1,044 research outputs found
Properties of Newly Formed Dust Grains in The Luminous Type IIn Supernova 2010jl
Supernovae (SNe) have been proposed to be the main production sites of dust
grains in the Universe. Our knowledge on their importance to dust production
is, however, limited by observationally poor constraints on the nature and
amount of dust particles produced by individual SNe. In this paper, we present
a spectrum covering optical through near-Infrared (NIR) light of the luminous
Type IIn supernova (SN IIn) 2010jl around one and half years after the
explosion. This unique data set reveals multiple signatures of newly formed
dust particles. The NIR portion of the spectrum provides a rare example where
thermal emission from newly formed hot dust grains is clearly detected. We
determine the main population of the dust species to be carbon grains at a
temperature of ~1,350 - 1,450K at this epoch. The mass of the dust grains is
derived to be ~(7.5 - 8.5) x 10^{-4} Msun. Hydrogen emission lines show
wavelength-dependent absorption, which provides a good estimate on the typical
size of the newly formed dust grains (~0.1 micron, and most likely <~0.01
micron). We attribute the dust grains to have been formed in a dense cooling
shell as a result of a strong SN-circumstellar media (CSM) interaction. The
dust grains occupy ~10% of the emitting volume, suggesting an inhomogeneous,
clumpy structure. The average CSM density is required to be >~3 x 10^{7}
cm^{-3}, corresponding to a mass loss rate of >~0.02 Msun yr^{-1} (for a mass
loss wind velocity of ~100 km s^{-1}). This strongly supports a scenario that
SN 2010jl and probably other luminous SNe IIn are powered by strong
interactions within very dense CSM, perhaps created by Luminous Blue Variable
(LBV)-like eruptions within the last century before the explosion.Comment: 18 pages, 11 figures. Accepted by ApJ on 30 July 2013. The accepted
version was submitted on 8 July 2013, and the original version was submitted
on 3 March 201
Recommended from our members
Mitochondrial Dysfunction Induces Formation of Lipid Droplets as a Generalized Response to Stress
Lipid droplet (LD) formation is a hallmark of cellular stress. Cells attempt to combat noxious stimuli by switching their metabolism from oxidative phosphorylation to glycolysis, sparing resources in LDs for generating cellular reducing power and for anabolic biosynthesis. Membrane phospholipids are also a source of LDs. To elucidate the formation of LDs, we exposed mice to hyperoxia, hypoxia, myocardial ischemia, and sepsis induced by cecal ligation and puncture (CLP). All the above-mentioned stressors enhanced the formation of LDs, as assessed by transmission electron microscopy, with severe mitochondrial swelling. Disruption of mitochondria by depleting mitochondrial DNA (ρ0 cells) significantly augmented the formation of LDs, causing transcriptional activation of fatty acid biosynthesis and metabolic reprogramming to glycolysis. Heme oxygenase (HO)-1 counteracts CLP-mediated septic shock in mouse models. In HO-1-deficient mice, LD formation was not observed upon CLP, but a concomitant decrease in “LD-decorating proteins” was observed, implying a link between LDs and cytoprotective activity. Collectively, LD biogenesis during stress can trigger adaptive LD formation, which is dependent on mitochondrial integrity and HO-1 activity; this may be a cellular survival strategy, apportioning energy-generating substrates to cellular defense
Variability of the NGC 1333 IRAS 4A Outflow: Molecular Hydrogen and Silicon Monoxide Images
The NGC 1333 region was observed in the H2 1-0 S(1) line. The H2 images cover
a 5' x 7' region around IRAS 4. Numerous H2 emission features were detected.
The northeast-southwest bipolar outflow driven by IRAS 4A was studied by
combining the H2 images with SiO maps published previously. The SiO-H2 outflows
are continuous on the southwestern side but show a gap on the northeastern
side. The southwestern outflow lobe curves smoothly, and the position angle
increases with the distance from the driving source. The base and the outer tip
of the northeastern outflow lobe are located at positions opposite to the
corresponding parts of the southwestern lobe. This point-symmetry suggests that
the outflow axis may be drifting or precessing clockwise in the plane of the
sky and that the cause of the axis drift may be intrinsic to the outflow
engine. The axis drift model is supported by the asymmetric lateral intensity
profile of the SiO outflow. The axis drift rate is about 0.011 deg yr-1. The
middle part of the northeastern outflow does not exactly follow the point
symmetry because of the superposition of two different kinds of directional
variability: the axis drift of the driving source and the deflection by a dense
core. The axis drift model provides a good explanation for the large deflection
angle of the northeastern outflow. Other H2 emission features around the IRAS 4
region are discussed briefly. Some of them are newly found outflows, and some
are associated with outflows already known before
OA031-04. Impairment of HIV-1-specific CD8+ T cell function by soluble epithelial adhesion molecules
Entanglement for a two-parameter class of states in quantum system
We exhibit a two-parameter class of states , in
quantum system for , which can be obtained from an
arbitrary state by means of local quantum operations and classical
communication, and which are invariant under all bilateral %unitary operations
%of the form on quantum system. We calculate the
negativity of , and a lower bound and a tight upper
bound on its entanglement of formation. It follows from this calculation that
the entanglement of formation of cannot exceed its
negativity.Comment: 10 pages, including 4 figures, accepted for publication in J. Phys.
Squeezed States of the Generalized Minimum Uncertainty State for the Caldirola-Kanai Hamiltonian
We show that the ground state of the well-known pseudo-stationary states for
the Caldirola-Kanai Hamiltonian is a generalized minimum uncertainty state,
which has the minimum allowed uncertainty , where is a constant depending on the damping
factor and natural frequency. The most general symmetric Gaussian states are
obtained as the one-parameter squeezed states of the pseudo-stationary ground
state. It is further shown that the coherent states of the pseudo-stationary
ground state constitute another class of the generalized minimum uncertainty
states.Comment: RevTex4, 9 pages, no fingure; to be published in Journal of Physics
SEEDS direct imaging of the RV-detected companion to V450 Andromedae, and characterization of the system
We report the direct imaging detection of a low-mass companion to a young,
moderately active star V450 And, that was previously identified with the radial
velocity method. The companion was found in high-contrast images obtained with
the Subaru Telescope equipped with the HiCIAO camera and AO188 adaptive optics
system. From the public ELODIE and SOPHIE archives we extracted available
high-resolution spectra and radial velocity (RV) measurements, along with RVs
from the Lick planet search program. We combined our multi-epoch astrometry
with these archival, partially unpublished RVs, and found that the companion is
a low-mass star, not a brown dwarf, as previously suggested. We found the
best-fitting dynamical masses to be and
M. We also performed spectral analysis of
the SOPHIE spectra with the iSpec code. The Hipparcos time-series photometry
shows a periodicity of d, which is also seen in SOPHIE spectra as an
RV modulation of the star A. We interpret it as being caused by spots on the
stellar surface, and the star to be rotating with the given period. From the
rotation and level of activity, we found that the system is
Myr old, consistent with an isochrone analysis ( Myr). This
work may serve as a test case for future studies of low-mass stars, brown
dwarfs and exoplanets by combination of RV and direct imaging data.Comment: 15 pages, 9 figures, 7 tables, to appear in Ap
- …