Aims. The transiting extrasolar planet WASP-12 b was found to be one of the most intensely irradiated exoplanets. It is unexpectedly bloated and is losing mass that may accrete into the host star. ...Our aim was to refine the parameters of this intriguing system and search for signs of transit timing variations. Methods. We gathered high-precision light curves for two transits of WASP-12 b. Assuming various limb-darkening laws, we generated best-fitting models and redetermined the parameters of the system. Error estimates were derived by the prayer-bead method and Monte Carlo simulations. Results. System parameters obtained by us are found to agree with previous studies within one sigma. Use of the non-linear limb-darkening laws results in the best-fitting models. With two new mid-transit times, the ephemeris was refined to BJDTDB = (2 454 508.97682 ± 0.00020) + (1.09142245 ± 0.00000033)E. Interestingly, indications of transit timing variation are detected at the level of 3.4 sigma. This signal can be induced by an additional planet in the system. Simplified numerical simulations show that a perturber could be a terrestrial-type planet if both planets are in a low-order orbital resonance. However, we emphasise that further observations are needed to confirm variation and to constrain properties of the perturber.
The vast majority of extrasolar planets are detected by indirect detection methods such as transit monitoring and radial velocity measurements. While these methods are very successful in detecting ...short-periodic planets, they are mostly blind to wide sub-stellar or even stellar companions on long orbits. In our study, we present high-resolution imaging observations of 60 exoplanet hosts carried out with the lucky imaging instrument AstraLux at the Calar Alto 2.2 m telescope as well as with the new Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) high-resolution adaptive optics imager at the ESO/VLT in the case of a known companion of specific interest. Our goal is to study the influence of stellar multiplicity on the planet formation process. We detected and confirmed four previously unknown stellar companions to the exoplanet hosts HD 197037, HD 217786, Kepler-21 and Kepler-68. In addition, we detected 11 new low-mass stellar companion candidates which must still be confirmed as bound companions. We also provide new astrometric and photometric data points for the recently discovered very close binary systems WASP-76 and HD 2638. Furthermore, we show for the first time that the previously detected stellar companion to the HD 185269 system is a very low mass binary. Finally, we provide precise constraints on additional companions for all observed stars in our sample.
The formation of massive planetary or brown dwarf companions at large projected separations from their host star is not yet well understood. In order to put constraints on formation scenarios, we ...search for signatures in the orbit dynamics of the systems. We are specifically interested in the eccentricities and inclinations since those parameters might tell us about the dynamic history of the systems and where to look for additional low-mass sub-stellar companions. For this purpose, we utilized VLT/NACO to take several well-calibrated high-resolution images of six target systems and analyse them together with available literature data points of those systems as well as Hubble Space Telescope archival data. We used a statistical least-squares Monte Carlo approach to constrain the orbit elements of all systems that showed significant differential motion of the primary star and companion. We show for the first time that the GQ Lup system shows significant change in both separation and position angle. Our analysis yields best-fitting orbits for this system, which are eccentric (e between 0.21 and 0.69), but cannot rule out circular orbits at high inclinations. Given our astrometry, we discuss formation scenarios of the GQ Lup system. In addition, we detected an even fainter new companion candidate to GQ Lup, which is most likely a background object. We also updated the orbit constraints of the PZ Tel system, confirming that the companion is on a highly eccentric orbit with e > 0.62. Finally, we show with a high significance, that there is no orbital motion observed in the cases of the DH Tau, HD 203030 and 1RXS J160929.1 210524 systems, and give the most precise relative astrometric measurement of the UScoCTIO 108 system to date.
