Physical Sciences and Mathematics Commons^™

Retired A Stars And Their Companions. Vii. 18 New Jovian Planets, John Asher Johnson, Christian Clanton, Andrew W. Howard, Brendan P. Bowler, Gregory W. Henry, Geoffrey W. Marcy, Justin R. Crepp, Michael Endl, William D. Cochran, Phillip J. Macqueen, Jason T. Wright, Howard Isaacson

Information Systems and Engineering Management Research Publications

We report the detection of 18 Jovian planets discovered as part of our Doppler survey of subgiant stars at Keck Observatory, with follow-up Doppler and photometric observations made at McDonald and Fairborn Observatories, respectively. The host stars have masses 0.927 ⩽ M⋆/M☉ ⩽ 1.95, radii 2.5 ⩽ R⋆/R☉ ⩽ 8.7, and metallicities −0.46 ⩽ [Fe/H] ⩽+0.30. The planets have minimum masses 0.9 MJup ⩽ MPsin i ≲ 13 MJup and semimajor axes a ⩾ 0.76 AU. These detections represent a 50% increase in the number of planets known to orbit stars more massive than 1.5 M☉ and provide valuable additional …

Hubble Space Telescope Transmission Spectroscopy Of The Exoplanet Hd 189733b: High-Altitude Atmospheric Haze In The Optical And Near-Ultraviolet With Stis, David K. Sing, Frederic Pont, Suzanne Aigrain, David Charbonneau, Jean-Michel Désert, Neale P. Gibson, Ronald Gilliland, Wolfgang Hayek, Gregory W. Henry, Heather Knutson, Alain Lecavelier Des Etangs, Tsevi Mazeh, Avi Shporer

Information Systems and Engineering Management Research Publications

We present Hubble Space Telescope (HST) optical and near-ultraviolet transmission spectra of the transiting hot Jupiter HD 189733b, taken with the repaired Space Telescope Imaging Spectrograph (STIS) instrument. The resulting spectra cover the range 2900–5700 Å and reach per exposure signal-to-noise ratio levels greater than 11 000 within a 500-Å bandwidth. We used time series spectra obtained during two transit events to determine the wavelength dependence of the planetary radius and measure the exoplanet’s atmospheric transmission spectrum for the first time over this wavelength range. Our measurements, in conjunction with existing HST spectra, now provide a broad-band transmission spectrum covering …

Revised Orbit And Transit Exclusion For Hd 114762b, Stephen R. Kane, Gregory W. Henry, Diana Dragomir, Debra A. Fischer, Andrew W. Howard, Xuesong Wang, Jason T. Wright

Information Systems and Engineering Management Research Publications

Transiting planets around bright stars have allowed the detailed follow-up and characterization of exoplanets, such as the study of exoplanetary atmospheres. The Transit Ephemeris Refinement and Monitoring Survey is refining the orbits of the known exoplanets to confirm or rule out both transit signatures and the presence of additional companions. Here we present results for the companion orbiting HD 114762 in an eccentric 84 day orbit. Radial velocity analysis performed on 19 years of Lick Observatory data constrain the uncertainty in the predicted time of mid-transit to ∼5 hr, which is less than the predicted one-half day transit duration. We …

A Spitzer Transmission Spectrum For The Exoplanet Gj 436b, Evidence For Stellar Variability, And Constraints On Dayside Flux Variations, Heather Knutson, Nikku Madhusudhan, Nicolas B. Cowan, Jessie L. Christiansen, Eric Agol, Drake Deming, Jean-Michel Désert, David Charbonneau, Gregory W. Henry, Derek Homeier, Jonathan Langton, Gregory Laughlin, Sara Seager

