2,738 research outputs found
Multiwavelength Studies of PSR J1420-6048, a Young Pulsar in the Kookaburra
We present X-ray, radio, and infrared observations of the 68 ms pulsar PSR
J1420-6048 and its surrounding nebula, a possible counterpart of the gamma-ray
source GeV J1417-6100/3EG J1420-6038. Pulsed X-ray emission at the radio period
is marginally detected by ASCA from a source embedded in the hard spectrum
X-ray nebula AX J1420.1-6049. At radio wavelengths, the pulsar is found to be
strongly linearly and circularly polarized, and the polarization sweep is
measured. A comparison of high resolution ATCA radio imaging of the
Kookaburra's upper wing (G313.6+0.3), which contains the pulsar and the X-ray
nebula, with infrared images suggests the radio emission is partly non-thermal.Comment: 8 pages, 4 figures, to appear in Astrophysical Journal Letter
Redesign participativo do aplicativo móvel Agritempo: a importância da interação usuário-desenvolvedor.
Este trabalho apresenta o impacto da aplicação do DCU no processo de desenvolvimento de um aplicativo móvel para o produtor agrícola por meio de uma validação colaborativa
First Astronomical Application of a Cryogenic TES Spectrophotometer
We report on the first astronomical observations with a photon counting pixel
detector that provides arrival time- (delta t = 100ns) and energy- (delta
E_gamma < 0.15eV) resolved measurements from the near IR through the near UV.
Our test observations were performed by coupling this Transition Edge Sensor
(TES) device to a 0.6m telescope; we have obtained the first simultaneous
optical near-IR phase-resolved spectra of the Crab pulsar. A varying infrared
turnover gives evidence of self-absorption in the pulsar plasma. The potential
of such detectors in imaging arrays from a space platform are briefly
described.Comment: 4 pages, 5 figure
A Multi-wavelength Study of the Host Environment of SMBHB 4C+37.11
4C+37.11, at z=0.055 shows two compact radio nuclei, imaged by VLBI at 7mas
separation, making it the closest known resolved super-massive black hole
binary (SMBHB). An important question is whether this unique object is young,
caught on the way to a gravitational in-spiral and merger, or has `stalled' at
7pc. We describe new radio/optical/X-ray observations of the massive host and
its surrounding X-ray halo. These data reveal X-ray/optical channels following
the radio outflow and large scale edges in the X-ray halo. These structures are
promising targets for further study which should elucidate their relationship
to the unique SMBHB core.Comment: To appear in the Astrophysical Journa
Responses from olfactory sensilla of Sitophilus zeamais to Andean essential oils.
Lamiaceae species are well-known in traditional medicine. In the last years, Essential Oils (EOs) of
many Lamiaceae have showed to be excellent repellents and/or insecticides. Tropical Andes are
extremely rich in endemic flora, possible source of new bioactive substances. Here, we verified the
insect repellent activity of the EOs extracted from Clinopodium tomentosum and C. nubigenum,
two Lamiaceae typical of the Ecuadorian Andes. The two EOs were tested against the maize weevil
Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), one of the most destructive pests of
stored and processed cereals. To characterize the olfactory sensilla of S. zeamais, its antennal
structure was investigated by scanning and transmission electron microscopy. The
electrophysiological and behavioural responses of the insect to the EOs were then investigated by
electroantennography and olfactometer trials. The morphological study revealed the presence of
three types of sensilla (Basiconic Sensillum 1, 2, and Grooved Peg Sensillum), that could be
involved in the perception of the EOs volatile compounds. Accordingly, the electroantennography
showed a positive dose-dependent response of the insect antennae to both the EOs. The
behavioural tests displayed a significative repellence of the EOs, starting from 8.4 μL L-1 air, and
that the efficacy and readiness of the response to the stimulus was higher for C. tomentosum. In
conclusion, both the EOs are detected by the insect by its antennae and exert a strong repellent
effect. The results confirm that Andean flora represents a valuable source of unexploited bioactive
substances that can be utilized as promising tools for foodstuff pests’ control
Contribution of pulsars to the gamma-ray background and their observation with the space telescopes GLAST and AGILE
Luminosities and uxes of the expected population of galactic gamma-ray
pulsars become foreseeable if physical distributions at birth and evolutive
history are assigned. In this work we estimate the contribution of pulsar uxes
to the gamma-ray background, which has been measured by the EGRET experiment on
board of the CGRO. For pulsar luminosities we select some of the most important
gamma-ray emission models, taking into account both polar cap and outer gap
scenarios. We nd that this contribution strongly depends upon controversial
neutron star birth properties. A comparison between our simulation results and
EGRET data is presented for each model, nding an average contribution of about
10%. In addition, we perform the calculation of the number of new gamma-ray
pulsars detectable by GLAST and AGILE, showing a remarkable di erence between
the two classes of models. Finally, we suggest some improvements in the
numerical code, including more sophisticated galactic m odels and di erent
populations of pulsars like binaries, milliseconds, anomalous pulsars and
magnetars.Comment: 6 pages, 6 figures, to be published in the Proceedings of the 6th
International Symposium ''Frontiers of Fundamental and Computational
Physics'' (FFP6), Udine (Italy), Sep. 26-29, 200
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