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Andrew W Howard - One of the best experts on this subject based on the ideXlab platform.
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wasp 4 is accelerating toward the earth
arXiv: Earth and Planetary Astrophysics, 2020Co-Authors: L G Bouma, Joshua N. Winn, Andrew W Howard, Howard Isaacson, Steve B Howell, Heather A Knutson, Rachel A MatsonAbstract:The orbital period of the hot Jupiter WASP-4b appears to be decreasing at a rate of $-8.64 \pm 1.26$ msec/yr, based on transit-timing measurements spanning 12 years. Proposed explanations for the period change include tidal orbital decay, apsidal precession, and acceleration of the system along the line of sight. To investigate further, we performed new radial velocity measurements and speckle imaging of WASP-4. The radial-velocity data show that the system is accelerating towards the Sun at a rate of $-0.0422\pm 0.0028$ m/s/day. The associated Doppler effect should cause the apparent period to shrink at a rate of $-5.94 \pm 0.39$ msec/yr, comparable to the observed rate. Thus, the observed change in the transit period is mostly or entirely produced by the line-of-sight acceleration of the system. This acceleration is probably caused by a wide-orbiting companion of mass 10-300$\,M_{\rm Jup}$ and orbital distance 10-100$\,$AU, based on the magnitude of the radial-velocity trend and the non-detection of any companion in the speckle images. We expect that the orbital periods of 1 out of 3 hot Jupiters will change at rates similar to WASP-4b, based on the hot-Jupiter companion statistics of Knutson et al. (2014). Continued radial velocity monitoring of hot Jupiters is therefore essential to distinguish the effects of tidal orbital decay or apsidal precession from line-of-sight acceleration.
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absence of a metallicity effect for ultra short period planets
The Astronomical Journal, 2017Co-Authors: Joshua N. Winn, Roberto Sanchisojeda, Andrew W Howard, Leslie A Rogers, Erik A Petigura, Howard Isaacson, Geoffrey W Marcy, Kevin C Schlaufman, Phillip A Cargile, Leslie HebbAbstract:Ultra-short-period (USP) planets are a newly recognized class of planets with periods shorter than one day and radii smaller than about 2 R⊕. It has been proposed that USP planets are the solid cores of hot Jupiters that have lost their gaseous envelopes due to photo-evaporation or Roche lobe overflow. We test this hypothesis by asking whether USP planets are associated with metal-rich stars, as has long been observed for hot Jupiters. We find the metallicity distributions of USP-planet and hot-Jupiter hosts to be significantly different (p = 3 × 10^(−4)) based on Keck spectroscopy of Keplerstars. Evidently, the sample of USP planets is not dominated by the evaporated cores of hot Jupiters. The metallicity distribution of stars with USP planets is indistinguishable from that of stars with short-period planets with sizes between 2 and 4 R⊕. Thus, it remains possible that the USP planets are the solid cores of formerly gaseous planets that are smaller than Neptune.
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friends of hot Jupiters ii no correspondence between hot Jupiter spin orbit misalignment and the incidence of directly imaged stellar companions
The Astrophysical Journal, 2015Co-Authors: Henry Ngo, Justin R Crepp, Andrew W Howard, Sasha Hinkley, Heather Knutson, Eric B Bechter, Konstantin Batygin, John A Johnson, Timothy D MortonAbstract:Multi-star systems are common, yet little is known about a stellar companion's influence on the formation and evolution of planetary systems. For instance, stellar companions may have facilitated the inward migration of hot Jupiters toward to their present day positions. Many observed short-period gas giant planets also have orbits that are misaligned with respect to their star's spin axis, which has also been attributed to the presence of a massive outer companion on a non-coplanar orbit. We present the results of a multi-band direct imaging survey using Keck NIRC2 to measure the fraction of short-period gas giant planets found in multi-star systems. Over three years, we completed a survey of 50 targets ("Friends of Hot Jupiters") with 27 targets showing some signature of multi-body interaction (misaligned or eccentric orbits) and 23 targets in a control sample (well-aligned and circular orbits). We report the masses, projected separations, and confirmed common proper motion for the 19 stellar companions found around 17 stars. Correcting for survey incompleteness, we report companion fractions of 48% ± 9%, 47% ± 12%, and 51% ± 13% in our total, misaligned/eccentric, and control samples, respectively. This total stellar companion fraction is 2.8σ larger than the fraction of field stars with companions approximately 50-2000 AU. We observe no correlation between misaligned/eccentric hot Jupiter systems and the incidence of stellar companions. Combining this result with our previous radial velocity survey, we determine that 72% ± 16% of hot Jupiters are part of multi-planet and/or multi-star systems.
