scholarly journals Exomoon indicators in high-precision transit light curves

2020 ◽  
Vol 638 ◽  
pp. A43
Author(s):  
Kai Rodenbeck ◽  
René Heller ◽  
Laurent Gizon
Keyword(s):  
Extrasolar Planets ◽  
Light Curves ◽  
Low Density ◽  
Instrumental Effects ◽  
The Moon ◽  
Hill Stability ◽  
Follow Up Studies ◽  
Transit Model ◽  
Limb Darkening

Context. While the Solar System contains about 20 times more moons than planets, no moon has been confirmed around any of the thousands of extrasolar planets discovered so far. Considering the large computational load required for the statistical vetting of exomoon candidates in a star–planet–moon framework, tools for an uncomplicated identification of the most promising exomoon candidates could be beneficial to streamline follow-up studies. Aims. Here we study three exomoon indicators that emerge if well-established planet-only models are fitted to a planet–moon transit light curve: transit timing variations (TTVs), transit duration variations (TDVs), and apparent planetary transit radius variations (TRVs). We re-evaluate under realistic conditions the previously proposed exomoon signatures in the TTV and TDV series. Methods. We simulated light curves of a transiting exoplanet with a single moon, taking into account stellar limb darkening, orbital inclinations, planet–moon occultations, and noise from both stellar granulation and instrumental effects. These model light curves were then fitted with a planet-only transit model whilst pretending there were no moon, and we explored the resulting TTV, TDV, and TRV series for evidence of the moon. Results. The previously described ellipse in the TTV-TDV diagram of an exoplanet with a moon emerges only for high-density moons. However, low-density moons distort the sinusoidal shapes of the TTV and the TDV series due to their photometric contribution to the combined planet–moon transit. Sufficiently large moons can nevertheless produce periodic apparent TRVs of their host planets that could be observable. We find that Kepler and PLATO have similar performances in detecting the exomoon-induced TRV effect around simulated bright (mV = 8) stars. Although these stars are rare in the Kepler sample, they will be abundant in the PLATO sample. Moreover, PLATO’s higher cadence yields a stronger TTV signal. We detect substantial TRVs of the Saturn-sized planet Kepler-856 b although an exomoon could only ensure Hill stability in a very narrow orbital range. Conclusions. The periodogram of the sequence of transit radius measurements can indicate the presence of a moon. The TTV and TDV series of exoplanets with moons could be more complex than previously assumed. We propose that TRVs could be a more promising means to identify exomoons in large exoplanet surveys.

scholarly journals Extrasolar planet detections with gravitational microlensing

2007 ◽  
Vol 3 (S249) ◽  
pp. 25-30
Author(s):  
Shude Mao ◽  
Eamonn Kerins ◽  
Nicholas J. Rattenbury
Keyword(s):  
Light Curve ◽  
Real Time ◽  
Extrasolar Planets ◽  
Light Curves ◽  
Extrasolar Planet ◽  
Galactic Centre ◽  
Wide Field ◽  
High Magnification ◽  
Gravitational Microlensing

AbstractMicrolensing light curves due to single stars are symmetric and typically last for a month. So far about 4000 microlensing events have been discovered in real-time, the vast majority toward the Galactic centre. The presence of planets around the primary lenses induces deviations in the usual light curve which lasts from hours (for an Earth-mass [M⊕] planet) to days (for a Jupiter-mass [Mj] planet). Currently the survey teams, OGLE and MOA, discover and announce microlensing events in real-time, and follow-up teams (together with the survey teams) monitor selected events intensively (usually with high magnification) in order to identify anomalies caused by planets. So far four extrasolar planets have been discovered using the microlensing technique, with half a dozen new planet candidates identified in 2007 (yet to be published). Future possibilities include a network of wide-field 2m-class telescopes from the ground (which can combine survey and follow-up in the same setup) and a 1m-class survey telescope from space.

scholarly journals The GTC exoplanet transit spectroscopy survey

2017 ◽  
Vol 605 ◽  
pp. A114 ◽  
Author(s):  
F. Murgas ◽  
E. Pallé ◽  
H. Parviainen ◽  
G. Chen ◽  
L. Nortmann ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Theoretical Models ◽  
Light Curves ◽  
Transmission Spectra ◽  
Atmospheric Species ◽  
Transiting Planets ◽  
Systematic Effects ◽  
Transit Model ◽  
In Transit ◽  
Molecular Compounds

