185 research outputs found
TOI-150: A transiting hot Jupiter in the TESS southern CVZ
We report the detection of a hot Jupiter ($M_{p}=1.75_{-0.17}^{+0.14}\
M_{J}R_{p}=1.38\pm0.04\ R_{J}\log
g=4.152^{+0.030}_{-0.043}\beta=-79.59^{\circ}$). We confirm the
planetary nature of the candidate TOI-150.01 using radial velocity observations
from the APOGEE-2 South spectrograph and the Carnegie Planet Finder
Spectrograph, ground-based photometric observations from the robotic
Three-hundred MilliMeter Telescope at Las Campanas Observatory, and Gaia
distance estimates. Large-scale spectroscopic surveys, such as APOGEE/APOGEE-2,
now have sufficient radial velocity precision to directly confirm the signature
of giant exoplanets, making such data sets valuable tools in the TESS era.
Continual monitoring of TOI-150 by TESS can reveal additional planets and
subsequent observations can provide insights into planetary system
architectures involving a hot Jupiter around a star about halfway through its
main-sequence life.Comment: 13 pages, 3 figures, 2 tables, accepted to ApJ
A demonstration of an affinity between pyrite and organic matter in a hydrothermal setting
One of the key-principles of the iron-sulphur world theory is to bring organic molecules close enough to interact with each other, using the surface of pyrite as a substrate in a hydrothermal setting. The present paper explores the relationship of pyrite and organic matter in a hydrothermal setting from the geological record; in hydrothermal calcite veins from Carboniferous limestones in central Ireland. Here, the organic matter is accumulated as coatings around, and through, pyrite grains. Most of the pyrite grains are euhedral-subhedral crystals, ranging in size from ca 0.1-0.5 mm in diameter, and they are scattered throughout the matrix of the vein calcite. The organic matter was deposited from a hydrothermal fluid at a temperature of at least 200°C, and gives a Raman signature of disordered carbon. This study points to an example from a hydrothermal setting in the geological record, demonstrating that pyrite can have a high potential for the concentration and accumulation of organic materials
TOI-3785 b: A Low-Density Neptune Orbiting an M2-Dwarf Star
Using both ground-based transit photometry and high-precision radial velocity
(RV) spectroscopy, we confirm the planetary nature of TOI-3785 b. This
transiting Neptune orbits an M2-Dwarf star with a period of ~4.67 days, a
planetary radius of 5.14 +/- 0.16 Earth Radii, a mass of 14.95 +4.10, -3.92
Earth Masses, and a density of 0.61 +0.18, -0.17 g/cm^3. TOI-3785 b belongs to
a rare population of Neptunes (4 Earth Radii < Rp < 7 Earth Radii) orbiting
cooler, smaller M-dwarf host stars, of which only ~10 have been confirmed. By
increasing the number of confirmed planets, TOI-3785 b offers an opportunity to
compare similar planets across varying planetary and stellar parameter spaces.
Moreover, with a high transmission spectroscopy metric (TSM) of ~150 combined
with a relatively cool equilibrium temperature of 582 +/- 16 K and an inactive
host star, TOI-3785 b is one of the more promising low-density M-dwarf Neptune
targets for atmospheric follow-up. Future investigation into atmospheric mass
loss rates of TOI-3785 b may yield new insights into the atmospheric evolution
of these low-mass gas planets around M-dwarfs.Comment: 22 pages, 6 figures, 6 tables, Submitted to A
TOI-5205b: A Jupiter transiting an M dwarf near the Convective Boundary
We present the discovery of TOI-5205b, a transiting Jovian planet orbiting a
solar metallicity M4V star, which was discovered using TESS photometry and then
confirmed using a combination of precise radial velocities, ground-based
photometry, spectra and speckle imaging. The host star TOI-5205 sits near the
eponymous `Jao gap', which is the transition region between partially and
fully-convective M dwarfs. TOI-5205b has one of the highest mass ratio for M
dwarf planets with a mass ratio of almost 0.3, as it orbits a host star
that is just . Its planetary radius is , while the mass is . Additionally, the large size
of the planet orbiting a small star results in a transit depth of ,
making it one of the deepest transits of a confirmed exoplanet orbiting a
main-sequence star. The large transit depth makes TOI-5205b a compelling target
to probe its atmospheric properties, as a means of tracing the potential
formation pathways. While there have been radial velocity-only discoveries of
giant planets around mid M dwarfs, this is the first transiting Jupiter with a
mass measurement discovered around such a low-mass host star. The high mass of
TOI-5205b stretches conventional theories of planet formation and disk scaling
relations that cannot easily recreate the conditions required to form such
planets.Comment: Submitted to ApJ. Comments are welcome. arXiv admin note: text
overlap with arXiv:2203.0717
The Habitable Zone Planet Finder Reveals a High Mass and Low Obliquity for the Young Neptune K2-25b
Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600â800 Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44 ± 0.12 R_â and 24.5_(-5.2)^(+5.7) M_â. These properties are compatible with a rocky core enshrouded by a thin hydrogenâhelium atmosphere (5% by mass). We measure an orbital eccentricity of e = 0.43 ± 0.05. The sky-projected stellar obliquity is λ = 3° ± 16°, compatible with spinâorbit alignment, in contrast to other "hot Neptunes" that have been studied around older stars
The Habitable-zone Planet Finder Reveals A High Mass and a Low Obliquity for the Young Neptune K2-25b
Using radial-velocity data from the Habitable-zone Planet Finder, we have
measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity
of its M4.5-dwarf host star in the 600-800MYr Hyades cluster. This is one of
the youngest planetary systems for which both of these quantities have been
measured, and one of the very few M dwarfs with a measured obliquity. Based on
a joint analysis of the radial velocity data, time-series photometry from the
K2 mission, and new transit light curves obtained with diffuser-assisted
photometry, the planet's radius and mass are
and . These properties are compatible
with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass).