Information Systems and Engineering Management Research Publications

In this paper, we describe a uniform analysis of eight transits and eleven secondary eclipses of the extrasolar planet GJ 436b obtained in the 3.6, 4.5, and 8.0 μm bands using the IRAC instrument on the Spitzer Space Telescope between UT 2007 June 29 and UT 2009 February 4. We find that the best-fit transit depths for visits in the same bandpass can vary by as much as 8% of the total (4.7σ significance) from one epoch to the next. Although we cannot entirely rule out residual detector effects or a time-varying, high-altitude cloud layer in the planet's atmosphere as …

Improved Orbital Parameters And Transit Monitoring For Hd 156846b, Stephen R. Kane, Andrew W. Howard, Genady Pilyavsky, Suvrath Mahadevan, Gregory W. Henry, Kaspar Von Braun, David R. Ciardi, Diana Dragomir, Debra A. Fischer, Eric L. N. Jensen, Gregory Laughlin, Solange V. Ramirez, Jason T. Wright

Information Systems and Engineering Management Research Publications

HD 156846b is a Jovian planet in a highly eccentric orbit (e = 0.85) with a period of 359.55 days. The pericenter passage at a distance of 0.16 AU is nearly aligned to our line of sight, offering an enhanced transit probability of 5.4% and a potentially rich probe of the dynamics of a cool planetary atmosphere impulsively heated during close approach to a bright star (V = 6.5). We present new radial velocity (RV) and photometric measurements of this star as part of the Transit Ephemeris Refinement and Monitoring Survey. The RV measurements from the Keck–High Resolution Echelle Spectrometer …

The Nasa-Uc Eta-Earth Program. Iii. A Super-Earth Orbiting Hd 97658 And A Neptune-Mass Planet Orbiting Gl 785*, Andrew W. Howard, John Asher Johnson, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Howard Isaacson, Jeff A. Valenti, Jay Anderson, Nikolai Piskunov

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We report the discovery of planets orbiting two bright, nearby early K dwarf stars, HD 97658 and Gl 785. These planets were detected by Keplerian modeling of radial velocities measured with Keck-HIRES for the NASA-UC Eta-Earth Survey. HD 97658 b is a close-in super-Earth with minimum mass Msin i = 8.2 ± 1.2 M⊕, orbital period P = 9.494 ± 0.005 days, and an orbit that is consistent with circular. Gl 785 b is a Neptune-mass planet with Msin i = 21.6 ± 2.0 M⊕, P = 74.39 ± 0.12 days, and orbital eccentricity e = 0.30 ± 0.09. Photometric …

The Nasa-Uc Eta-Earth Program. Ii. A Planet Orbiting Hd 156668 With A Minimum Mass Of Four Earth Masses*, Andrew W. Howard, John Asher Johnson, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Howard Isaacson, Jeff A. Valenti, Jay Anderson, Nikolai Piskunov

Information Systems and Engineering Management Research Publications

We report the discovery of HD 156668 b, an extrasolar planet with a minimum mass of MPsin i = 4.15 M⊕. This planet was discovered through Keplerian modeling of precise radial velocities from Keck-HIRES and is the second super-Earth to emerge from the NASA-UC Eta-Earth Survey. The best-fit orbit is consistent with circular and has a period of P = 4.6455 days. The Doppler semi-amplitude of this planet, K = 1.89 m s−1, is among the lowest ever detected, on par with the detection of GJ 581 e using HARPS. A longer period (P ≈ 2.3 years), low-amplitude signal of …

Transit Spectrophotometry Of The Exoplanet Hd 189733b Ii. New Spitzer Observations At 3.6 Μm, Jean-Michel Désert, David K. Sing, Alfred Vidal-Madjar, Guillaume Hébrard, David Ehrenreich, Alain Lecavelier Des Etangs, Vivien Parmentier, Roger Ferlet, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Context. We present a new primary transit observation of the hot-jupiter HD 189733b, obtained at 3.6 μm with the Infrared Array Camera (IRAC) onboard the Spitzer Space Telescope. Previous measurements at 3.6 microns suffered from strong systematics, and conclusions could hardly be obtained with confidence on the water detection by comparison of the 3.6 and 5.8 microns observations.