Context. Transiting planets offer an excellent opportunity for characterizing the atmospheres of extrasolar planets under very different conditions from those found in our solar system. Aims. We are currently carrying out a ground-based survey to obtain the transmission spectra of several extrasolar planets using the 10 m Gran Telescopio Canarias. In this paper we investigate the extrasolar planet WASP-48b, a hot Jupiter orbiting around an F-type star with a period of 2.14 days. Methods. We obtained long-slit optical spectroscopy of one transit of WASP-48b with the Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) spectrograph. We integrated the spectrum of WASP-48 and one reference star in several channels with different wavelength ranges, creating numerous color light curves of the transit. We fit analytic transit curves to the data taking into account the systematic effects present in the time series in an effort to measure the change of the planet-to-star radius ratio (Rp/Rs) across wavelength. The change in transit depth can be compared with atmosphere models to infer the presence of particular atomic or molecular compounds in the atmosphere of WASP-48b. Results. After removing the transit model and systematic trends to the curves we reached precisions between 261 ppm and 455–755 ppm for the white and spectroscopic light curves, respectively. We obtained Rp/Rs uncertainty values between 0.8 × 10-3 and 1.5 × 10-3 for all the curves analyzed in this work. The measured transit depth for the curves made by integrating the wavelength range between 530 nm and 905 nm is in agreement with previous studies. We report a relatively flat transmission spectrum for WASP-48b with no statistical significant detection of atmospheric species, although the theoretical models that fit the data more closely include TiO and VO.

scholarly journals MuSCAT2 multicolour validation of TESS candidates: an ultra-short-period substellar object around an M dwarf

2020 ◽  
Vol 633 ◽  
pp. A28 ◽  
Author(s):  
H. Parviainen ◽  
E. Palle ◽  
M. R. Zapatero-Osorio ◽  
P. Montanes Rodriguez ◽  
F. Murgas ◽  
...  
Keyword(s):  
Radius Ratio ◽  
Light Curves ◽  
Reliable Estimate ◽  
Brown Dwarf ◽  
Colour Difference ◽  
Stellar Radius ◽  
Short Period ◽  
Transit Model ◽  
M Dwarf

Context. We report the discovery of TOI 263.01 (TIC 120916706), a transiting substellar object (R = 0.87 RJup) orbiting a faint M3.5 V dwarf (V = 18.97) on a 0.56 d orbit. Aims. We setout to determine the nature of the Transiting Exoplanet Survey Satellite (TESS) planet candidate TOI 263.01 using ground-based multicolour transit photometry. The host star is faint, which makes radial-velocity confirmation challenging, but the large transit depth makes the candidate suitable for validation through multicolour photometry. Methods. Our analysis combines three transits observed simultaneously in r′, i′, and zs bands usingthe MuSCAT2 multicolour imager, three LCOGT-observed transit light curves in g′, r′, and i′ bands, a TESS light curve from Sector 3, and a low-resolution spectrum for stellar characterisation observed with the ALFOSC spectrograph. We modelled the light curves with PYTRANSIT using a transit model that includes a physics-based light contamination component, allowing us to estimate the contamination from unresolved sources from the multicolour photometry. Using this information we were able to derive the true planet–star radius ratio marginalised over the contamination allowed by the photometry.Combining this with the stellar radius, we were able to make a reliable estimate of the absolute radius of the object. Results. The ground-based photometry strongly excludes contamination from unresolved sources with a significant colour difference to TOI 263. Furthermore, contamination from sources of the same stellar type as the host is constrained to levels where the true radius ratio posterior has a median of 0.217 and a 99 percentile of0.286. The median and maximum radius ratios correspond to absolute planet radii of 0.87 and 1.41 RJup, respectively,which confirms the substellar nature of the planet candidate. The object is either a giant planetor a brown dwarf (BD) located deep inside the so-called “brown dwarf desert”. Both possibilities offer a challenge to current planet/BD formation models and make TOI 263.01 an object that merits in-depth follow-up studies.

