Search For Transitions Research Articles

Signal preservation of exomoon transits during light curve folding

In the search for moons around extrasolar planets (exomoons), astronomers are confronted with a stunning observation. Although 3400 of the 4500 exoplanets were discovered with the transit method and although there are well over 25 times as many moons than planets known in the Solar System (two of which are larger than Mercury), no exomoon has been discovered to date. In the search for exoplanet transits, stellar light curves are usually phase-folded over a range of trial epochs and periods. This approach, however, is not applicable in a straightforward manner to exomoons. Planet-moon transits either have to be modeled in great detail (including their orbital dynamics, mutual eclipses, etc.), which is computationally expensive, or key simplifications have to be assumed in the modeling. One such simplification is to search for moon transits outside of the planetary transits. The question we address in this report is how much in-transit data of an exomoon remains uncontaminated by the near-simultaneous transits of its host planet. We develop an analytical framework based on the probability density of the sky-projected apparent position of an exomoon relative to its planet and test our results with a numerical planet-moon transit simulator. For exomoons with planet-moon orbital separations similar to the Galilean moons, we find that only a small fraction of their in-transit data is uncontaminated by planetary transits: 14% for Io, 20% for Europa, 42% for Ganymede, and 73% for Callisto. The signal-to-noise ratio (S/N) of an out-of-planetary-transit folding technique is reduced compared to a full photodynamical model to about 38% (Io), 45% (Europa), 65% (Ganymede), and 85% (Callisto), respectively. For the Earth’s Moon, we find an uncontaminated data fraction of typically just 18% and a resulting S/N reduction to 42%. These values are astonishingly small and suggest that the gain in speed for any exomoon transit search algorithm that ignores the planetary in-transit data comes at the heavy price of losing a substantial fraction of what is supposedly a tiny signal in the first place. We conclude that photodynamical modeling of the entire light curve has substantial, and possibly essential, advantages over folding techniques of exomoon transits outside the planetary transits, in particular for small exomoons comparable to those of the Solar System.

Searching for continuous phase transitions in 5D SU(2) lattice gauge theory

We study the phase diagram of 5-dimensional SU(2) Yang-Mills theory on the lattice. We consider two extensions of the fundamental plaquette Wilson action in the search for the continuous phase transition suggested by the 4 + ϵ expansion. The extensions correspond to new terms in the action: i) a unit size plaquette in the adjoint representation or ii) a two-unit sided square plaquette in the fundamental representation. We use Monte Carlo to sample the first and second derivative of the entropy near the confinement phase transition, with lattices up to 125. While we exclude the presence of a second order phase transition in the parameter space we sampled for model i), our data is not conclusive in some regions of the parameter space of model ii).

Search for in-band transitions in the candidate superdeformed band in Si28

Search for in-band transitions in the candidate superdeformed band in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Si</mml:mi><mml:mprescripts /><mml:none /><mml:mn>28</mml:mn></mml:mmultiscripts></mml:math>

A Uniform Search for Nearby Planetary Companions to Hot Jupiters in TESS Data Reveals Hot Jupiters Are Still Lonely

Abstract We present the results of a uniform search for additional planets around all stars with confirmed hot Jupiters observed by the Transiting Exoplanet Survey Satellite (TESS) in its Cycle 1 survey of the southern ecliptic hemisphere. Our search comprises 184 total planetary systems with confirmed hot Jupiters with R p &gt; 8 R ⊕ and orbital period &lt;10 days. The Transit Least Squares algorithm was utilized to search for periodic signals that may have been missed by other planet search pipelines. While we recovered 169 of these confirmed hot Jupiters, our search yielded no new statistically validated planetary candidates in the parameter space searched (P &lt; 14 days). A lack of planet candidates nearby hot Jupiters in the TESS data supports results from previous transit searches of each individual system, now down to the photometric precision of TESS. This is consistent with expectations from a high-eccentricity migration formation scenario, but additional formation indicators are needed for definitive confirmation. We injected transit signals into the light curves of the hot Jupiter sample to probe the pipeline’s sensitivity to the target parameter space, finding a dependence proportional to R p 2.32 P − 0.88 for planets within 0.3 ≤ R p ≤ 4 R ⊕ and 1 ≤ P ≤ 14 days. A statistical analysis accounting for this sensitivity provides a median and 90% confidence interval of 7.3 − 7.3 + 15.2 % for the rate of hot Jupiters with nearby companions in this target parameter space. This study demonstrates how TESS uniquely enables comprehensive searches for nearby planetary companions to nearly all the known hot Jupiters.

