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1

Search for Planets in Hot Jupiter Systems with Multi-Sector TESS Photometry. III. A Study of Ten Systems Enhanced with New Ground-Based Photometry

Maciejewski G., Fernández M., Sota A., Amado P. J., Ohlert J., Bischoff ., Stenglein W., Mugrauer M., Michel K.-U., Golonka J., Blanco Solsona A., Lapeña E., Molins Freire J., de los Ríos Curieses A., Temprano Sicilia J. A.

Acta Astronomica

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2023

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Vol. 73, No. 1

57--86

EN

The loneliness of hot Jupiters supports the high-eccentricity migration as a primary path leading to the formation of systems with those planets stripped of any close-in planetary companions. Here we present the null results of searches for low-mass planets close to hot Jupiters in 10 planetary systems: HAT-P-4, HAT-P-10, HAT-P-12, HAT-P-17, HAT-P-19, HAT-P-32, HAT-P-44, Qatar-6, TrES-4, and WASP-48. We employed multi-sector time-series photometry from the Transiting Exoplanet Survey Satellite enhanced with new ground-based transit light curves to determine the sizes of hypothetical planets that might still avoid being detected. We redetermined transit parameters for the known hot Jupiters using a homogeneous approach. We refuted transit timing variations for HAT-P-12 b, claimed recently in the literature. The transit timing data permitted us to place tighter constraints on third bodies in HAT-P-19 and HAT-P-32 systems detected in Doppler measurements. We also study four multi-periodic pulsating variable stars in the field around HAT-P-17.

2

Candidates for Transiting Planets in OGLE-IV Galactic Bulge Fields

Mróz M., Pietrukowicz P., Poleski R., Udalski A., Szymański M. K., Gromadzki M., Ulaczyk K., Kozłowski S., Skowron J., Skowron D. M., Soszyński I., Mróz P., Ratajczak M., Rybicki K. A., Iwanek P., Wrona M.

Acta Astronomica

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2023

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Vol. 73, No. 2

127--158

EN

We present results of a search for transiting exoplanets in 10-yr long photometry with thousands of epochs taken in the direction of the Galactic bulge. This photometry was collected in the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV). Our search covered ≈222 000 stars brighter than I=15.5 mag. Selected transits were verified using a probabilistic method. The search resulted in 99 high-probability candidates for transiting exoplanets. The estimated distances to these targets are between 0.4 kpc and 5.5 kpc, which is a significantly wider range than for previous transit searches. The planets found are Jupiter-size, with the exception of one (named OGLE-TR-1003b) located in the hot Neptune desert. If the candidate is confirmed, it can be important for studies of highly irradiated intermediate-size planets. The existing long-term, high-cadence photometry of our candidates increases the chances of detecting transit timing variations at long timescales. Selected candidates will be observed by the future NASA flagship mission, the Nancy Grace Roman Space Telescope, in its search for Galactic bulge microlensing events, which will further enhance the photometric coverage of these stars.

3

HD 17092 b Revisited

Adamów M., Niedzielski A. T., Wolszczan A., Maciejewski G.

Acta Astronomica

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2022

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Vol. 72, No. 4

257--266

EN

We present previously unpublished precise radial velocity measurements for HD 17092 and updated keplerian parameters of its low-mass companion HD 17092 b.

4

Wide-Orbit Exoplanets are Common. Analysis of Nearly 20 Years of OGLE Microlensing Survey Data

Poleski R., Skowron J., Mróz P., Udalski A., Szymański M. K., Pietrukowicz P., Ulaczyk K., Rybicki K., Iwanek P., Wrona M., Gromadzki M.

Acta Astronomica

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2021

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Vol. 71, No. 1

1--23

EN

We use nearly 20 yr of photometry obtained by the OGLE survey to measure the occurrence rate of wide-orbit (or ice giant) microlensing planets, i.e., with separations from ≈5 a.u. to ≈15 a.u. and mass-ratios from 10-4 to 0.033. In a sample of 3112 events we find six previously known wide-orbit planets and a new microlensing planet or brown dwarf OGLE-2017-BLG-0114Lb, for which close and wide orbits are possible and close orbit is preferred. We run extensive simulations of the planet detection efficiency, robustly taking into account the finite-source effects. We find that the extrapolation of the previously measured rate of microlensing planets significantly under-predicts the number of wide-orbit planets. On average, every microlensing star hosts 1.4+0.9_-0.6 ice giant planets.