Context. We present the results of a survey to detect low-mass companions of Ursa Major (UMa) group members, carried out in 2003–2006 with NACO at the ESO VLT. While many extra-solar planets and ...planetary candidates have been found in close orbits around stars by the radial velocity and the transit methods, direct detections at wider orbits are rare. The UMa group, a young nearby stellar association at an age of about 200–600 Myr, has not yet been addressed as a whole although its members represent a very interesting sample to search for and characterize substellar companions by direct imaging. Aims. Our goal was to find or to provide detection limits on wide substellar companions around nearby UMa group members using high-resolution imaging. Methods. We searched for faint companions around 20 UMa group members within 30 pc. The primaries were placed below a semi-transparent coronagraph, a rarely used mode of NACO, to increase the dynamic range of the images. In most cases, second epoch images of companion candidates were taken to check whether they share common proper motion with the primary. Results. Our coronagraphic images rule out substellar companions around the stars of the sample. A typical dynamical range of 13–15 mag in the Ks band was achieved at separations beyond 3′′ from the star. Candidates as faint as Ks ≈ 20 were securely identified and measured. The survey is most sensitive between separations of 100 and 200 au but only on average because of the very different target distance. Field coverage reaches about 650 au for the most distant targets. Most of the 200 candidates detected in the covered fields are visible in two epochs and were rejected because they are distant background objects.
We present the design and testing of a prototype in-plane echelle spectrograph based on an actively controlled fiber-fed double-pass design. This system aims to be small and efficient with the ...minimum number of optical surfaces-currently a collimator/camera lens, cross-dispersing prism, grating and a reflector to send light to the detector. It is built from catalog optical components and has dimensions of approximately 20 × 30 cm. It works in the optical regime with a resolution of >70,000. The spectrograph is fed by a bifurcated fiber with one fiber to a telescope and the other used to provide simultaneous Thorium Argon light illumination for wavelength calibration. The positions of the arc lines on the detector are processed in real time and commercial auto-guiding software is used to treat the positions of the arc lines as guide stars. The guiding software sends any required adjustments to mechanical piezo-electric actuators which move the mirror sending light to the camera removing any drift in the position of the arc lines. The current configuration using an sCMOS detector provides a precision of 3.5 milli-pixels equivalent to 4 m s−1 in a standard laboratory environment.
A broad-band scalar vortex coronagraph Errmann, R; Minardi, S; Pertsch, T
Monthly notices of the Royal Astronomical Society,
10/2013, Letnik:
435, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Broad-band coronagraphy with deep nulling and small inner working angle has the potential of delivering images and spectra of exoplanets and other faint objects. In recent years, many coronagraphic ...schemes have been proposed, the most promising being the optical vortex phase mask coronagraphs. In this paper, a new scheme of broad-band optical scalar vortex coronagraph is proposed and characterized experimentally in the laboratory. Our setup employs a pair of computer-generated phase gratings (one of them containing a singularity) to control the chromatic dispersion of phase plates and achieves a constant peak-to-peak attenuation below 1 × 10−3 over a bandwidth of 120 nm centred at 700 nm. An inner working angle of ∼λ/D is demonstrated along with a raw contrast of 11.5 mag at 2λ/D.
Aims. The transiting hot-Jupiter planet Qatar-1 b exhibits variations in transit times that could be perturbative. A hot Jupiter with a planetary companion on a nearby orbit would constitute an ...unprecedented planetary configuration, which is important for theories of the formation and evolution of planetary systems. We performed a photometric follow-up campaign to confirm or refute transit timing variations. Methods. We extend the baseline of transit observations by acquiring 18 new transit light curves acquired with 0.6−2.0 m telescopes. These photometric time series, together with data available in the literature, were analyzed in a homogenous way to derive reliable transit parameters and their uncertainties. Results. We show that the dataset of transit times is consistent with a linear ephemeris leaving no hint of any periodic variations with a range of 1 min. We find no compelling evidence of a close-in planetary companion to Qatar-1 b. This finding is in line with a paradigm that hot Jupiters are not components of compact multiplanetary systems. Based on dynamical simulations, we place tighter constraints on the mass of any fictitious nearby planet in the system. Furthermore, new transit light curves allowed us to redetermine system parameters with better precision than reported in previous studies. Our values generally agree with previous determinations.
