scholarly journals Late-time Spectral Observations of Type IIP Supernovae

2015 ◽  
Vol 11 (A29B) ◽  
pp. 472-472
Author(s):  
Jeffrey M. Silverman ◽  
Stephanie Pickett ◽  
J. Craig Wheeler ◽  
Alexei V. Filippenko
Keyword(s):  
Temporal Evolution ◽  
Optical Spectra ◽  
Photometric Data ◽  
Emission Lines ◽  
Late Time ◽  
Type Ii ◽  
Insight Into

We are analysing late-time (older than about 150 d past explosion) optical spectra of Type II-Plateau (IIP) supernovae (SNe), which are H-rich SNe that come from red supergiant (RSG) progenitors. The dataset includes nearly 100 spectra of about 40 objects, making this the largest sample of SN IIP nebular spectra ever investigated. Quantitative criteria from within the spectra themselves are employed to determine if an observation is truly nebular, and thus should be included in the study. We present the temporal evolution of the fluxes, shapes, and velocities of various emission lines (see, for example, Fig. 1). These measured values are also compared to photometric data in order to search for correlations that can allow us to gain insight into the diversity of RSG progenitors and learn more about the details of the explosion itself.

Discovery of five new Galactic symbiotic stars in the VPHAS+ survey

2021 ◽  
Vol 502 (2) ◽  
pp. 2513-2517
Author(s):  
Stavros Akras ◽  
Denise R Gonçalves ◽  
Alvaro Alvarez-Candal ◽  
Claudio B Pereira
Keyword(s):  
Spectroscopic Data ◽  
Selection Criterion ◽  
Optical Spectra ◽  
Emission Lines ◽  
High Rate ◽  
Symbiotic Stars ◽  
Selection Of

ABSTRACT We report the validation of a recently proposed infrared (IR) selection criterion for symbiotic stars (SySts). Spectroscopic data were obtained for seven candidates, selected from the SySt candidates of Akras et al. by employing the new supplementary IR selection criterion for SySts in the VST/OmegaCAM Photometric H-Alpha Survey. Five of them turned out to be genuine SySts after the detection of H α, He ii, and [O iii] emission lines as well as TiO molecular bands. The characteristic O vi Raman-scattered line is also detected in one of these SySts. According to their IR colours and optical spectra, all five newly discovered SySts are classified as S-type. The high rate of true SySts detections of this work demonstrates that the combination of the H α emission and the new IR criterion improves the selection of target lists for follow-up observations by minimizing the number of contaminants and optimizing the observing time.

scholarly journals R Coronae Borealis Stars: Long-Term Photometric & Spectroscopic Studies

1998 ◽  
Vol 11 (1) ◽  
pp. 379-379
Author(s):  
P.L. Cottrell ◽  
L. Skuljan ◽  
P.M. Kilmartin ◽  
C. Gilmore ◽  
W.A. Lawson
Keyword(s):  
Radial Velocity ◽  
Spectroscopic Studies ◽  
Photometric Data ◽  
Decline Phase ◽  
Dust Clouds ◽  
Medium Resolution ◽  
Formation And Evolution ◽  
R Coronae Borealis Stars ◽  
Insight Into

For more than a decade we have been able to acquire and analyse a significant amount of photometric data of the highly variable R Coronae Borealis (RCB) stars. This has made been possible by a photometric service observing programme instigated at the Observatory. These photometric data have been combined with less extensive spectroscopic coverage, particularly of the decline phase of these stars. These have been supplemented by observations obtained at Mount Stromlo and Siding Spring Observatories for a radial velocity study. Significantly more spectroscopic observations are now being acquired with the development of a new medium resolution spectrograph at Mount John University Observatory. In this poster we will present recent photometric and spectroscopic results for a number of the RCB stars in our sample. This observational and analysis work can be used to provide further insight into the nature of these stars, their likely progeny and progenitors and the processes that are involved in the formation and evolution of the obscuring dust clouds which cause the decline phase.

scholarly journals Nebular and auroral emission lines of [Cl III] in the optical spectra of planetary nebulae

2000 ◽  
Vol 97 (9) ◽  
pp. 4551-4555 ◽  
Author(s):  
F. P. Keenan ◽  
L. H. Aller ◽  
C. A. Ramsbottom ◽  
K. L. Bell ◽  
F. L. Crawford ◽  
...  
Keyword(s):  
Planetary Nebulae ◽  
Optical Spectra ◽  
Emission Lines ◽  
Auroral Emission

