Home | << 1 2 3 >> |
![]() |
Ahrer, E. M., Alderson, L., Batalha, N. M., Batalha, N. E., Bean, J. L., Beatty, T. G., et al. (2023). Identification of carbon dioxide in an exoplanet atmosphere. Nature, Early Access.
Abstract: Carbon dioxide (CO2) is a key chemical species that is found in a wide range of planetary atmospheres. In the context of exoplanets, CO2 is an indicator of the metal enrichment (that is, elements heavier than helium, also called 'metallicity')(1-3), and thus the formation processes of the primary atmospheres of hot gas giants(4-6). It is also one of the most promising species to detect in the secondary atmospheres of terrestrial exoplanets(7-9). Previous photometric measurements of transiting planets with the Spitzer Space Telescope have given hints of the presence of CO2, but have not yielded definitive detections owing to the lack of unambiguous spectroscopic identification(10-12). Here we present the detection of CO2 in the atmosphere of the gas giant exoplanet WASP-39b from transmission spectroscopy observations obtained with JWST as part of the Early Release Science programme(13,14). The data used in this study span 3.0-5.5micrometres in wavelength and show a prominent CO2 absorption feature at 4.3micrometres (26-sigma significance). The overall spectrum is well matched by one-dimensional, ten-times solar metallicity models that assume radiative-convective-thermochemical equilibrium and have moderate cloud opacity. These models predict that the atmosphere should have water, carbon monoxide and hydrogen sulfide in addition to CO2, but little methane. Furthermore, we also tentatively detect a small absorption feature near 4.0micrometres that is not reproduced by these models.
Keywords: GIANT PLANETS; BROWN DWARFS; LINE LISTS; H2O; SKY
|
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.
|
Bergsten, G. J., Pascucci, I., Hardegree-Ullman, K. K., Fernandes, R. B., Christiansen, J. L., & Mulders, G. D. (2023). No Evidence for More Earth-sized Planets in the Habitable Zone of Kepler's M versus FGK Stars. Astron. J., 166(6), 234.
Abstract: Reliable detections of Earth-sized planets in the habitable zone remain elusive in the Kepler sample, even for M dwarfs. The Kepler sample was once thought to contain a considerable number of M-dwarf stars ( T-eff < 4000 K), which hosted enough Earth-sized ([0.5, 1.5] R-circle plus) planets to estimate their occurrence rate (eta(circle plus)) in the habitable zone. However, updated stellar properties from Gaia have shifted many Kepler stars to earlier spectral type classifications, with most stars (and their planets) now measured to be larger and hotter than previously believed. Today, only one partially reliable Earth-sized candidate remains in the optimistic habitable zone, and zero in the conservative zone. Here we performed a new investigation of Kepler's Earth-sized planets orbiting M-dwarf stars, using occurrence rate models with considerations of updated parameters and candidate reliability. Extrapolating our models to low instellations, we found an occurrence rate of eta(circle plus) = 8.58( – 8.22 )(+ 17.94) % for the conservative habitable zone (and 14.22 (- 12.71) (+ 24.96 )% for the optimistic one), consistent with previous works when considering the large uncertainties. Comparing these estimates to those from similarly comprehensive studies of Sun-like stars, we found that the current Kepler sample does not offer evidence to support an increase in eta(circle plus) from FGK to M stars. While the Kepler sample is too sparse to resolve an occurrence trend between early and mid-to-late M dwarfs for Earth-sized planets, studies including larger planets and/or data from the K2 and TESS missions are well suited to this task.
|
Bergsten, G. J., Pascucci, I., Mulders, G. D., Fernandes, R. B., & Koskinen, T. T. (2022). The Demographics of Kepler's Earths and Super-Earths into the Habitable Zone. Astron. J., 164(5), 190.