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friends of hot Jupiters i a radial velocity search for massive long period companions to close in gas giant planets
The Astrophysical Journal, 2014Co-Authors: Heather A Knutson, Justin R Crepp, Andrew W Howard, Benjamin T Montet, Benjamin J Fulton, Melodie M Kao, Henry Ngo, Sasha Hinkley, G A BakosAbstract:In this paper we search for distant massive companions to known transiting hot Jupiters that may have influenced the dynamical evolution of these systems. We present new radial velocity observations for a sample of 51 hot Jupiters obtained using the Keck HIRES instrument, and use these observations to search for long-term radial velocity accelerations. We find new, statistically significant accelerations in seven systems, including: HAT-P-10, HAT-P-20, HAT-P-22, HAT-P-29, HAT-P-32, WASP-10, and XO-2. We combine our radial velocity fits with Keck NIRC2 AO imaging data to place constraints on the allowed masses and orbital periods of the companions. The estimated masses of the companions range between 1-500 M_(Jup), with orbital semi-major axes typically between 1-75 AU. A significant majority of the companions detected by our survey are constrained to have minimum masses comparable to or larger than those of the short-period hot Jupiters in these systems, making them candidates for influencing the orbital evolution of the inner hot Jupiters. They also appear to occur preferentially in systems with more metal-rich host stars, and with typical orbital separations that are larger than those of multi-planet systems without hot Jupiters. We estimate a total occurrence rate of 55% +11% / -10% for companions with masses between 1-13 M_(Jup) and orbital semi-major axes between 1-20 AU in our sample. We find no statistically significant difference between the frequency of companions in hot Jupiter systems with misaligned or eccentric orbits and those with well-aligned, circular orbits. We combine our expanded sample of radial velocity measurements with constraints from transit and secondary eclipse observations to provide improved measurements of the physical and orbital characteristics of all of the hot Jupiters included in our survey.
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the mass of koi 94d and a relation for planet radius mass and incident flux
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: Lauren M Weiss, Jonathan J Fortney, Andrew W Howard, Howard Isaacson, Geoffrey W Marcy, Debra A Fischer, Jason F Rowe, Neil Miller, Briceolivier Demory, Elisabeth R AdamsAbstract:We measure the mass of a modestly irradiated giant planet, KOI-94d. We wish to determine whether this planet, which is in a 22-day orbit and receives 2700 times as much incident flux as Jupiter, is as dense as Jupiter or rarefied like inflated hot Jupiters. KOI-94 also hosts 3 smaller transiting planets, all of which were detected by the Kepler Mission. With 26 radial velocities of KOI-94 from the W. M. Keck Observatory and a simultaneous fit to the Kepler light curve, we measure the mass of the giant planet and determine that it is not inflated. Support for the planetary interpretation of the other three candidates comes from gravitational interactions through transit timing variations, the statistical robustness of multi-planet systems against false positives, and several lines of evidence that no other star resides within the photometric aperture. The radial velocity analyses of KOI-94b and KOI-94e offer marginal (>2\sigma) mass detections, whereas the observations of KOI-94c offer only an upper limit to its mass. Using the KOI-94 system and other planets with published values for both mass and radius (138 exoplanets total, including 35 with M < 150 Earth masses), we establish two fundamental planes for exoplanets that relate their mass, incident flux, and radius from a few Earth masses up to ten Jupiter masses. These equations can be used to predict the radius or mass of a planet.
Erik A Petigura - One of the best experts on this subject based on the ideXlab platform.
