1,356 research outputs found

    EPIC 219388192 b - an inhabitant of the brown dwarf desert in the Ruprecht 147 open cluster

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    We report the discovery of EPIC 219388192 b, a transiting brown dwarf in a 5.3-day orbit around a member star of Ruprecht-147, the oldest nearby open cluster association, which was photometrically monitored by K2 during its Campaign 7. We combine the K2 time-series data with ground-based adaptive optics imaging and high resolution spectroscopy to rule out false positive scenarios and determine the main parameters of the system. EPIC 219388192 b has a radius of RbR_\mathrm{b}=0.937±0.0420.937\pm0.042~RJup\mathrm{R_{Jup}} and mass of MbM_\mathrm{b}=36.50±0.0936.50\pm0.09~MJup\mathrm{M_{Jup}}, yielding a mean density of 59.0±8.159.0\pm8.1~g cm−3\mathrm{g\,cm^{-3}}. The host star is nearly a Solar twin with mass M⋆M_\star=0.99±0.050.99\pm0.05~M⊙\mathrm{M_{\odot}}, radius R⋆R_\star=1.01±0.041.01\pm0.04~R⊙\mathrm{R_{\odot}}, effective temperature Teff\mathrm{T_{eff}}=5850±855850\pm85~K and iron abundance [Fe/H]=0.03±0.080.03\pm0.08~dex. Its age, spectroscopic distance, and reddening are consistent with those of Ruprecht-147, corroborating its cluster membership. EPIC 219388192 b is the first brown dwarf with precise determinations of mass, radius and age, and serves as benchmark for evolutionary models in the sub-stellar regime.Comment: 13 pages, 11 figures, 4 tables, submitted to AAS Journal

    Three Small Planets Transiting a Hyades Star

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    We present the discovery of three small planets transiting K2-136 (LP 358 348, EPIC 247589423), a late K dwarf in the Hyades. The planets have orbital periods of 7.9757±0.00117.9757 \pm 0.0011, 17.30681−0.00036+0.0003417.30681^{+0.00034}_{-0.00036}, and 25.5715−0.0040+0.003825.5715^{+0.0038}_{-0.0040} days, and radii of 1.05±0.161.05 \pm 0.16, 3.14±0.363.14 \pm 0.36, and 1.55−0.21+0.241.55^{+0.24}_{-0.21} R⊕R_\oplus, respectively. With an age of 600-800 Myr, these planets are some of the smallest and youngest transiting planets known. Due to the relatively bright (J=9.1) host star, the planets are compelling targets for future characterization via radial velocity mass measurements and transmission spectroscopy. As the first known star with multiple transiting planets in a cluster, the system should be helpful for testing theories of planet formation and migration.Comment: Accepted to The Astronomical Journa

    Exoplanets around Low-mass Stars Unveiled by K2

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    We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5-10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96-33 days. For one of the planets (K2-151b) we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius RpR_p on stellar insolation and metallicity [Fe/H]. We confirm that for periods Pâ‰Č2P\lesssim 2 days, planets with a radius Rp≳2 R⊕R_p\gtrsim 2\,R_\oplus are less common than planets with a radius between 1-2 R⊕\,R_\oplus. We also see a hint of the "radius valley" between 1.5 and 2 R⊕\,R_\oplus that has been seen for close-in planets around FGK stars. These features in the radius/period distribution could be attributed to photoevaporation of planetary envelopes by high-energy photons from the host star, as they have for FGK stars. For the M dwarfs, though, the features are not as well defined, and we cannot rule out other explanations such as atmospheric loss from internal planetary heat sources, or truncation of the protoplanetary disk. There also appears to be a relation between planet size and metallicity: those few planets larger than about 3 R⊕R_\oplus are found around the most metal-rich M dwarfs.Comment: 29 pages, 21 figures, 6 tables, Accepted in Astronomical Journa

    Dise?o, procura, construcci?n e implementaci?n de la torre de control para la nueva base aeronaval del Callao

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    Concebido por un equipo multidisciplinario, con diferentes visiones y experiencias para abordar los procesos de inicio y planificaci?n del proyecto ?Dise?o, procura, construcci?n e implementaci?n de la torre de control para la nueva base aeronaval del Callao?; permitiendo as? que la direcci?n de proyectos en sus diferentes fases de planeaci?n sea un proceso innovador, por medio de GISA, empresa de ingenier?a y construcci?n con una trayectoria de 20 a?os. El proyecto forma parte del megaproyecto de remodelaci?n de la base aeronaval del Callao para la Marina de Guerra del Per?. ?ste abarca la gesti?n, dise?o, procura construcci?n de una torre de control de medidas reglamentarias, implementaci?n de equipos de telecomunicaci?n de ?ltima generaci?n y capacitaci?n al personal usuario del cliente, hasta obtener la certificaci?n internacional. GISA ha establecido objetivos de eficiencia (2) alineados con la triple restricci?n, objetivos de producto (2) orientados a la conexi?n de los equipos de telecomunicaciones, as? como la obtenci?n de la certificaci?n aeron?utica internacional y satisfacci?n de stakeholders; para ello ha desarrollado los planes subsidiarios necesarios con plena conciencia de los factores pol?ticos, econ?micos, tecnol?gicos, ecol?gicos, legales y socioculturales presentes. El ?xito del proyecto posicionar? a GISA como un contratista preferente para el Estado

