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Neptune-sized planets exhibit a wide range of compositions and densities, depending on factors related to their formation and evolution history, such as the distance from their host stars and atmospheric escape processes. They can vary from relatively low-density planets with thick hydrogen–helium atmospheres 1 , 2 to higher-density planets with a substantial amount of water or a rocky interior with a thinner atmosphere, such as HD 95338 b (ref.  3 ), TOI-849 b (ref.  4 ) and TOI-2196 b (ref.  5 ). The discovery of exoplanets in the hot-Neptune desert 6 , a region close to the host stars with a deficit of Neptune-sized planets, provides insights into the formation and evolution of planetary systems, including the existence of this region itself. Here we show observations of the transiting planet TOI-1853 b, which has a radius of 3.46 ± 0.08 Earth radii and orbits a dwarf star every 1.24 days. This planet has a mass of 73.2 ± 2.7 Earth masses, almost twice that of any other Neptune-sized planet known so far, and a density of 9.7 ± 0.8 grams per cubic centimetre. These values place TOI-1853 b in the middle of the Neptunian desert and imply that heavy elements dominate its mass. The properties of TOI-1853 b present a puzzle for conventional theories of planetary formation and evolution, and could be the result of several proto-planet collisions or the final state of an initially high-eccentricity planet that migrated closer to its parent star. Observations of the super-massive Neptune-sized transiting planet TOI-1853 b show a mass almost twice that of any other Neptune-sized planet known so far and a bulk density implying that heavy elements dominate its mass.

Giant exoplanets orbiting close to their host stars are unlikely to have formed in their present configurations 1 . These ‘hot Jupiter’ planets are instead thought to have migrated inward from beyond the ice line and several viable migration channels have been proposed, including eccentricity excitation through angular-momentum exchange with a third body followed by tidally driven orbital circularization 2 , 3 . The discovery of the extremely eccentric ( e  = 0.93) giant exoplanet HD 80606 b (ref.  4 ) provided observational evidence that hot Jupiters may have formed through this high-eccentricity tidal-migration pathway 5 . However, no similar hot-Jupiter progenitors have been found and simulations predict that one factor affecting the efficacy of this mechanism is exoplanet mass, as low-mass planets are more likely to be tidally disrupted during periastron passage 6 – 8 . Here we present spectroscopic and photometric observations of TIC 241249530 b, a high-mass, transiting warm Jupiter with an extreme orbital eccentricity of e  = 0.94. The orbit of TIC 241249530 b is consistent with a history of eccentricity oscillations and a future tidal circularization trajectory. Our analysis of the mass and eccentricity distributions of the transiting-warm-Jupiter population further reveals a correlation between high mass and high eccentricity. The spectroscopic and photometric observations of a high-mass, transiting warm Jupiter, TIC 241249530 b, with an orbital eccentricity of 0.94, provide evidence that hot Jupiters may have formed by means of a high-eccentricity tidal-migration pathway.

About 1 out of 200 Sun-like stars has a planet with an orbital period shorter than one day: an ultrashort-period planet 1 , 2 . All of the previously known ultrashort-period planets are either hot Jupiters, with sizes above 10 Earth radii ( R ⊕ ), or apparently rocky planets smaller than 2  R ⊕ . Such lack of planets of intermediate size (the ‘hot Neptune desert’) has been interpreted as the inability of low-mass planets to retain any hydrogen/helium (H/He) envelope in the face of strong stellar irradiation. Here we report the discovery of an ultrashort-period planet with a radius of 4.6  R ⊕ and a mass of 29  M ⊕ , firmly in the hot Neptune desert. Data from the Transiting Exoplanet Survey Satellite 3 revealed transits of the bright Sun-like star LTT 9779 every 0.79 days. The planet’s mean density is similar to that of Neptune, and according to thermal evolution models, it has a H/He-rich envelope constituting 9.0 − 2.9 + 2.7 % of the total mass. With an equilibrium temperature around 2,000 K, it is unclear how this ‘ultrahot Neptune’ managed to retain such an envelope. Follow-up observations of the planet’s atmosphere to better understand its origin and physical nature will be facilitated by the star’s brightness ( V mag  = 9.8). LTT 9779 b is Neptune-sized planet rotating around its star with a period of 0.79 days and an equilibrium temperature of 2,000 K. It is not clear how it retained its atmospheric envelope, which contains ~10% of H/He, as it should have been photoevaporated by now.

