202 research outputs found
A Holistic and Probabilistic Approach to the Ground-based and Spaceborne Data of HAT-P-19 System
We update the main physical and orbital properties of the transiting hot Saturn planet HAT-P-19 b, based on a global modelling of high-precision transit and occultation light curves, taken with ground-based and space telescopes, archive spectra and radial velocity measurements, brightness values from broadband photometry, and Gaia parallax. We collected 65 light curves by amateur and professional observers, measured mid-transit times, analyzed their differences from calculated transit timings based on reference ephemeris information, which we update as a result. We havenât found any periodicity in the residuals of a linear trend, which we attribute to the accumulation of uncertainties in the reference mid-transit time and the orbital period. We comment on the scenarios describing the formation and migration of this hot-Saturn type exoplanet with a bloated atmosphere yet a small core, although it is orbiting a metal-rich ([Fe/H] = 0.24 dex) host star. Finally, we review the planetary mass-radius, the orbital period-radius and density, and the stellar metallicity-core mass diagrams, based on the parameters we derive for HAT-P-19 b and those of the other seventy transiting Saturn-mass planets from the NASA Exoplanet Archive
WASP-4b Arrived Early for the TESS Mission
The Transiting Exoplanet Survey Satellite (TESS) recently observed 18
transits of the hot Jupiter WASP-4b. The sequence of transits occurred 81.6
11.7 seconds earlier than had been predicted, based on data stretching
back to 2007. This is unlikely to be the result of a clock error, because TESS
observations of other hot Jupiters (WASP-6b, 18b, and 46b) are compatible with
a constant period, ruling out an 81.6-second offset at the 6.4 level.
The 1.3-day orbital period of WASP-4b appears to be decreasing at a rate of
milliseconds per year. The apparent period change
might be caused by tidal orbital decay or apsidal precession, although both
interpretations have shortcomings. The gravitational influence of a third body
is another possibility, though at present there is minimal evidence for such a
body. Further observations are needed to confirm and understand the timing
variation.Comment: AJ accepte
GJ 1252 b: A 1.2 R\u3csub\u3eâ\u3c/sub\u3e Planet Transiting An M3 Dwarf At 20.4 pc
We report the discovery of GJ 1252 b, a planet with a radius of 1.193 ± 0.074 Râ and an orbital period of 0.52 days around an M3-type star (0.381 ± 0.019 Mâ, 0.391 ± 0.020 Râ) located 20.385 ± 0.019 pc away. We use Transiting Exoplanet Survey Satellite (TESS) data, ground-based photometry and spectroscopy, Gaia astrometry, and high angular resolution imaging to show that the transit signal seen in the TESS data must originate from a transiting planet. We do so by ruling out all false-positive scenarios that attempt to explain the transit signal as originating from an eclipsing stellar binary. Precise Doppler monitoring also leads to a tentative mass measurement of 2.09 ± 0.56 Mâ. The host star proximity, brightness (V = 12.19 mag, K = 7.92 mag), low stellar activity, and the system\u27s short orbital period make this planet an attractive target for detailed characterization, including precise mass measurement, looking for other objects in the system, and planet atmosphere characterization
Background model systematics for the Fermi GeV excess
The possible gamma-ray excess in the inner Galaxy and the Galactic center
(GC) suggested by Fermi-LAT observations has triggered a large number of
studies. It has been interpreted as a variety of different phenomena such as a
signal from WIMP dark matter annihilation, gamma-ray emission from a population
of millisecond pulsars, or emission from cosmic rays injected in a sequence of
burst-like events or continuously at the GC. We present the first comprehensive
study of model systematics coming from the Galactic diffuse emission in the
inner part of our Galaxy and their impact on the inferred properties of the
excess emission at Galactic latitudes and 300 MeV to 500
GeV. We study both theoretical and empirical model systematics, which we deduce
from a large range of Galactic diffuse emission models and a principal
component analysis of residuals in numerous test regions along the Galactic
plane. We show that the hypothesis of an extended spherical excess emission
with a uniform energy spectrum is compatible with the Fermi-LAT data in our
region of interest at CL. Assuming that this excess is the extended
counterpart of the one seen in the inner few degrees of the Galaxy, we derive a
lower limit of ( CL) on its extension away from the GC. We
show that, in light of the large correlated uncertainties that affect the
subtraction of the Galactic diffuse emission in the relevant regions, the
energy spectrum of the excess is equally compatible with both a simple broken
power-law of break energy GeV, and with spectra predicted by the
self-annihilation of dark matter, implying in the case of final
states a dark matter mass of GeV.Comment: 65 pages, 28 figures, 7 table
A New Era in the Quest for Dark Matter
There is a growing sense of `crisis' in the dark matter community, due to the
absence of evidence for the most popular candidates such as weakly interacting
massive particles, axions, and sterile neutrinos, despite the enormous effort
that has gone into searching for these particles. Here, we discuss what we have
