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Bergmann, C., Jones, M. I., Zhao, J., Mustill, A. J., Brahm, R., Torres, P., et al. (2021). HD 76920 b pinned down: A detailed analysis of the most eccentric planetary system around an evolved star. PUBL. ASTRON. SOC. AUST., 38, e019.
Abstract: We present 63 new multi-site radial velocity (RV) measurements of the K1III giant HD 76920, which was recently reported to host the most eccentric planet known to orbit an evolved star. We focused our observational efforts on the time around the predicted periastron passage and achieved near-continuous phase coverage of the corresponding RV peak. By combining our RV measurements from four different instruments with previously published ones, we confirm the highly eccentric nature of the system and find an even higher eccentricity of , an orbital period of 415.891(-0.039)(+0.043) d, and a minimum mass of 3.13(-0.43)(+0.41) M-J for the planet. The uncertainties in the orbital elements are greatly reduced, especially for the period and eccentricity. We also performed a detailed spectroscopic analysis to derive atmospheric stellar parameters, and thus the fundamental stellar parameters (M-*, R-*, L-*) taking into account the parallax from Gaia DR2, and independently determined the stellar mass and radius using asteroseismology. Intriguingly, at periastron, the planet comes to within 2.4 stellar radii of its host star's surface. However, we find that the planet is not currently experiencing any significant orbital decay and will not be engulfed by the stellar envelope for at least another 50-80 Myr. Finally, while we calculate a relatively high transit probability of 16%, we did not detect a transit in the TESS photometry.
Keywords: EXTRA-SOLAR PLANETS; RADIAL-VELOCITY; GIANT STAR; STELLAR EVOLUTION; MASS COMPANION; EXOPLANETS; PRECISION; SEARCH; TRANSIT; I.
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Brahm, R., Nielsen, L. D., Wittenmyer, R. A., Wang, S. H., Rodriguez, J. E., Espinoza, N., et al. (2020). TOI-481 b and TOI-892 b: Two Long-period Hot Jupiters from the Transiting Exoplanet Survey Satellite. Astron. J., 160(5), 14 pp.
Abstract: We present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of ground-based facilities. TOI-481.b and TOI-892.b have similar radii (0.99.+/-.0.01 R-J and 1.07.+/-.0.02 R-J, respectively), and orbital periods (10.3311 days and 10.6266 days, respectively), but significantly different masses (1.53.+/-.0.03 MJ versus 0.95.+/-.0.07 MJ, respectively). Both planets orbit metal-rich stars ([Fe H] = + 0.26. 0.05 dex and [Fe H] = +0.24. 0.05 for TOI-481 and TOI-892, respectively) but at different evolutionary stages. TOI-481 is a M*=.1.14.+/-.0.02 M., R*=.1.66.+/-.0.02 R. G-type star (T-eff = 5735 +/- 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-eff = 6261 +/- 80 K), which has a mass of M*=.1.28.+/-.0.03 M-circle dot and a radius of R*=.1.39.+/-.0.02 R-circle dot. 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.
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Carmichael, T. W., Quinn, S. N., Mustill, A. J., Huang, C., Zhou, G., Persson, C. M., et al. (2020). Two Intermediate-mass Transiting Brown Dwarfs from the TESS Mission. Astron. J., 160(1), 15 pp.
