1,724,446 research outputs found
A região nuclear da galáxia Seyfert NGC 7469
No full textO espectro no núcleo da galáxia Seyfert 1 NGC 7469 apresenta linhas de emissão intensas e largas, com assimetria para o vermelho no caso das linhas de Balmer do HI, e para o azul no caso de linhas proibidas.The nuclear spectrum of the Seyfert 1 galaxy NGC 7469 exhibits intense and broad emission lines: the HI Balmer lines areasymmetric to the blue
Observational effects of interaction in the Seyfert galaxy NGC 7469
Get PDFSome pecularities of the circummucleus of the Seyfert galaxy NGC 7469 were revealed, plausibly caused by interaction with the satellite IC 5283 and a starlike detail, situated on the edge of the west spiral branch 14 seconds from the nucleus. Shock excited H II regions were noted in the part of NGC 7469 turned toward the satellite IC 5283. The galaxy's central radio structure (lambda approx. 6 cm) stretches in the direction toward the satellite IC 5283 and the starlike detail. The spectum and color index of the starlike detail suggest that it is a cluster of early type stars (M sub V = -19 sup m) and dust clouds (A sub V = 3 sup m), in NGC 7469
The nuclear region of NGC 7469
No full textWe have made spectrophotometric observations of the nuclear and circumnuclear regions of the Seyfert 1 galaxy NGC 7469, and we analyze the dynamics and structure of the emission-line regions. In the nuclear region of NGC 7469, we found a broad, an intermediate, and a narrow line-emitting region. The broad !ines (FWHM7800 km s-ˡ) are formed within a distance R0.05 pc from the central source. For the narrow line region, there is a large range in electron density and a scheme of ionization structure. The circumnuclear stellar population consists mostly of very old stars, and at a distance R 8" from the nucleus, we detected the presence of hot, young stars. The gas at R 8" is nitrogen overabundant
[North Western Pacific R.R., Engine Drawing Card, Sketch 7469]
No full textThis engine drawing card was created for Northwestern Pacific Railroad Company, Class 14-48 1/4 F. Section J-14 1/4 F. Sketch 7469. Copy Spec. [field left blank]
AstroSat observations of interacting galaxies NGC 7469 and IC 5283
No full textAims. We carry out deep near-ultrviolet (NUV) and far-ultrviolet (FUV) imaging of an interacting galaxy system, comprised of a Seyfert type 1 galaxy NGC 7469 and its companion IC 5283. Our aim is to resolve and map the star-forming regions in the outer arms and look for signs of interaction between the two galaxies.
Methods. We used AstroSat Ultra Violet Imaging Telescope (UVIT) to obtain NUV and FUV images of NGC 7469 in a range of filters. We have carried out photometry of star-forming regions in the two galaxies and found their spatial distributions. We also obtained the distributions of star formation rates (SFR) in NGC 7469 and IC 5283 using the estimates obtained from the FUV and NUV bands. We also carried out Kolmogorov-Smirnov tests to look for differences in the SFRs in the two galaxies. We derived the spectral energy distribution (SED), leading to the determination of physical parameters, including the overall SFR, stellar mass (M*), dust mass (MDust), and specific star formation rates (sSFRs) in both the galaxies.
Results. Our NUV and FUV images show the presence of an outer spiral arm that is better resolved. We have identified 33 new star-forming regions out of 51 total identified in the UVIT composite image. Enhanced star formation activity is observed to coincide with the interaction, and KS tests show that there are no significant differences in the SFR distributions of NGC 7469 and IC 5283, indicating that the interaction between the galaxies has not influenced their star formation processes differently. The SED plots and the photometric results demonstrate that most of the star formation activity is confined inside the central starburst (SB) ring
Reverberation mapping of the Seyfert 1 galaxy NGC 7469
No full textA large reverberation-mapping study of the Seyfert 1 galaxy NGC 7469 has yielded emission-line lags for Hβ λ4861 and He II λ4686 and a central black hole mass measurement M ≈ 1 × 10 M, consistent with previous measurements. A very low level of variability during the monitoring campaign precluded meeting our original goal of recovering velocity-delay maps from the data, but with the new Hβ measurement, NGC 7469 is no longer an outlier in the relationship between the size of the Hβ-emitting broad-line region and the luminosity of the active galactic nucleus. It was necessary to detrend the continuum and Hβ and He II λ4686 line light curves and those from archival UV data for different time-series analysis methods to yield consistent results
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On the origin of ~ 100 TeV neutrinos from the Seyfert galaxy NGC 7469
No full textInternational audienceThe origin of TeV-PeV neutrinos detected by IceCube remains largely unknown. The most significant individual neutrino source is the close-by Seyfert galaxy NGC 1068 at 4.2 level with a soft spectral index. Another notable candidate is the Seyfert galaxy NGC 7469, which has been recently proposed as a potential neutrino emitter. The likelihood fit of the IceCube data for this source returned a very hard spectral index of ~ 1.9 and the excess is dominated by two high-energy events, issued as two neutrino alerts IC220424A and IC230416A. The energies of the two neutrinos are estimated to be 100-200 TeV, implying a maximum proton energy > 2 PeV, significantly higher than that in NGC 1068. The lack of lower-energy neutrinos from NGC 7469 also suggests a neutrino spectrum harder than that of NGC 1068. In this paper, we analyze the Fermi-LAT observations of NGC 7469, which yield non-detection. By requiring the cascade flux accompanying neutrino production not to exceed the upper limit of the GeV flux, the size of the neutrino-emitting region can be constrained when the neutrino flux takes a high value of the allowed range. We suggest that protons are accelerated to PeV energies via turbulence or magnetic reconnection in the corona of NGC 7469 and interact with OUV photons from the accretion disk and X-rays from the corona through the process, producing neutrinos with energy of 100-200 TeV. In the turbulence acceleration scenario, the required maximum proton energy can be achieved with a magnetization parameter close to unity (), while in the reconnection scenario, a magnetization parameter with is needed. In both scenarios, a pair dominated composition for the corona is preferred. The difference in the neutrino spectrum between NGC 7469 and NGC 1068 could be due to a different magnetization despite that they belong to the same type of AGN
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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