125 research outputs found
Grantecan spectroscopic observations and confirmations of Planetary Nebulae candidates in the Northern Galactic Plane
We present Grantecan 10 m telescope (GTC) spectroscopic confirmations of 55
faint Planetary Nebulae (PNe) candidates discovered largely in the INT
Photometric H Survey of the Northern Galactic Plane (IPHAS) by our
pro-am collaboration. We confirm 46 of them as 'True' (T), 4 as 'Likely' (L)
and 5 as 'Possible' (P) PNe and including 5 new PNe central star (CSPN)
discoveries. This was from observations of 62 new candidates yielding a maximum
PN discovery success rate of 89%. The sensitivity and longer wavelength
coverage of IPHAS allows PNe to be found in regions of greater extinction and
at these lower Galactic latitudes, including PNe in a more advanced
evolutionary state and at larger distances compared to previously known
Galactic PNe. We use an holistic set of observed characteristics and optical
emission-line diagnostics to confirm candidates. Plasma properties have been
determined in a self-consistent way using PyNeb. This work is facilitated by
the functionality of our powerful, multi-wavelength database 'HASH' (Hong Kong,
Australian Astronomical Observatory, Strasbourg Observatory H-alpha Planetary
Nebula catalogue) that federates known imaging, spectroscopy and other
pertinent data for all Galactic T, L, P PNe and the significant numbers of
mimics. Reddenings, corrected radial velocities and PNe electron density and
temperature estimates are provided for these new PNe where possible.Comment: Accepted for publication by MNRA
The stellar remnant of SN 1181
We report observations and modelling of the stellar remnant and presumed
double-degenerate merger of Type~Iax supernova SN 1181 AD. It is the only known
bound stellar SN remnant and the only star with Wolf-Rayet features that is
neither a planetary nebula central star nor a massive Pop I progenitor. We
model the unique emission-line spectrum with broad, strong O VI and O VIII
lines as a fast stellar wind and shocked, hot gas. Non-LTE wind modeling
indicates a mass-loss rate of and a
terminal velocity of 15,000 km s, consistent with earlier results.
O VIII lines indicate shocked gas temperatures of MK. We derive a
magnetic field upper limit of MG, below earlier suggestions. The
luminosity indicates a remnant mass of with ejecta
mass . Archival photometry suggests the stellar
remnant has dimmed by 0.5 magnitudes over 100 years. A low Ne/O
argues against a O-Ne white dwarf in the merger. A cold dust shell is only the
second detection of dust in a SN Iax and the first of cold dust. Our ejecta
mass and kinetic energy estimates of the remnant are consistent with Type Iax
extragalactic sources.Comment: 19 pages, 13 figures, 3 tables. Submitte
New measurement of exotic decay of Ac by C emission
The branching ratio of Ac decay by emission of C was remeasured under improved experimental conditions by using a radioactive source produced at the ISOLDE mass-separator at CERN and a nuclear track detector technique. The result, B=, is consistent with the anomalously high value obtained in the 1993 experiment thus confirming the importance of nuclear structure effects in this exotic decay
NEBULAS: high performance data-driven event building architectures based on asynchronous self-routing packet-switching networks
A compact equipment for the sulfur content estimation in heavy oil using neutrons and gamma-rays
Optical fiber distributed sensing based on Rayleigh scatter frequency domain reflectometry for Sodium leakage detection within SFR reactors
Study of the Flow Temperature and Ring Design Influence on the Response of a New Reduced-Size Calorimetric Cell for Nuclear Heating Quantification
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