5

Massive Search for Spot- and Facula-Crossing Events in 1598 Exoplanetary Transit Light Curves

Baluev R. V., Sokov E. N., Sokova I. A., Shaidulin V. Sh., Veselova A. V., Aitov V. N., Mitiani G. Sh., Valeev A. F., Gadelshin D. R., Gutaev A. G., Beskin G. M., Valyavin G. G., Antonyuk K., Barkaoui K., Gillon M., Jehin E., Delrez L., Guðmundsson S., Dale H. A., Fernández-Lajús E., Di Sisto R. P., Bretton M., Wunsche A., Hentunen V.-P., Shadick S., Jongen Y., Kang W., Kim T., Pakštienė E., Qvam J. K. T., Knight C. R., Guerra P., Marchini A., Salvaggio F., Papini R., Evans P., Salisbury M., Garlitz J., Esseiva N., Ogmen Y., Bosch-Cabot P., Selezneva A., Hinse T. C.

Acta Astronomica

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2021

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Vol. 71, No. 1

25--53

EN

We developed a dedicated statistical test for a massive detection of spot- and facula-crossing anomalies in multiple exoplanetary transit light curves, based on the frequentist p-value thresholding. This test was used to augment our algorithmic pipeline for transit light curves analysis. It was applied to 1598 amateur and professional transit observations of 26 targets being monitored in the EXPANSION project. We detected 109 statistically significant candidate events revealing a roughly 2:1 asymmetry in favor of spots-crossings over faculae-crossings. Although some candidate anomalies likely appear non-physical and originate from systematic errors, such asymmetry between negative and positive events should indicate a physical difference between the frequency of star spots and faculae. Detected spot-crossing events also reveal positive correlation between their amplitude and width, possibly due to spot size correlation. However, the frequency of all detectable crossing events appears just about a few per cent, so they cannot explain excessive transit timing noise observed for several targets.

6

Analysis of the Most Precise Light Curves of HAT-P-36 Detrended from Spot Signals

Yalçınkaya S., Baştürk Ö., El Helweh F., Esmer E. M., Yörükoğlu O., Yılmaz M., Şenavcı H. V., Kılıçoğlu T., Selam S. O.

Acta Astronomica

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2021

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Vol. 71, No. 3

223--242

EN

We study the most precise light curves of the planet-host HAT-P-36 that we obtained from the ground primarily with a brand-new 80 cm telescope (T80) very recently installed at Ankara University Kreiken Observatory (AUKR), Turkey and also from the space with Transiting Exoplanet Survey Satellite (TESS). The main objective of the study is to analyze the Transit Timing Variations (TTV) observed in the hot-Jupiter type planet HAT-P-36 b, a strong candidate for orbital decay. Our analysis is based on our own observations as well as those acquired by professional and amateur observers since its discovery. HAT-P-36 displays out-of-transit variability as well as light curve anomalies during the transits of its planet due to stellar spots. We collected and detrended from these anomalies all complete transit light curves we had access to. We modeled transits with EXOFAST and measured the mid-transit times forming a homogeneous data set for a TTV analysis. We found an increase in the orbital period of HAT-P-36 b at a rate of 0.014 s per year from the best fitting quadratic function. This increase is only found in the TTV constructed from the mid-transit times measured from detrended light curves. We refined the values of the system parameters by modeling with EXOFASTv2 the Spectral Energy Distribution of the host star, its archival radial velocity observations from multiple instruments, and the most precise transit light curves from the space and ground covering a wide range of wavelengths. We also analyzed the out-of-transit variability from TESS observations to search for potential rotational modulations through a frequency analysis. We report a statistically significant periodicity in the TESS light curve at 4.22±0.02 d, which might have been caused by instrumental systematics but should be tracked in the future observations of the target.

7

Multiple Stellar Encounters on Protoplanetary Disks in Birth Clusters of Stars

Jiménez-Torres J. J.

