323 research outputs found
KELT-14b and KELT-15b: an independent discovery of WASP-122b and a new hot Jupiter
We report the discovery of KELT-14b and KELT-15b, two hot Jupiters from the KELT-South survey. KELT-14b, an independent discovery of the recently announced WASP-122b, is an inflated Jupiter mass planet that orbits a similar to 5.0(-0.7)(+0.3) (0)7 Gyr, V= 11.0, G2 star that is near the main sequence turnoff. The host star, KELT-14 (TYC 7638-981-1), has an inferred mass M* = 1.18(-0.7)(+0.3) M-circle dot and radius R* = 1.37 +/- -0.08 R-circle dot), and has T-eff = 58021 K, log g* = 4.23(-0.7)(+0.3) SI and [Fe/H] = 0.33 +/- -0.09. The planet orbits with a period of 1.7100588 +/- 0.0000025 days (T-0 = 2457091.02863 +/- 0.00047) and has a radius R-p = 1.521 Ri and mass Mp = 1.196 +/- 0.072 MI, and the eccentricity is consistent with zero. KELT-15b is another inflated Jupiter mass planet that orbits a similar to 4.6(-0.4)(+0.5) Gyr, V = 11.2, GO star (TYC 8146-86-1) that is near the 'blue hook' stage of evolution prior to the Hertzsprung gap, and has an inferred mass M* = 1.181(0.050)(+0.05) M-circle dot and radius R* = 1.481 R-circle dot, and T-eff = 6003-% K, log g* = 4.17(-0.04)(+0.02) and [Fe/H] = 0.05 +/- 0.03. The planet orbits on a period of 3.329441 +/- 0.000016 days (T0 = 2457029.1663 0.0073) and has a radius Rp = 1.443 (o)Ols7 Ri and mass M-p = 0.91 531 MI and an eccentricity consistent with zero. KELT-14b has the second largest expected emission signal in the K-band for known transiting planets brighter than K < 10.5. Both KELT-14b and KELT-15b are predicted to have large enough emission signals that their secondary eclipses should be detectable using ground-based observatories
KELT-19Ab: A P ∼ 4.6-day Hot Jupiter Transiting a Likely Am Star with a Distant Stellar Companion
We present the discovery of the giant planet KELT-19Ab, which transits the moderately bright (V ∼ 9.9) A8V star TYC 764-1494-1 with an orbital period of 4.61 days. We confirm the planetary nature of the companion via a combination of radial velocities, which limit the mass to ≳4.1 MJ (3s), and a clear Doppler tomography signal, which indicates a retrograde projected spin-orbit misalignment of λ = -179.7-3.8+3.7 degrees. Global modeling indicates that the Teff = 7500 ±110 K host star has M M = 1.62+0.20-0.25 and R = 1.83 0.10 R. The planet has a radius of RP = 1.91 0.11 RJ and receives a stellar insolation flux of ∼ 3.2 10 erg s-1 cm-2, leading to an inferred equilibrium temperature of Teq ∼ 1935 K assuming zero albedo and complete heat redistribution. With a v I sin 84.8 ±2.0 km s = -1, the host is relatively slowly rotating compared to other stars with similar effective temperatures, and it appears to be enhanced in metallic elements but deficient in calcium, suggesting that it is likely an Am star. KELT-19A would be the first detection of an Am host of a transiting planet of which we are aware. Adaptive optics observations of the system reveal the existence of a companion with late-G9V/early-K1V spectral type at a projected separation of »160 au. Radial velocity measurements indicate that this companion is bound. Most Am stars are known to have stellar companions, which are often invoked to explain the relatively slow rotation of the primary. In this case, the stellar companion is unlikely to have caused the tidal braking of the primary. However, it may have emplaced the transiting planetary companion via the Kozai-Lidov mechanism
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The low‐degree shape of Mercury
The shape of Mercury, particularly when combined with its geoid, provides clues to the planet's internal structure, thermal evolution, and rotational history. Elevation measurements of the northern hemisphere acquired by the Mercury Laser Altimeter on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, combined with 378 occultations of radio signals from the spacecraft in the planet's southern hemisphere, reveal the low‐degree shape of Mercury. Mercury's mean radius is 2439.36 ± 0.02 km, and there is a 0.14 km offset between the planet's centers of mass and figure. Mercury is oblate, with a polar radius 1.65 km less than the mean equatorial radius. The difference between the semimajor and semiminor equatorial axes is 1.25 km, with the long axis oriented 15° west of Mercury's dynamically defined principal axis. Mercury's geoid is also oblate and elongated, but it deviates from a sphere by a factor of 10 less than Mercury's shape, implying compensation of elevation variations on a global scale