QLP Data Release Notes 001: K2 + TESS Analysis

Abstract TESS will target the ecliptic plane in Sectors 42–46. These sectors overlap with campaigns from the K2 mission, providing a unique opportunity for multi-mission light curve analysis. This data release note describes the combined analysis of K2 and TESS light curves as part of the Quick-Look Pipeline procedure, which processes light curves for all targets in TESS Full-Frame Images down to TESS magnitude T = 13.5. We describe updates to our codebase, and the planet transit search, candidate triage, and report generation that are affected by this combined analysis.

A Search for Transits among the Delta Scuti Variables in Kepler

Abstract We search for transits around all known pulsating δ Sct variables (6500 K &lt; T eff &lt; 10,000 K) in the long-cadence Kepler data after subtracting the pulsation signal through an automated routine. To achieve this, we devise a simple and computationally inexpensive method for distinguishing between low-frequency pulsations and transits in light curves. We find three new candidate transit events that were previously hidden behind the pulsations, but caution that they are likely to be false positive events. We also examined the Kepler Objects of Interest catalog and identify 13 additional host stars that show δ Sct pulsations. For each star in our sample, we use the nondetection of pulsation timing variations for a planet that is known to be transiting a δ Sct variable to obtain both an upper limit on the mass of the planet and the expected radial velocity semi-amplitude of the host star. Simple injection tests of our pipeline imply 100% recovery for planets of 0.5 R Jup or greater. Extrapolating our number of Kepler δ Sct stars, we expect 12 detectable planets above 0.5 R Jup in TESS. Our sample contains some of the hottest known transiting planets around evolved stars, and is the first complete sample of transits around δ Sct variables. We make available our code and pulsation-subtracted light curves to facilitate further analysis (https://github.com/danhey/dsct-exoplanet).

An exploratory study for the establishment of a welfare and wellness community for the elderly and re-establishment of the service delivery system according to the prolonged COVID-19

본 연구는 경기 남부지역 복지관 이용 어르신 (만 60세이상) 중 코로나 감염병 발생으로 인한 복지관 일시 폐쇄 및 이용 제한으로 온라인 프로그램 참여자 중 25명을 편의 추출하여 면담조사를 실시하였다. 코로나19 장기화에 따른 노인복지 웰니스 공동체 구성 및 복지 서비스 전달체계에 대한 어르신 대상자의 면담조사를 통해 코로나19 장기화로 인한 사회적 고립과 삶의 변화, 비대면 프로그램 전환에 대한 생각, 마을 중심의 공동체 구축 서비스에 대한 소고를 구체화 하였다. 면담조사 결과를 통해 노인복지 서비스 전달체계 재구축과 웰니스 공동체 구성을 위하여 노인복지관은 재난 복지 도입의 기능강화, 포스트 코로나 대응 IT 기술 활용 서비스 전환시도 요구, 재난협력 민관 협력 시스템 구축 강화, 마을 중심 돌봄 지지체계 강화, 보건복지연계 융합서비스 강화, 코로나 블루 극복 일상회복 서비스 지원으로 전략화하였다.This study aims to understand deeply the meaning of welfare community for the elderly and establishment of welfare service delivery system. Qualitative in-depth interviews using FGI were performed to 25 participants and 5 social workers in the senior center. The results showed the 3 categories searching for service conversion to spread COVID-19 infectious disease, 3 categories of the impact of switching to non-face-to-face programs due to restrictions, and 4 categories of exploring the search for service transition to build a wellness community. For the respondents who are involved in aging services, the results showed that 3 categories searching for service conversion to spread COVID-19 infectious disease, 2 categories of developing the customized development, and 2 categories of strategies for responding to blind spots in care. Based on the results, we drew the understanding of establishment of elderly welfare service delivery system and formation of wellness community.