Abstract: Understanding the occurrence of Earth-sized planets in the habitable zone of Sun-like stars is essential to the search for Earth analogs. Yet a lack of reliable Kepler detections for such planets has forced many estimates to be derived from the close-in (2 < P-orb < 100 days) population, whose radii may have evolved differently under the effect of atmospheric mass-loss mechanisms. In this work, we compute the intrinsic occurrence rates of close-in super-Earths (similar to 1-2 R-circle plus and sub-Neptunes (similar to 2-3.5 R-circle plus) for FGK stars (0.56-1.63 M-circle dot) as a function of orbital period and find evidence of two regimes: where super-Earths are more abundant at short orbital periods, and where sub-Neptunes are more abundant at longer orbital periods. We fit a parametric model in five equally populated stellar mass bins and find that the orbital period of transition between these two regimes scales with stellar mass, like P-trans proportional to M-*(1.7 +/- 0.2). Ptrans These results suggest a population of former sub-Neptunes contaminating the population of gigayear-old close-in super-Earths, indicative of a population shaped by atmospheric loss. Using our model to constrain the long-period population of intrinsically rocky planets, we estimate an occurrence rate of Gamma(circle plus) = 15(-4)(+6)% for Earth-sized habitable zone planets, and predict that sub-Neptunes may be similar to twice as common as super-Earths in the habitable zone (when normalized over the natural log-orbital period and radius range used). Finally, we discuss our results in the context of future missions searching for habitable zone planets.
|
Bozhilov, V., Antonova, D., Hobson, M. J., Brahm, R., Jordan, A., Henning, T., et al. (2023). A 2:1 Mean-motion Resonance Super-Jovian Pair Revealed by TESS, FEROS, and HARPS. Astrophys. J. Lett., 946(2), L36.
Abstract: We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for planet formation and orbital evolution analysis. The system was discovered thanks to a single-transit event recorded by the Transiting Exoplanet Survey Satellite mission, which pointed to a Jupiter-sized companion with poorly constrained orbital parameters. We began ground-based precise radial velocity (RV) monitoring with HARPS and FEROS within the Warm gIaNts with tEss survey to constrain the transiting body's period, mass, and eccentricity. The RV measurements revealed not one but two massive planets with periods of 76.80(-0.06)(+0.06) and 155.3(-0.7)(+0.7) days, respectively. A combined analysis of transit and RV data yields an inner transiting planet with a mass of 6.14(-0.42)(+0.39) M-Jup and a radius of 1.00(-0.04)(+0.04) R-Jup, and an outer planet with a minimum mass of 8.02(-0.18)(+0.18) M-Jup, indicating a massive giant pair. A detailed dynamical analysis of the system reveals that the planets are locked in a strong firstorder, eccentricity-type 2:1 MMR, which makes TIC 279401253 one of the rare examples of truly resonant architectures supporting disk-induced planet migration. The bright host star, V approximate to 11.9 mag, the relatively short orbital period (P-b = 76.80(-0.06)(+0.06) days), and pronounced eccentricity (e = 0.448(-0.029)(+0.029)) make the transiting planet a valuable target for atmospheric investigation with the James Webb Space Telescope and ground-based extremely large telescopes.
Keywords: GIANT PLANETS; ECCENTRICITY; EVOLUTION; EXOPLANET; ORIGIN; MASS
|
Carleo, I., Malavolta, L., Desidera, S., Nardiello, D., Wang, S., Turrini, D., et al. (2024). The GAPS programme at TNG. Astron. Astrophys., 682, A135.
Abstract: Context. Different theories have been developed to explain the origins and properties of close-in giant planets, but none of them alone can explain all of the properties of the warm Jupiters (WJs, Porb = 10-200 days). One of the most intriguing characteristics of WJs is that they have a wide range of orbital eccentricities, challenging our understanding of their formation and evolution. Aims. The investigation of these systems is crucial in order to put constraints on formation and evolution theories. TESS is providing a significant sample of transiting WJs around stars bright enough to allow spectroscopic follow-up studies. Methods. We carried out a radial velocity (RV) follow-up study of the TESS candidate TOI-4515 b with the high-resolution spectrograph HARPS-N in the context of the GAPS project, the aim of which is to characterize young giant planets, and the TRES and FEROS spectrographs. We then performed a joint analysis of the HARPS-N, TRES, FEROS, and TESS data in order to fully characterize this planetary system. Results. We find that TOI-4515 b orbits a 1.2 Gyr-old G-star, has an orbital period of Pb = 15.266446 +/- 0.000013 days, a mass of Mb = 2.01 +/- 0.05 MJ, and a radius of Rb = 1.09 +/- 0.04 RJ. We also find an eccentricity of e = 0.46 +/- 0.01, placing this planet among the WJs with highly eccentric orbits. As no additional companion has been detected, this high eccentricity might be the consequence of past violent scattering events.
|
Carone, L., Molliere, P., Zhou, Y. F., Bouwman, J., Yan, F., Baeyens, R., et al. (2021). Indications for very high metallicity and absence of methane in the eccentric exo-Saturn WASP-117b. Astron. Astrophys., 646, A168.
