2,191 research outputs found
Late-Time Spectral Observations of the Strongly Interacting Type Ia Supernova PTF11kx
PTF11kx was a Type Ia supernova (SN Ia) that showed time-variable absorption
features, including saturated Ca II H&K lines that weakened and eventually went
into emission. The strength of the emission component of H{\alpha} increased,
implying that the SN was undergoing significant interaction with its
circumstellar medium (CSM). These features were blueshifted slightly and showed
a P-Cygni profile, likely indicating that the CSM was directly related to, and
probably previously ejected by, the progenitor system itself. These and other
observations led Dilday et al. (2012) to conclude that PTF11kx came from a
symbiotic nova progenitor like RS Oph. In this work we extend the spectral
coverage of PTF11kx to 124-680 rest-frame days past maximum brightness. These
spectra of PTF11kx are dominated by H{\alpha} emission (with widths of ~2000
km/s), strong Ca II emission features (~10,000 km/s wide), and a blue
"quasi-continuum" due to many overlapping narrow lines of Fe II. Emission from
oxygen, He I, and Balmer lines higher than H{\alpha} is weak or completely
absent at all epochs, leading to large observed H{\alpha}/H{\beta} intensity
ratios. The broader (~2000 km/s) H{\alpha} emission appears to increase in
strength with time for ~1 yr, but it subsequently decreases significantly along
with the Ca II emission. Our latest spectrum also indicates the possibility of
newly formed dust in the system as evidenced by a slight decrease in the red
wing of H{\alpha}. During the same epochs, multiple narrow emission features
from the CSM temporally vary in strength. The weakening of the H{\alpha} and Ca
II emission at late times is possible evidence that the SN ejecta have
overtaken the majority of the CSM and agrees with models of other strongly
interacting SNe Ia. The varying narrow emission features, on the other hand,
may indicate that the CSM is clumpy or consists of multiple thin shells.Comment: 12 pages, 7 figures, 1 table, re-submitted to Ap
A novel experimental design of a real-time VR tracking device
Virtual Reality (VR) is progressively adopted at different stages of design and product development. Consequently, evolving interaction requirements in engineering design and development for VR are essential for technology adoption. One of these requirements is real-time positional tracking. This paper aims to present an experimental design of a new real-time positional tracking device (tracker), that is more compact than the existing solution, while addressing factors such as wearability and connectivity. We compare the simulation of the proposed device and the existing solution, discuss the results, and the limitations. The new experimental shape of the device is tailored towards research, allowing the engineering designer to take advantage of a new tracker alternative in new ways, and opens the door to new VR applications in research and product development
Supernova PTF 09uj: A possible shock breakout from a dense circumstellar wind
Type-IIn supernovae (SNe), which are characterized by strong interaction of
their ejecta with the surrounding circumstellar matter (CSM), provide a unique
opportunity to study the mass-loss history of massive stars shortly before
their explosive death. We present the discovery and follow-up observations of a
Type IIn SN, PTF 09uj, detected by the Palomar Transient Factory (PTF).
Serendipitous observations by GALEX at ultraviolet (UV) wavelengths detected
the rise of the SN light curve prior to the PTF discovery. The UV light curve
of the SN rose fast, with a time scale of a few days, to a UV absolute AB
magnitude of about -19.5. Modeling our observations, we suggest that the fast
rise of the UV light curve is due to the breakout of the SN shock through the
dense CSM (n~10^10 cm^-3). Furthermore, we find that prior to the explosion the
progenitor went through a phase of high mass-loss rate (~0.1 solar mass per
year) that lasted for a few years. The decay rate of this SN was fast relative
to that of other SNe IIn.Comment: Accepted to Apj, 6 pages, 4 figure
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