1,621 research outputs found
Separated twins or just siblings? A multi-planet system around an M dwarf including a cool sub-Neptune
We report the discovery of two TESS sub-Neptunes orbiting the early M dwarf
TOI-904 (TIC 261257684). Both exoplanets, TOI-904 b and c, were initially
observed in TESS sector 12 with twin sizes of 2.49R and
2.31R, respectively. Through observations in five additional sectors
in the TESS primary mission and the first and second extended missions, the
orbital periods of both planets were measured to be 10.8870.001 and
83.9990.001 days, respectively. Reconnaissance radial velocity
measurements (taken with EULER/CORALIE) and high resolution speckle imaging
with adaptive optics (obtained from SOAR/HRCAM and Gemini South/ZORRO) show no
evidence of an eclipsing binary or a nearby companion, which together with the
low false positive probabilities calculated with the statistical validation
software TRICERATOPS establish the planetary nature of these candidates. The
outer planet, TOI-904 c, is the longest-period M dwarf exoplanet found by TESS,
with an estimated equilibrium temperature of 217K. As the three other validated
planets with comparable host stars and orbital periods were observed by Kepler
around much dimmer stars (J 12), TOI-904 c, orbiting a brighter
star (J 9.6), is the coldest M dwarf planet easily accessible for
atmospheric follow-up. Future mass measurements and transmission spectroscopy
of the similar sized planets in this system could determine whether they are
also similar in density and composition, suggesting a common formation pathway,
or whether they have distinct origins.Comment: 18 pages, 6 figures, Accepted by the Astrophysical Journal Letter
TOI-199 b: A well-characterized 100-day transiting warm giant planet with TTVs seen from Antarctica
We present the spectroscopic confirmation and precise mass measurement of the
warm giant planet TOI-199 b. This planet was first identified in TESS
photometry and confirmed using ground-based photometry from ASTEP in Antarctica
including a full 6.5h long transit, PEST, Hazelwood, and LCO; space
photometry from NEOSSat; and radial velocities (RVs) from FEROS, HARPS,
CORALIE, and CHIRON. Orbiting a late G-type star, TOI-199\,b has a
period, a mass of
, and a radius of .
It is the first warm exo-Saturn with a precisely determined mass and radius.
The TESS and ASTEP transits show strong transit timing variations, pointing to
the existence of a second planet in the system. The joint analysis of the RVs
and TTVs provides a unique solution for the non-transiting companion TOI-199 c,
which has a period of and an estimated
mass of . This period places it within
the conservative Habitable Zone.Comment: 33 pages, 23 figures. Accepted for publication in A
The Iceland Microcontinent and a continental Greenland-Iceland-Faroe Ridge
The breakup of Laurasia to form the Northeast Atlantic Realm was the culmination of a long period of tectonic unrest extending back to the Late Palaeozoic. Breakup was prolonged and complex and disintegrated an inhomogeneous collage of cratons sutured by cross-cutting orogens. Volcanic rifted margins formed, which are blanketed by lavas and underlain variously by magma-inflated, extended continental crust and mafic high-velocity lower crust of ambiguous and probably partly continental provenance. New rifts formed by diachronous propagation along old zones of weakness. North of the Greenland-Iceland-Faroe Ridge the newly forming rift propagated south along the Caledonian suture. South of the Greenland-Iceland-Faroe Ridge it propagated north through the North Atlantic Craton along an axis displaced ~ 150 km to the west of the northern rift. Both propagators stalled where the confluence of the Nagssugtoqidian and Caledonian orogens formed a transverse barrier. Thereafter, the ~ 400-km-wide latitudinal zone between the stalled rift tips extended in a distributed, unstable manner along multiple axes of extension that frequently migrated or jumped laterally with shearing occurring between them in diffuse transfer zones. This style of deformation continues to the present day. It is the surface expression of underlying magma-assisted stretching of ductile mid- and lower continental crust which comprises the Icelandic-type lower crust that underlies the Greenland-Iceland-Faroe Ridge. This, and probably also one or more full-crustal-thickness microcontinents incorporated in the Ridge, are capped by surface lavas. The Greenland-Iceland-Faroe Ridge thus has a similar structure to some zones of seaward-dipping reflectors. The contemporaneous melt layer corresponds to the 3–10 km thick Icelandic-type upper crust plus magma emplaced in the ~ 10–30-km-thick Icelandic-type lower crust. This model can account for seismic and gravity data that are inconsistent with a gabbroic composition for Icelandic-type lower crust, and petrological data that show no reasonable temperature or source composition could generate the full ~ 40-km thickness of Icelandic-type crust observed. Numerical modeling confirms that extension