Abstract: We report the discovery of two intermediate-mass transiting brown dwarfs (BDs), TOI-569b and TOI-1406b, from NASA's Transiting Exoplanet Survey Satellite mission. TOI-569b has an orbital period of P = 6.55604 0.00016 days, a mass of M-b = 64.1 1.9 , and a radius of R-b = 0.75 0.02 . Its host star, TOI-569, has a mass of M-star = 1.21 0.05, a radius of R-star = 1.47 0.03 dex, and an effective temperature of T-eff = 5768 110 K. TOI-1406b has an orbital period of P = 10.57415 0.00063 days, a mass of M-b = 46.0 2.7 , and a radius of R-b = 0.86 0.03 . The host star for this BD has a mass of M-star = 1.18 0.09 a radius of R-star = 1.35 0.03 dex, and an effective temperature of T-eff = 6290 100 K. Both BDs are in circular orbits around their host stars and are older than 3 Gyr based on stellar isochrone models of the stars. TOI-569 is one of two slightly evolved stars known to host a transiting BD (the other being KOI-415). TOI-1406b is one of three known transiting BDs to occupy the mass range of 40-50 and one of two to have a circular orbit at a period near 10 days (with the first being KOI-205b). Both BDs have reliable ages from stellar isochrones, in addition to their well-constrained masses and radii, making them particularly valuable as tests for substellar isochrones in the BD mass-radius diagram.
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Clark, J. T., Addison, B. C., Okumura, J., Vach, S., Errico, A., Heitzmann, A., et al. (2023). Spinning up a Daze: TESS Uncovers a Hot Jupiter Orbiting the Rapid Rotator TOI-778. Astron. J., 165(5), 207.
Abstract: NASA's Transiting Exoplanet Survey Satellite (TESS) mission has been uncovering a growing number of exoplanets orbiting nearby, bright stars. Most exoplanets that have been discovered by TESS orbit narrow-line, slow-rotating stars, facilitating the confirmation and mass determination of these worlds. We present the discovery of a hot Jupiter orbiting a rapidly rotating (v sin (i) = 35.1 +/- 1.0 km s(-1) early F3V-dwarf, HD 115447 (TOI-778). The transit signal taken from Sectors 10 and 37 of TESS's initial detection of the exoplanet is combined with follow-up ground-based photometry and velocity measurements taken from MINERVA-Australis, TRES, CORALIE, and CHIRON to confirm and characterize TOI-778 b. A joint analysis of the light curves and the radial velocity measurements yields a mass, a radius, and an orbital period for TOI-778 b of 2.76(-0.23)(+0.24) M-J, 1.370 +/- 0.043 R-J, and similar to 4.63 days, respectively. The planet orbits a bright (V = 9.1 mag) F3-dwarf with M = 1.40 +/- 0.05 M-circle dot, R = 1.70 +/- 0.05 R-circle dot, and log g = 4.05 +/- 0.17. We observed a spectroscopic transit of TOI-778 b, which allowed us to derive a sky-projected spin-orbit angle of 18 degrees +/- 11 degrees, consistent with an aligned planetary system. This discovery demonstrates the capability of smaller-aperture telescopes such as MINERVA-Australis to detect the radial velocity signals produced by planets orbiting broad-line, rapidly rotating stars.
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Cortes, C. E., Jara-Moroni, P., Moreno, E., & Pineda, C. (2013). Stochastic transit equilibrium. Transp. Res. Pt. B-Methodol., 51, 29–44.
Abstract: We present a transit equilibrium model in which boarding decisions are stochastic. The model incorporates congestion, reflected in higher waiting times at bus stops and increasing in-vehicle travel time. The stochastic behavior of passengers is introduced through a probability for passengers to choose boarding a specific bus of a certain service. The modeling approach generates a stochastic common-lines problem, in which every line has a chance to be chosen by each passenger. The formulation is a generalization of deterministic transit assignment models where passengers are assumed to travel according to shortest hyperpaths. We prove existence of equilibrium in the simplified case of parallel lines (stochastic common-lines problem) and provide a formulation for a more general network problem (stochastic transit equilibrium). The resulting waiting time and network load expressions are validated through simulation. An algorithm to solve the general stochastic transit equilibrium is proposed and applied to a sample network; the algorithm works well and generates consistent results when considering the stochastic nature of the decisions, which motivates the implementation of the methodology on a real-size network case as the next step of this research. (C) 2013 Elsevier Ltd. All rights reserved.