Acta Astronomica

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2020

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Vol. 70, No. 1

53--74

EN

We investigate the orbital modification of planetesimals in protoplanetary disks due to multiple stellar encounters in star formation clusters. We modeled multiple encounters with different flyby masses ranging from 0.02 M⊙ up to 0.5 M⊙, approach distances within 400 a.u. and virial velocities to simulate conditions of encounters in star formation regions. We propose an analysis of mass densities as a function of time and found that densities from 3×103 M⊙/pc3 to 1.4×104 M⊙/pc3 can produce from one up to three stellar encounters on a cross sectional area with a radius of 400 a.u. containing a 100 a.u. planetary disk in a period of time of 1×106 yr. We found that the orbital structure of observed transneptunian objects such as 2005 QU182 and the sednoid 2012 VP113 can simultaneously be produced with multiple encounters. We also found that the effect of multiple encounters with low mass stars (<0.5 M⊙) can reproduce similar orbital eccentricities and inclinations as produced by a single stellar encounter with a mass in the order of 1 M⊙. This corresponds to a realistic scenario considering that low mass stars represent the majority of the new born stars in a birth cluster of stars. We provide a relation between the number of stellar encounters on a cross sectional area and the stellar mass density. With interferometers such as ALMA, the influence of stellar encounters in star formation regions may become testable, which suggests the incorporation of different planetary disk conditions in future studies.

8

A Newtonian Model for the WASP-148 Exoplanetary System Enhanced with TESS and Ground-based Photometric Observations

Maciejewski G., Fernández M., Sota A., García Segura A. J.

Acta Astronomica

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2020

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Vol. 70, No. 3

203--217

EN

The WASP-148 planetary system has a rare architecture with a transiting Saturn-mass planet on a tight orbit which is accompanied by a slightly more massive planet on a nearby outer orbit. Using new space-born photometry and ground-based follow-up transit observations and data available in literature, we performed modeling that accounts for gravitational interactions between both planets. Thanks to the new transit timing data for planet b, uncertainties of orbital periods and eccentricities for both planets were reduced relative to previously published values by a factor of 3-4. Variation in transit timing has an amplitude of about 20 min and can be easily followed-up with a 1-m class telescopes from the ground. An approximated transit ephemeris, which accounts for gravitational interactions with an accuracy up to 5 min, is provided. No signature of transits was found for planet c down to the Neptune-size regime. No other transiting companions were found down to a size of about 2.4 Earth radii for interior orbits. We notice, however, that the regime of terrestrial-size planets still remains unexplored in that system.

9

K2-295 b and K2-237 b: Two Transiting Hot Jupiters

Smith A. M. S., Csizmadia Sz., Gandolfi D., Albrecht S., Alonso R., Barragán O., Cabrera J., Cochran W. D., Dai F., Deeg H., Eigmüller Ph., Endl M., Erikson A., Fridlund M., Fukui A., Grziwa S., Guenther E. W., Hatzes A. P., Hidalgo D., Hirano T., Korth J., Kuzuhara M., Livingston J., Narita N., Nespral D., Niraula P., Nowak G., Palle E., Pätzold M., Persson C. M., Prieto-Arranz J., Rauer H., Redfield S., Ribas I., Van Eylen V.

Acta Astronomica

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2019

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Vol. 69, No. 2

135--158

EN

We report the discovery from K2 of two transiting hot Jupiter systems. K2-295 (observed in Campaign 8) is a K5 dwarf which hosts a planet slightly smaller than Jupiter, orbiting with a period of 4.0 d. We have made an independent discovery of K2-237 b (Campaign 11), which orbits an F9 dwarf every 2.2 d and has an inflated radius 60-70% larger than that of Jupiter. We use high-precision radial velocity measurements, obtained using the HARPS and FIES spectrographs, to measure the planetary masses. We find that K2-295 b has a similar mass to Saturn, while K2-237 b is a little more massive than Jupiter.

10

CoRoT-18 b: Analysis of High-Precision Transit Light Curves with Starspot Features

Raetz St., Heras A. M., Gondoin P., Fernández M., Casanova V., Schmidt T. O. B., Maciejewski G.