Aims. We aim at constraining the atmospheric structure and composition of the planet and improving previously derived parameters.

Methods. We use a high-S/NSpitzer photometric transit light curve to improve the precision of the near infrared radius of …

Rotation Periods Of Exoplanet Host Stars, E. K. Simpson, Sallie L. Baliunas, Gregory W. Henry, Christopher A. Watson

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The stellar rotation periods of 10 exoplanet host stars have been determined using newly analysed Ca ii H&K flux records from the Mount Wilson Observatory and Strömgren b, y photometric measurements from Tennessee State University's automatic photometric telescopes at the Fairborn Observatory. Five of the rotation periods have not previously been reported, with that of HD 130322 very strongly detected at Prot= 26.1 ± 3.5 d. The rotation periods of five other stars have been updated using new data. We use the rotation periods to derive the line-of-sight inclinations of the stellar rotation axes, which may be used to probe …

The Lick–Carnegie Exoplanet Survey: A 3.1 M⊕ Planet In The Habitable Zone Of The Nearby M3v Star Gliese 581, Steve Vogt, R. Paul Butler, Eugenio J. Rivera, Nader Haghighipour, Gregory W. Henry, Michael H. Williamson

Information Systems and Engineering Management Research Publications

We present 11 years of HIRES precision radial velocities (RVs) of the nearby M3V star Gliese 581, combining our data set of 122 precision RVs with an existing published 4.3-year set of 119 HARPS precision RVs. The velocity set now indicates six companions in Keplerian motion around this star. Differential photometry indicates a likely stellar rotation period of ∼94 days and reveals no significant periodic variability at any of the Keplerian periods, supporting planetary orbital motion as the cause of all the RV variations. The combined data set strongly confirms the 5.37-day, 12.9-day, 3.15-day, and 67-day planets previously announced by …

Xmm-Newton Observations Of Hd 189733 During Planetary Transits, Ignazio Pillitteri, Scott J. Wolk, Ofer Cohen, Vinay Kashyap, Heather Knutson, Carey M. Lisse, Gregory W. Henry

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We report on two XMM-Newton observations of the planetary host star HD 189733. The system has a close in planet and it can potentially affect the coronal structure via interactions with the magnetosphere. We have obtained X-ray spectra and light curves from EPIC and the Reflection Grating Spectrometer on board XMM-Newton which we have analyzed and interpreted. We reduced X-ray data from the primary transit and secondary eclipse that occurred on 2007 April 17 and 2009 May 18, respectively. In the 2007 April observation, only variability due to weak flares is recognized. In 2009 HD 189733 exhibited an X-ray flux …

The Climate Of Hd 189733b From Fourteen Transits And Eclipses Measured By Spitzer, Eric Agol, Nicolas B. Cowan, Heather A. Knutson, Drake Deming, Jason H. Steffen, Gregory W. Henry, David Charbonneau

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We present observations of six transits and six eclipses of the transiting planet system HD 189733 taken with the Spitzer Space Telescope's Infrared Array Camera (IRAC) at 8 μm, as well as a re-analysis of previously published data. We use several novel techniques in our data analysis, the most important of which is a new correction for the detector "ramp" variation with a double-exponential function, which performs better and is a better physical model for this detector variation. Our main scientific findings are (1) an upper limit on the variability of the dayside planet flux of 2.7% (68% confidence); (2) …

The California Planet Survey. I. Four New Giant Exoplanets*, Andrew W. Howard, John Asher Johnson, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, David Bernat, Gregory W. Henry, Kathryn M. G. Peek, Howard Isaacson, Kevin Apps, Michael Endl, William D. Cochran, Jeff A. Valenti, Jay Anderson, Nikolai E. Piskunov

