1,470 research outputs found
Nuclear shell evolution and in-medium NN interaction
We report on a quantitative study of the evolution of the nuclear shell structure, in particular, effective single-particle energies (ESPEs), based on the spin-tensor decomposition of an effective two-body shell-model interaction. While the global trend of the ESPEs is mainly due to the central term of the effective interaction, variations of shell gaps invoke various components of the in-medium NN force. From a detailed analysis of a well-fitted realistic interaction in the sdpf shell-model space, two most important contributions for the evolution of the N = 20 and N = 28 shell gaps are confirmed to be the central term and the tensor term. The role of the latter is dominant to explain the energy shift of spin-orbit partners. Spin-tensor analysis of microscopic effective interactions in sd, pf, and gds shell-model spaces, contrasted with that of the phenomenologically adjusted ones, shows no evidence of amplification of the tensor component contribution; however, it points toward the neglect of three-body forces in the present microscopic interactions
Nested shells reveal the rejuvenation of the Orion-Eridanus superbubble
The Orion-Eridanus superbubble is the prototypical superbubble due to its
proximity and evolutionary state. Here, we provide a synthesis of recent
observational data from WISE and Planck with archival data, allowing to draw a
new and more complete picture on the history and evolution of the
Orion-Eridanus region. We discuss the general morphological structures and
observational characteristics of the superbubble, and derive quantitative
properties of the gas- and dust inside Barnard's Loop. We reveal that Barnard's
Loop is a complete bubble structure which, together with the lambda Ori region
and other smaller-scale bubbles, expands within the Orion-Eridanus superbubble.
We argue that the Orion-Eridanus superbubble is larger and more complex than
previously thought, and that it can be viewed as a series of nested shells,
superimposed along the line of sight. During the lifetime of the superbubble,
HII region champagne flows and thermal evaporation of embedded clouds
continuously mass-load the superbubble interior, while winds or supernovae from
the Orion OB association rejuvenate the superbubble by sweeping up the material
from the interior cavities in an episodic fashion, possibly triggering the
formation of new stars that form shells of their own. The steady supply of
material into the superbubble cavity implies that dust processing from interior
supernova remnants is more efficient than previously thought. The cycle of
mass-loading, interior cleansing, and star formation repeats until the
molecular reservoir is depleted or the clouds have been disrupted. While the
nested shells come and go, the superbubble remains for tens of millions of
years.Comment: 20 pages, 6 figures, accepted for publication in Ap
Symmetry restoration for odd-mass nuclei with a Skyrme energy density functional
In these proceedings, we report first results for particle-number and
angular-momentum projection of self-consistently blocked triaxial
one-quasiparticle HFB states for the description of odd-A nuclei in the context
of regularized multi-reference energy density functionals, using the entire
model space of occupied single-particle states. The SIII parameterization of
the Skyrme energy functional and a volume-type pairing interaction are used.Comment: 8 pages, 3 figures, workshop proceeding
Star Formation in the Gulf of Mexico
We present an optical/infrared study of the dense molecular cloud, L935,
dubbed "The Gulf of Mexico", which separates the North America and the Pelican
nebulae, and we demonstrate that this area is a very active star forming
region. A wide-field imaging study with interference filters has revealed 35
new Herbig-Haro objects in the Gulf of Mexico. A grism survey has identified 41
Halpha emission-line stars, 30 of them new. A small cluster of partly embedded
pre-main sequence stars is located around the known LkHalpha 185-189 group of
stars, which includes the recently erupting FUor HBC 722.Comment: Submitted to A&A, 14 pages, 18 figure
Ab Initio Treatment of Collective Correlations and the Neutrinoless Double Beta Decay of Ca
Working with Hamiltonians from chiral effective field theory, we develop a
novel framework for describing arbitrary deformed medium-mass nuclei by
combining the in-medium similarity renormalization group with the generator
coordinate method. The approach leverages the ability of the first method to
capture dynamic correlations and the second to include collective correlations
without violating symmetries. We use our scheme to compute the matrix element
that governs the neutrinoless double beta decay of Ca to Ti, and
find it to have the value , near or below the predictions of most
phenomenological methods. The result opens the door to ab initio calculations
of the matrix elements for the decay of heavier nuclei such as Ge,
Te, and Xe.Comment: 6 pages, 4 figures and 1 table. supplementary material included.
version to be publishe
- …