It is commonly accepted that exoplanets with orbital periods shorter than one day, also known as ultra-short-period (USP) planets, formed further out within their natal protoplanetary disks before migrating to their current-day orbits via dynamical interactions. One of the most accepted theories suggests a violent scenario involving high-eccentricity migration followed by tidal circularization. Here we present the discovery of a four-planet system orbiting the bright (V = 10.5) K6 dwarf star TOI-500. The innermost planet is a transiting, Earth-sized USP planet with an orbital period of ~13 hours, a mass of 1.42 ± 0.18  M ⊕ , a radius of 1.16 6 − 0.058 + 0.061 R ⊕ and a mean density of 4.8 9 − 0.88 + 1.03 g cm − 3 . Via Doppler spectroscopy, we discovered that the system hosts 3 outer planets on nearly circular orbits with periods of 6.6, 26.2 and 61.3 days and minimum masses of 5.03 ± 0.41  M ⊕ , 33.12 ± 0.88  M ⊕ and 15.0 5 − 1.11 + 1.12 M ⊕ , respectively. The presence of both a USP planet and a low-mass object on a 6.6-day orbit indicates that the architecture of this system can be explained via a scenario in which the planets started on low-eccentricity orbits then moved inwards through a quasi-static secular migration. Our numerical simulations show that this migration channel can bring TOI-500 b to its current location in 2 Gyr, starting from an initial orbit of 0.02 au. TOI-500 is the first four-planet system known to host a USP Earth analogue whose current architecture can be explained via a non-violent migration scenario. TOI-500 hosts at least four planets, the innermost of which is an Earth-sized ultra-short-period body with a density similar to Earth. The architecture of the TOI-500 system can be explained by a slow, secular, low-eccentricity migration scenario.

Classroom management and school-wide discipline is a struggle for teachers and administrators across our nation. This quasi-experimental cohort study sought to examine the impact the implementation of the Nine Modules and Love and Logic had on office referrals and students’ academic achievement. The study also looked at teachers’ perception of the program. The sample population consisted of approximately 1100 students, 65 teachers, and administrators in a Title I school in southeast Tennessee. Statistical significance was found between the control and treatment groups for both behavior infractions and math proficiency levels, but not for ELA scores or proficiency levels. Conclusions reflect the Nine Modules were effective in reducing office referrals and had a positive impact on teachers’ perception of the program.

Large astronomical surveys find thousands of interesting transient events, such as exoplanets. Beyond detection, these surveys are limited in their ability to study the properties of these discoveries. In particular, a common problem with wide-field surveys is because they observe huge swaths of the sky, their resolution is often quite coarse, leading to source confusion and photometric contamination. In this dissertation, I discuss the use of robotic, high-resolution instruments to confirm and characterize exoplanets and also better understand the demographics of stellar populations. These surveys are only feasible with autonomous instruments due to the order-of-magnitude increase in observational time efficiency gained with automation. I present first the design and construction of Robo-SOAR, a moderate-order NGS-AO system in development for the SOAR telescope. With robotic software adapted from Robo-AO, Robo-SOAR will be capable of observing hundreds of targets a night. With an innovative, low-cost dual knife-edge WFS, similar in concept to a pyramid WFS but with reduced chromatic aberrations, Robo-SOAR can reach the diffraction limit on brighter targets. I then discuss the observations of 348 cool subdwarf stars with Robo-AO, a pilot study for future kilo-target surveys. Cool subdwarfs are remnants of the first population of stars formed in the Milky Way. I find that approximately 12% of cool subdwarfs have binary companions, a multiplicity fraction three times lower than similar dwarf stars. The disparity between the two populations may be evidence of the different environments in which they formed. The lack of companions to cool subdwarfs suggests they may have formed in less dense regions, or over their long lifetimes may have had more disruptive encounters with other stars and the Galactic tide. It is also possible that they are galactic interlopers, and formed in small, less-dense galaxies that merged with the Milky Way. We show that the disparity between cool subdwarf and red dwarf multiplicity is consistent with this scenario. I report the results of the Robo-AO survey of every planetary candidate discovered with Kepler to search for previously unknown nearby stars. These stars contaminate the exquisite photometry of Kepler and can either dilute the transit signal from a real planet, resulting in underestimated radii estimates, or be the source of an astrophysical false positive transit signal. More than half of the over 4000 Kepler planetary candidates have only been observed with Robo-AO. We find 610 stars within 4'' of a planetary candidate host star, and correct the derived radii estimates of the more than 800 planets within these systems. On average, we find that the planetary radii increase by a factor of approximately 1.59 in systems with a detected nearby star. We quantify the probability of association for over 150 multiple systems hosting planets using multi-band photometry. In particular, we examine five planetary candidate host stars with four nearby stars detected by Robo-AO and quantify the probability they are high-order planet-hosting systems. Lastly, I use the results of the Robo-AO Kepler survey to search for evidence of the impact multiple star systems have on planets. The presence of a companion star is believed to have a significant impact on the properties of planetary systems. I find that hot Jupiters are more likely than any other planet to be found in a binary star system. This suggests that stellar companions drive orbital migration of giant planets. I also find that single and multiple-transiting planet systems are equally likely to be found in a binary. I find that KOIs from later data releases are less likely to have a nearby star than systems from earlier data releases, possibly a result of the automation of the Kepler vetting pipeline. I find that KOIs follow trends observed in field stars with respect to the relationship between stellar multiplicity and stellar effective temperature and metallicity.