Information Systems and Engineering Management Research Publications

We present precise Doppler measurements of four stars obtained during the past decade at Keck Observatory by the California Planet Survey (CPS). These stars, namely, HD 34445, HD 126614, HD 13931, and Gl 179, all show evidence for a single planet in Keplerian motion. We also present Doppler measurements from the Hobby-Eberly Telescope (HET) for two of the stars, HD 34445 and Gl 179, that confirm the Keck detections and significantly refine the orbital parameters. These planets add to the statistical properties of giant planets orbiting near or beyond the ice line, and merit follow-up by astrometry, imaging, and space-borne …

On The Transit Potential Of The Planet Orbiting Iota Draconis, Stephen R. Kane, Sabine Reffert, Gregory W. Henry, Debra A. Fischer, Christian Schwab, Kelsey I. Clubb, Christoph Bergmann

Information Systems and Engineering Management Research Publications

Most of the known transiting exoplanets are in short-period orbits, largely due to the bias inherent in detecting planets through the transit technique. However, the eccentricity distribution of the known radial velocity planets results in many of those planets having a non-negligible transit probability. One such case is the massive planet orbiting the giant star iota Draconis, a situation where both the orientation of the planet's eccentric orbit and the size of the host star inflate the transit probability to a much higher value than for a typical hot Jupiter. Here we present a revised fit of the radial velocity …

The Lick-Carnegie Exoplanet Survey: A Saturn-Mass Planet In The Habitable Zone Of The Nearby M4v Star Hip 57050, Nader Haghighipour, Steve Vogt, R. Paul Butler, Eugenio J. Rivera, Gregory Laughlin, Stefano Meschiari, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Precision radial velocities (RV) from Keck/HIRES reveal a Saturn-mass planet orbiting the nearby M4V star HIP 57050. The planet has a minimum mass of Msin i ∼ 0.3 MJ, an orbital period of 41.4 days, and an orbital eccentricity of 0.31. V-band photometry reveals a clear stellar rotation signature of the host star with a period of 98 days, well separated from the period of the RV variations and reinforcing a Keplerian origin for the observed velocity variations. The orbital period of this planet corresponds to an orbit in the habitable zone of HIP 57050, with an expected planetary temperature …

Refined Stellar, Orbital And Planetary Parameters Of The Eccentric Hat-P-2 Planetary System, András Pál, Gáspár Á. Bakos, Guillermo Torres, Robert W. Noyes, Debra A. Fischer, John A. Johnson, Gregory W. Henry, R. Paul Butler, Geoffrey W. Marcy, Andrew W. Howard, Brigitta Sipőcz, David W. Latham, Gilbert A. Esquerdo

Information Systems and Engineering Management Research Publications

We present refined parameters for the extrasolar planetary system HAT-P-2 (also known as HD 147506), based on new radial velocity and photometric data. HAT-P-2b is a transiting extrasolar planet that exhibits an eccentric orbit. We present a detailed analysis of the planetary and stellar parameters, yielding consistent results for the mass and radius of the star, better constraints on the orbital eccentricity and refined planetary parameters. The improved parameters for the host star are M★= 1.36 ± 0.04 M⊙ and R★= 1.64 ± 0.08 R⊙, while the planet has a mass of Mp= 9.09 ± 0.24 MJup and radius of …

A Long-Period Planet Orbiting A Nearby Sun-Like Star, Hugh R. A. Jones, R. Paul Butler, Chris Tinney, Simon O'Toole, Rob Wittenmyer, Gregory W. Henry, Stefano Meschiari, Steve Vogt, Eugenio Rivera, Greg Laughlin, Brad D. Carter, Jeremy Bailey, James S. Jenkins

Information Systems and Engineering Management Research Publications

The Doppler wobble induced by the extra-solar planet HD 134987b was first detected by data from the Keck Telescope nearly a decade ago, and was subsequently confirmed by data from the Anglo-Australian Telescope (AAT). However, as more data have been acquired for this star over the years since, the quality of a single Keplerian fit to that data has been getting steadily worse. The best-fitting single Keplerian to the 138 Keck and AAT observations now in hand has an root-mean-square (rms) scatter of 6.6 m s−1. This is significantly in excess of both the instrumental precision achieved by both the …