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a warm Jupiter sized planet transiting the pre main sequence star v1298 tau
The Astronomical Journal, 2019Co-Authors: Trevor J David, Ann Marie Cody, Christina Hedges, Eric E Mamajek, Lynne A Hillenbrand, David R Ciardi, Charles A Beichman, Erik A PetiguraAbstract:We report the detection of V1298 Tau b, a warm Jupiter-sized planet (R_P = 0.91 ± 0.05 R_(Jup), P = 24.1 days) transiting a young solar analog with an estimated age of 23 Myr. The star and its planet belong to Group 29, a young association in the foreground of the Taurus–Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5%), host star brightness (K_s = 8.1 mag), and rapid stellar rotation (v sin i = 23 km s^(−1)). Although the planet is Jupiter-sized, its mass is currently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
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a warm Jupiter sized planet transiting the pre main sequence star v1298 tau
arXiv: Earth and Planetary Astrophysics, 2019Co-Authors: Trevor J David, Ann Marie Cody, Christina Hedges, Eric E Mamajek, Lynne A Hillenbrand, David R Ciardi, Charles A Beichman, Erik A PetiguraAbstract:We report the detection of V1298 Tau b, a warm Jupiter-sized planet ($R_P$ = 0.91 $\pm$ 0.05~ $R_\mathrm{Jup}$, $P = 24.1$ days) transiting a young solar analog with an estimated age of 23 million years. The star and its planet belong to Group 29, a young association in the foreground of the Taurus-Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5\%), host star brightness ($K_s$ = 8.1 mag), and rapid stellar rotation ($v\sin{i}$ = 23 \kms). Although the planet is Jupiter-sized, its mass is presently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
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absence of a metallicity effect for ultra short period planets
The Astronomical Journal, 2017Co-Authors: Joshua N. Winn, Roberto Sanchisojeda, Andrew W Howard, Leslie A Rogers, Erik A Petigura, Howard Isaacson, Geoffrey W Marcy, Kevin C Schlaufman, Phillip A Cargile, Leslie HebbAbstract:Ultra-short-period (USP) planets are a newly recognized class of planets with periods shorter than one day and radii smaller than about 2 R⊕. It has been proposed that USP planets are the solid cores of hot Jupiters that have lost their gaseous envelopes due to photo-evaporation or Roche lobe overflow. We test this hypothesis by asking whether USP planets are associated with metal-rich stars, as has long been observed for hot Jupiters. We find the metallicity distributions of USP-planet and hot-Jupiter hosts to be significantly different (p = 3 × 10^(−4)) based on Keck spectroscopy of Keplerstars. Evidently, the sample of USP planets is not dominated by the evaporated cores of hot Jupiters. The metallicity distribution of stars with USP planets is indistinguishable from that of stars with short-period planets with sizes between 2 and 4 R⊕. Thus, it remains possible that the USP planets are the solid cores of formerly gaseous planets that are smaller than Neptune.
Eric E Mamajek - One of the best experts on this subject based on the ideXlab platform.
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a warm Jupiter sized planet transiting the pre main sequence star v1298 tau
The Astronomical Journal, 2019Co-Authors: Trevor J David, Ann Marie Cody, Christina Hedges, Eric E Mamajek, Lynne A Hillenbrand, David R Ciardi, Charles A Beichman, Erik A PetiguraAbstract:We report the detection of V1298 Tau b, a warm Jupiter-sized planet (R_P = 0.91 ± 0.05 R_(Jup), P = 24.1 days) transiting a young solar analog with an estimated age of 23 Myr. The star and its planet belong to Group 29, a young association in the foreground of the Taurus–Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5%), host star brightness (K_s = 8.1 mag), and rapid stellar rotation (v sin i = 23 km s^(−1)). Although the planet is Jupiter-sized, its mass is currently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
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a warm Jupiter sized planet transiting the pre main sequence star v1298 tau
arXiv: Earth and Planetary Astrophysics, 2019Co-Authors: Trevor J David, Ann Marie Cody, Christina Hedges, Eric E Mamajek, Lynne A Hillenbrand, David R Ciardi, Charles A Beichman, Erik A PetiguraAbstract:We report the detection of V1298 Tau b, a warm Jupiter-sized planet ($R_P$ = 0.91 $\pm$ 0.05~ $R_\mathrm{Jup}$, $P = 24.1$ days) transiting a young solar analog with an estimated age of 23 million years. The star and its planet belong to Group 29, a young association in the foreground of the Taurus-Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5\%), host star brightness ($K_s$ = 8.1 mag), and rapid stellar rotation ($v\sin{i}$ = 23 \kms). Although the planet is Jupiter-sized, its mass is presently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
Charles A Beichman - One of the best experts on this subject based on the ideXlab platform.