Transit Search for Exoplanets around Alpha Centauri A and B with ASTERIA

Abstract Alpha Centauri is a triple star system with two Sun-like stars, α Cen A (V = 0.01) and B (V = 1.33), and a third fainter red dwarf star, Proxima Centauri. Most current transit missions cannot produce precision photometry of α Cen A and B as their detectors saturate for these very bright stars. The Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) was a technology demonstration mission that successfully demonstrated two key technologies necessary for precision photometry achieving line-of-sight fine-pointing stability of 0.5″ rms and focal plane temperature control of ±0.01 K over a period of 20 minutes. The payload consisted of a 6.7 cm aperture diameter refractive camera and used a scientific complementary metal-oxide semiconductor detector that enabled monitoring of the brightest stars without saturating. We obtained spatially unresolved (blended) observations of α Cen A and B during opportunistic science campaigns as part of ASTERIA’s extended mission. The resulting 1σ photometric precision for the blended α Cen A and B data is 250 ppm (parts per million) per 9 s exposure. We do not find evidence of transits in the blended data. We establish limits for transiting exoplanets around both α Cen A and B using transit signal injection and recovery tests. We find that ASTERIA is sensitive to planets with radii as small as 3.0 R ⊕ around α Cen A and 3.7 R ⊕ around α Cen B, corresponding to signals of ∼500 ppm (signal-to-noise ratio = 5.0) in the blended data, with periods ranging from 0.5 to 6 days.

The search for blue transitions in aquaculture‐dominant countries

AbstractThe capacity for aquaculture to provide an alternative source of fish and seafood to capture fisheries was once promoted as a tool to reduce demand for wild fish and thus tackle overfishing. To date, there is little evidence to suggest that aquaculture growth has successfully reduced fishing effort on wild populations. Recent theory on “blue transitions” suggests that displacement may only occur as aquaculture production surpasses that of capture operations. Yet, there has been no systematic attempt to understand whether aquaculture‐driven fisheries displacement has occurred in countries where aquaculture is now the dominant production form. We investigate the role of aquaculture on fisheries landings in these “aquaculture‐dominant” countries using national‐level production, trade, consumption and socioeconomic data from 1980 to 2017. Importantly, we find that aquaculture growth is associated with fisheries decline in aquaculture‐dominant countries, but the marginal effects of aquaculture have a far weaker influence on wild‐caught landings than other promoting factors, such as fish consumption and trade. Further, our qualitative analysis of the state of wild fisheries in aquaculture‐dominant nations suggests that overexploitation continues to be pervasive and that any minimal displacement effects from aquaculture are unlikely to have offset the environmental impacts imposed by the growing sector. The rise of aquaculture as an alternative production form can provide valuable insights for growing industries developing sustainable new foods. Unless coupled with effective food consumption policy, such products may simply add to rather than displace the environmental impacts of human food production.

NEMESIS: Exoplanet Transit Survey of Nearby M-dwarfs in TESS FFIs. I.

