1,729 research outputs found
Trace elements and isotopes analyses on historical samples of white sharks from the Mediterranean Sea
The white shark Carcharodon carcharias has been present in the Mediterranean Sea since 3.2 million years ago. Nevertheless, the current population shows a low genetic variability suggesting an endangered small population, on which there is scarce information regarding ecotoxicology or trophic ecology. Given that white shark's sightings are rare in the Mediterranean and the possibility of obtaining samples is highly limited, the aim of this research was to provide general information regarding the concentration of trace elements and stable isotopes (delta N-15 and delta C-13). Laboratory analyses were performed on 18 and 12 subsamples from two different white sharks' vertebrae obtained from two adult specimens caught in 1987, in Favignana Island, Italy. Perforations were made along the vertebrae to describe both trace elements and stable isotopes at different life stages. A total of 38 trace elements were analysed, in which the highest concentrations were found in Fe, Sr, U, Pb, and Zn. The fluctuations of these elements during the ontogeny of both individuals could have been related to changes in diet and environment, although the specific origin remains unknown. Regarding stable isotopes, the vertebrae from the male showed an isotopic range from 9.6 parts per thousand to 10.8 parts per thousand (delta N-15) and from -16.5 parts per thousand to -13.0 parts per thousand (delta C-13) with a mean +/- SD value of 10.3 +/- 0.4 parts per thousand for delta N-15 and -14.6 +/- 1.3 parts per thousand for delta C-13; whereas the female vertebrae had an isotopic range from 9.8 parts per thousand to 11.1 parts per thousand (delta N-15) and from -16.9 parts per thousand to -15.0 parts per thousand (delta C-13), with a mean +/- SD value of 10.8 +/- 0.6 parts per thousand for delta N-15 and -15.8 +/- 0.8 parts per thousand for delta C-13. There were no significant delta N-15 differences (U = 6, p = 0.07346) between the two individuals. However, there were just significant differences in delta C-13 (t = -1.8, p = 0.049256), which could suggest sexual segregation in terms of habitat use and feeding habits
The 2HWC HAWC Observatory Gamma Ray Catalog
We present the first catalog of TeV gamma-ray sources realized with the
recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the
most sensitive wide field-of-view TeV telescope currently in operation, with a
1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an
instantaneous field of view >1.5 sr and >90% duty cycle, it continuously
surveys and monitors the sky for gamma ray energies between hundreds GeV and
tens of TeV.
HAWC is located in Mexico at a latitude of 19 degree North and was completed
in March 2015. Here, we present the 2HWC catalog, which is the result of the
first source search realized with the complete HAWC detector. Realized with 507
days of data and represents the most sensitive TeV survey to date for such a
large fraction of the sky. A total of 39 sources were detected, with an
expected contamination of 0.5 due to background fluctuation. Out of these
sources, 16 are more than one degree away from any previously reported TeV
source. The source list, including the position measurement, spectrum
measurement, and uncertainties, is reported. Seven of the detected sources may
be associated with pulsar wind nebulae, two with supernova remnants, two with
blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa
Remarks on the morphology and distribution of some rare centric diatoms in southern Brazilian continental shelf and slope waters
Envisioning a World Beyond APCs/BPCs
This archival page includes documents and recordings related to the international symposium, âEnvisioning a World Beyond APCs/BPCs,â held in Lawrence, Kansas, on Thursday and Friday, November 17-18. The presenters were a group of 18 internationally respected scholars, publishers, university librarians, and executives from foundations and organizations, who were asked to participate in a discussion about current models available for achieving an expansive, inclusive, and balanced worldwide open publishing ecosystem. The symposium was co-sponsored by the University of Kansas Libraries, Open Access Network (a project of K|N Consultants), Allen Press, SPARC, and ARL. The materials included here are the symposium schedule, recordings of Parts 1 and 2 of the Nov. 17 livestream, a transcript of the livestream, and team proposals originating from the Nov. 18 morning session.This symposium was sponsored by the University of Kansas Libraries, Open Access Network (a project of K|N Consultants), Allen Press, and SPARC
The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegardenâs Star
