208 research outputs found
Prospects of long-time-series observations from Dome C for transit search
The detection of transiting extrasolar planets requires high-photometric
quality and long-duration photometric stellar time-series. In this paper, we
investigate the advantages provided by the Antarctic observing platform Dome C
for planet transit detections during its long winter period, which allows for
relatively long, uninterrupted time-series. Our calculations include limiting
effects due to the Sun and Moon, cloud coverage and the effect of reduced
photometric quality for high extinction of target fields. We compare the
potential for long time-series from Dome C with a single site in Chile, a
three-site low-latitude network as well as combinations of Dome C with Chile
and the network, respectively. Dome C is one of the prime astronomical sites on
Earth for obtaining uninterrupted long-duration observations in terms of
prospects for a high observational duty cycle. The duty cycle of a project can,
however, be significantly improved by integrating Dome C into a network of
sites.Comment: 10 pages, 9 figures, accepted by PAS
Results from the Exoplanet Search Programmes with BEST and TEST
Thueringer Landessternwarte Tautenburg (TLS) has started to operate a small
dedicated telescope - the Tautenburg Exoplanet Search Telescope (TEST) -
searching for transits of extrasolar planets in photometric time series
observations. In a joint effort with the Berlin Exoplanet Search Telescope
(BEST) operated by the Institut fuer Planetenforschung of the "Deutsches
Zentrum fuer Luft- und Raumfahrt (DLR)" at the Observatoire de Haute-Provence
(OHP), France, two observing sites are used to optimise transit search. Here,
we give a short overview of these systems and the data analysis. We describe a
software pipeline that we have set up to identify transit events of extrasolar
planets and variable stars in time series data from these and other telescopes,
and report on some first results.Comment: 6 pages, 5 figures, contributed paper to the "Solar and Stellar
Physics Through Eclipses" conference, eds. O. Demircan, S.O. Selam, B.
Albayrak (Turkey, March 2006
Hva vi snakker om når vi snakker om innholdsmarkedsføring: et akademisk perspektiv på fenomen, begrep og praksis
Studiets formål: Innholdsmarkedsføring som litterært område er begrenset med tvetydig begrepsapparat og ingen empiriske studier å vise til. Dette gjenspeiles i bransjen og den offentlige debatten. Oppgaven tar tak i denne problematikken og gir et forsøk på å skape klarhet for praktikere og teoretikere omkring hva innholdsmarkedsføring er. Teoretiske grunnlag: En skriveundersøkelse tar for seg den mest anerkjente litteraturen på innholdsmarkedsføring, relevant påvirkningsteori med utspring fra markedsførings- og psykologifaget. Videre trekkes det inn kommentarer, innlegg og artikler fra nasjonale- og internasjonale bransjeblader. Metode: Det gjøres først et eksperiment med 70 respondenter. Formålet er å avdekke forskjell mellom reklame og innholdsmarkedsføring. Resultatet viser ingen signifikante funn. Derfor gjennomføres et eksplorativt design med 11 semistrukturerte dybdeintervjuer med 6 bransjeaktører (G1) og 6 forbrukere (G2). Funn: Forfatterne definerer innholdsmarkedsføring som innhold produsert og publisert i merkevarens egne kanaler for å etterstrebe rangeringer i søkemotorer. Forfatterne slår fast at innholdsmarkedsføring ikke er reklame fordi reklame er kommunikasjon i kjøpte kanaler. G2 virker å være mer tilbøyelig til å like innhold som er visuelt tiltalende og innehar redaksjonelle virkemidler, til tross for innholdets kommersielle budskap. G1 virker å vektlegge enkle operasjonelle mål som trafikktall, og i mindre grad anerkjente mål innen markedsføringsteori. Begrensninger: Kvalitativ metode med få respondenter gir ingen mulighet for å generalisere. Forutinntatte holdninger kan ha preget innhenting av sekundære– og primære data. Ingen tidligere empiriske studier å arbeide ut i fra gjør det vanskelig å studere innholdsmarkedsføring. Teoretiske- og praktiske implikasjoner: Oppgaven er bidragsgivende i avklaring og presisering av begrepsterminologien som brukes i bransjen og i litteraturen. Oppgaven kan brukes som et utgangspunkt for videre studier og ny litteratur. Oppgaven indikerer at bransjeaktører burde vektlegge anerkjente markedsføringsmål