Abstract In this work, we present an analysis of 33,054 M-dwarf stars, located within 100 parsecs, via the Transiting Exoplanet Survey Satellite (TESS) full-frame images (FFIs) of observed sectors 1–5. We present a new pipeline called NEMESIS, developed to extract detrended photometry, and to perform transit searches of single-sector data in TESS FFIs. As many M-dwarfs are faint, and are not observed with a two-minute cadence by TESS, FFI transit surveys can provide an empirical validation of how many planets are missed, using the 30-minute cadence data. In this work, we detect 183 threshold crossing events, and present 29 candidate planets for sectors 1–5, 24 of which are new detections. Our sample contains orbital periods ranging from 1.25 to 6.84 days, and planetary radii from 1.26 to 5.31 R ⊕. With the addition of our new planet candidate detections, along with detections previously observed in sectors 1–5, we calculate an integrated occurrence rate of 2.49 ± 1.58 planets per star, for the period range ∈ [1, 9] days, and planet radius range ∈ [0.5,11] R ⊕. We project an estimated yield of 122 ± 11 transit detections of nearby M-dwarfs. Of our new candidates, 23 have signal-to-noise ratios &gt;7, transmission spectroscopy metrics &gt;38, and emission spectroscopy metrics &gt;10. We present all of our data products for our planet candidates via the Filtergraph data visualization service, located at https://filtergraph.com/NEMESIS.

A search for the quark-hadron phase transition in simulated pp collisions at $$\sqrt{{\varvec{s}}}$$ = 13 TeV using UrQMD model by the scaled factorial moment method

A search for the quark-hadron phase transition in simulated pp collisions at $$\sqrt{{\varvec{s}}}$$ = 13 TeV using UrQMD model by the scaled factorial moment method

Direct Search for Low Energy Nuclear Isomeric Transition of Th-229m With TES Detector

Precise knowledge of the energy and lifetime of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th isomeric state has notable importance as a basis for a nuclear clock. Such a clock would be capable to extend precision on the oscillator frequency by up to four orders of magnitude compared to the presently best atomic clocks. However, the technique proposed for the clock requires that the isomeric state energy is accessible with existing laser systems. Previous measurement placed this state at ∼8 eV (150 nm), in the Vacuum Ultra Violet (VUV) range of the electromagnetic spectrum. A precise direct measurement of the energy of this state is necessary to determine whether the nuclear clock can be made using existing laser technology. We are developing a cryogenic microcalorimeter to measure the energy and lifetime of the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th isomeric state directly. The experiment will use a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">233</sup> U source whose alpha-decay will populate the <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th isomeric state with 2% probability. The subsequent decay of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th will be measured by a Transition Edge Sensor (TES) with <1 eV resolution. Such a technique will allow to observe all possible types of decays of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">229m</sup> Th in the range of energy from 3 to 50 eV and lifetimes >5 microseconds. The single-photon TES has sufficient resolving power combined with high efficiency in the whole energy band for this experiment. Here we present a prototype of TES based on a 200 nm thick iridium-gold (Ir/Au) film which was tested with a pulsed laser source and demonstrated ∼0.8 eV energy resolution and 5.8 ± 2.1 μs signal recovery time.

HD 219134 Revisited: Planet d Transit Upper Limit and Planet f Transit Nondetection with ASTERIA and TESS

Abstract HD 219134 is a K3V dwarf star with six reported radial-velocity discovered planets. The two innermost planets b and c show transits, raising the possibility of this system to be the nearest (6.53 pc), brightest (V = 5.57) example of a star with a compact multiple transiting planet system. Ground-based searches for transits of planets beyond b and c are not feasible because of the infrequent transits, long transit duration (∼5 hr), shallow transit depths (&lt;1%), and large transit time uncertainty (∼half a day). We use the space-based telescopes the Arcsecond Space Telescope Enabling Research in Astrophysics (ASTERIA) and the Transiting Exoplanet Survey Satellite (TESS) to search for transits of planets f (P = 22.717 days and ) and d (P = 46.859 days and ). ASTERIA was a technology demonstration CubeSat with an opportunity for science in an extended program. ASTERIA observations of HD 219134 were designed to cover the 3σ transit windows for planets f and d via repeated visits over many months. While TESS has much higher sensitivity and more continuous time coverage than ASTERIA, only the HD 219134 f transit window fell within the TESS survey’s observations. Our TESS photometric results definitively rule out planetary transits for HD 219134 f. We do not detect the Neptune-mass HD 219134 d transits and our ASTERIA data are sensitive to planets as small as 3.6 R ⊕. We provide TESS updated transit times and periods for HD 219134 b and c, which are designated TOI 1469.01 and 1469.02 respectively.