scholarly journals Ephemeris refinement of 21 hot Jupiter exoplanets with high timing uncertainties

2019 ◽  
Vol 622 ◽  
pp. A81 ◽  
Author(s):  
M. Mallonn ◽  
C. von Essen ◽  
E. Herrero ◽  
X. Alexoudi ◽  
T. Granzer ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Light Curves ◽  
Timing Information ◽  
Hot Jupiter

Transit events of extrasolar planets offer a wealth of information for planetary characterization. However, for many known targets, the uncertainty of their predicted transit windows prohibits an accurate scheduling of follow-up observations. In this work, we refine the ephemerides of 21 hot Jupiter exoplanets with the largest timing uncertainties. We collected 120 professional and amateur transit light curves of the targets of interest, observed with a range of telescopes of 0.3 m–2.2 m, and analyzed them along with the timing information of the planets discovery papers. In the case of WASP-117b, we measured a timing deviation compared to the known ephemeris of about 3.5 h, and for HAT-P-29b and HAT-P-31b the deviation amounted to about 2 h and more. For all targets, the new ephemeris predicts transit timings with uncertainties of less than 6 min in the year 2018 and less than 13 min until 2025. Thus, our results allow for an accurate scheduling of follow-up observations in the next decade.

What graduate follow-up studies can tell us

2000 ◽  
Vol 34 (12) ◽  
pp. 976-977 ◽  
Author(s):  
Linda H Distlehorst
Keyword(s):  
Follow Up Studies

Beurteilung der Adriamycin-Kardiotoxizität mittels der Äquilibrium-Radionuklid-Ventrikulographie

1987 ◽  
Vol 26 (05) ◽  
pp. 206-211 ◽  
Author(s):  
P. Knesewitsch ◽  
N. H. Göldel ◽  
S. Fritsch ◽  
E. Moser
Keyword(s):  
Left Ventricular ◽  
Peak Filling Rate ◽  
Base System ◽  
Filling Rate ◽  
Time To Peak ◽  
Ejection Rate ◽  
Follow Up Studies ◽  
Pathologic Findings ◽  
Peak Ejection Rate

Results of 606 equilibrium radionuclide ventriculographies (ERNV) performed in 348 non-selected patients receiving Adriamycin (ADM) therapy were stored in a data base system. The aim of the study was to assess the influence of a potential cardiotoxic therapy on left ventricular pump function. Increasing ADM doses yielded a significant (p <0.05) decrease of the resting ejection fraction (R-gEF), the peak ejection rate and the peak filling rate. Enddiastolic and endsystolic volumes increased significantly. Stroke volume, heart rate and time to peak filling rate did not change significantly. 368 follow-up studies were performed in 128 patients: 65/128 patients presented a decrease of R-gEF, but only in 45 of these patients R-gEF values fell into the pathologic range. In 44 of these follow-ups, R-gEF remained unchanged. In 19 patients, a R-gEF increase was observed. At the beginning of ADM therapy 14% of the patients had subnormal R-gEF values. With increasing ADM doses pathologic findings increased to 86% in patients with ADM doses higher than 500 mg/m2.

Synthesis and Biological Evaluation of the Antimicrobial Natural Product Lipoxazolidinone A

2018 ◽  
Author(s):  
Jonathan J. Mills ◽  
Kaylib R. Robinson ◽  
Troy E. Zehnder ◽  
Joshua G. Pierce
Keyword(s):  
Natural Products ◽  
Natural Product ◽  
Mechanism Of Action ◽  
Marine Natural Products ◽  
Biological Evaluation ◽  
Lead Compounds ◽  
Follow Up Studies ◽  
Initial Resistance ◽  
Synthesis And Biological Evaluation

The lipoxazolidinone family of marine natural products, with an unusual 4-oxazolidinone heterocycle at their core, represents a new scaffold for antimicrobial discovery; however, questions regarding their mechanism of action and high lipophilicity have likely slowed follow-up studies. Herein, we report the first synthesis of lipoxazolidinone A, 15 structural analogs to explore its active pharmacophore, and initial resistance and mechanism of action studies. These results suggest that 4-oxazolidinones are valuable scaffolds for antimicrobial development and reveal simplified lead compounds for further optimization.

