Young exoplanets are snapshots of the planetary evolution process. Planets that orbit stars in young associations are particularly important because the age of the planetary system is well ...constrained. We present the discovery of a transiting planet larger than Neptune but smaller than Saturn in the 45 Myr Tucana-Horologium young moving group. The host star is a visual binary, and our follow-up observations demonstrate that the planet orbits the G6V primary component, DS Tuc A (HD 222259A, TIC 410214986). We first identified transits using photometry from the Transiting Exoplanet Survey Satellite (TESS; alerted as TOI 200.01). We validated the planet and improved the stellar parameters using a suite of new and archival data, including spectra from SOAR/Goodman, SALT/HRS and LCO/NRES; transit photometry from Spitzer; and deep adaptive optics imaging from Gemini/GPI. No additional stellar or planetary signals are seen in the data. We measured the planetary parameters by simultaneously modeling the photometry with a transit model and a Gaussian process to account for stellar variability. We determined that the planetary radius is \(5.70\pm0.17\) Earth radii and that the orbital period is 8.1 days. The inclination angles of the host star's spin axis, the planet's orbital axis, and the visual binary's orbital axis are aligned within 15 degrees to within the uncertainties of the relevant data. DS Tuc Ab is bright enough (V=8.5) for detailed characterization using radial velocities and transmission spectroscopy.
Data from the newly-commissioned \textit{Transiting Exoplanet Survey Satellite} (TESS) has revealed a "hot Earth" around LHS 3844, an M dwarf located 15 pc away. The planet has a radius of \(1.32\pm ...0.02\) \(R_\oplus\) and orbits the star every 11 hours. Although the existence of an atmosphere around such a strongly irradiated planet is questionable, the star is bright enough (\(I=11.9\), \(K=9.1\)) for this possibility to be investigated with transit and occultation spectroscopy. The star's brightness and the planet's short period will also facilitate the measurement of the planet's mass through Doppler spectroscopy.
High resolution spectroscopy and spectropolarimetry have been undertaken at the Anglo-Australian Telescope in order to identify suitable targets for magnetic studies of young sun-like stars, for the ...proxy study of early solar evolution. This study involved the investigation of some variable late F-/early G-type sun-like stars originally identified by the Hipparcos mission. Of the 38 stars observed for this study, HIP 31021, HIP 64732, HIP 73780 were found to be spectroscopic binary stars while HIP 19072, HIP 67651 and HIP 75636 are also likely to be binaries while HIP 33111 could even be a triple system. Magnetic fields were detected on a number of the survey stars: HIP 21632, HIP 43720, HIP 48770, HIP 62517, HIP 71933, HIP 77144, HIP 89829, HIP 90899 and HIP 105388, making these stars good candidates for follow-up Zeeman Doppler imaging studies.
We report the discovery of KELT-10b, the first transiting exoplanet discovered using the KELT-South telescope. KELT-10b is a highly inflated sub-Jupiter mass planet transiting a relatively bright \(V ...= 10.7\) star (TYC 8378-64-1), with T\(_{eff}\) = \(5948\pm74\) K, \(\log{g}\) = \(4.319_{-0.030}^{+0.020}\) and Fe/H = \(0.09_{-0.10}^{+0.11}\), an inferred mass M\(_{*}\) = \(1.112_{-0.061}^{+0.055}\) M\(_{\odot}\) and radius R\(_{*}\) = \(1.209_{-0.035}^{+0.047}\) R\(_{\odot}\). The planet has a radius R\(_{P}\) = \(1.399_{-0.049}^{+0.069}\) R\(_{J}\) and mass M\(_{P}\) = \(0.679_{-0.038}^{+0.039}\) M\(_{J}\). The planet has an eccentricity consistent with zero and a semi-major axis \(a\) = \(0.05250_{-0.00097}^{+0.00086}\) AU. The best fitting linear ephemeris is \(T_{0}\) = 2457066.72045\(\pm\)0.00027 BJD\(_{TDB}\) and P = 4.1662739\(\pm\)0.0000063 days. This planet joins a group of highly inflated transiting exoplanets with a radius much larger and a mass much less than those of Jupiter. The planet, which boasts deep transits of 1.4%, has a relatively high equilibrium temperature of T\(_{eq}\) = \(1377_{-23}^{+28}\) K, assuming zero albedo and perfect heat redistribution. KELT-10b receives an estimated insolation of \(0.817_{-0.054}^{+0.068}\) \(\times\) 10\(^9\) erg s\(^{-1}\) cm\(^{-2}\), which places it far above the insolation threshold above which hot Jupiters exhibit increasing amounts of radius inflation. Evolutionary analysis of the host star suggests that KELT-10b is unlikely to survive beyond the current subgiant phase, due to a concomitant in-spiral of the planet over the next \(\sim\)1 Gyr. The planet transits a relatively bright star and exhibits the third largest transit depth of all transiting exoplanets with V \(<\) 11 in the southern hemisphere, making it a promising candidate for future atmospheric characterization studies.