Acta Astronomica

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2019

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Vol. 69, No. 3

205--226

EN

When a planet occults a spotty area on a stellar surface, the flux increases and a characteristic feature in a light curve - a bump - is observed. Among the planets detected by the CoRoT-mission CoRoT-18 is especially interesting as it exhibited spot crossings that we have analyzed in detail. We used four ground-based observations obtained at a 1.5-m telescope in Spain and the 13 available CoRoT-transits to refine and constrain stellar, planetary and geometrical parameters of the system. We found that the derived physical properties slightly deviate from the previously published values, most likely due to the different treatment of the stellar activity. Following of a spot over several transits enabled us to measure the stellar rotation period and the spin-orbit alignment. Our derived values of Prot=5.19±0.03 d and λ=6±13° are in agreement with the literature values that were obtained with other methods. Although we cannot exclude a very old age for CoRoT-18, our observations support the young star hypothesis and, hence, yield constraints on the time-scale of planet formation and migration.

11

OGLE-2017-BLG-1434Lb: Eighth q<1×10-4 Mass-Ratio Microlens Planet Confirms Turnover in Planet Mass-Ratio Function

Udalski A., Ryu Y.-H., Sajadian S., Gould A., Mróz P., Poleski R., Szymański M. K., Skowron J., Soszyński I., Kozłowski S., Pietrukowicz P., Ulaczyk K., Pawlak M., Rybicki K., Iwanek P., Albrow M. D., Chung S. -J., Han C., Hwang K.-H., Jung Y. K., Shin I.-G., Shvartzvald Y., Yee J. C., Zang W., Zhu W., Cha S.-M., Kim D.-J., Kim H.-W., Kim S.-L., Lee C.-U., Lee D.-J, Lee Y., Park B.-G., Pogge R. W., Bozza W., Dominik M., Helling C., Hundertmark M., Jørgensen U. G., Longa-Peña P., Lowry S., Burgdorf M., Campbell-White J., Ciceri S., Evans D., Jaimes R. F., Fujii Y. I., Haikala L. K., Henning T., Hinse T. C., Mancini L., Peixinho N., Rahvar S., Rabus M., Skottfelt J., Snodgrass C., Southworth J., von Essen C.

Acta Astronomica

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2018

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Vol. 68, No. 1

1--42

EN

We report the discovery of a cold Super-Earth planet (mp=4.4±0.5 M⊕) orbiting a low-mass (M=0.23±0.03 M⊙) M dwarf at projected separation a⊥=1.18±0.10 a.u., i.e., about 1.9 times the distance the snow line. The system is quite nearby for a microlensing planet, DL=0.86±0.09 kpc. Indeed, it was the large lens-source relative parallax πrel=1.0 mas (combined with the low mass M) that gave rise to the large, and thus well-measured, "microlens parallax" πE∝(πrel/M)1/2 that enabled these precise measurements. OGLE-2017-BLG-1434Lb is the eighth microlensing planet with planet-host mass ratio q<1×10-4. We apply a new planet-detection sensitivity method, which is a variant of "V/Vmax", to seven of these eight planets to derive the mass-ratio function in this regime. We find dN/d lnq ∝ qp, with p=1.05+0.78 -0.68, which confirms the "turnover" in the mass function found by Suzuki et al. relative to the power law of opposite sign n=-0.93±0.13 at higher mass ratios q≳2×10-4. We combine our result with that of Suzuki et al. to obtain p=0.73+0.42 -0.34.

12

OGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing Degeneracy

Skowron J., Ryu Y.-H., Hwang K.-H., Udalski A., Mróz P., Kozłowski S., Soszyński I., Pietrukowicz P., Szymański M. K., Poleski R., Ulaczyk K., Pawlak M., Rybicki K., Iwanek P., Albrow M. D., Chung S.-J., Gould A., Han C., Jung Y. K., Shin I.-G., Shvartzvald Y., Yee J. C., Zang W., Zhu W., Cha S.-M., Kim D.-J., Kim H.-W., Kim S.-L., Lee C.-U., Lee D.-J, Lee Y., Park B.-G., Pogge R. W.

