304 research outputs found
The molecular environment of the pillar-like features in the HII region G46.5-0.2
At the interface of HII regions and molecular gas peculiar structures appear,
some of them with pillar-like shapes. Understanding their origin is important
for characterizing triggered star formation and the impact of massive stars on
the interstellar medium. In order to study the molecular environment and the
influence of the radiation on two pillar-like features related to the HII
region G46.5-0.2, we performed molecular line observations with the Atacama
Submillimeter Telescope Experiment, and spectroscopic optical observations with
the Isaac Newton Telescope. From the optical observations we identified the
star that is exciting the HII region as a spectral type O4-6. The molecular
data allowed us to study the structure of the pillars and a HCO+ cloud lying
between them. In this HCO+ cloud, which have not any well defined 12CO
counterpart, we found direct evidence of star formation: two molecular outflows
and two associated near-IR nebulosities. The outflows axis orientation is
perpendicular to the direction of the radiation flow from the HII region.
Several Class I sources are also embedded in this HCO+ cloud, showing that it
is usual that the YSOs form large associations occupying a cavity bounded by
pillars. On the other hand, it was confirmed that the RDI process is not
occurring in one of the pillar tips.Comment: Accepted in MNRAS (2017 June 13
The Calar Alto Legacy Integral Field Area Survey: spatial resolved properties
We present the analysis performed using the pyPipe3D pipeline for the 895
galaxies that comprises the eCALIFA data release Sanchez et al. submitted, data
with a significantly improved spatial resolution (1.0-1.5"/FWHM). We include a
description of (i) the analysis performed by the pipeline, (ii) the adopted
datamodel for the derived spatially resolved properties and (iii) the catalog
of integrated, characteristics and slope of the radial gradients for a set of
observational and physical parameters derived for each galaxy. We illustrate
the results of the analysis (i) using the NGC\,2906 as an archetypal galaxy,
showing the spatial distribution of the different derived parameters and
exploring in detail the properties of the ionized gas, and (ii) showing
distribution of the spatial resolved ionized gas across the classical
[OIII]/H vs. [NII]/H for the whole galaxy sample. In general our
results agree with previous published ones, however, tracing radial patterns
and segregating individual ionized structures is improved when using the
current dataset. All the individual galaxy dataproducts and the catalog
discussed along this article are distributed as part of the eCALIFA data
release http://ifs.astroscu.unam.mx/CALIFA_WEB/public_html/Comment: 47 pages, 8 tables, 9 figures, submitted the 12th of April 2023 to
RMxA
Near-Earth asteroids spectroscopic survey at Isaac Newton Telescope
The population of near-Earth asteroids (NEAs) shows a large variety of
objects in terms of physical and dynamical properties. They are subject to
planetary encounters and to strong solar wind and radiation effects. Their
study is also motivated by practical reasons regarding space exploration and
long-term probability of impact with the Earth. We aim to spectrally
characterize a significant sample of NEAs with sizes in the range of 0.25
- 5.5 km (categorized as large), and search for connections between their
spectral types and the orbital parameters. Optical spectra of NEAs were
obtained using the Isaac Newton Telescope (INT) equipped with the IDS
spectrograph. These observations are analyzed using taxonomic classification
and by comparison with laboratory spectra of meteorites. A total number of 76
NEAs were observed. We classified 44 of them as Q/S-complex, 16 as B/C-complex,
eight as V-types, and another eight belong to the remaining taxonomic classes.
Our sample contains 27 asteroids categorized as potentially hazardous and 31
possible targets for space missions including (459872) 2014 EK24, (436724) 2011
UW158, and (67367) 2000 LY27. The spectral data corresponding to (276049) 2002
CE26 and (385186) 1994 AW1 shows the 0.7 m feature which indicates the
presence of hydrated minerals on their surface. We report that Q-types have the
lowest perihelia (a median value and absolute deviation of AU)
and are systematically larger than the S-type asteroids observed in our sample.
We explain these observational evidences by thermal fatigue fragmentation as
the main process for the rejuvenation of NEA surfaces. In general terms, the
taxonomic distribution of our sample is similar to the previous studies and
matches the broad groups of the inner main belt asteroids. Nevertheless, we
found a wide diversity of spectra compared to the standard taxonomic types.Comment: Accepted in Astronomy & Astrophysics (A&A
The Onfp Class in the Magellanic Clouds
The Onfp class of rotationally broadened, hot spectra was defined some time
ago in the Galaxy, where its membership to date numbers only eight. The
principal defining characteristic is a broad, centrally reversed He II
4686 emission profile; other emission and absorption lines are also
rotationally broadened. Recent surveys in the Magellanic Clouds (MCs) have
brought the class membership there, including some related spectra, to 28. We
present a survey of the spectral morphology and rotational velocities, as a
first step toward elucidating the nature of this class. Evolved, rapidly
rotating hot stars are not expected theoretically, because the stellar winds
should brake the rotation. Luminosity classification of these spectra is not
possible, because the principal criterion (He II 4686) is peculiar;
however, the MCs provide reliable absolute magnitudes, which show that they
span the entire range from dwarfs to supergiants. The Onfp line-broadening
distribution is distinct and shifted toward larger values from those of normal
O dwarfs and supergiants with >99.99% confidence. All cases with multiple
observations show line-profile variations, which even remove some objects from
the class temporarily. Some of them are spectroscopic binaries; it is possible
that the peculiar profiles may have multiple causes among different objects.
The origin and future of these stars are intriguing; for instance, they could
be stellar mergers and/or gamma-ray-burst progenitors.Comment: 27 pages, 8 figures, 2 tables; AJ accepte
Contemporary changes and civil society in Portugal and the Russian Federation
Portugal and the Russian Federation share some aspects of traditional culture and similar experiences in modern history, but they also exhibit significant differences that determine specific modes of civil society’s development. Results of a comparative and diachronic analysis show that the major differences between the two countries reside in civil society’s openness and composition. Organized civil society is not very distinct in relative size when comparing Portugal and the Russian Federation, but it is globally more autonomous, expressive, trusted and institutionalized in Portugal than in the Russian Federation and among the factors that contribute to this condition are an earlier and revolutionary transition to democracy, a larger middle class, a greater prevalence of the value of interdependence, and a regime that endorses bigger public social expenditure in Portugal, all this within the framework of the European Union that has a longer history of social demand and institutional incentives for civil society. Despite those unequal conditions, civil society faces similar current challenges in both countries, mainly with the outsourcing of the public provision of social services.info:eu-repo/semantics/acceptedVersio
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