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Dong, J. Y., Huang, C. X., Dawson, R. I., Foreman-Mackey, D., Collins, K. A., Quinn, S. N., et al. (2021). Warm Jupiters in TESS Full-frame Images: A Catalog and Observed Eccentricity Distribution for Year 1. Astrophys. J. Suppl. Ser., 255(1), 6.
Abstract: Warm Jupiters-defined here as planets larger than 6 Earth radii with orbital periods of 8-200 days-are a key missing piece in our understanding of how planetary systems form and evolve. It is currently debated whether Warm Jupiters form in situ, undergo disk or high-eccentricity tidal migration, or have a mixture of origin channels. These different classes of origin channels lead to different expectations for Warm Jupiters' properties, which are currently difficult to evaluate due to the small sample size. We take advantage of the Transiting Exoplanet Survey Satellite (TESS) survey and systematically search for Warm Jupiter candidates around main-sequence host stars brighter than the TESS-band magnitude of 12 in the full-frame images in Year 1 of the TESS Prime Mission data. We introduce a catalog of 55 Warm Jupiter candidates, including 19 candidates that were not originally released as TESS objects of interest by the TESS team. We fit their TESS light curves, characterize their eccentricities and transit-timing variations, and prioritize a list for ground-based follow-up and TESS Extended Mission observations. Using hierarchical Bayesian modeling, we find the preliminary eccentricity distributions of our Warm-Jupiter-candidate catalog using a beta distribution, a Rayleigh distribution, and a two-component Gaussian distribution as the functional forms of the eccentricity distribution. Additional follow-up observations will be required to clean the sample of false positives for a full statistical study, derive the orbital solutions to break the eccentricity degeneracy, and provide mass measurements.
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Eberhardt, J., Hobson, M. J., Henning, T., Trifonov, T., Brahm, R., Espinoza, N., et al. (2023). Three Warm Jupiters around Solar-analog Stars Detected with TESS. Astron. J., 166(6), 271.
Abstract: We report the discovery and characterization of three giant exoplanets orbiting solar-analog stars, detected by the TESS space mission and confirmed through ground-based photometry and radial velocity measurements taken at La Silla observatory with FEROS. TOI-2373 b is a warm Jupiter orbiting its host star every similar to 13.3 days, and is one of the most massive known exoplanet with a precisely determined mass and radius around a star similar to the Sun, with an estimated mass of m(p) = 9.3(-0.2)(+0.2)Mjup and a radius of r(p) = 0.93(-0.2)(+0.2) jup. With a mean density of r = 14.4 1.0 g cm + 0.9 -3, TOI-2373 b is among the densest planets discovered so far. TOI-2416 b orbits its host star on a moderately eccentric orbit with a period of similar to 8.3 days and an eccentricity of e = 0.32 0.02 + 0.02. TOI-2416 b is more massive than Jupiter with m(p) = 3.0 +0.09 M 0.10 jup, however is significantly smaller with a radius of r(p) = 0.88 + 0.02 ,R 0.02 jup, leading to a high mean density of r = 5.4 0.3 g cm + 0.3 -3. TOI-2524 b is a warm Jupiter near the hot Jupiter transition region, orbiting its star every similar to 7.2 days on a circular orbit. It is less massive than Jupiter with a mass of m(p)=0.64- + 0.04 M 0.04 jup, and is consistent with an inflated radius of r(p)= 1.00- + 0.03 R 0.02 jup, leading to a low mean density of r = 0.79 0.08 g cm + 0.08 -3. The newly discovered exoplanets TOI-2373 b, TOI-2416 b, and TOI-2524 b have estimated equilibrium temperatures of 860 10 +10 K, 1080 10 +10 K, and 1100-20 +20 K, respectively, placing them in the sparsely populated transition zone between hot and warm Jupiters.
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Espinoza-Retamal, J. I., Brahm, R., Petrovich, C., Jordán, A., Stefánsson, G., Sedaghati, E., et al. (2023). The Aligned Orbit of the Eccentric Proto Hot Jupiter TOI-3362b. Astrophys. J. Lett., 958(2), L20.
