In recent years we have witnessed an explosion of photometric time-series data, collected for the purpose of finding a small number of rare sources, such as transiting extrasolar planets and gravitational microlenses. Once combed, these data are often set aside, and are not further searched for the many other variable sources that they undoubtedly...
Article
Full-text available
We summarize the results of two experiments to address important issues related to the correlation between planet frequencies and properties and the metallicity of the hosts. Our results can usefully inform formation, structural, and evolutionary models of gas giant planets. Comment: 2 pages, no figures. To appear in the proceedings of "IAU confere...
Article
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I present the discovery of three transiting planets (TrES-2, TrES-3, and TrES-4) of nearby bright stars made with the ten-centimeter telescope Sleuth as part of the Trans-atlantic Exoplanet Survey (TrES). TrES-2 is the first transiting exoplanet detected in the field of view of NASA’s Kepler mission. Of the 20 known transiting exoplanets, TrES-3 ha...
Article
We have just announced the discovery of TrES-4, which is by far the largest and least dense of the 22 known transiting explanets. The inflated radius is seriously at odds with published models of the physical structure of hot Jupiters, and is an extreme case within the general class of close-in gas giants with very low densities. We propose to dete...
Article
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The TrES project is designed to search for exoplanetary transits using three wide-field optical telescopes of 10-cm in diameter, in three different observatories. We describe the instruments and strategies used by the team, which has been working as a network since 2003. We summarize the major findings and difficulties faced during these years, whi...
Article
Full-text available
Our incomplete understanding of the formation of gas giants and of their mass-radius relationship has motivated ground-based, wide-field surveys for new transiting extrasolar giant planets. Yet, astrophysical false positives have dominated the yield from these campaigns. Astronomical systems where the light from a faint eclipsing binary and a brigh...
Article
Full-text available
The Trans-atlantic Exoplanet Survey (TrES) is a network of three small-aperture telescopes dedicated to searching the skies for new transiting extrasolar gas giants. The TrES team have discovered two of the 14 known transiting exoplanets. We discuss the detection and exploration of these nearby planets and present the latest observations of TrES-2....
Article
Full-text available
We present RIz photometry of four consecutive transits of the newly discovered exoplanet XO-1b. We improve upon the estimates of the transit parameters, finding the planetary radius to be RP = 1.184 +0.028/-0.018 RJupiter and the stellar radius to be RS = 0.928 +0.018/-0.013 RSun, assuming a stellar mass of MS = 1.00 0.03 MSun. The uncertainties in...
Article
Full-text available
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 p...
Article
We propose to observe the newly-discovered transiting planet TrES-1 during the time of secondary eclipse (when the planet passes behind the star). A successful measurement of this eclipse would constitute the first direct detection of emission from an extrasolar planet. The secondary eclipse will reveal two key quantities of the planet: its tempera...
Article
Full-text available
The most significant challenge currently facing photometric surveys for transiting gas-giant planets is that of confusion with eclipsing binary systems that mimic the photometric signature. A simple way to reject most forms of these false positives is high-precision, rapid-cadence monitoring of the suspected transit at higher angular resolution and...
Article
Full-text available
We discuss preliminary results from our first search campaign for transiting planets performed using Sleuth, an automated 10 cm telescope with a 6 degree square field of view. We monitored a field in Hercules for 40 clear nights between UT 2003 May 10 and July 01, and obtained an rms precision (per 15-min average) over the entire data set of better...

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