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a warm Jupiter sized planet transiting the pre main sequence star v1298 tau
The Astronomical Journal, 2019Co-Authors: Trevor J David, Ann Marie Cody, Christina Hedges, Eric E Mamajek, Lynne A Hillenbrand, David R Ciardi, Charles A Beichman, Erik A PetiguraAbstract:We report the detection of V1298 Tau b, a warm Jupiter-sized planet (R_P = 0.91 ± 0.05 R_(Jup), P = 24.1 days) transiting a young solar analog with an estimated age of 23 Myr. The star and its planet belong to Group 29, a young association in the foreground of the Taurus–Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5%), host star brightness (K_s = 8.1 mag), and rapid stellar rotation (v sin i = 23 km s^(−1)). Although the planet is Jupiter-sized, its mass is currently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
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a warm Jupiter sized planet transiting the pre main sequence star v1298 tau
arXiv: Earth and Planetary Astrophysics, 2019Co-Authors: Trevor J David, Ann Marie Cody, Christina Hedges, Eric E Mamajek, Lynne A Hillenbrand, David R Ciardi, Charles A Beichman, Erik A PetiguraAbstract:We report the detection of V1298 Tau b, a warm Jupiter-sized planet ($R_P$ = 0.91 $\pm$ 0.05~ $R_\mathrm{Jup}$, $P = 24.1$ days) transiting a young solar analog with an estimated age of 23 million years. The star and its planet belong to Group 29, a young association in the foreground of the Taurus-Auriga star-forming region. While hot Jupiters have been previously reported around young stars, those planets are non-transiting and near-term atmospheric characterization is not feasible. The V1298 Tau system is a compelling target for follow-up study through transmission spectroscopy and Doppler tomography owing to the transit depth (0.5\%), host star brightness ($K_s$ = 8.1 mag), and rapid stellar rotation ($v\sin{i}$ = 23 \kms). Although the planet is Jupiter-sized, its mass is presently unknown due to high-amplitude radial velocity jitter. Nevertheless, V1298 Tau b may help constrain formation scenarios for at least one class of close-in exoplanets, providing a window into the nascent evolution of planetary interiors and atmospheres.
John Asher Johnson - One of the best experts on this subject based on the ideXlab platform.
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wasp 12b and hat p 8b are members of triple star systems
arXiv: Earth and Planetary Astrophysics, 2013Co-Authors: Eric B Bechter, John Asher Johnson, Justin R Crepp, Heather A Knutson, Henry Ngo, Sasha Hinkley, Konstantin Batygin, Philip S MuirheadAbstract:We present high spatial resolution images that demonstrate the hot Jupiters WASP-12b and HAT-P-8b orbit the primary star of hierarchical triple star systems. In each case, two distant companions with colors and brightness consistent with M dwarfs co-orbit the planet host as well as one another. Our adaptive optics images spatially resolve the secondary around WASP-12, previously identified by Bergfors et al. 2011 and Crossfield et al. 2012, into two distinct sources separated by 84.3+/-0.6 mas (21 +/- 3 AU). We find that the secondary to HAT-P-8, also identified by Bergfors et al. 2011, is in fact composed of two stars separated by 65.3+/-0.5 mas (15+/-1 AU). Our follow-up observations demonstrate physical association through common proper-motion. HAT-P-8 C has a particularly low mass, which we estimate to be 0.18+/-0.02Msun using photometry. Due to their hierarchy, WASP-12 BC and HAT-P-8 BC will enable the first dynamical mass determination for hot Jupiter stellar companions. These previously well-studied planet hosts now represent higher-order multi-star systems with potentially complex dynamics, underscoring the importance of diffraction-limited imaging and providing additional context for understanding the migrant population of transiting hot Jupiters.
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the photoeccentric effect and proto hot Jupiters ii koi 1474 01 a candidate eccentric planet perturbed by an unseen companion
The Astrophysical Journal, 2012Co-Authors: Rebekah I Dawson, Daniel C Fabrycky, John Asher Johnson, Timothy D Morton, Justin R Crepp, Ruth Murrayclay, Andrew W HowardAbstract:The exoplanets known as hot Jupiters—Jupiter-sized planets with periods of less than 10 days—likely are relics of dynamical processes that shape all planetary system architectures. Socrates et al. argued that high eccentricity migration (HEM) mechanisms proposed for situating these close-in planets should produce an observable population of highly eccentric proto-hot Jupiters that have not yet tidally circularized. HEM should also create failed-hot Jupiters, with periapses just beyond the influence of fast circularization. Using the technique we previously presented for measuring eccentricities from photometry (the "photoeccentric effect"), we are distilling a collection of eccentric proto- and failed-hot Jupiters from the Kepler Objects of Interest (KOI). Here, we present the first, KOI-1474.01, which has a long orbital period (69.7340 days) and a large eccentricity e = 0.81^(+0.10)_(–0.07), skirting the proto-hot Jupiter boundary. Combining Kepler photometry, ground-based spectroscopy, and stellar evolution models, we characterize host KOI-1474 as a rapidly rotating F star. Statistical arguments reveal that the transiting candidate has a low false-positive probability of 3.1%. KOI-1474.01 also exhibits transit-timing variations of the order of an hour. We explore characteristics of the third-body perturber, which is possibly the "smoking-gun" cause of KOI-1474.01's large eccentricity. We use the host star's period, radius, and projected rotational velocity to measure the inclination of the stellar spin. Comparing KOI 1474.01's inclination, we find that its orbit is marginally consistent with being aligned with the stellar spin axis, although a reanalysis is warranted with future additional data. Finally, we discuss how the number and existence of proto-hot Jupiters will not only demonstrate that hot Jupiters migrate via HEM, but also shed light on the typical timescale for the mechanism.