    The transiting multi-planet system HD3167: a 5.7 MEarth Super-Earth and a 8.3 MEarth mini-Neptune

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    HD3167 is a bright (V=8.9 mag) K0V star observed by the NASA's K2 space mission during its Campaign 8. It has been recently found to host two small transiting planets, namely, HD3167b, an ultra short period (0.96 d) super-Earth, and HD3167c, a mini-Neptune on a relatively long-period orbit (29.85 d). Here we present an intensive radial velocity follow-up of HD3167 performed with the FIES@NOT, [email protected], and HARPS-N@TNG spectrographs. We revise the system parameters and determine radii, masses, and densities of the two transiting planets by combining the K2 photometry with our spectroscopic data. With a mass of 5.69+/-0.44 MEarth, radius of 1.574+/-0.054 REarth, and mean density of 8.00(+1.0)(-0.98) g/cm^3, HD3167b joins the small group of ultra-short period planets known to have a rocky terrestrial composition. HD3167c has a mass of 8.33 (+1.79)(-1.85) MEarth and a radius of 2.740(+0.106)(-0.100) REarth, yielding a mean density of 2.21(+0.56)(-0.53) g/cm^3, indicative of a planet with a composition comprising a solid core surrounded by a thick atmospheric envelope. The rather large pressure scale height (about 350 km) and the brightness of the host star make HD3167c an ideal target for atmospheric characterization via transmission spectroscopy across a broad range of wavelengths. We found evidence of additional signals in the radial velocity measurements but the currently available data set does not allow us to draw any firm conclusion on the origin of the observed variation.Comment: 18 pages, 11 figures, 5 table

    K2-60b and K2-107b. A Sub-Jovian and a Jovian Planet from the K2 Mission

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    We report the characterization and independent detection of K2-60b, as well as the detection and characterization of K2-107b, two transiting hot gaseous planets from the K2 space mission. We confirm the planetary nature of the two systems and determine their fundamental parameters combining the K2 time-series data with FIES @ NOT and HARPS-N @ TNG spectroscopic observations. K2-60b has a radius of 0.683 +/- 0.037 R-Jup and a mass of 0.426 +/- 0.037 M-Jup and orbits a G4 V star with an orbital period of 3.00267 +/- 0.00006 days. K2-107b has a radius of 1.44 +/- 0.15 R-Jup and a mass of 0.84 +/- 0.08 M-Jup and orbits an F9 IV star every 3.31392 +/- 0.00002 days. K2-60b is among the few planets at the edge of the so-called desert of short-period sub-Jovian planets. K2107b is a highly inflated Jovian planet orbiting an evolved star about to leave the main sequence

    Web-based monitoring tools for Resistive Plate Chambers in the CMS experiment at CERN

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    The Resistive Plate Chambers (RPC) are used in the CMS experiment at the trigger level and also in the standard offline muon reconstruction. In order to guarantee the quality of the data collected and to monitor online the detector performance, a set of tools has been developed in CMS which is heavily used in the RPC system. The Web-based monitoring (WBM) is a set of java servlets that allows users to check the performance of the hardware during data taking, providing distributions and history plots of all the parameters. The functionalities of the RPC WBM monitoring tools are presented along with studies of the detector performance as a function of growing luminosity and environmental conditions that are tracked over time

    Radiation background with the CMS RPCs at the LHC

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    The Resistive Plate Chambers (RPCs) are employed in the CMS Experiment at the LHC as dedicated trigger system both in the barrel and in the endcap. This article presents results of the radiation background measurements performed with the 2011 and 2012 proton-proton collision data collected by CMS. Emphasis is given to the measurements of the background distribution inside the RPCs. The expected background rates during the future running of the LHC are estimated both from extrapolated measurements and from simulation

    A Radial Velocity Study of the Planetary System of pi Mensae: Improved Planet Parameters for pi Mensae c and a Third Planet on a 125 Day Orbit

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    π Men hosts a transiting planet detected by the Transiting Exoplanet Survey Satellite space mission and an outer planet in a 5.7 yr orbit discovered by radial velocity (RV) surveys. We studied this system using new RV measurements taken with the HARPS spectrograph on ESO's 3.6 m telescope, as well as archival data. We constrain the stellar RV semiamplitude due to the transiting planet, π Men c, as Kc = 1.21 ± 0.12 m s^{−1}, resulting in a planet mass of M_{c} = 3.63 ± 0.38 M_{⊕}. A planet radius of R_{c} = 2.145 ± 0.015 R_{⊕} yields a bulk density of ρc = 2.03 ± 0.22 g cm^{−3}. The precisely determined density of this planet and the brightness of the host star make π Men c an excellent laboratory for internal structure and atmospheric characterization studies. Our HARPS RV measurements also reveal compelling evidence for a third body, π Men d, with a minimum mass M_{d} sin i_{d} = 13.38 ± 1.35 M_{⊕} orbiting with a period of Porb,d = 125 days on an eccentric orbit (e_{d} = 0.22). A simple dynamical analysis indicates that the orbit of π Men d is stable on timescales of at least 20 Myr. Given the mutual inclination between the outer gaseous giant and the inner rocky planet and the presence of a third body at 125 days, π Men is an important planetary system for dynamical and formation studies
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