KELT-24b: A 5M_J Planet on a 5.6 day Well-Aligned Orbit around the Young V=8.3 F-star HD 93148
We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V=8.3 mag, K=7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a T_(eff) =6508±49 K, a mass of M∗ = 1.461^(+0.056)_(−0.060) M_⊙, radius of R∗ = 1.506±0.022 R_⊙, and an age of 0.77^(+0.61)_(−0.42) Gyr. Its planetary companion (KELT-24 b) has a radius of R_P = 1.272^(+0.021)_(−0.022) R_J, a mass of MP = 5.18^(+0.21)_(−0.22) M_J, and from Doppler tomographic observations, we find that the planet's orbit is well-aligned to its host star's projected spin axis (λ = 2.6^(+5.1)_(−3.6)). The young age estimated for KELT-24 suggests that it only recently started to evolve from the zero-age main sequence. KELT-24 is the brightest star known to host a transiting giant planet with a period between 5 and 10 days. Although the circularization timescale is much longer than the age of the system, we do not detect a large eccentricity or significant misalignment that is expected from dynamical migration. The brightness of its host star and its moderate surface gravity make KELT-24b an intriguing target for detailed atmospheric characterization through spectroscopic emission measurements since it would bridge the current literature results that have primarily focused on lower mass hot Jupiters and a few brown dwarfs
Alignment of the CMS tracker with LHC and cosmic ray data
© CERN 2014 for the benefit of the CMS collaboration, published under the terms of the Creative Commons Attribution 3.0 License by IOP Publishing Ltd and Sissa Medialab srl. Any further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation and DOI.The central component of the CMS detector is the largest silicon tracker ever built. The precise alignment of this complex device is a formidable challenge, and only achievable with a significant extension of the technologies routinely used for tracking detectors in the past. This article describes the full-scale alignment procedure as it is used during LHC operations. Among the specific features of the method are the simultaneous determination of up to 200 000 alignment parameters with tracks, the measurement of individual sensor curvature parameters, the control of systematic misalignment effects, and the implementation of the whole procedure in a multi-processor environment for high execution speed. Overall, the achieved statistical accuracy on the module alignment is found to be significantly better than 10μm
Alignment of the CMS silicon tracker during commissioning with cosmic rays
This is the Pre-print version of the Article. The official published version of the Paper can be accessed from the link below - Copyright @ 2010 IOPThe CMS silicon tracker, consisting of 1440 silicon pixel and 15 148 silicon strip detector modules, has been aligned using more than three million cosmic ray charged particles, with additional information from optical surveys. The positions of the modules were determined with respect to cosmic ray trajectories to an average precision of 3–4 microns RMS in the barrel and 3–14 microns RMS in the endcap in the most sensitive coordinate. The results have been validated by several studies, including laser beam cross-checks, track fit self-consistency, track residuals in overlapping module regions, and track parameter resolution, and are compared with predictions obtained from simulation. Correlated systematic effects have been investigated. The track parameter resolutions obtained with this alignment are close to the design performance.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,
and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS
(Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia);
Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG,
and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT,
SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)
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