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the photoeccentric effect and proto hot Jupiters ii koi 1474 01 a candidate eccentric planet perturbed by an unseen companion
arXiv: Earth and Planetary Astrophysics, 2012Co-Authors: Rebekah I Dawson, Daniel C Fabrycky, John Asher Johnson, Timothy D Morton, Justin R Crepp, Ruth Murrayclay, Andrew W HowardAbstract:The exoplanets known as hot Jupiters---Jupiter-sized planets with periods less than 10 days---likely are relics of dynamical processes that shape all planetary system architectures. Socrates et al. (2012) argued that high eccentricity migration (HEM) mechanisms proposed for situating these close-in planets should produce an observable population of highly eccentric proto-hot Jupiters that have not yet tidally circularized. HEM should also create failed-hot Jupiters, with periapses just beyond the influence of fast circularization. Using the technique we previously presented for measuring eccentricities from photometry (the "photoeccentric effect"), we are distilling a collection of eccentric proto- and failed-hot Jupiters from the Kepler Objects of Interest (KOI). Here we present the first, KOI-1474.01, which has a long orbital period (69.7340 days) and a large eccentricity e = 0.81+0.10/-0.07, skirting the proto-hot Jupiter boundary. Combining Kepler photometry, ground-based spectroscopy, and stellar evolution models, we characterize host KOI-1474 as a rapidly-rotating F-star. Statistical arguments reveal that the transiting candidate has a low false-positive probability of 3.1%. KOI-1474.01 also exhibits transit timing variations of order an hour. We explore characteristics of the third-body perturber, which is possibly the "smoking-gun" cause of KOI-1474.01's large eccentricity. Using the host-star's rotation period, radius, and projected rotational velocity, we find KOI-1474.01's orbit is marginally consistent with aligned with the stellar spin axis, although a reanalysis is warranted with future additional data. Finally, we discuss how the number and existence of proto-hot Jupiters will not only demonstrate that hot Jupiters migrate via HEM, but also shed light on the typical timescale for the mechanism.
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a third exoplanetary system with misaligned orbital and stellar spin axes
arXiv: Earth and Planetary Astrophysics, 2009Co-Authors: John Asher Johnson, Joshua N. Winn, Andrew W Howard, Geoffrey W Marcy, Simon Albrecht, Zachary J GazakAbstract:We present evidence that the WASP-14 exoplanetary system has misaligned orbital and stellar-rotational axes, with an angle lambda = 33.1 +/- 7.4 deg between their sky projections. The evidence is based on spectroscopic observations of the Rossiter-McLaughlin effect as well as new photometric observations. WASP-14 is now the third system known to have a significant spin-orbit misalignment, and all three systems have "super-Jupiter" planets (M_P > 3 Mjup) and eccentric orbits. This finding suggests that the migration and subsequent orbital evolution of massive, eccentric exoplanets is somehow different from that of less massive close-in Jupiters, the majority of which have well-aligned orbits.
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A Third Exoplanetary System with Misaligned Orbital and Stellar Spin Axes
Publications of the Astronomical Society of the Pacific, 2009Co-Authors: John Asher Johnson, Joshua N. Winn, Andrew W Howard, Geoffrey W Marcy, Simon Albrecht, J. Zachary GazakAbstract:We present evidence that the WASP-14 exoplanetary system has misaligned orbital and stellar-rotational axes, with an angle λ = -33.1° ± 7.4° between their sky projections. The evidence is based on spectroscopic observations of the Rossiter-McLaughlin effect as well as new photometric observations. WASP-14 is now the third system known to have a significant spin-orbit misalignment, and all three systems have “super-Jupiter” planets (M_P > 3 M_(Jup)) and eccentric orbits. This finding suggests that the migration and subsequent orbital evolution of massive, eccentric exoplanets is somehow different from that of less massive close-in Jupiters, the majority of which have well-aligned orbits.