Adsorption isotherms can be used to determine surface area of a substrate and the heat released when adsorption occurs. Our measurements are done determining the equilibrium pressures corresponding to a given amount of gas adsorbed on a substrate at constant temperature. The adsorption studies were done on aggregates of open dahlia-like carbon nanohorns. The nanohorns were oxidized for 9 hours at 550 °C to open them up and render their interior space accessible for adsorption. Volumetric adsorption measurements of Ne were performed at twelve different temperatures between 19 K and 48 K. The isotherms showed two substeps. The first substep corresponds to adsorption on the high energy binding sites in the interior of the nanohorns, near the tip. The second substep corresponds to low energy binding sites both on the outside of the nanotubes and inside the nanotube away from the tip. The isosteric heat measurements obtained from the isotherm data also shows these two distinct substeps. The effective surface area of the open nanotubes was determined from the isotherms using the point-B method. The isosteric heat and surface area data for neon on open nanohorns were compared to two similar experiments of neon adsorbed on aggregates of closed nanohorns.

The first generation of transiting planet searches in globular clusters yielded no detections, and in hindsight, only placed occurrence rate limits slightly higher than the measured occurrence rate in the higher-metallicity Galactic thick disk. To improve these limits, we present the first results of a new wide field search for transiting hot Jupiters in the globular cluster 47~Tucanae. We have observed 47~Tuc as part of the Multiband Imaging Survey for High-Alpha Planets (MISHAPS). Using 24 partial and full nights of observations taken with the Dark Energy Camera on the 4-m Blanco telescope at CTIO, we perform a search on 19,930 stars in the outer regions of the cluster. Though we find no clear planet detections, by combining our result with the upper limit enabled by Gilliland et al.'s 2000 Hubble search for planets around an independent sample of 34,091 stars in the inner cluster, we place the strongest limit to date on hot Jupiters with periods of \\(0.8 \\leq P \\leq 8.3\\) days and \\(0.5~R_{\\rm Jup} \\leq R_{\\rm P} \\leq 2.0~R_{\\rm Jup}\\) of \\(f_{\\rm HJ} < 0.11\\%\\), a factor of \\({\\sim}\\)4 below the occurrence rate in the \\textit{Kepler} field. Our search found 35 transiting planet candidates, though we are ultimately able to rule out each without follow-up observations. We also found 4 eclipsing binaries, including 3 previously-uncataloged detached eclipsing binary stars.

We report the discovery and confirmation of TOI-4465 b, a \\(1.25^{+0.08}_{-0.07}~R_{J}\\), \\(5.89\\pm0.26~M_{J}\\) giant planet orbiting a G dwarf star at \\(d\\simeq\\) 122 pc. The planet was detected as a single-transit event in data from Sector 40 of the Transiting Exoplanet Survey Satellite (TESS) mission. Radial velocity (RV) observations of TOI-4465 showed a planetary signal with an orbital period of \\(\\sim\\)102 days, and an orbital eccentricity of \\(e=0.24\\pm0.01\\). TESS re-observed TOI-4465 in Sector 53 and Sector 80, but did not detect another transit of TOI-4465 b, as the planet was not expected to transit during these observations based on the RV period. A global ground-based photometry campaign was initiated to observe another transit of TOI-4465 b after the RV period determination. The \\(\\sim\\)12 hour-long transit event was captured from multiple sites around the world, and included observations from 24 citizen scientists, confirming the orbital period as \\(\\sim\\)102 days. TOI-4465 b is a relatively dense (\\(3.73\\pm0.53~\\rm{g/cm^3}\\)), temperate (375-478 K) giant planet. Based on giant planet structure models, TOI-4465 b appears to be enriched in heavy elements at a level consistent with late-stage accretion of icy planetesimals. Additionally, we explore TOI-4465 b's potential for atmospheric characterization, and obliquity measurement. Increasing the number of long-period planets by confirming single-transit events is crucial for understanding the frequency and demographics of planet populations in the outer regions of planetary systems.