Acta Astronomica

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2018

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Vol. 68, No. 1

43--61

EN

We report the discovery of microlensing planet OGLE-2017-BLG-0373Lb. We show that while the planet-host system has an unambiguous microlens topology, there are two geometries within this topology that fit the data equally well, which leads to a factor 2.5 difference in planet-host mass ratio, i.e., q=1.5×10-3 vs. q=0.6×10-3. We show that this is an "accidental degeneracy" in the sense that it is due to a gap in the data. We dub it "the caustic-chirality degeneracy". We trace the mathematical origins of this degeneracy, which should enable similar degenerate solutions to be easily located in the future. A Bayesian estimate, based on a Galactic model, yields a host mass M=0.25+0.30 -0.15 M⊙ at a distance DL=5.9+1.3 -1.95 kpc. The lens-source relative proper motion is relatively fast, μ=9 mas/yr, which implies that the host mass and distance can be determined by high-resolution imaging after about 10 years. The same observations could in principle resolve the discrete degeneracy in q, but this will be more challenging.

13

The Properties of XO-5b and WASP-82b Redetermined Using New High-Precision Transit Photometry and Global Data Analyses

Smith A. M. S.

Acta Astronomica

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2015

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Vol. 65, No. 1

117--125

EN

This paper presents new transit photometry from the Isaac Newton Telescope of two transiting exoplanetary systems, XO-5 and WASP-82. In each case the new transit light curve is more precise than any other of that system previously published. The new data are analyzed alongside previously-published photometry and radial velocities, resulting in an improved orbital ephemeris and a refined set of system parameters in each case. The observational baseline of XO-5 is extended by very nearly four years, resulting in a determination of the orbital period of XO-5b to a precision of just 50 ms. The mass and radius of XO-5b are 1.19±0.03 and 1.14±0.03 times those of Jupiter, respectively. The light curve of WASP-82 is only the second published for this system. The planetary mass is 1.25±0.05 MJup, and the radius is 1.71±0.08 RJup.

14

Transiting Planets Orbiting Source Stars in Microlensing Events

Rybicki K., Wyrzykowski Ł.

Acta Astronomica

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2014

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Vol. 64, No. 1

65--75

EN

The phenomenon of microlensing has successfully been used to detect extrasolar planets. By observing characteristic, rare deviations in the gravitational microlensing light curve one can discover that a lens is a star-planet system. In this paper we consider an opposite case where the lens is a single star and the source has a transiting planetary companion. We have studied the light curve of a source star with transiting companion magnified during microlensing event. Our model shows that in dense stellar fields, in which blending is significant, the light drop generated by transits is greater near the maximum of microlensing, which makes it easier to detect. We derive the probability for the detection of a planetary transit in a microlensed source to be of 2×10-6 for an individual microlensing event.

15

Revisiting Parameters for the WASP-1 Planetary System

Maciejewski G., Ohlert J., Dimitrov D., Puchalski D., Nedoroščík J., Vaňko M., Marka C., Baar S., Raetz St., Seeliger M., Neuhäuser R.

Acta Astronomica

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2014

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Vol. 64, No. 1

27--43

EN

We present thirteen new transit light curves for the WASP-1b exoplanet. Observations were acquired with 0.5 m-1.2 m telescopes between 2007 and 2013. Our homogeneous analysis, which also includes the literature data, results in determining precise system parameters. New values are in agreement with those reported in previous studies. Transit times follow a linear ephemeris with no sign of any transit time variations. This finding is in line with the paradigm that Jupiter-like planets on tight orbits are devoid of close planetary companions. Key words: planetary systems - Stars: individual: WASP-1 - Planets and satellites: individual: WASP-1b

16

On the GJ 436 Planetary System

Maciejewski G., Niedzielski A., Nowak G., Pallé E., Tingley B., Errmann R., Neuhäuser R.