A Super-Earth And Two Neptunes Orbiting The Nearby Sun-Like Star 61 Virginis, Steve Vogt, Robert A. Wittenmyer, R. Paul Butler, Simon O'Toole, Gregory W. Henry, Eugenio J. Rivera, Stefano Meschiari, Gregory Laughlin, Chris G. Tinney, Hugh R. A. Jones, Jeremy Bailey, Brad D. Carter, Konstantin Batygin

Information Systems and Engineering Management Research Publications

We present precision radial velocity data that reveal a multiple exoplanet system orbiting the bright nearby G5V star 61 Virginis. Our 4.6 years of combined Keck/HIRES and Anglo-Australian Telescope precision radial velocities indicate the hitherto unknown presence of at least three planets orbiting this well-studied star. These planets are all on low-eccentricity orbits with periods of 4.2, 38.0, and 124.0 days, and projected masses (Msin i) of 5.1, 18.2, and 24.0 M⊕, respectively. Test integrations of systems consistent with the radial velocity data suggest that the configuration is dynamically stable. Depending on the effectiveness of tidal dissipation within the inner …

A Super-Earth Orbiting The Nearby Sun-Like Star Hd 1461, Eugenio J. Rivera, R. Paul Butler, Steve Vogt, Gregory Laughlin, Gregory W. Henry, Stefano Meschiari

Information Systems and Engineering Management Research Publications

We present precision radial velocity (RV) data that reveal a Super-Earth mass planet and two probable additional planets orbiting the bright nearby G0V star HD 1461. Our 12.8 years of Keck High Resolution Echelle Spectrometer precision RVs indicate the presence of a 7.4 M⊕ planet on a 5.77 day orbit. The data also suggest, but cannot yet confirm, the presence of outer planets on low-eccentricity orbits with periods of 446.1 and 5017 days, and projected masses (Msin i) of 27.9 and 87.1 M⊕, respectively. Test integrations of systems consistent with the RV data suggest that the configuration is dynamically stable. …

Five Planets And An Independent Confirmation Of Hd 196885ab From Lick Observatory, Debra A. Fischer, Peter Driscoll, Howard Isaacson, Matthew J. Giguere, Geoffrey W. Marcy, Jeff A. Valenti, Jason T. Wright, Gregory W. Henry, John Asher Johnson, Andrew W. Howard, Kathryn M. G. Peek, Chris Mccarthy

Information Systems and Engineering Management Research Publications

We present time series Doppler data from Lick Observatory that reveal the presence of long-period planetary companions orbiting nearby stars. The typical eccentricity of these massive planets are greater than the mean eccentricity of known exoplanets. HD 30562b has Msin i = 1.29 MJup, with semimajor axis of 2.3 AU and eccentricity 0.76. The host star has a spectral type F8V and is metal rich. HD 86264b has Msin i = 7.0 MJup, arel = 2.86 AU, an eccentricity e = 0.7 and orbits a metal-rich, F7V star. HD 87883b has Msin i = 1.78 MJup, arel = 3.6 AU, …

The 8 Μm Phase Variation Of The Hot Saturn Hd 149026b, Heather Knutson, David Charbonneau, Nicolas B. Cowan, Jonathan J. Fortney, Adam P. Showman, Eric Agol, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We monitor the star HD 149026 and its Saturn-mass planet at 8.0 μm over slightly more than half an orbit using the Infrared Array Camera on the Spitzer Space Telescope. We find an increase of 0.0227% ± 0.0066% (3.4σ significance) in the combined planet–star flux during this interval. The minimum flux from the planet is 45% ± 19% of the maximum planet flux, corresponding to a difference in brightness temperature of 480 ± 140 K between the two hemispheres. We derive a new secondary eclipse depth of 0.0411% ± 0.0076% in this band, corresponding to a dayside brightness temperature of …

