2,079 research outputs found
Reaffirming the connection between the Galactic stellar warp and the Canis Major overdensity
We perform a critical re-analysis and discussion of recent results presented
in the literature which interpret the CMa overdensity as the signature of an
accreting dwarf galaxy or a new substructure within the Galaxy. Several issues
are addressed. We show that arguments against the ``warp'' interpretation are
based on an erroneous perception of the Milky Way. There is nothing anomalous
with colour--magnitude diagrams on opposite sides of the average warp mid-plane
being different. We witnessed the rise and fall of the blue plume population,
first attributed to young stars in a disrupting dwarf galaxy and now discarded
as a normal disc population. Similarly, there is nothing anomalous in the outer
thin+thick disc metallicities being low (-1<[Fe/H]<-0.5), and spiral arms (as
part of the thin disc) should, and do, warp. Most importantly, we show
unambiguously that, contrary to previous claims, the warp produces a stellar
overdensity that is distance-compatible with that observed in CMa.The CMa
over-density remains fully accounted for in a first order approach by Galactic
models without new substructures. Given the intrinsic uncertainties (concerning
the properties of the warp, flare and disc cutoff, the role of extinction and
degeneracy), minor deviations with respect to these models are not enough to
support the hypothesis of an accreted dwarf galaxy or new substructure within
the Milky Way disc.Comment: A&A Letter, accepted, 4 pages, 3 figure
Young open clusters in the Milky Way and Small Magellanic Cloud
NGC6611, Trumpler 14, Trumpler 15, Trumpler 16, Collinder 232 are very young
open clusters located in star-formation regions of the Eagle Nebula or the
Carina in the MW, and NGC346 in the SMC. With different instrumentations and
techniques, it was possible to detect and classify new Herbig Ae/Be stars,
classical Be stars and to provide new tests / comparisons about the Be stars
appearance models. Special stars (He-strong) of these star-formation regions
are also presented.Comment: Proceedings IAUS266 at the IAU-GA 200
Faculty Psychology in the Holiness Theology of Asa Mahan
As America awakened to a greater antislavery consciousness, Asa Mahan, president of the Oberlin Collegiate Institute, presented his seminal reflection on Christian Perfection. Mahan offered an unusually precise definition of perfection or holiness. The Oberlin president borrowed from Scottish Common Sense Realism to suggest an understanding of Christian Perfection that was both personally rigorous and socially prophetic. This conception of holiness was also rooted in a commitment to objective truth
NTT infrared imaging of star cluster candidates towards the central parts of the Galaxy
We address the issue whether the central parts of the Galaxy harbour young
clusters other than Arches, Quintuplet and the Nuclear Young Cluster. A large
sample of centrally projected cluster candidates has been recently identified
from the 2MASS J, H and Ks Atlas. We provide a catalogue of higher angular
resolution and deeper images for 57 2MASS cluster candidates, obtained with the
near-IR camera SOFI at the ESO NTT telescope. We classify 10 objects as star
clusters, some of them deeply embedded in gas and/or dust clouds. Three other
objects are probably star clusters, although the presence of dust in the field
does not exclude the possibility of their being field stars seen through
low-absorption regions. Eleven objects are concentrations of stars in areas of
little or no gas, and are classified as dissolving cluster candidates. Finally,
31 objects turned out to be the blend of a few bright stars, not resolved as
such in the low resolution 2MASS images. By combining the above results with
other known objects we provide an updated sample of 42 embedded clusters and
candidates projected within 7 degrees. As a first step we study Object 11 of
Dutra & Bica (2000) projected at approximately 1 degree from the nucleus. We
present H and Ks photometry and study the colour-magnitude diagram and
luminosity function. Object 11 appears to be a less massive cluster than Arches
or Quintuplet, and it is located at a distance from the Sun d=8 kpc, with a
visual absorption Av=15.Comment: accepted to A&A, 9 pages, 10 figure
A new red giant-based distance modulus of 13.3 Mpc to the Antennae galaxies and its consequences
The Antennae galaxies are the closest example of an ongoing major galaxy
merger, and thereby represent a unique laboratory for furthering the
understanding of the formation of exotic objects (e.g., tidal dwarf galaxies,
ultra-luminous X-ray sources, super-stellar clusters, etc). In a previous paper
HST/WFPC2 observations were used to demonstrate that the Antennae system might
be at a distance considerably less than that conventionally assumed in the
literature. Here we report new, much deeper HST/ACS imaging that resolves the
composite stellar populations, and most importantly, reveals a well-defined red
giant branch. The tip of this red giant branch (TRGB) is unambiguously detected
at Io(TRGB)=26.65 +/- 0.09 mag. Adopting the most recent calibration of the
luminosity of the TRGB then yields a distance modulus for the Antennae of
(m-M)o= 30.62 +/- 0.17 corresponding to a distance of 13.3 +/- 1.0 Mpc. This is
consistent with our earlier result, once the different calibrations for the
standard candle are considered. We briefly discuss the implications of this now
well determined shorter distance.Comment: 11 pages, 3 figures, accepted for publication in the Ap
Aspergillus nidulans Pmts form heterodimers in all pairwise combinations
AbstractEukaryotic protein O-mannosyltransferases (Pmts) are divided into three subfamilies (Pmt1, Pmt2, and Pmt4) and activity of Pmts in yeasts and animals requires assembly into complexes. In Saccharomyces cerevisiae, Pmt1 and Pmt2 form a heteromeric complex and Pmt 4 forms a homomeric complex. The filamentous fungus Aspergillus nidulans has three Pmts: PmtA (subfamily 2), PmtB (subfamily 1), and PmtC (subfamily 4). In this study we show that A. nidulans Pmts form heteromeric complexes in all possible pairwise combinations and that PmtC forms homomeric complexes. We also show that MsbA, an ortholog of a Pmt4-modified protein, is not modified by PmtC
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