Abstract: Aims. We investigate the atmospheric composition of the long-period (P-orb = 10 days) eccentric exo-Saturn WASP-117b. WASP-117b could be similar in atmospheric temperature and chemistry to WASP-107b. In mass and radius, WASP-117b is similar to WASP-39b, which allows a comparative study of these planets.Methods. We analyzed a near-infrared transmission spectrum of WASP-117b taken with the Hubble Space Telescope (HST) WFC3 G141, which was reduced with two independent pipelines. High-resolution measurements were taken with VLT/ESPRESSO in the optical.Results. We report the robust (3 sigma) detection of a water spectral feature. In a 1D atmosphere model with isothermal temperature, uniform cloud deck, and equilibrium chemistry, the Bayesian evidence of a retrieval analysis of the transmission spectrum indicates a preference for a high atmospheric metallicity
[Fe/H] = 2.58(-0.37)(+0.26) [Fe/H]=2.58-0.37+0.26 and clear skies. The data are also consistent with a lower metallicity composition [Fe/H] < 1.75 and a cloud deck between 10(-2.2) and 10(-5.1) bar, but with weaker Bayesian preference. We retrieve a low CH4 abundance of <10(-4) volume fraction within 1 sigma and <2 x 10(-1) volume fraction within 3<sigma>. We cannot constrain the equilibrium temperature between theoretically imposed limits of 700 and 1000 K. Further observations are needed to confirm quenching of CH4 with K-zz >= 10(8) cm(2) s(-1). We report indications of Na and K in the VLT/ESPRESSO high-resolution spectrum with substantial Bayesian evidence in combination with HST data. |
Casassus, S., & Carcamo, M. (2022). Variable structure in the PDS 70 disc and uncertainties in radio-interferometric image restoration. Mon. Not. Roy. Astron. Soc., 513(4), 5790–5798.
Abstract: The compact mm-wavelength signal in the central cavity of the PDS 70 disc, revealed by deep ALMA observations, is aligned with unresolved H alpha emission, and is thought to stem from a circumplanetary disc (CPD) around PDS 70c. We revisit the available ALMA data on PDS 70c with alternative imaging strategies, and with special attention to uncertainties and to the impact of the so-called 'JvM correction', which is thought to improve the dynamic range of restored images. We also propose a procedure for the alignment and joint imaging of multi-epoch visibility data. We find that the JvM correction exaggerates the peak signal-to-noise of the data, by up to a factor of 10. In the case of PDS 70, we recover the detection of PDS 70c from the 2019 July data, but only at 8 sigma. However, its non-detection in 2017 Dec. suggests that PDS 70c is variable by at least 42 per cent +/- 13 per cent over a 1.75 yr time-span, so similar to models of the H alpha variability. We also pick up fine structure in the inner disc, such that its peak is offset by similar to 0 ''.04 from the disc centre. The inner disc is variable too, which we tentatively ascribe to Keplerian rotation as well as intrinsic morphological changes.
|
Christie, D. A., E.K.H., Innes, H., Noti, P. A., Charnay, B., Fauchez, T. J., et al. (2022). CAMEMBERT: A Mini-Neptunes General Circulation Model Intercomparison, Protocol Version 1.0.A CUISINES Model Intercomparison Project. Planet. Sci., 3(11), 261.