Searching for Possible Exoplanet Transits from BRITE Data through a Machine Learning Technique

The photometric light curves of BRITE satellites were examined through a machine learning technique to investigate whether there are possible exoplanets moving around nearby bright stars. Focusing on different transit periods, several convolutional neural networks were constructed to search for transit candidates. The convolutional neural networks were trained with synthetic transit signals combined with BRITE light curves until the accuracy rate was higher than 99.7%. Our method could efficiently lead to a small number of possible transit candidates. Among these ten candidates, two of them, HD37465, and HD186882 systems, were followed up through future observations with a higher priority. The codes of convolutional neural networks employed in this study are publicly available at http://www.phys.nthu.edu.tw/~jiang/BRITE2020YehJiangCNN.tar.gz.

Constraining the Bulk Composition of Disintegrating Exoplanets Using Combined Transmission Spectra from JWST and SPICA

Abstract Disintegrating planets are ultrashort-period exoplanets that appear to have a comet-like dust tail. They are commonly interpreted as low-mass planets whose solid surface is evaporating, and whose tails are made of recondensing minerals. Transmission spectroscopy of the dust tails could thus allow us to directly probe the elementary compositions of these planets. Previous work already investigated the feasibility of such observations using the James Webb Space Telescope (JWST) mid-infrared instrument. In this study, we explore if one can obtain a strong constrain on the tail composition by adding spectroscopy at longer wavelengths using the Space Infrared Telescope for Cosmology and Astrophysics (SPICA) mid-infrared instrument. We use a simple model for the spatial distribution of the dust tails and produce their synthetic transmission spectra assuming various dust compositions. We find that combined infrared spectra from JWST and SPICA will allow us to diagnose various components of the dust tails. JWST will be able to detect silicate and carbide absorption features with a feature-to-noise ratio of ≳3 in the tail transmission spectrum of a disintegrating planet located within 100 pc from the Earth, with a transit depth deeper than 0.5%. SPICA can distinguish between Fe- and Mg-bearing crystalline silicates for planets at ≲100 pc with a transit depth of ≳2%. Transit searches with current and future space telescopes (e.g., TESS and PLATO) will provide ideal targets for such spectroscopic observations.

Exploring QCD Matter at High Baryon Density

This contribution presents a brief summary of the recent past efforts to experimentally explore the QCD phase diagram at high baryon chemical potentials through heavy-ion collisions. A few measurements are highlighted to present the current status in the search for a first-order phase transition, for a possible critical endpoint, and for evidence of chiral symmetry restoration. Finally, the outlook for the ongoing beam energy scan II program and future experiments at the FAIR complex are discussed.