Abstract: High-eccentricity tidal migration predicts the existence of highly eccentric proto hot Jupiters on the “tidal circularization track,” meaning that they might eventually become hot Jupiters, but that their migratory journey remains incomplete. Having experienced moderate amounts of tidal evolution of their orbital elements, proto hot Jupiter systems can be powerful test beds for the underlying mechanisms of eccentricity growth. Notably, they may be used for discriminating between variants of high-eccentricity migration, each predicting a distinct evolution of misalignment between the star and the planet's orbit. We constrain the spin-orbit misalignment of the proto hot Jupiter TOI-3362b with high-precision radial-velocity observations using ESPRESSO at Very Large Telescope. The observations reveal a sky-projected obliquity lambda=1.2+2.8(degrees)/-2.7 and constrain the orbital eccentricity to e = 0.720 +/- 0.016, making it one of the most eccentric gas giants for which the obliquity has been measured. Although the large eccentricity and the striking orbit alignment of the planet are puzzling, we suggest that ongoing coplanar high-eccentricity migration driven by a distant companion is a possible explanation for the system's architecture. This distant companion would need to reside beyond 5 au at 95% confidence to be compatible with the available radial-velocity observations.
Keywords: IN-SITU FORMATION; PLANET; TRANSIT; EVOLUTION; BINARY; PHOTOMETRY; SCATTERING; TELESCOPE; MIGRATION; COMPANION
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Ferrada, F., Babonneau, F., Homem-de-Mello, T., & Jalil-Vega, F. (2023). The role of hydrogen for deep decarbonization of energy systems: A Chilean case study. Energy Policy, 177, 113536.
Abstract: In this paper we implement a long-term multi-sectoral energy planning model to evaluate the role of green hydrogen in the energy mix of Chile, a country with a high renewable potential, under stringent emission reduction objectives in 2050. Our results show that green hydrogen is a cost-effective and environmentally friendly route especially for hard-to-abate sectors, such as interprovincial and freight transport. They also suggest a strong synergy of hydrogen with electricity generation from renewable sources. Our numerical simulations show that Chile should (i) start immediately to develop hydrogen production through electrolyzers all along the country, (ii) keep investing in wind and solar generation capacities ensuring a low cost hydrogen production and reinforce the power transmission grid to allow nodal hydrogen production, (iii) foster the use of electric mobility for cars and local buses and of hydrogen for long-haul trucks and interprovincial buses and, (iv) develop seasonal hydrogen storage and hydrogen cells to be exploited for electricity supply, especially for the most stringent emission reduction objectives.
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Hartman, J. D., Jordan, A., Bayliss, D., Bakos, G. A., Bento, J., Bhatti, W., et al. (2020). HATS-47b, HATS-48Ab, HATS-49b, and HATS-72b: Four Warm Giant Planets Transiting K Dwarfs. Astron. J., 159(4), 23 pp.
Abstract: We report the discovery of four transiting giant planets around K dwarfs. The planets HATS-47b, HATS-48Ab, HATS49b, and HATS-72b have masses of 0.369+ 0.0210.031MJ, 0.243+ 0.0300.022 MJ, 0.353+ 0.0270.038 MJ, and 0.1254. 0.0039 MJ, respectively, and radii of 1.117. 0.014 RJ, 0.800. 0.015 RJ, 0.765. 0.013 RJ, and 0.7224. 0.0032 RJ, respectively. The planets orbit close to their host stars with orbital periods of 3.9228 days, 3.1317 days, 4.1480 days, and 7.3279 days, respectively. The hosts are main-sequence K dwarfs with masses of 0.674+ 0.0120.016.M, 0.7279. 0.0066.M, 0.7133. 0.0075.M, and 0.7311. 0.0028, and with V-band magnitudes of V = 14.829. 0.010, 14.35. 0.11, 14.998. 0.040 and 12.469. 0.010. The super-Neptune HATS-72b (a.k.a. WASP-191b and TOI 294.01) was independently identified as a transiting planet candidate by the HATSouth, WASP, and TESS surveys, and we present a combined analysis of all of the data gathered by each of these projects (and their follow-up programs). An exceptionally precise mass is measured for HATS-72b thanks to high-precision radial velocity (RV) measurements obtained with VLT/ESPRESSO, FEROS, HARPS, and Magellan/PFS. We also incorporate TESS observations of the warm Saturn-hosting systems HATS-47 (a.k.a. TOI.1073.01), HATS-48A, and HATS-49. HATS-47 was independently identified as a candidate by the TESS team, while the other two systems were not previously identified from the TESS data. The RV orbital variations are measured for these systems using Magellan/PFS. HATS-48A has a resolved 5.. 4 neighbor in Gaia.DR2, which is a common-proper-motion binary star companion to HATS-48A with a mass of 0.22.M and a current projected physical separation of similar to 1400 au.