We measure an orbital eccentricity of . The sky-projected
stellar obliquity is , compatible with spin-orbit
alignment, in contrast to other "hot Neptunes" that have been studied around
older stars.Comment: Accepted for publication in AJ, 31 pages, 14 figure
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A Mini-Neptune and a Radius Valley Planet Orbiting the Nearby M2 Dwarf TOI-1266 in Its Venus Zone: Validation with the Habitable-zone Planet Finder
We report on the validation of two planets orbiting the nearby (36 pc) M2 dwarf TOI-1266 observed by the TESS mission. This system is one of a few M dwarf multiplanet systems with close-in planets where the inner planet is substantially larger than the outer planet. The inner planet is sub-Neptune-sized (R = 2.46 ± 0.08 R_â) with an orbital period of 10.9 days, while the outer planet has a radius of 1.67_(-0.11)^(+0.09) R_â and resides in the exoplanet radius valleyâthe transition region between rocky and gaseous planets. With an orbital period of 18.8 days, the outer planet receives an insolation flux of 2.4 times that of Earth, similar to the insolation of Venus. Using precision near-infrared radial velocities with the Habitable-zone Planet Finder Spectrograph, we place upper mass limits of 15.9 and 6.4 M_â at 95% confidence for the inner and outer planet, respectively. A more precise mass constraint of both planets, achievable with current radial velocity instruments given the host star brightness (V = 12.9, J = 9.7), will yield further insights into the dominant processes sculpting the exoplanet radius valley
Assessing the application of miscible CO2 flooding in oil reservoirs: a case study from Pakistan
Miscible carbon dioxide (CO2) flooding has been recognized as a promising approach to enhance the recovery of oil reservoirs. However, depending on the injection strategy and rock/fluid characteristics, efficiency of the miscible CO2flooding varies from reservoir to reservoir. Although, many studies have been carried out to evaluate the performance of the miscible CO2flooding, a specific strategy which can be strictly followed for a hydrocarbon reservoir has not been established yet. The aim of this study is to assess one of Pakistanâs oil reservoirs for miscible CO2flooding by applying a modified screening criterion and numerical modeling. As such, the most recent miscible CO2screening criteria were modified, and a numerical modeling was applied on the prospective reservoir. Based on the results obtained, South oil reservoir (S3) is chosen for a detailed assessment of miscible CO2flooding. It was also found that implementation of CO2water-alternating gas (CO2-WAG) injection at early stages of production can increase the production life of the reservoir
Ecosystem resilience despite large-scale altered hydroclimatic conditions
Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological model for many regions. Large-scale, warm droughts have recently occurred in North America, Africa, Europe, Amazonia and Australia, resulting in major effects on terrestrial ecosystems, carbon balance and food security. Here we compare the functional response of above-ground net primary production to contrasting hydroclimatic periods in the late twentieth century (1975-1998), and drier, warmer conditions in the early twenty-first century (2000-2009) in the Northern and Southern Hemispheres. We find a common ecosystem water-use efficiency (WUE e: Above-ground net primary production/ evapotranspiration) across biomes ranging from grassland to forest that indicates an intrinsic system sensitivity to water availability across rainfall regimes, regardless of hydroclimatic conditions. We found higher WUE e in drier years that increased significantly with drought to a maximum WUE e across all biomes; and a minimum native state in wetter years that was common across hydroclimatic periods. This indicates biome-scale resilience to the interannual variability associated with the early twenty-first century drought - that is, the capacity to tolerate low, annual precipitation and to respond to subsequent periods of favourable water balance. These findings provide a conceptual model of ecosystem properties at the decadal scale applicable to the widespread altered hydroclimatic conditions that are predicted for later this century. Understanding the hydroclimatic threshold that will break down ecosystem resilience and alter maximum WUE e may allow us to predict land-surface consequences as large regions become more arid, starting with water-limited, low-productivity grasslands. © 2013 Macmillan Publishers Limited. All rights reserved
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