1,725,378 research outputs found
The starbust galaxy NGC 7714
No full textThis is an electronic version of an article published in The Astrophysical Journal. González-Delgado, R.M. et al. The starbust galaxy NGC 7714. The Astrophysical Journal 439 (1995): 604-62
Spitzer Infrared Spectrograph Spectroscopy of the Prototypical Starburst Galaxy NGC 7714
No full textInternational audienceWe present observations of the starburst galaxy NGC 7714 with the Infrared Spectrograph on board the Spitzer Space Telescope. The spectra yield a wealth of ionic and molecular features that allow a detailed characterization of its properties. NGC 7714 has an H II region-like spectrum with strong polycyclic aromatic hydrocarbon emission features. We find no evidence for an obscured active galactic nucleus, and with [NeIII]/[NeII]~0.73, NGC 7714 lies near the upper end of normal-metallicity starburst galaxies. With very little silicate absorption and a temperature of the hottest dust component of 340 K, NGC 7714 is the perfect template for a young, unobscured starburst
Linked collectors and determiners for: ATBI Parc national du Mercantour / Parco naturale Alpi Marittime - Jeux de données provenant de l'ATBI Mercantour.
No full textNatural history specimen data linked to collectors and determiners held within, "ATBI Parc national du Mercantour / Parco naturale Alpi Marittime - Jeux de données provenant de l'ATBI Mercantour". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/2e409ff6-7714-417e-89ef-678207f66071">https://bionomia.net/dataset/2e409ff6-7714-417e-89ef-678207f66071</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/2e409ff6-7714-417e-89ef-678207f66071">https://gbif.org/dataset/2e409ff6-7714-417e-89ef-678207f66071</a>. Formatted as a Frictionless Data package
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
A variable ultra-luminous X-ray source in the colliding galaxy NGC 7714
No full textWe studied the colliding galaxy NGC 7714 with two XMM-Newton
observations, six months apart.
The galaxy contains two bright X-ray sources:
we show that they have different physical nature.
The off-nuclear source is an accreting compact object,
one of the brightest ultraluminous X-ray sources (ULXs) found to date.
It showed spectral and luminosity changes between the two observations,
from a low/soft to a high/hard state; in the high state, it reached
erg s-1.
Its lightcurve in the high state
suggests variability on a ≈ h timescale.
Its peculiar location, where the tidal bridge between
NGC 7714 and NGC 7715 joins the outer stellar ring of NGC 7714,
makes it an interesting example of the connection between gas flows
in colliding galaxies and ULX formation.
The nuclear source ( erg s-1)
coincides with a starburst region, and is the combination
of thin thermal plasma emission and a point-source contribution
(with a power-law spectrum). Variability in the power-law component
between the two observations hints at the presence
of a single, bright point source (L_{\rm x} \ga 3 \times 10^{40} erg s-1): either a hidden AGN or another ULX
The stellar content of giant H II regions in NGC 7714
Get PDFThis is an electronic version of an article published in The Astrophysical Journal. García-Vargas, M.L., González-Delgado, R.M., Pérez, E., Alloin, D., Díaz, A. and E. Terlevich. The stellar content of giant H II regions in NGC 7714. The Astrophysical Journal 478 (1997): 112-12
Near-infrared line imaging of the starburst galaxies NGC 520, NGC 1614 and NGC 7714
No full textWe present high spatial resolution (∼0 fraction of arcsecond6) near-infrared
broad-band JHK images and Brγ 2.1661 μm and H2 1-0
2.122 μm emission line images of the nuclear regions in the interacting
starburst galaxies NGC 520, NGC 1614 and NGC 7714. The near-infrared
emission line and radio morphologies are in general agreement, although there
are differences in details. In NGC 1614, we detect a nuclear double structure
in Brγ, in agreement with the radio double structure. We derive average
extinctions of AK = 0.41 and AK = 0.18 toward the nuclear regions of
NGC 1614 and NGC 7714, respectively.
For NGC 520, the extinction
is much higher, . The observed H2/Brγ ratios indicate
that the main excitation mechanism of the molecular gas is fluorescence by
intense UV radiation from clusters of hot young stars, while shock excitation
can be ruled out.
The starburst regions in all galaxies exhibit small Brγ equivalent widths.
Assuming a constant star formation model, even with a lowered upper mass
cutoff of , results in rather old ages ( Myr), in
disagreement with the clumpy near-infrared morphologies.
We prefer a model of an instantaneous burst of star
formation with
, occurring ∼6-7 Myr ago, in
agreement with previous determinations and with the detection of W-R
features in NGC 1614 and NGC 7714. Finally, we note a possible systematic
difference in the amount of hot molecular gas between starburst and Seyfert
galaxies
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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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