Keywords: Exoplanets; Extrasolar gas giants; Hot Jupiters; Transits
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Heitzmann, A., Zhou, G., Quinn, S. N., Huang, C. X., Dong, J. Y., Bouma, L. G., et al. (2023). TOI-4562b: A Highly Eccentric Temperate Jupiter Analog Orbiting a Young Field Star. Astron. J., 165(3), 121.
Abstract: We report the discovery of TOI-4562b (TIC-349576261), a Jovian planet orbiting a young F7V-type star, younger than the Praesepe/Hyades clusters (< 700 Myr). This planet stands out because of its unusually long orbital period for transiting planets with known masses (Porb = 225.11781(- 0.00022) (+0.00025 )days) and because it has a substantial eccentricity (e = 0.76(- 0.02) (+0.02)). The location of TOI-4562 near the southern continuous viewing zone of TESS allowed observations throughout 25 sectors, enabling an unambiguous period measurement from TESS alone. Alongside the four available TESS transits, we performed follow-up photometry using the South African Astronomical Observatory node of the Las Cumbres Observatory and spectroscopy with the CHIRON spectrograph on the 1.5 m SMARTS telescope. We measure a radius of 1.118 (+0.013) (-0.014) R(J )and a mass of 2.30(-0.47)(+0.48)M(J) for TOI-4562b. The radius of the planet is consistent with contraction models describing the early evolution of the size of giant planets. We detect tentative transit timing variations at the similar to 20 minutes level from five transit events, favoring the presence of a companion that could explain the dynamical history of this system if confirmed by future follow-up observations. With its current orbital configuration, tidal timescales are too long for TOI-4562b to become a hot Jupiter via high eccentricity migration though it is not excluded that interactions with the possible companion could modify TOI4562b's eccentricity and trigger circularization. The characterization of more such young systems is essential to set constraints on models describing giant-planet evolution.
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Holguin-Veras, J., Yushimito, W. F., Aros-Vera, F., & Reilly, J. (2012). User rationality and optimal park-and-ride location under potential demand maximization. Transp. Res. Pt. B-Methodol., 46(8), 949–970.