Abstract: With an increased focus on the observing and modeling of mini-Neptunes, there comes a need to better understand the tools we use to model their atmospheres. In this Paper, we present the protocol for the Comparing Atmospheric Models of Extrasolar Mini-Neptunes Building and Envisioning Retrievals and Transits, CAMEMBERT, project, an intercomparison of general circulation models (GCMs) used by the exoplanetary science community to simulate the atmospheres of mini-Neptunes. We focus on two targets well studied both observationally and theoretically with planned JWST cycle 1 observations: the warm GJ 1214b and the cooler K2-18b. For each target, we consider a temperature-forced case, a clear sky dual-gray radiative transfer case, and a clear sky multiband radiative transfer case, covering a range of complexities and configurations where we know differences exist between GCMs in the literature. This Paper presents all the details necessary to participate in the intercomparison, with the intention of presenting the results in future papers. Currently, there are eight GCMs participating (ExoCAM, Exo-FMS, FMS PCM, Generic PCM, MITgcm, RM-GCM, THOR, and the Unified Model), and membership in the project remains open. Those interested in participating are invited to contact the authors.
Keywords: ATMOSPHERIC CIRCULATION; DYNAMICAL CORES; HABITABLE-ZONE; TEMPERATE; PLANETS; DESIGN; CLOUDS; K2-18B; SUITE; HARPS
|
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.
|
Cont, D., Yan, F., Reiners, A., Nortmann, L., Molaverdikhani, K., Palle, E., et al. (2022). Silicon in the dayside atmospheres of two ultra-hot Jupiters. Astron. Astrophys., 657, L2.
Abstract: Atmospheres of highly irradiated gas giant planets host a large variety of atomic and ionic species. Here we observe the thermal emission spectra of the two ultra-hot Jupiters WASP-33b and KELT-20b /MASCARA-2b in the near-infrared wavelength range with CARMENES. Via high-resolution Doppler spectroscopy, we searched for neutral silicon (Si) in their dayside atmospheres. We detect the Si spectral signature of both planets via cross-correlation with model spectra. Detection levels of 4.8 sigma and 5.4 sigma, respectively, are observed when assuming a solar atmospheric composition. This is the first detection of Si in exoplanet atmospheres. The presence of Si is an important finding due to its fundamental role in cloud formation and, hence, for the planetary energy balance. Since the spectral lines are detected in emission, our results also confirm the presence of an inverted temperature profile in the dayside atmospheres of both planets.
|
Dempsey, A. M., Munoz, D. J., & Lithwick, Y. (2021). Outward Migration of Super-Jupiters. Astrophys. J. Lett., 918(2), L36.
Abstract: Recent simulations show that giant planets of about 1 M (J) migrate inward at a rate that differs from the type II prediction. Here we show that at higher masses, planets migrate outward. Our result differs from previous ones because of our longer simulation times, lower viscosity, and boundary conditions that allow the disk to reach a viscous steady state. We show that, for planets on circular orbits, the transition from inward to outward migration coincides with the known transition from circular to eccentric disks that occurs for planets more massive than a few Jupiters. In an eccentric disk, the torque on the outer disk weakens due to two effects: the planet launches weaker waves, and those waves travel further before damping. As a result, the torque on the inner disk dominates, and the planet pushes itself outward. Our results suggest that the many super-Jupiters observed by direct imaging at large distances from the star may have gotten there by outward migration.
Keywords: GIANT PLANETS; ECCENTRIC MODES; DENSITY WAVES; DISK; ACCRETION; EVOLUTION; SATELLITES; VISCOSITY; GAPS
|
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.
|
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.
|
Eberhardt, J., Trifonov, T., Kurster, M., Stock, S., Henning, T., Wollbold, A., et al. (2022). Dynamical Architecture of the HD 107148 Planetary System. Astron. J., 163(5), 198.
Abstract: We present an independent Doppler validation and dynamical orbital analysis of the two-planet system HD 107148, which was recently announced in Rosenthal et al. Our detailed analyses are based on literature HIRES data and newly obtained HARPS and CARMENES radial-velocity (RV) measurements as part of our survey in search for additional planets around single-planet systems. We perform a periodogram analysis of the available HIRES and HARPS precise RVs and stellar activity indicators. We do not find any apparent correlation between the RV measurements and the stellar activity indicators, thus linking the two strong periodicities to a moderately compact multiplanet system. We carry out orbital fitting analysis by testing various one- and two-planet orbital configurations and studying the posterior probability distribution of the fitted parameters. Our results solidify the existence of a Saturn-mass planet (HD 107148b, discovered first) with a period of P (b) similar to 77.2 days and a second, eccentric (e (c) similar to 0.4), Neptune-mass exoplanet (HD 107148c) with an orbital period of P (c) similar to 18.3 days. Finally, we investigate the two-planet system's long-term stability and overall orbital dynamics with the posterior distribution of our preferred orbital configuration. Our N-body stability simulations show that the system is long-term stable and exhibits large secular osculations in eccentricity but in no particular mean motion resonance configuration. The HD 107148 system, consisting of a solar-type main-sequence star with two giant planets in a rare configuration, features a common proper-motion white dwarf companion and is therefore a valuable target for understanding the formation and evolution of planetary systems.