Two Exoplanets Discovered At Keck Observatory, Jeff A. Valenti, Debra A. Fischer, Geoffrey W. Marcy, John Asher Johnson, Gregory W. Henry, Jason T. Wright, Andrew W. Howard, Matthew J. Giguere, Howard Isaacson

Information Systems and Engineering Management Research Publications

We present two exoplanets detected at Keck Observatory. HD 179079 is a G5 subgiant that hosts a hot Neptune planet with M sin i = 27.5 M⊕ in a 14.48 days, low-eccentricity orbit. The stellar reflex velocity induced by this planet has a semiamplitude of K = 6.6 m s−1. HD 73534 is a G5 subgiant with a Jupiter-like planet of M sin i = 1.1 MJup and K = 16 m s−1 in a nearly circular 4.85 yr orbit. Both stars are chromospherically inactive and metal-rich. We discuss a known, classical bias in measuring eccentricities for orbits with velocity …

Transit Spectrophotometry Of The Exoplanet Hd 189733b I. Searching For Water But Finding Haze With Hst Nicmos, David K. Sing, Jean-Michel Désert, Alain Lecavelier Des Etangs, Gilda E. Ballester, Alfred Vidal-Madjar, Vivien Parmentier, Guillaume Hébrard, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We present Hubble Space Telescope near-infrared transit photometry of the nearby hot-Jupiter HD 189733b. The observations were taken with the NICMOS instrument during five transits, with three transits executed with a narrowband filter at 1.87 m and two performed with a narrowband filter at 1.66 m. Our observing strategy using narrowband filters is insensitive to the usual HST intra-orbit and orbit-to-orbit measurement of systematic errors, allowing us to accurately and robustly measure the near-IR wavelength dependance of the planetary radius. Our measurements fail to reproduce the previously claimed detection of an absorption signature of atmospheric H₂O below …

A Third Giant Planet Orbiting Hip 14810, Jason T. Wright, Debra A. Fischer, Eric B. Ford, Dimitri Veras, Ji Wang, Gregory W. Henry, Geoffrey W. Marcy, Andrew W. Howard, John Asher Johnson

Information Systems and Engineering Management Research Publications

We present new precision radial velocities and a three-planet Keplerian orbit fit for the V = 8.5, G5 V star HIP 14810. We began observing this star at Keck Observatory as part of the N2K Planet Search Project. Wright et al. announced the inner two planets to this system, and subsequent observations have revealed the outer planet and the proper orbital solution for the middle planet. The planets have minimum masses of 3.9, 1.3, and 0.6 MJup and orbital periods of 6.67, 147.7, and 952 day, respectively. We have numerically integrated the family of orbital solutions consistent with the data …

A Search For Multi-Planet Systems Using The Hobby–Eberly Telescope, Robert A. Wittenmyer, Michael Endl, William D. Cochran, Harold F. Levison, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Extrasolar multiple-planet systems provide valuable opportunities for testing theories of planet formation and evolution. The architectures of the known multiple-planet systems demonstrate a fascinating level of diversity, which motivates the search for additional examples of such systems in order to better constrain their formation and dynamical histories. Here we describe a comprehensive investigation of 22 planetary systems in an effort to answer three questions: (1) are there additional planets? (2) where could additional planets reside in stable orbits? and (3) what limits can these observations place on such objects? We find no evidence for additional bodies in any of these …

The Nasa-Uc Eta-Earth Program. I. A Super-Earth Orbiting Hd 7924, Andrew W. Howard, John Asher Johnson, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Matthew J. Giguere, Howard Isaacson, Jeff A. Valenti, Jay Anderson, Nikolai Piskunov