This thesis presents an investigation of two new techniques for eliminating redundancy inherent in uses of dynamic polymorphism operations such as virtual dispatches and type tests. The novelty of ...both approaches derives from taking a subject-oriented perspective which considers multiple applications to the same run-time values, as opposed to previous site-oriented reductions which treat each operation independently. The first optimization (redundant polymorphism elimination -- RPE) targets reuse over intraprocedural contexts, while the second (instance-specializing polymorphism elimination -- ISPE) considers repeated uses of the same fields over the lifetime of individual object and class instances. In both cases, the specific formulations of the techniques are guided by a study of intentionally polymorphic constructions as seen in applications of common object-oriented design patterns. The techniques are implemented in Jikes RVM for the dynamic polymorphism operations supported by the Java programming language, namely virtual and interface dispatching, type tests, and type casts. In studying the complexities of Jikes RVM's adaptive optimization system and run-time environment, an improved evaluation methodology is derived for characterizing the performance of adaptive just-in-time compilation strategies. This methodology is applied to demonstrate that the proposed optimization techniques yield several significant improvements when applied to the DaCapo benchmarks. Moreover, dramatic improvements are observed for two programs designed to highlight the costs of redundant polymorphism. In the case of the intraprocedural RPE technique, a speed up of 14% is obtained for a program designed to focus on the costs of polymorphism in applications of the Iterator pattern. For the instance-specific technique, an improvement of 29% is obtained for a program designed to focus on the costs inherent in constructions similar to the Decorator pattern. Further analyses also point to several ways in which the results of this work may be used to complement and extend existing optimization techniques, and provide clarification regarding the role of polymorphism in object-oriented design.
Program tracing is a common technique employed by software and hardware developers who are interested in characterizing the dynamic behavior of complex software systems. However, despite the ...popularity of trace-driven analyses, there are surprisingly few options for encoding trace data in a standard format.
In the past, many developers have resorted to creating their own ad-hoc trace encoding solutions, tailored specifically to the data they are considering. Such efforts are usually redundant, and in many cases lead to an obscure and poorly documented trace format which ultimately limits the reuse and sharing of potentially valuable information.
The STEP system was created to address this problem by providing a standard method for encoding general program trace data in a flexible and compact format. The system consists of a trace data definition language along with a compiler for the language and an encoding architecture that implements a number of common trace compaction techniques. The system simplifies the development and interoperability of trace clients by encapsulating the encoding process and presenting the data as an abstract object stream.
This thesis presents a detailed description of the STEP system and evaluates its utility by applying it to a variety of trace data from Java programs. Initial results indicate that compressed STEP encodings are often substantially more compact than similarly compressed naive formats.
Program tracing is a common technique employed by software and hardware developers who are interested in characterizing the dynamic behavior of complex software systems. However, despite the ...popularity of trace-driven analyses, there are surprisingly few options for encoding trace data in a standard format. In the past, many developers have resorted to creating their own ad-hoc trace encoding solutions, tailored specifically to the data they are considering. Such efforts are usually redundant, and in many cases lead to an obscure and poorly documented trace format which ultimately limits the reuse and sharing of potentially valuable information. The STEP system was created to address this problem by providing a standard method for encoding general program trace data in a flexible and compact format. The system consists of a trace data definition language along with a compiler for the language and an encoding architecture that implements a number of common trace compaction techniques. The system simplifies the development and interoperability of trace clients by encapsulating the encoding process and presenting the data as an abstract object stream. This thesis presents a detailed description of the STEP system and evaluates its utility by applying it to a variety of trace data from Java programs. Initial results indicate that compressed STEP encodings are often substantially more compact than similarly compressed naïve formats.
The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey for transiting planets orbiting bright stars for over ten years. The KELT images have a pixel scale ...of ~23"/pixel---very similar to that of NASA's Transiting Exoplanet Survey Satellite (TESS)---as well as a large point spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3'. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with higher spatial resolution, cadence, and photometric precision than the KELT telescopes, as well as spectroscopic observations of the candidate host stars. The KELT-FUN team has followed-up over 1,600 planet candidates since 2011, resulting in more than 20 planet discoveries. Excluding ~450 false alarms of non-astrophysical origin (i.e., instrumental noise or systematics), we present an all-sky catalog of the 1,128 bright stars (6<V<10) that show transit-like features in the KELT light curves, but which were subsequently determined to be astrophysical false positives (FPs) after photometric and/or spectroscopic follow-up observations. The KELT-FUN team continues to pursue KELT and other planet candidates and will eventually follow up certain classes of TESS candidates. The KELT FP catalog will help minimize the duplication of follow-up observations by current and future transit surveys such as TESS.
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