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تسجيل مستخدم جديدThe Transiting Exoplanet Survey Satellite
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The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I = 4-13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the stars ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations.
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We present the discovery of two new 10-day period giant planets from the Transiting Exoplanet Survey Satellite ($TESS$) mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481 b and TOI-892 b have si
milar radii ($0.99pm0.01$ $rm R_{J}$ and $1.07pm0.02$ $rm R_{J}$, respectively), and orbital periods (10.3311 days and 10.6266 days, respectively), but significantly different masses ($1.53pm0.03$ $rm M_{J}$ versus $0.95pm0.07$ $rm M_{J}$, respectively). Both planets orbit metal-rich stars ([Fe/H]= $+0.26pm 0.05$ dex and [Fe/H] = $+0.24 pm 0.05$ dex, for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a $rm M_{star}$ = $1.14pm0.02$ $rm M_{odot}$, $rm R_{star}$ = $1.66pm0.02$ $rm R_{odot}$ G-type star ($T_{rm eff}$ = $5735 pm 72$ K), that with an age of 6.7 Gyr, is in the turn-off point of the main sequence. TOI-892, on the other hand, is a F-type dwarf star ($T_{rm eff}$ = $6261 pm 80$ K), which has a mass of $rm M_{star}$ = $1.28pm0.03$ $rm M_{odot}$, and a radius of $rm R_{star}$ = $1.39pm0.02$ $rm R_{odot}$. TOI-481 b and TOI-892 b join the scarcely populated region of transiting gas giants with orbital periods longer than 10 days, which is important to constrain theories of the formation and structure of hot Jupiters.
The {it Transiting Exoplanet Survey Satellite} (TESS) searches for planets transiting bright and nearby stars using high-cadence, large-scale photometric observations. Full Frame Images provided by the TESS mission include large number of serendipito
usly observed main-belt asteroids. Due to the cadence of the published Full Frame Images we are sensitive to periods as long as of order tens of days, a region of phase space that is generally not accessible through traditional observing. This work represents a much less biased measurement of the period distribution in this period range. We have derived rotation periods for 300~main-belt asteroids and have partial lightcurves for a further 7277 asteroids, including 43 with periods $P > 100$ h; this large number of slow rotators is predicted by theory. Of these slow rotators we find none requiring significant internal strength to resist rotational reshaping. We find our derived rotation periods to be in excellent agreement with results in the Lightcurve Database for the 55~targets that overlap. Over the nominal two-year lifetime of the mission, we expect the detection of around 85,000 unique asteroids with rotation period solutions for around 6000 asteroids. We project that the systematic analysis of the entire TESS data set will increase the number of known slow-rotating asteroids (period > 100~h) by a factor of 10. Comparing our new period determinations with previous measurements in the literature, we find that the rotation period of asteroid (2320) Blarney has decreased by at least 20% over the past decade, potentially due to surface activity or subcatastrophic collisions.
A novel artificial intelligence (AI) technique that uses machine learning (ML) methodologies combines several algorithms, which were developed by ThetaRay, Inc., is applied to NASAs Transiting Exoplanets Survey Satellite (TESS) dataset to identify ex
oplanetary candidates. The AI/ML ThetaRay system is trained initially with Kepler exoplanetary data and validated with confirmed exoplanets before its application to TESS data. Existing and new features of the data, based on various observational parameters, are constructed and used in the AI/ML analysis by employing semi-supervised and unsupervised machine learning techniques. By the application of ThetaRay system to 10,803 light curves of threshold crossing events (TCEs) produced by the TESS mission, obtained from the Mikulski Archive for Space Telescopes, the algorithm yields about 50 targets for further analysis, and we uncover three new exoplanetary candidates by further manual vetting. This study demonstrates for the first time the successful application of the particular combined multiple AI/ML-based methodologies to a large astrophysical dataset for rapid automated classification of TCEs.
We report the discovery of TOI-172 b from the Transiting Exoplanet Survey Satellite (TESS) mission, a massive hot Jupiter transiting a slightly evolved G-star with a 9.48-day orbital period. This is the first planet to be confirmed from analysis of o
nly the TESS full frame images, because the host star was not chosen as a two minute cadence target. From a global analysis of the TESS photometry and follow-up observations carried out by the TESS Follow-up Observing Program Working Group, TOI-172 (TIC 29857954) is a slightly evolved star with an effective temperature of $T_{rm eff}$ =$5645pm50$ K, a mass of $M_{star}$ = $1.128^{+0.065}_{-0.061}$ $M_{odot}$, radius of $R_{star}$ = $1.777^{+0.047}_{-0.044}$ $R_{odot}$, a surface gravity of $log$ $g_{star}$ = $3.993^{+0.027}_{-0.028}$, and an age of $7.4^{+1.6}_{-1.5}$ Gyr. Its planetary companion (TOI-172 b) has a radius of $R_{rm P}$ = $0.965^{+0.032}_{-0.029}$ $R_{rm J}$, a mass of $M_{rm P}$ = $5.42^{+0.22}_{-0.20}$ $M_{rm J}$, and is on an eccentric orbit ($e = 0.3806^{+0.0093}_{-0.0090}$). TOI-172 b is one of the few known massive giant planets on a highly eccentric short-period orbit. Future study of the atmosphere of this planet and its system architecture offer opportunities to understand the formation and evolution of similar systems.
We report the discovery of WASP-13b, a low-mass $ M_p = 0.46 ^{+ 0.06}_{- 0.05} M_J$ transiting exoplanet with an orbital period of $4.35298 pm 0.00004$ days. The transit has a depth of 9 mmag, and although our follow-up photometry does not allow us
to constrain the impact parameter well ($0 < b < 0.46$), with radius in the range $R_p sim 1.06 - 1.21 R_J$ the location of WASP-13b in the mass-radius plane is nevertheless consistent with H/He-dominated, irradiated, low core mass and core-free theoretical models. The G1V host star is similar to the Sun in mass (M$_{*} = 1.03^{+0.11}_ {- 0.09} M_{odot}$) and metallicity ([M/H]=$0.0pm0.2$), but is possibly older ($8.5^{+ 5.5}_{- 4.9}$ Gyr).
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