2,032 research outputs found
Internal and relative motions of the Taurus and Ophiuchus star-forming regions
We investigate the internal and relative motions of the Taurus and Ophiuchus
star-forming regions using a sample of young stars with accurately measured
radial velocities and proper motions. We find no evidence for expansion or
contraction of the Taurus complex, but a clear indication for a global
rotation, resulting in velocity gradients, this suggests a common origin,
possibly related to that of Gould's Belt.Comment: 2 figure
An astrometric planetary companion candidate to the M9 Dwarf TVLM 513-46546
Astrometric observations of the M9 dwarf TVLM 51346546 taken with the VLBA
reveal an astrometric signature consistent with a period of 221 5 days.
The orbital fit implies that the companion has a mass m = 0.350.42
, a circular orbit (), a semi-major axis a = 0.280.31 AU
and an inclination angle i = 7188. The detected companion,
TVLM~513, is one of the few giant-mass planets found associated to UCDs. The
presence of a Saturn-like planet on a circular orbit, 0.3 AU from a 0.060.08
star, represents a challenge to planet formation theory. This is the
first astrometric detection of a planet at radio wavelengths.Comment: 12 pages, 6 figures, AJ, in pres
Sociologia, economia i ciència política: Guía per a una docència universitària amb perspectiva de gènere
La sociologia ha construït una cosmovisió del món en masculí que comporta una interpretació esbiaixada de la realitat social. Per la seua banda, l’economia tradicional ha invisibilitzat la dependència que té l’esfera mercantil de l’esfera domèstica. I en l’àmbit de les ciències polítiques, trobem també molts biaixos de gènere en conceptes bàsics com els de justícia, igualtat o ciutadania.
La Guia per a una docència universitària amb perspectiva de gènere de Sociologia, Economia i Ciència Política ofereix propostes, exemples de bones pràctiques, recursos docents i eines de consulta per contribuir a una major igualtat entre dones i homes en l’àmbit de la docència, la transferència de coneixement i la recerca en aquestes disciplines.Ortiz Monera, RM.; Morero Beltrán, AM. (2018). Sociologia, economia i ciència política: Guía per a una docència universitària amb perspectiva de gènere. Xarxa Vives d'Universitats. http://hdl.handle.net/10251/11908
The Gould's Belt Very Large Array Survey II: The Serpens region
We present deep (Jy) radio continuum observations of the Serpens
molecular cloud, the Serpens south cluster, and the W40 region obtained using
the Very Large Array in its A configuration. We detect a total of 146 sources,
29 of which are young stellar objects (YSOs), 2 are BV stars and 5 more are
associated with phenomena related to YSOs. Based on their radio variability and
spectral index, we propose that about 16 of the remaining 110 unclassified
sources are also YSOs. For approximately 65% of the known YSOs detected here as
radio sources, the emission is most likely non-thermal, and related to stellar
coronal activity. As also recently observed in Ophiuchus, our sample of YSOs
with X-ray counterparts lies below the fiducial G\"udel & Benz relation.
Finally, we analyze the proper motions of 9 sources in the W40 region. This
allows us to better constrain the membership of the radio sources in the
region.Comment: Accepted in The Astrophysical Journa
Cross-reaction of naturally-produced β-lactamases from Citrobacter farmeri and Citrobacter amalonaticus with immunological detection of CTX-M enzymes.
The NG-Test CTX-M MULTI immunochromatographic assay has been developed to identify CTX-M-type β-lactamases in Enterobacterales, being the most widespread extended-spectrum β-lactamases. We showed here that the chromosomally-encoded ß-lactamases from Citrobacter farmeri and Citrobacter amalonaticus generated false-positive NG-Test CTX-M MULTI results, compromising the specificity of the test
Integrated Gap Analysis Project: Assessing Conservation of Freshwater, Estuarine, Marine, and Terrestrial Biodiversity.
Gaia-DR2 confirms VLBA parallaxes in Ophiuchus, Serpens and Aquila
We present Gaia-DR2 astrometry of a sample of YSO candidates in Ophiuchus,
Serpens Main and Serpens South/W40 in the Aquila Rift, which had been mainly
identified by their infrared excess with Spitzer. We compare the Gaia-DR2
parallaxes against published and new parallaxes obtained from our Very Long
Baseline Array (VLBA) program GOBELINS. We obtain consistent results between
Gaia and the VLBA for the mean parallaxes in each of the regions analyzed here.
We see small offsets, when comparing mean values, of a few tens of
micro-arcseconds in the parallaxes, which are either introduced by the Gaia
zero-point error or due to a selection effect by Gaia toward the brightest,
less obscured stars. Gaia-DR2 data alone conclusively places Serpens Main and
Serpens South at the same distance, as we first inferred from VLBA data alone
in a previous publication. Thus, Serpens Main, Serpens South and W40 are all
part of the same complex of molecular clouds, located at a mean distance of
436+/-9 pc. In Ophiuchus, both Gaia and VLBA suggest a small parallax gradient
across the cloud, and the distance changes from 144.2+/-1.3 pc to 138.4+/-2.6
pc when going from L1689 to L1688.Comment: Accepted for publication in ApJ
The Gould's Belt Distances Survey (GOBELINS). V. Distances and Kinematics of the Perseus molecular cloud
We derive the distance and structure of the Perseus molecular cloud by
combining trigonometric parallaxes from Very Long Baseline Array (VLBA)
observations, taken as part of the GOBELINS survey, and Gaia Data Release 2.
Based on our VLBA astrometry, we obtain a distance of 321+/-10 pc for IC 348.
This is fully consistent with the mean distance of 320+/-26 measured by Gaia.
The VLBA observations toward NGC 1333 are insufficient to claim a successful
distance measurement to this cluster. Gaia parallaxes, on the other hand, yield
a mean distance of 293+/-22 pc. Hence, the distance along the line of sight
between the eastern and western edges of the cloud is ~30 pc, which is
significantly smaller than previously inferred. We use Gaia proper motions and
published radial velocities to derive the spatial velocities of a selected
sample of stars. The average velocity vectors with respect to the LSR are
(u,v,w) = (-6.1+/-1.6, 6.8+/-1.1, -0.9+/-1.2) and (-6.4+/-1.0, 2.1+/-1.4,
-2.4+/-1.0) km/s for IC 348 and NGC 1333, respectively. Finally, our analysis
of the kinematics of the stars has shown that there is no clear evidence of
expansion, contraction, or rotational motions within the clusters.Comment: Accepted for publication in Ap
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