|
Espinoza, N., Brahm, R., Henning, T., Jordan, A., Dorn, C., Rojas, F., et al. (2020). HD 213885b: a transiting 1-d-period super-Earth with an Earth-like composition around a bright (V=7.9) star unveiled by TESS. Mon. Not. Roy. Astron. Soc., 491(2), 2982–2999.
Abstract: We report the discovery of the 1.008-d, ultrashort period (USP) super-EarthHD213885b (TOI141b) orbiting the bright (V= 7.9) star HD 213885 (TOI-141, TIC 403224672), detected using photometry from the recently launched TESS mission. Using FEROS, HARPS, and CORALIE radial velocities, we measure a precise mass of 8.8 +/- 0.6M. for this 1.74 +/- 0.05 R. exoplanet, which provides enough information to constrain its bulk composition – similar to Earth's but enriched in iron. The radius, mass, and stellar irradiation of HD 213885b are, given our data, very similar to 55 Cancri e, making this exoplanet a good target to perform comparative exoplanetology of short period, highly irradiated super-Earths. Our precise radial velocities reveal an additional 4.78-d signal which we interpret as arising from a second, non-transiting planet in the system, HD 213885c, whoseminimum mass of 19.9 +/- 1.4M. makes it consistent with being a Neptune-mass exoplanet. The HD 213885 system is very interesting from the perspective of future atmospheric characterization, being the second brightest star to host an USP transiting super-Earth (with the brightest star being, in fact, 55 Cancri). Prospects for characterization with present and future observatories are discussed.
|
Fernandes, R. B., Mulders, G. D., Pascucci, I., Bergsten, G. J., Koskinen, T. T., Hardegree-Ullman, K. K., et al. (2022). pterodactyls: A Tool to Uniformly Search and Vet for Young Transiting Planets in TESS Primary Mission Photometry. Astron. J., 164(3), 78.
Abstract: Kepler's short-period exoplanet population has revealed evolutionary features such as the Radius Valley and the Hot Neptune desert that are likely sculpted by atmospheric loss over time. These findings suggest that the primordial planet population is different from the Gyr-old Kepler population, and motivates exoplanet searches around young stars. Here, we present pterodactyls, a data reduction pipeline specifically built to address the challenges in discovering exoplanets around young stars and to work with TESS Primary Mission 30-minute cadence photometry, since most young stars were not preselected TESS two-minute cadence targets. pterodactyls builds on publicly available and tested tools in order to extract, detrend, search, and vet transiting young planet candidates. We search five clusters with known transiting planets: the Tucana-Horologium Association, IC 2602, Upper Centaurus Lupus, Ursa Major, and Pisces-Eridani. We show that pterodactyls recovers seven out of the eight confirmed planets and one out of the two planet candidates, most of which were initially detected in two-minute cadence data. For these clusters, we conduct injection-recovery tests to characterize our detection efficiency, and compute an intrinsic planet occurrence rate of 49% +/- 20% for sub-Neptunes and Neptunes (1.8-6 R (circle plus)) within 12.5 days, which is higher than Kepler's Gyr-old occurrence rates of 6.8% +/- 0.3%. This potentially implies that these planets have shrunk with time due to atmospheric mass loss. However, a proper assessment of the occurrence of transiting young planets will require a larger sample unbiased to planets already detected. As such, pterodactyls will be used in future work to search and vet for planet candidates in nearby clusters and moving groups.