This data paper presents lightcurves of 101 near Earth asteroids (NEAs) observed mostly between 2014 and 2017 as part of the EURONEAR photometric survey using 11 telescopes with diameters between 0.4 ...and 4.2 m located in Spain, Chile, Slovakia and Romania. Most targets had no published data at the time of observing, but some objects were observed in the same period mainly by B. Warner, allowing us to confirm or improve the existing results. To plan the runs and select the targets, we developed the public
Long Planning
tool in PHP. For preliminary data reduction and rapid follow-up planning we developed the
LiDAS
pipeline in Python and IRAF. For final data reduction, flux calibration, night linkage and Fourier fitting, we used mainly
MPO Canopus
. Periods of 18 targets are presented for the first time, and we could solve or constrain rotation for 16 of them. We secured periods for 45 targets (
U
∼
3
), found candidate periods for other 16 targets (
U
∼
2
), and we propose tentative periods for other 32 targets (
U
∼
1
). We observed 7 known or candidate binary NEAs, fiting 3 of them (2102 Tantalus, 5143 Heracles and 68348). We observed 8 known or candidate tumbling NEAs, deriving primary periods for 3 objects (9400, 242708 and 470510). We evidenced rapid oscillations (few minutes) and could fit fast tentative periods
TP
2 for 5 large newly suggested tumbling or binary candidates (27346, 112985, 285625, 377732, 408980), probably discovering at least one new binary NEA (2011 WO41). We resolved periods of 4 special objects which include two proposed space mission targets (163249 and 101955 Bennu), one very fast rotator NEA discovered by EURONEAR (2014 NL52) and the “Halloween asteroid” (2015 TB145). Using Mercator in simultaneous 3 band MAIA imaging, we could evidence for the first time clear variation in the color lightcurves of 10 NEAs. The periods derived from the
g
–
r
color lightcurves are found to match individual band period fits for 4 NEAs (27346, 86067, 112985 and 275976).
Homogeneous observations and careful analysis of transit light curves can lead to the identification of transit timing variations (TTVs). TrES-2 is one of few exoplanets, which offer the matchless ...possibility to combine long-term ground-based observations with continuous satellite data. Our research aimed at the search for TTVs that would be indicative of perturbations from additional bodies in the system. We also wanted to refine the system parameters and the orbital elements. We obtained 44 ground-based light curves of 31 individual transit events of TrES-2. Eight 0.2–2.2-m telescopes located at six observatories in Germany, Poland and Spain were used. In addition, we analysed 18 quarters (Q0–Q17) of observational data from NASA's space telescope Kepler including 435 individual transit events and 11 publicly available ground-based light curves. Assuming different limb darkening (LD) laws we performed an analysis for all light curves and redetermined the parameters of the system. We also carried out a joint analysis of the ground- and space-based data. The long observation period of seven years (2007–2013) allowed a very precise redetermination of the transit ephemeris. For a total of 490 transit light curves of TrES-2, the time of transit mid-point was determined. The transit times support neither variations on long time-scale nor on short time-scales. The nearly continuous observations of Kepler show no statistically significant increase or decrease in the orbital inclination i and the transit duration D. Only the transit depth shows a slight increase which could be an indication of an increasing stellar activity. In general, system parameters obtained by us were found to be in agreement with previous studies but are the most precise values to date.
We present long-term photometric observations of the young open cluster IC 348 with a baseline time-scale of 2.4 yr. Our study was conducted with several telescopes from the Young Exoplanet Transit ...Initiative (YETI) network in the Bessel R band to find periodic variability of young stars. We identified 87 stars in IC 348 to be periodically variable; 33 of them were unreported before. Additionally, we detected 61 periodic non-members of which 41 are new discoveries. Our wide field of view was the key to those numerous newly found variable stars. The distribution of rotation periods in IC 348 has always been of special interest. We investigate it further with our newly detected periods but we cannot find a statistically significant bimodality. We also report the detection of a close eclipsing binary in IC 348 composed of a low-mass stellar component (...) and a K0 pre-main-sequence star (...). Furthermore, we discovered three detached binaries among the background stars in our field of view and confirmed the period of a fourth one. (ProQuest: ... denotes formulae/symbols omitted.)
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