Context.Teegardenâs Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0 V),the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES.Aims.As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of TeegardenâsStar and analysed them for planetary signals.Methods.We find periodic variability in the radial velocities of Teegardenâs Star. We also studied photometric measurements to rule out stellarbrightness variations mimicking planetary signals.Results.We find evidence for two planet candidates, each with 1.1Mâminimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. Noevidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotationand old age.Conclusions.The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cooldwarf for which the masses have been determined using radial velocities.We thank the referee Rodrigo DĂaz for a careful review andhelpful comments. M.Z. acknowledges support from the Deutsche Forschungs-gemeinschaft under DFG RE 1664/12-1 and Research Unit FOR2544 âBluePlanets around Red Starsâ, project no. RE 1664/14-1. CARMENES isan instrument for the Centro AstronĂłmico Hispano-AlemĂĄn de Calar Alto(CAHA, AlmerĂa, Spain). CARMENES is funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de InvestigacionesCientĂficas (CSIC), the European Union through FEDER/ERF FICTS-2011-02 funds, and the members of the CARMENES Consortium (Max-Planck-Institut fĂŒr Astronomie, Instituto de AstrofĂsica de AndalucĂa, LandessternwarteKönigstuhl, Institut de CiĂšncies de lâEspai, Institut fĂŒr Astrophysik Göttingen,Universidad Complutense de Madrid, ThĂŒringer Landessternwarte Tautenburg,Instituto de AstrofĂsica de Canarias, Hamburger Sternwarte, Centro de Astro-biologĂa and Centro AstronĂłmico Hispano-AlemĂĄn), with additional contribu-tions by the Spanish Ministry of Economy, the German Science Foundationthrough the Major Research Instrumentation Programme and DFG ResearchUnit FOR2544 âBlue Planets around Red Starsâ, the Klaus Tschira Stiftung, thestates of Baden-WĂŒrttemberg and Niedersachsen, and by the Junta de AndalucĂa.Based on data from the CARMENES data archive at CAB (INTA-CSIC). Thisarticle is based on observations made with the MuSCAT2 instrument, devel-oped by ABC, at Telescopio Carlos SĂĄnchez operated on the island of Tener-ife by the IAC in the Spanish Observatorio del Teide. Data were partly col-lected with the 150-cm and 90-cm telescopes at the Sierra Nevada Observa-tory (SNO) operated by the Instituto de AstrofĂsica de AndalucĂa (IAA-CSIC).Data were partly obtained with the MONET/South telescope of the MOnitoringNEtwork of Telescopes, funded by the Alfried Krupp von Bohlen und HalbachFoundation, Essen, and operated by the Georg-August-UniversitĂ€t Göttingen,the McDonald Observatory of the University of Texas at Austin, and the SouthAfrican Astronomical Observatory. We acknowledge financial support from theSpanish Agencia Estatal de InvestigaciĂłn of the Ministerio de Ciencia, Inno-vaciĂłn y Universidades and the European FEDER/ERF funds through projectsAYA2015-69350-C3-2-P, AYA2016-79425-C3-1/2/3-P, AYA2018-84089, BES-2017-080769, BES-2017-082610, ESP2015-65712-C5-5-R, ESP2016-80435-C2-1/2-R, ESP2017-87143-R, ESP2017-87676-2-2, ESP2017-87676-C5-1/2/5-R, FPU15/01476, RYC-2012-09913, the Centre of Excellence âSevero Ochoaâand âMarĂa de Maeztuâ awards to the Instituto de AstrofĂsica de Canarias (SEV-2015-0548), Instituto de AstrofĂsica de AndalucĂa (SEV-2017-0709), and Cen-tro de AstrobiologĂa (MDM-2017-0737), the Generalitat de Catalunya throughCERCA programmeâ, the Deutsches Zentrum fĂŒr Luft- und Raumfahrt throughgrants 50OW0204 and 50OO1501, the European Research Council through grant694513, the Italian Ministero dellâinstruzione, dellâuniversitĂ de della ricerca andUniversitĂ degli Studi di Roma Tor Vergata through FFABR 2017 and âMis-sion: Sustainability 2016â, the UK Science and Technology Facilities Council through grant ST/P000592/1, the Israel Science Foundation through grant848/16, the Chilean CONICYT-FONDECYT through grant 3180405, the Mexi-can CONACYT through grant CVU 448248, the JSPS KAKENHI through grantsJP18H01265 and 18H05439, and the JST PRESTO through grant JPMJPR1775
The CARMENES search for exoplanets around M dwarfs High-resolution optical and near-infrared spectroscopy of 324 survey stars
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520â1710 nm at a resolution of at least R >80 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700â900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m sâ1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3â4 m sâ1
The CARMENES search for exoplanets around M dwarfs High-resolution optical and near-infrared spectroscopy of 324 survey stars