Stereotactic radiation treatment planning and follow-up studies involving fused multimodality imaging

2004 ◽  
Vol 101 (Supplement3) ◽  
pp. 326-333 ◽  
Author(s):  
Klaus D. Hamm ◽  
Gunnar Surber ◽  
Michael Schmücking ◽  
Reinhard E. Wurm ◽  
Rene Aschenbach ◽  
...  
Keyword(s):  
Image Fusion ◽  
Treatment Planning ◽  
Radiation Treatment ◽  
Data Sets ◽  
Slice Thickness ◽  
Radiation Treatment Planning ◽  
Content Type ◽  
Follow Up Studies ◽  
Fine Print

Object. Innovative new software solutions may enable image fusion to produce the desired data superposition for precise target definition and follow-up studies in radiosurgery/stereotactic radiotherapy in patients with intracranial lesions. The aim is to integrate the anatomical and functional information completely into the radiation treatment planning and to achieve an exact comparison for follow-up examinations. Special conditions and advantages of BrainLAB's fully automatic image fusion system are evaluated and described for this purpose. Methods. In 458 patients, the radiation treatment planning and some follow-up studies were performed using an automatic image fusion technique involving the use of different imaging modalities. Each fusion was visually checked and corrected as necessary. The computerized tomography (CT) scans for radiation treatment planning (slice thickness 1.25 mm), as well as stereotactic angiography for arteriovenous malformations, were acquired using head fixation with stereotactic arc or, in the case of stereotactic radiotherapy, with a relocatable stereotactic mask. Different magnetic resonance (MR) imaging sequences (T1, T2, and fluid-attenuated inversion-recovery images) and positron emission tomography (PET) scans were obtained without head fixation. Fusion results and the effects on radiation treatment planning and follow-up studies were analyzed. The precision level of the results of the automatic fusion depended primarily on the image quality, especially the slice thickness and the field homogeneity when using MR images, as well as on patient movement during data acquisition. Fully automated image fusion of different MR, CT, and PET studies was performed for each patient. Only in a few cases was it necessary to correct the fusion manually after visual evaluation. These corrections were minor and did not materially affect treatment planning. High-quality fusion of thin slices of a region of interest with a complete head data set could be performed easily. The target volume for radiation treatment planning could be accurately delineated using multimodal information provided by CT, MR, angiography, and PET studies. The fusion of follow-up image data sets yielded results that could be successfully compared and quantitatively evaluated. Conclusions. Depending on the quality of the originally acquired image, automated image fusion can be a very valuable tool, allowing for fast (∼ 1–2 minute) and precise fusion of all relevant data sets. Fused multimodality imaging improves the target volume definition for radiation treatment planning. High-quality follow-up image data sets should be acquired for image fusion to provide exactly comparable slices and volumetric results that will contribute to quality contol.

scholarly journals MAPPING AND ENHANCING DESIGN STUDIES WITH PSI META-THEORETIC DESIGN FRAMEWORK

2021 ◽  
Vol 1 ◽  
pp. 2007-2016
Author(s):  
Yoram Reich ◽  
Eswaran Subrahmanian
Keyword(s):  
Design Research ◽  
The Other ◽  
Design Studies ◽  
Abstraction Level ◽  
Follow Up Studies ◽  
The One ◽  
The Right ◽  
Abstract Framework ◽  
Tools And Methods

AbstractDesign research as a field has been studied from diverse perspectives starting from product inception to their disposal. The product of these studies includes knowledge, tools, methods, processes, frameworks, approaches, and theories. The contexts of these studies are innumerable. The unit of these studies varies from individuals to organizations, using a variety of theoretical tools and methods that have fragmented the field, making it difficult to understand the map of this corpus of knowledge across this diversity.In this paper, we propose a model-based approach that on the one hand, does not delve into the details of the design object itself, but on the other hand, unifies the description of design problem at another abstraction level. The use of this abstract framework allows for describing and comparing underlying models of published design studies using the same language to place them in the right context in which design takes place and to enable to inter-relate them, to understand the wholes and the parts of design studies.Patterns of successful studies could be generated and used by researchers to improve the design of new studies, understand the outcome of existing studies, and plan follow-up studies.

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