Abstract: The paper develops analytical formulations to gain insight into the optimal location, i.e., the one that maximizes the potential market, and to estimate the potential catchment area of Park and Ride (P&R) facilities. The formulations are based on the assumption that a traveler would use a P&R facility if and only if the corresponding generalized cost is lower than the drive only alternative. The paper considers two different scenarios: a linear city (or a travel corridor), and a two-dimensional city with Euclidean travel. Analytical derivations were obtained for both cases using, as starting point, the necessary condition for P&R use. In the case of the linear city, the paper identifies two breakeven distances (BEDs) of great import to the estimation of the potential P&R market: the (trip) origin BED, i.e., the distance below which a traveler could drive upstream to use the P&R facility to access its downstream destination, and still be better off; and the (trip) destination BED, i.e., the travel distance using transit below which it does not make sense to use P&R. The paper proves that the optimal location of P&R sites is shifted upstream of what seems to be an intuitive solution, i.e., the edge of the congested region. by a distance that depends on the relative values of the origin and destination BEDs. In the two-dimensional city case, the analytical derivations prove that, for a given trip from i to j, the set of feasible locations follows an ellipse-like figure with the trip origin as a focus. These shapes-referred to as limiting functions-depend on variables such as trip distance, transit level of service (LOS), and the like. The analyses indicate that the area enclosed by the limiting functions increases with the transit LOS and trip distance, and so do the corresponding catchment areas. This is because the catchment area is determined by the marginal trip origins, i.e., those for which the P&R facility is just inside the limiting function. In its final section, the paper develops a parabolic approximation to the catchment area for a given P&R site. The approximating parabola is defined by three critical points: the origin BED, and two points that identify the marginal trip origins at the chord of parabola evaluated at the P&R. The numerical experiments indicate that the parabolic approximation provides a fairly good estimate of the catchment area that is easy to produce, conceptually valid, and overcomes the limitations of alternative approaches and rules of thumb used by practitioners and researchers. (c) 2012 Elsevier Ltd. All rights reserved.
Keywords: Park and Ride; Optimal location; Transit
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Jordan, A., Brahm, R., Espinoza, N., Henning, T., Jones, M. I., Kossakowski, D., et al. (2020). TOI-677b: A Warm Jupiter (P=11.2 days) on an Eccentric Orbit Transiting a Late F-type Star. Astron. J., 159(4), 10 pp.
Abstract: We report the discovery of TOI-677.b, first identified as a candidate in light curves obtained within Sectors 9 and 10 of the Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with radial velocities. TOI-677.b has a mass of M-p = 1.236(-0.067)(+0.069) M-J, a radius of R-P = 1.170 +/- 0.03 R-J, and orbits its bright host star (V=.9.8 mag) with an orbital period of 11.23660 +/- 0.00011 d, on an eccentric orbit with e = 0.435 +/- 0.024. The host star has a mass of M-star = 1.181 +/- 0.058 M-circle dot, a radius of R. = 1.28(-0.03)(+0.03) R-circle dot, an age of 2.92(-0.73)(+0.80) Gyr and solar metallicity, properties consistent with a main-sequence late-F star with T-eff = 6295 +/- 77 K. We find evidence in the radial velocity measurements of a secondary long-term signal, which could be due to an outer companion. The TOI-677.b system is a well-suited target for Rossiter-Mclaughlin observations that can constrain migration mechanisms of close-in giant planets.
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Kalyaan, A., Pinilla, P., Krijt, S., Banzatti, A., Rosotti, G., Mulders, G. D., et al. (2023). The Effect of Dust Evolution and Traps on Inner Disk Water Enrichment. Astrophys. J., 954(1), 66.
Abstract: Substructures in protoplanetary disks can act as dust traps that shape the radial distribution of pebbles. By blocking the passage of pebbles, the presence of gaps in disks may have a profound effect on pebble delivery into the inner disk, crucial for the formation of inner planets via pebble accretion. This process can also affect the delivery of volatiles (such as H2O) and their abundance within the water snow line region (within a few au). In this study, we aim to understand what effect the presence of gaps in the outer gas disk may have on water vapor enrichment in the inner disk. Building on previous work, we employ a volatile-inclusive disk evolution model that considers an evolving ice-bearing drifting dust population, sensitive to dust traps, which loses its icy content to sublimation upon reaching the snow line. We find that the vapor abundance in the inner disk is strongly affected by the fragmentation velocity (v( f)) and turbulence, which control how intense vapor enrichment from pebble delivery is, if present, and how long it may last. Generally, for disks with low to moderate turbulence (a = 1 x 10(-3)) and a range of v( f), radial locations and gap depths (especially those of the innermost gaps) can significantly alter enrichment. Shallow inner gaps may continuously leak material from beyond it, despite the presence of additional deep outer gaps. We finally find that for realistic v( f) (=10 m s(-1)), the presence of gaps is more important than planetesimal formation beyond the snow line in regulating pebble and volatile delivery into the inner disk.