The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520â1710 nm at a resolution of at least R >80 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700â900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m sâ1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3â4 m sâ1
The CARMENES search for exoplanets around M dwarfs HD147379 b: A nearby Neptune in the temperate zone of an early-M dwarf
We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 (Vâ=â8.9 mag, Mâ=â0.58â±â0.08âMâ), a bright M0.0 V star at a distance of 10.7 pc, is found to undergo periodic RV variations with a semi-amplitude of Kâ=â5.1 ± 0.4 m sâ1 and a period of Pâ=â86.54 ± 0.06 d. The RV signal is found in our CARMENES data, which were taken between 2016 and 2017, and is supported by HIRES/Keck observations that were obtained since 2000. The RV variations are interpreted as resulting from a planet of minimum mass mPâsinâiâ=â25â±â2âMâ, 1.5 times the mass of Neptune, with an orbital semi-major axis aâ=â0.32 au and low eccentricity (e < 0.13). HD 147379 b is orbiting inside the temperate zone around the star, where water could exist in liquid form. The RV time-series and various spectroscopic indicators show additional hints of variations at an approximate period of 21.1 d (and its first harmonic), which we attribute to the rotation period of the star.FEDER/ERF FICTS-2011-02 fundsMajor Research Instrumentation Programme
and DFG Research Unit FOR2544 âBlue Planets around Red StarsEuropean Research Council (ERC-279347), Deutsche Forschungsgemeinschaft
(RE 1664/12-1, RE 2694/4-1), Bundesministerium fĂŒr Bildung
und Forschung (BMBF-05A14MG3, BMBF-05A17MG3), Spanish Ministry
of Economy and Competitiveness (MINECO, grants AYA2015-68012-C2-2-P,
AYA2016-79425-C3-1,2,3-P, AYA2015-69350-C3-2-P, AYA2014-54348-C03-
01, AYA2014-56359-P, AYA2014-54348-C3-2-R, AYA2016-79425-C3-3-P and
2013 RamĂČn y Cajal program RYC-2013-14875), Fondo Europeo de Desarrollo
Regional (FEDER, grant ESP2016-80435-C2-1-R, ESP2015-65712-C5-
5-R), Generalitat de Catalunya/CERCA programme, Spanish Ministerio de
EducaciĂłn, Cultura y Deporte, programa de FormaciĂłn de Profesorado Universitario
(grant FPU15/01476), Deutsches Zentrum fĂŒr Luft- und Raumfahrt
(grants 50OW0204 and 50OO1501), Office of Naval Research Global (award
no. N62909-15-1-2011), Mexican CONACyT grant CB-2012-183007
The Robotic Multiobject Focal Plane System of the Dark Energy Spectroscopic Instrument (DESI)
A system of 5020 robotic fiber positioners was installed in 2019 on the Mayall Telescope, at Kitt Peak National Observatory. The robots automatically retarget their optical fibers every 10-20 minutes, each to a precision of several microns, with a reconfiguration time of fewer than 2 minutes. Over the next 5 yr, they will enable the newly constructed Dark Energy Spectroscopic Instrument (DESI) to measure the spectra of 35 million galaxies and quasars. DESI will produce the largest 3D map of the universe to date and measure the expansion history of the cosmos. In addition to the 5020 robotic positioners and optical fibers, DESIâs Focal Plane System includes six guide cameras, four wave front cameras, 123 fiducial point sources, and a metrology camera mounted at the primary mirror. The system also includes associated structural, thermal, and electrical systems. In all, it contains over 675,000 individual parts. We discuss the design, construction, quality control, and integration of all these components. We include a summary of the key requirements, the review and acceptance process, on-sky validations of requirements, and lessons learned for future multiobject, fiber-fed spectrographs
Selection of the silicon sensor thickness for the Phase-2 upgrade of the CMS Outer Tracker
During the operation of the CMS experiment at the High-Luminosity LHC the silicon sensors of the Phase-2 Outer Tracker will be exposed to radiation levels that could potentially deteriorate their performance. Previous studies had determined that planar float zone silicon with n-doped strips on a p-doped substrate was preferred over p-doped strips on an n-doped substrate. The last step in evaluating the optimal design for the mass production of about 200 m of silicon sensors was to compare sensors of baseline thickness (about 300 ÎŒm) to thinned sensors (about 240 ÎŒm), which promised several benefits at high radiation levels because of the higher electric fields at the same bias voltage. This study provides a direct comparison of these two thicknesses in terms of sensor characteristics as well as charge collection and hit efficiency for fluences up to 1.5 Ă 10 n/cm. The measurement results demonstrate that sensors with about 300 ÎŒm thickness will ensure excellent tracking performance even at the highest considered fluence levels expected for the Phase-2 Outer Tracker
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