of the continental crust can continue for many tens of Myr by lower-crustal flow from beneath the adjacent continents. Petrological estimates of the maximum potential temperature of the source of Icelandic lavas are up to 1450 °C, no more than ~ 100 °C hotter than MORB source. The geochemistry is compatible with a source comprising hydrous peridotite/pyroxenite with a component of continental mid- and lower crust. The fusible petrology, high source volatile contents, and frequent formation of new rifts can account for the true ~ 15–20 km melt thickness at the moderate temperatures observed. A continuous swathe of magma-inflated continental material beneath the 1200-km-wide Greenland-Iceland-Faroe Ridge implies that full continental breakup has not yet occurred at this latitude. Ongoing tectonic instability on the Ridge is manifest in long-term tectonic disequilibrium on the adjacent rifted margins and on the Reykjanes Ridge, where southerly migrating propagators that initiate at Iceland are associated with diachronous swathes of unusually thick oceanic crust. Magmatic volumes in the NE Atlantic Realm have likely been overestimated and the concept of a monogenetic North Atlantic Igneous Province needs to be reappraised. A model of complex, piecemeal breakup controlled by pre-existing structures that produces anomalous volcanism at barriers to rift propagation and distributes continental material in the growing oceans fits other oceanic regions including the Davis Strait and the South Atlantic and West Indian oceans
Genome-Wide Analysis of Central Corneal Thickness in Primary Open-Angle Glaucoma Cases in the NEIGHBOR and GLAUGEN Consortia
To investigate the effects of central corneal thickness (CCT)-associated variants on primary open-angle glaucoma (POAG) risk using single nucleotide polymorphisms (SNP) data from the Glaucoma Genes and Environment (GLAUGEN) and National Eye Institute (NEI) Glaucoma Human Genetics Collaboration (NEIGHBOR) consortia
TIC-320687387 B : a long-period eclipsing M-dwarf close to the hydrogen burning limit
We are using precise radial velocities from CORALIE together with precision photometry from the Next Generation Transit Survey (NGTS) to follow up stars with single-transit events detected with the Transiting Exoplanet Survey Satellite (TESS). As part of this survey we identified a single transit on the star TIC-320687387, a bright (T = 11.6) G-dwarf observed by TESS in Sector 13 and 27. From subsequent monitoring of TIC-320687387 with CORALIE, NGTS, and Lesedi we determined that the companion, TIC-320687387 B, is a very low-mass star with a mass of MJ and radius of RJ placing it close to the hydrogen burning limit (∼80 MJ). TIC-320687387 B is tidally decoupled and has an eccentric orbit, with a period of 29.77381 days and an eccentricity of 0.366 ± 0.003. Eclipsing systems such as TIC-320687387 AB allow us to test stellar evolution models for low-mass stars, which in turn are needed to calculate accurate masses and radii for exoplanets orbiting single low-mass stars. The sizeable orbital period of TIC-320687387 B makes it particularly valuable as its evolution can be assumed to be free from perturbations caused by tidal interactions with its G-type host star
Measurement of differential cross sections in the kinematic angular variable phi* for inclusive Z boson production in pp collisions at root s=8 TeV
Measurements of differential cross sections d sigma/d phi* and double-differential cross sections d(2)sigma/ld phi*d/y/ for inclusive Z boson production are presented using the dielectron and dimuon final states. The kinematic observable phi* correlates with the dilepton transverse momentum but has better resolution, and y is the dilepton rapidity. The analysis is based on data collected with the CMS experiment at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb(-1). The normalised cross section (1/sigma) d sigma/d phi*, within the fiducial kinematic region, is measured with a precision of better than 0.5% for phi* <1. The measurements are compared to theoretical predictions and they agree, typically, within few percent.Peer reviewe
Measurement of the underlying event activity in inclusive Z boson production in proton-proton collisions at root s=13 TeV
This paper presents a measurement of the underlying event activity in proton-proton collisions at a center-of-mass energy of 13TeV, performed using inclusive Z boson production events collected with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 2.1 fb(-1). The underlying event activity is quantified in terms of the charged particle multiplicity, as well as of the scalar sum of the charged particles' transverse momenta in different topological regions defined with respect to the Z boson direction. The distributions are unfolded to the stable particle level and compared with predictions from various Monte Carlo event generators, as well as with similar CDF and CMS measurements at center-of-mass energies of 1.96 and 7TeV respectively.Peer reviewe
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