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Kirk, J., Rackham, B. V., MacDonald, R. J., Lopez-Morales, M., Espinoza, N., Lendl, M., et al. (2021). ACCESS and LRG-BEASTS: A Precise New Optical Transmission Spectrum of the Ultrahot Jupiter WASP-103b. Astron. J., 162(1), 34.
Abstract: We present a new ground-based optical transmission spectrum of the ultrahot Jupiter WASP-103b (Teq=2484
Keywords: GAS-GIANT EXOPLANET; HOT JUPITERS; ATMOSPHERES; TRANSIT; PLANET; EFFICIENT; SPECTROSCOPY; RETRIEVAL; CHEMISTRY; EXPLAIN
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McGruder, C. D., Lopez-Morales, M., Brahm, R., & Jordan, A. (2023). The Similar Seven: A Set of Very Alike Exoplanets to Test Correlations between System Parameters and Atmospheric Properties. Astrophys. J. Lett., 944(2), L56.
Abstract: Studies of exoplanetary atmospheres have found no definite correlations between observed high-altitude aerosols and other system parameters. This could be, in part, because of the lack of homogeneous exoplanet samples for which specific parameters can be isolated and inspected. Here, we present a set of seven exoplanets with very similar system parameters. We analyze existing photometric time series, Gaia parallax, and high-resolution spectroscopic data to produce a new set of homogeneous stellar, planetary, and orbital parameters for these systems. With this, we confirm that most measured parameters for all systems are very similar, except for the host stars' metallicities and possibly high-energy irradiation levels, which require UV and X-ray observations to constrain. From the sample, WASP-6b, WASP-96b, and WASP-110b have observed transmission spectra that we use to estimate their aerosol coverage levels using the Na i doublet 5892.9 angstrom. We find a tentative correlation between the metallicity of the host stars and the planetary aerosol levels. The trend we find with stellar metallicity can be tested by observing transmission spectra of the remaining planets in the sample. Based on our prediction, WASP-25b and WASP-55b should have higher levels of aerosols than WASP-124b and HATS-29b. Finally, we highlight how targeted surveys of alike planets similar to the ones presented here might prove key for identifying driving factors for atmospheric properties of exoplanets in the future and could be used as a sample selection criterion for future observations with, e.g., JWST, ARIEL, and the next generation of ground-based telescopes.
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McGruder, C. D., Lopez-Morales, M., Kirk, J., Rackham, B. V., May, E., Ahrer, E. M., et al. (2023). ACCESS, LRG-BEASTS, and MOPSS: Featureless Optical Transmission Spectra of WASP-25b and WASP-124b. Astron. J., 166(3), 120.
Abstract: We present new optical transmission spectra for two hot Jupiters: WASP-25b (M = 0.56 M ( J ); R = 1.23 R ( J ); P = 3.76 days) and WASP-124b (M = 0.58 M ( J ); R = 1.34 R ( J ); P = 3.37 days), with wavelength coverages of 4200-9100 & ANGS; and 4570-9940 & ANGS;, respectively. These spectra are from the ESO Faint Object Spectrograph and Camera (v.2) mounted on the New Technology Telescope and Inamori-Magellan Areal Camera & Spectrograph on Magellan Baade. No strong spectral features were found in either spectra, with the data probing 4 and 6 scale heights, respectively. Exoretrievals and PLATON retrievals favor stellar activity for WASP-25b, while the data for WASP-124b did not favor one model over another. For both planets the retrievals found a wide range in the depths where the atmosphere could be optically thick (& SIM;0.4 & mu;-0.2 bars for WASP-25b and 1.6 & mu;-32 bars for WASP-124b) and recovered a temperature that is consistent with the planets' equilibrium temperatures, but with wide uncertainties (up to & PLUSMN;430 K). For WASP-25b, the models also favor stellar spots that are & SIM;500-3000 K cooler than the surrounding photosphere. The fairly weak constraints on parameters are owing to the relatively low precision of the data, with an average precision of 840 and 1240 ppm per bin for WASP-25b and WASP-124b, respectively. However, some contribution might still be due to an inherent absence of absorption or scattering in the planets' upper atmospheres, possibly because of aerosols. We attempt to fit the strength of the sodium signals to the aerosol-metallicity trend proposed by McGruder et al., and find WASP-25b and WASP-124b are consistent with the prediction, though their uncertainties are too large to confidently confirm the trend.