NGTS: a robotic transit survey to detect Neptune and Super-Earth mass planets
NGTS is a new ground-based transit survey aimed at detecting sub-Neptune sized exoplanets around bright stars. The instrument will be installed at the ESO Paranal observatory in order to benefit from the excellent observing conditions and follow-up synergy with the VLT and E-ELT. It will be a robotic facility composed of 12, 200 mm telescopes equipped with 2Kx2K NIR sensitive detectors. It is built on the legacy of the WASP experience
EPIC 219388192 b - an inhabitant of the brown dwarf desert in the Ruprecht 147 open cluster
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 =~ and mass of
=~, yielding a mean density of
~. The host star is nearly a Solar twin with
mass =~, radius
=~, effective temperature
=~K and iron abundance [Fe/H]=~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
The SARS algorithm: detrending CoRoT light curves with Sysrem using simultaneous external parameters
Surveys for exoplanetary transits are usually limited not by photon noise but
rather by the amount of red noise in their data. In particular, although the
CoRoT spacebased survey data are being carefully scrutinized, significant new
sources of systematic noises are still being discovered. Recently, a
magnitude-dependant systematic effect was discovered in the CoRoT data by Mazeh
& Guterman et al. and a phenomenological correction was proposed. Here we tie
the observed effect a particular type of effect, and in the process generalize
the popular Sysrem algorithm to include external parameters in a simultaneous
solution with the unknown effects. We show that a post-processing scheme based
on this algorithm performs well and indeed allows for the detection of new
transit-like signals that were not previously detected.Comment: MNRAS accepted. 5 pages, 3 figure
Three Small Planets Transiting a Hyades Star
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 , , and
days, and radii of , , and , 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
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 on stellar insolation and
metallicity [Fe/H]. We confirm that for periods days, planets
with a radius are less common than planets with a
radius between 1-2. We also see a hint of the "radius valley"
between 1.5 and 2 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 are found
around the most metal-rich M dwarfs.Comment: 29 pages, 21 figures, 6 tables, Accepted in Astronomical Journa
A comparative study on quality, shelf life and sensory attributes of Atlantic salmon slaughtered on board slaughter vessels against traditional land-based facilities
The purpose of this study was to investigate the shelf life and quality of Atlantic salmon (Salmo salar) slaughtered onboard vessels and shipped to Denmark in −0.8 °C refrigerated seawater (RSW) as compared to traditional land-based slaughtering facilities having fish on ice. The quality and shelf life were measured on fresh and smoked fillets including blood spot counting, fillet gaping, texture hardness, microbiological counts, Quality Index Method (QIM) and sensory analysis. Blood spot counting and fillet gaping were measured on smoked fillets. Fresh fish slaughtered onboard the vessel had significantly lower fillet gaping scores as compared to those slaughtered at the facility, while no difference was found on smoked fillets. There were no significant differences in blood spots counts nor texture hardness between any of the groups. Salmon slaughtered on the vessel had a significant lower QIM score. The total mesophilic count and H2S producing bacteria for fish slaughtered onboard vessels were significant lower at the end of storage (21d). Sensory analysis after 18 days of storage revealed minimal differences between the groups, whereas fish from the vessel had lower protein precipitation. We conclude that fish slaughtered onboard vessels and transported in superchilled RSW onboard a slaughter vessel presents good quality and improves shelf life over time.publishedVersio
The transiting multi-planet system HD3167: a 5.7 MEarth Super-Earth and a 8.3 MEarth mini-Neptune
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
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