Acta Astronomica

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2014

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Vol. 64, No. 4

323--335

EN

The GJ 436 system contains a transiting planet GJ 436 b which is a hot analogue of Neptune on an eccentric orbit. Recently, two additional transiting sub-Earth planets have been postulated in the literature. We observed three transits of GJ 436 b over the course of three years using two-meter class telescopes, each with a photometric precision better than one millimagnitude. We studied system dynamics based on the existence of the additional planets. We redetermined system parameters, which were in agreement with those found in the literature. We refined the orbital period of GJ 436 b and found no evidence of transit timing variations. The orbital motion of the GJ 436 c planet candidate was found to be significantly affected by the planet b with variations in transit times at a level of 20 minutes. As the orbital period of the GJ 436 d planet candidate remains unknown, our numerical experiments rule out orbits in low-order resonances with GJ 436 b. The GJ 436 system with the hot Neptune and additional two Earth-like planets, if confirmed, would be an important laboratory for studies of formation and evolution of planetary systems.

17

The Qatar Exoplanet Survey

Alsubai K. A., Parley N. R., Bramich D. M., Horne K., Collier Cameron A., West R. G., Sorensen M. P., Pollacco D., Smith J. C., Fors O.

Acta Astronomica

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2013

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Vol. 63, No. 4

465--480

EN

The Qatar Exoplanet Survey (QES) is discovering hot Jupiters and aims to discover hot Saturns and hot Neptunes that transit in front of relatively bright host stars. QES currently operates a robotic wide-angle camera system to identify promising transiting exoplanet candidates among which are the confirmed exoplanets Qatar 1b and 2b. This paper describes the first generation QES instrument, observing strategy, data reduction techniques, and follow-up procedures. The QES cameras in New Mexico complement the SuperWASP cameras in the Canary Islands and South Africa, and we have developed tools to enable the QES images and light curves to be archived and analysed using the same methods developed for the SuperWASP datasets. With its larger aperture, finer pixel scale, and comparable field of view, and with plans to deploy similar systems at two further sites, the QES, in collaboration with SuperWASP, should help to speed the discovery of smaller radius planets transiting bright stars in northern skies.

18

The new theory of gravitation representing the movement of planets

Borowski T.

International Letters of Chemistry, Physics and Astronomy

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2012

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Vol. 1

1-5

EN

In this paper, a theory of the phenomenon of planetary circulation around the Sun is presented, as well as the stability of solar systems is explained. This theory describes the circulation of planets and Rother mass-holding bodies around the Sun as a phenomenon consisting in the principle of differentia pressure in solar systems and thus excludes gravitation phenomenon as the phenomenon of attraction.

19

Refining Parameters of the XO-5 Planetary System with High-Precision Transit Photometry

Maciejewski G., Seeliger M., Adam Ch., Raetz St., Neuhäuser R.

Acta Astronomica

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2011

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Vol. 61, No. 1

25--35

EN

Studies of transiting extrasolar planets provide unique opportunity to get to know the internal structure of those worlds. The transiting exoplanet XO-5 b was found to have an anomalously high Safronov number and surface gravity. Our aim was to refine parameters of this intriguing system and search for signs of transit timing variations. We gathered high-precision light curves for two transits of XO-5 b. Assuming three different limb darkening laws, we found the best-fitting model and redetermined parameters of the system, including planet-to-star radius ratio, impact parameter and central time of transits. Error estimates were derived by the prayer bead method and Monte Carlo simulations. Although system's parameters obtained by us were found to agree with previous studies within one sigma, the planet was found to be notable smaller with the radius of 1.03+0.06-0.05 Jupiter radii. Our results confirm the high Safronov number and surface gravity of the planet. With two new mid-transit times, the ephemeris was refined to BJDTDB=(2454485.66842±0.00028)+(4.1877537±0.000017)E. No significant transit timing variation was detected.

20

Planets in Stellar Clusters Extensive Search. V. Search for Planets and Identification of 18 new Variable Stars in the Old Open Cluster NGC 188

Mochejska B. J., Stanek K. Z., Sasselov D. D., Szentgyorgyi A. H., Cooper R. L., Hickox R. C., Hradecky V., Marrone D., P., Winn J. N., Schwarzenberg-Czerny A.

Acta Astronomica

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2008

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Vol. 58, No. 3

263--278

EN

We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 188, an old, rather populous cluster. We have monitored the cluster for more than 87 hours, spread over 45 nights. We have not detected any good transiting planet candidates. We have discovered 18 new variable stars in the cluster, bringing the total number of identified variables to 28, and present for them high precision light curves, spanning 15 months.