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Mora, F., Coullet, P., Rica, S., & Tirapegui, E. (2018). Numerical path integral calculation of the probability function and exit time: an application to non-gradient drift forces. Philos. Trans. R. Soc. A-Math. Phys. Eng. Sci., 376(2135), 11 pp.
Abstract: We provide numerical solutions based on the path integral representation of stochastic processes for non-gradient drift Langevin forces in the presence of noise, to follow the temporal evolution of the probability density function and to compute exit times even for arbitrary noise. We compare the results with theoretical calculations, obtaining excellent agreement in the weak noise limit. This article is part of the theme issue 'Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 2)'.
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Nasirov, S., Agostini, C., Silva, C., & Caceres, G. (2018). Renewable energy transition: a market-driven solution for the energy and environmental concerns in Chile. Clean Technol. Environ. Policy, 20(1), 3–12.
Abstract: Chile is undergoing a remarkable energy matrix transition to renewable energy. Renewable energies are expanding extraordinarily fast, exceeding earlier predictions. As a result, the country is expected to meet its 2025 goal of generating 20% of its electricity from renewable energy sources quite before. Chile has become one of the first countries in the world with subsidy-free markets, where renewable projects compete directly with other conventional sources. Favorable market conditions and successful policy reforms were keys to fostering this renewable energy development. Although the country has achieved a substantial growth in renewable energy investment in a relatively short period of time, this optimism should be treated with caution. A successful transition requires a combination of a clear decision making, persistent and consistent government policies, and a clear commitment to tackling challenges to accommodate renewable energy in the power system. In this context, this paper analyses the Chilean renewable industry and the required government policies to succeed in this transition. For this purpose, we identify several critical factors that have attracted and that could attract investment to the renewable energy sector and propose key recommendations to effectively address the major challenges faced for the future development of the industry.
Keywords: Energy transition; Energy policy; Renewable energy technologies; Chile
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Pineda, C., Cortes, C. E., Jara-Moroni, P., & Moreno, E. (2016). Integrated traffic-transit stochastic equilibrium model with park-and-ride facilitiesd. Transp. Res. Pt. C-Emerg. Technol., 71, 86–107.
Abstract: We propose an Integrated Stochastic Equilibrium model that considers both private automobile traffic and transit networks to incorporate the interactions between these two modes in terms of travel time and generalized costs. In addition, in the general version of the model, travelers are allowed to switch from personal vehicles to mass transit at specific locations in a park-and-ride scheme. The assignment for traffic equilibrium is based on the Markovian Traffic Equilibrium model of Baillon and Cominetti (2008), whereas the equilibrium of the transit network is represented by the Stochastic Transit Equilibrium model of Cortes et al. (2013). Stochastic travel decisions are made at the node level, thereby avoiding the enumeration of routes or strategies and incorporating various perception and uncertainty issues. We propose a Method-of-Successive-Averages algorithm to calculate an Integrated Stochastic Equilibrium and conduct numerical experiments to highlight the effect of stochasticity on equilibrium flows and travel times. Our experiments show that higher stochasticity implies greater dispersion of equilibrium flows and longer expected travel times. Results on a real network with mode combination and park and ride facilities provide insights regarding the use of park and ride in terms of number and location, potential modal share of the combined mode option under different circumstances, and travel time impact due to the implementation of such park and ride facilities in a real setting. (C) 2016 Elsevier Ltd. All rights reserved.
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