Keywords: POWERED MASS-LOSS; ZODIACAL EXOPLANETS; RADIUS DISTRIBUTION; DWARF; HUNT; STAR; FREQUENCY; EFFICIENT; KEPLER; SYSTEM
|
Grieves, N., Bouchy, F., Ulmer-Moll, S., Gill, S., Anderson, D. R., Psaridi, A., et al. (2023). An old warm Jupiter orbiting the metal-poor G-dwarf TOI-5542. Astron. Astrophys., 668, A29.
Abstract: We report the discovery of a 1.32(-0.10)(+0.10)M(Jup) planet orbiting on a 75.12 day period around the G3V 10.8(-3.6)(+2.1) Gyr old star TOI-5542 (TIC 466206508; TYC 9086-1210-1). The planet was first detected by the Transiting Exoplanet Survey Satellite (TESS) as a single transit event in TESS Sector 13. A second transit was observed 376 days later in TESS Sector 27. The planetary nature of the object has been confirmed by ground-based spectroscopic and radial velocity observations from the CORALIE and HARPS spectrographs. A third transit event was detected by the ground-based facilities NGTS, EulerCam, and SAAO. We find the planet has a radius of 1.009(-0.035)(+0.036)R(Jup) and an insolation of 9.6(-0.8)(+0.9)S(circle plus), along with a circular orbit that most likely formed via disk migration or in situ formation, rather than high-eccentricity migration mechanisms. Our analysis of the HARPS spectra yields a host star metallicity of [Fe/H] = -0.21 +/- 0.08, which does not follow the traditional trend of high host star metallicity for giant planets and does not bolster studies suggesting a difference among low- and high-mass giant planet host star metallicities. Additionally, when analyzing a sample of 216 well-characterized giant planets, we find that both high masses (4 M-Jup < M-p < 13 M-Jup) and low masses (0.5 M-Jup < M-p < 4 M-Jup), as well as both both warm (P > 10 days) and hot (P < 10 days) giant planets are preferentially located around metal-rich stars (mean [Fe/H] > 0.1). TOI-5542b is one of the oldest known warm Jupiters and it is cool enough to be unaffected by inflation due to stellar incident flux, making it a valuable contribution in the context of planetary composition and formation studies.
|
Grieves, N., Nielsen, L. D., Vines, J. I., Bryant, E. M., Gill, S., Bouchy, F., et al. (2021). NGTS-13b: a hot 4.8 Jupiter-mass planet transiting a subgiant star. Astron. Astrophys., 647, A180.
Abstract: We report the discovery of the massive hot Jupiter NGTS-13b by the Next Generation Transit Survey (NGTS). The V = 12.7 host star is likely in the subgiant evolutionary phase with logg(*) = 4.04 +/- 0.05, T-eff = 5819 +/- 73 K, M-* = 1.30(-0.18)(+0.11) M-circle dot, and R-* = 1.79 +/- 0.06 R-circle dot. The NGTS detected a transiting planet with a period of P = 4.12 days around the star, which was later validated with the Transiting Exoplanet Survey Satellite (TESS; TIC 454069765). We confirm the planet using radial velocities from the CORALIE spectrograph. Using NGTS and TESS full-frame image photometry combined with CORALIE radial velocities, we determine NGTS-13b to have a radius of R-P = 1.142 +/- 0.046 R-Jup, a mass of M-P = 4.84 +/- 0.44 M-Jup, and an eccentricity of e = 0.086 +/- 0.034. Previous studies have suggested that similar to 4 M-Jup may be the border separating two formation scenarios (e.g., core accretion and disk instability) and that massive giant planets share similar formation mechanisms as lower-mass brown dwarfs. NGTS-13b is just above 4 M-Jup, making it an important addition to the statistical sample needed to understand the differences between various classes of substellar companions. The high metallicity of NGTS-13, [Fe/H] = 0.25 +/- 0.17, does not support previous suggestions that massive giants are found preferentially around lower metallicity host stars, but NGTS-13b does support findings that more massive and evolved hosts may have a higher occurrence of close-in massive planets than lower-mass unevolved stars.
Keywords: planets and satellites: detection; planets and satellites: individual: NGTS-13b; techniques: photometric; techniques: radial velocities
Area: 0004-6361
|
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
|