learned about the nature of dark matter from past experiments, and the
implications for planned dark matter searches in the next decade. We argue that
diversifying the experimental effort, incorporating astronomical surveys and
gravitational wave observations, is our best hope to make progress on the dark
matter problem.Comment: Published in Nature, online on 04 Oct 2018. 13 pages, 1 figur
TIC 168789840: A Sextuply Eclipsing Sextuple Star System
We report the discovery of a sextuply eclipsing sextuple star system from TESS data, TIC 168789840, also known as TYC 7037-89-1, the first known sextuple system consisting of three eclipsing binaries. The target was observed in Sectors 4 and 5 during Cycle 1, with lightcurves extracted from TESS Full Frame Image data. It was also previously observed by the WASP survey and ASAS-SN. The system consists of three gravitationally bound eclipsing binaries in a hierarchical structure of an inner quadruple system with an outer binary subsystem. Follow-up observations from several different observatories were conducted as a means of determining additional parameters. The system was resolved by speckle interferometry with a 0farcs42 separation between the inner quadruple and outer binary, inferring an estimated outer period of ~2 kyr. It was determined that the fainter of the two resolved components is an 8.217 day eclipsing binary, which orbits the inner quadruple that contains two eclipsing binaries with periods of 1.570 days and 1.306 days. Markov Chain Monte Carlo (MCMC) analysis of the stellar parameters has shown that the three binaries of TIC 168789840 are triplets, as each binary is quite similar to the others in terms of mass, radius, and Teff. As a consequence of its rare composition, structure, and orientation, this object can provide important new insight into the formation, dynamics, and evolution of multiple star systems. Future observations could reveal if the intermediate and outer orbital planes are all aligned with the planes of the three inner eclipsing binaries
A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113
We report the discovery of HD 110113 b (TESS object of interest-755.01), a transiting mini-Neptune exoplanet on a 2.5-d orbit around the solar-analogue HD 110113 (Teff = 5730 K). Using TESS photometry and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities gathered by the NCORES program, we find that HD 110113 b has a radius of 2.05 ± 0.12 Râ and a mass of 4.55 ± 0.62 Mâ. The resulting density of g cm-3 is significantly lower than would be expected from a pure-rock world; therefore HD 110113 b must be a mini-Neptune with a significant volatile atmosphere. The high incident flux places it within the so-called radius valley; however, HD 110113 b was able to hold on to a substantial (0.1-1 per cent) H-He atmosphere over its âŒ4 Gyr lifetime. Through a novel simultaneous Gaussian process fit to multiple activity indicators, we were also able to fit for the strong stellar rotation signal with period 20.8 ± 1.2 d from the RVs and confirm an additional non-transiting planet, HD 110113 c, which has a mass of 10.5 ± 1.2 Mâ and a period of d.Fil: Osborn, H. P.. University of Bern; Suiza. Massachusetts Institute of Technology; Estados UnidosFil: Armstrong, D. J.. University of Warwick; Reino UnidoFil: Adibekyan, V.. Universidad de Porto; PortugalFil: Collins, K. A.. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Delgado Mena, E.. Universidad de Porto; PortugalFil: Howell, S. B.. National Aeronautics and Space Administration; Estados UnidosFil: Hellier, C.. Keele University. Faculty Of Humanities And Social Sciences.; Reino UnidoFil: King, G. W.. University of Warwick; Reino UnidoFil: Lillo Box, J.. Consejo Superior de Investigaciones Cientificas. Centro de Astrobiologia.; EspañaFil: Nielsen, Louise D.. Universidad de Ginebra; SuizaFil: Otegi, J. F.. Universidad de Ginebra; SuizaFil: Santos, N. C.. Universidad de Porto; PortugalFil: Ziegler, C.. University of Toronto; CanadĂĄFil: Anderson, D. R.. University of Warwick; Reino UnidoFil: Briceno, C.. Cerro Tololo Inter American Observatory; ChileFil: Burke, C.. Massachusetts Institute of Technology; Estados UnidosFil: Bayliss, D.. University of Warwick; Reino UnidoFil: Barrado, D.. Consejo Superior de Investigaciones Cientificas. Centro de Astrobiologia.; EspañaFil: Bryant, E. M.. University of Warwick; Reino UnidoFil: Brown, D. J. A.. University of Warwick; Reino UnidoFil: Barros, S. C. C.. Universidad de Porto; PortugalFil: Bouchy, F.. Universidad de Ginebra; SuizaFil: Caldwell, D. A.. SETI Institute; Estados UnidosFil: Conti, D. M.. American Association of Variable Star Observers; Estados UnidosFil: Diaz, Rodrigo Fernando. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Ciencias FĂsicas. - Universidad Nacional de San MartĂn. Instituto de Ciencias FĂsicas; Argentina. International Center for Advanced Studies; Argentina. Universidad Nacional de San MartĂn. Escuela de Ciencia y TecnologĂa. Centro Internacional de Estudios Avanzados; ArgentinaFil: Dragomir, D.. University of New Mexico; Estados UnidosFil: Deleuil, M.. Universidad de Aix-Marsella; Francia. Centre National de la Recherche Scientifique; FranciaFil: Demangeon, O. D. S.. Universidad de Porto; PortugalFil: Dorn, C.. Universitat Zurich; SuizaFil: Daylan, T.. Massachusetts Institute of Technology; Estados Unido
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