Information Systems and Engineering Management Research Publications

We report the discovery of the first low-mass planet to emerge from the NASA-UC Eta-Earth Program, a super-Earth orbiting the K0 dwarf HD 7924. Keplerian modeling of precise Doppler radial velocities reveals a planet with minimum mass MPsin i = 9.26 M⊕ in a P = 5.398 d orbit. Based on Keck-HIRES measurements from 2001 to 2008, the planet is robustly detected with an estimated false alarm probability of less than 0.001. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 7924 is photometrically constant over the radial velocity period to 0.19 mmag, supporting the existence …

The Transit Light Curve Project. X. A Christmas Transit Of Hd 17156b, Joshua N. Winn, Matthew J. Holman, Gregory W. Henry, Guillermo Torres, Debra A. Fischer, John Asher Johnson, Geoffrey W. Marcy, Avi Shporer, Tsevi Mazeh

Information Systems and Engineering Management Research Publications

Photometry is presented of the 2007 December 25 transit of HD 17156b, which has the longest orbital period and highest orbital eccentricity of all the known transiting exoplanets. New measurements of the stellar radial velocity are also presented. All the data are combined and integrated with stellar-evolutionary modeling to derive refined system parameters. The planet's mass and radius are found to be 3.212+0.069−0.082 MJup and 1.023+0.070−0.055 RJup. The corresponding stellar properties are 1.263+0.035−0.047 M☉ and 1.446+0.099−0.067 R☉. The planet is smaller by 1σ than a theoretical solar-composition gas giant with the same mass and equilibrium temperature, a possible indication of …

Discovery Of A Low-Mass Companion To The Solar-Type Star Tyc 2534-698-1, Stephen R. Kane, Suvrath Mahadevan, William D. Cochran, Rachel A. Street, Sivarani Thirupathi, Gregory W. Henry, Michael H. Williamson

Information Systems and Engineering Management Research Publications

Brown dwarfs and low-mass stellar companions are interesting objects to study since they occupy the mass region between deuterium and hydrogen burning. We report here the serendipitous discovery of a low-mass companion in an eccentric orbit around a solar-type main-sequence star. The stellar primary, TYC 2534-698-1, is a G2V star that was monitored both spectroscopically and photometrically over the course of several months. Radial velocity observations indicate a minimum mass of 0.037 M☉ and an orbital period of ∼103 days for the companion. Photometry outside of the transit window shows the star to be stable to within ∼6 millimags. The …

Multiwavelength Constraints On The Day–Night Circulation Patterns Of Hd 189733b, Heather Knutson, David Charbonneau, Nicolas B. Cowan, Jonathan J. Fortney, Adam P. Showman, Eric Agol, Gregory W. Henry, Mark E. Everett, Lori E. Allen

Information Systems and Engineering Management Research Publications

We present new Spitzer observations of the phase variation of the hot Jupiter HD 189733b in the MIPS 24 μm bandpass, spanning the same part of the planet's orbit as our previous observations in the IRAC 8 μm bandpass (Knutson et al. 2007). We find that the minimum hemisphere-averaged flux from the planet in this bandpass is 76% ± 3% of the maximum flux; this corresponds to minimum and maximum hemisphere-averaged brightness temperatures of 984 ± 48 K and 1220 ±  47 K, respectively. The planet reaches its maximum flux at an orbital phase of 0.396 ± 0.022, corresponding to …

Five New Transits Of The Super-Neptune Hd 149026b, Joshua N. Winn, Gregory W. Henry, Guillermo Torres, Matthew J. Holman

Information Systems and Engineering Management Research Publications

We present new photometry of HD 149026 spanning five transits of its "super-Neptune" planet. In combination with previous data, we improve on the determination of the planet-to-star radius ratio: Rp/R⋆ = 0.0491+ 0.0018−0.0005. We find the planetary radius to be 0.71 ± 0.05 RJup, in accordance with previous theoretical models invoking a high metal abundance for the planet. The limiting error is the uncertainty in the stellar radius. Although we find agreement among four different ways of estimating the stellar radius, the uncertainty remains at 7%. We also present a refined transit ephemeris and a constraint on the orbital eccentricity …