Occurrence rate of exoplanets orbiting ultracool dwarfs as probed by K2

Context. With the discovery of a planetary system around the ultracool dwarf TRAPPIST-1, there has been a surge of interest in such stars as potential planet hosts. Planetary systems around ultracool dwarfs represent our best chance of characterising temperate rocky-planet atmospheres with the James Webb Space Telescope. However, TRAPPIST-1 remains the only known system of its kind and the occurrence rate of planets around ultracool dwarfs is still poorly constrained. Aims. We seek to perform a complete transit search on the ultracool dwarfs observed by NASA’s K2 mission, and use the results to constrain the occurrence rate of planets around these stars. Methods. We filter and characterise the sample of ultracool dwarfs observed by K2 by fitting their spectral energy distributions and using parallaxes from Gaia. We build an automatic pipeline to perform photometry, detrend the light curves, and search for transit signals. Using extensive injection-recovery tests of our pipeline, we compute the detection sensitivity of our search, and thus the completeness of our sample. We infer the planetary occurrence rates within a hierarchical Bayesian model (HBM) to treat uncertain planetary parameters. With the occurrence rate parametrised by a step-wise function, we present a convenient way to directly marginalise over the second level of our HBM (the planetary parameters). Our method is applicable generally and can greatly speed up inference with larger catalogues of detected planets. Results. We detect one planet in our sample of 702 ultracool dwarfs: a previously validated mini-Neptune. We thus infer a mini-Neptune (2−4 R⊕) occurrence rate of η = 0.20−0.11+0.16 within orbital periods of 1−20 days. For super-Earths (1−2 R⊕) and ice or gas giants (4−6 R⊕) within 1−20 days, we place 95% credible intervals of η &lt; 1.14 and η &lt; 0.29, respectively. If TRAPPIST-1-like systems were ubiquitous, we would have a ~96% chance of finding at least one.

Phase behavior of continuous-space systems: A supervised machine learning approach.

The phase behavior of complex fluids is a challenging problem for molecular simulations. Supervised machine learning (ML) methods have shown potential for identifying the phase boundaries of lattice models. In this work, we extend these ML methods to continuous-space systems. We propose a convolutional neural network model that utilizes grid-interpolated coordinates of molecules as input data of ML and optimizes the search for phase transitions with different filter sizes. We test the method for the phase diagram of two off-lattice models, namely, the Widom-Rowlinson model and a symmetric freely jointed polymer blend, for which results are available from standard molecular simulations techniques. The ML results show good agreement with results of previous simulation studies with the added advantage that there is no critical slowing down. We find that understanding intermediate structures near a phase transition and including them in the training set is important to obtain the phase boundary near the critical point. The method is quite general and easy to implement and could find wide application to study the phase behavior of complex fluids.

Global analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey

ABSTRACT We conducted a global analysis of the TRAPPIST Ultra-Cool Dwarf Transit Survey – a prototype of the SPECULOOS transit search conducted with the TRAPPIST-South robotic telescope in Chile from 2011 to 2017 – to estimate the occurrence rate of close-in planets such as TRAPPIST-1b orbiting ultra-cool dwarfs. For this purpose, the photometric data of 40 nearby ultra-cool dwarfs were reanalysed in a self-consistent and fully automated manner starting from the raw images. The pipeline developed specifically for this task generates differential light curves, removes non-planetary photometric features and stellar variability, and searches for transits. It identifies the transits of TRAPPIST-1b and TRAPPIST-1c without any human intervention. To test the pipeline and the potential output of similar surveys, we injected planetary transits into the light curves on a star-by-star basis and tested whether the pipeline is able to detect them. The achieved photometric precision enables us to identify Earth-sized planets orbiting ultra-cool dwarfs as validated by the injection tests. Our planet-injection simulation further suggests a lower limit of 10 per cent on the occurrence rate of planets similar to TRAPPIST-1b with a radius between 1 and 1.3 R⊕ and the orbital period between 1.4 and 1.8 d.

Direct Measurement of the Forbidden 2^{3}S_{1}→3^{3}S_{1} Atomic Transition in Helium.

We present the detection of the highly forbidden 2^{3}S_{1}→3^{3}S_{1} atomic transition in helium, the weakest transition observed in any neutral atom. Our measurements of the transition frequency, upper state lifetime, and transition strength agree well with published theoretical values and can lead to tests of both QED contributions and different QED frameworks. To measure such a weak transition, we develop two methods using ultracold metastable (2^{3}S_{1}) helium atoms: low background direct detection of excited then decayed atoms for sensitive measurement of the transition frequency and lifetime, and a pulsed atom laser heating measurement for determining the transition strength. These methods could possibly be applied to other atoms, providing new tools in the search for ultraweak transitions and precision metrology.