Magnetic Field Aligned Potentials as an Acceleration Mechanism at Jupiter

2021 ◽  
Author(s):  
Dave Constable ◽  
Licia Ray ◽  
Sarah Badman ◽  
Chris Arridge ◽  
Chris Lorch ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Temporal Evolution ◽  
Charged Particles ◽  
Uniform Mesh ◽  
Time Varying ◽  
Potential Structure ◽  
Field Aligned Current ◽  
Field Lines ◽  
The Magnetic Field ◽  
Insight Into

<p>Since arriving at Jupiter, Juno has observed instances of field-aligned proton and electron beams, in both the upward and downward current regions. These field-aligned beams are identified by inverted-V structures in plasma data, which indicate the presence of potential structures aligned with the magnetic field. The direction, magnitude and location of these potential structures is important, as it affects the characteristics of any resultant field-aligned current. At high latitudes, Juno has observed potentials of 100’s of kV occurring in both directions. Charged particles that are accelerated into Jupiter’s atmosphere and precipitate can excite aurora; likewise, particles accelerated away from the planet can contribute to the population of the magnetosphere.</p> <p>Using a time-varying 1-D spatial, 2-D velocity space Vlasov code, we examine magnetic field lines which extend from Jupiter into the middle magnetosphere. By applying and varying a potential difference at the ionosphere, we can gain insight into the effect these have on the plasma population, the potential structure, and plasma densities along the field line. Utilising a non-uniform mesh, additional resolution is applied in regions where particle acceleration occurs, allowing the spatial and temporal evolution of the plasma to be examined. Here, we present new results from our model, constrained, and compared with recent Juno observations, and examining both the upward and downward current regions.</p>

scholarly journals Ultraviolet Variability of the Symbiotic Star AG PEG

1988 ◽  
Vol 103 ◽  
pp. 263-264
Author(s):  
D. Chochol ◽  
Z. Komárek ◽  
A. Vittone
Keyword(s):  
Optical Spectra ◽  
Radial Velocities ◽  
Roche Lobe ◽  
Emission Lines ◽  
High Dispersion ◽  
Symbiotic Star ◽  
Observational Material

Symbiotic star AG Peg consists of a hot subdwarf with a WN6 spectrum and a cool M3 giant, which is not filling its Roche lobe (Boyarchuk 1967, 1985). A detailed study of profiles, equivalent widths and radial velocities of emission lines in optical spectra allowed Hutchings et al. (1975) to conclude that a hot subluminous star approximately 1 M⊙ rotates rapidly and ejects material which streams towards the cool M giant with the mass 3-4 M⊙. UV observations seems to support this model.UV observations provided from the databank of the IUE satellite were obtained in 1978–81 by different observers. The observational material consists of 12 high dispersion SWP spectra and covers the region 1200 – 2100 A. The spectra were reduced at Trieste observatory using standard IUESIPS package. The radial velocities of emission lines were measured on tracings and corrected for the motion of Earth and satellite.

The strain induced type-II band re-alignment of blue phosphorus-GeX (X = C/H/Se) heterostructures

2020 ◽  
Vol 89 (1) ◽  
pp. 10103
Author(s):  
Honglin Li ◽  
Yuting Cui ◽  
Haijun Luo ◽  
Wanjun Li
Keyword(s):  
High Performance ◽  
Strain Range ◽  
Interlayer Coupling ◽  
Photovoltaic Cell ◽  
Catalytic Performance ◽  
Band Alignment ◽  
First Principles Calculation ◽  
Type Ii ◽  
2D Structure ◽  
Insight Into

Efforts to efficiently use of the next generation 2-dimension (2D) structured monolayers is getting a lot of attention for their excellent properties recently. In this work, we composite the blue phosphorus (BP) and monolayer GeX (X = C/H/Se) via van der Waals force (vdW) interaction to obtain well defined type-II band alignment heterostructures. A systematic theoretic study is conducted to explore the interlayer coupling effects and the bands re-alignment of BP-GeX (X = C/H/Se) heterostructure after the strain imposed. To devise usable and efficient materials to degrade pollutant or used as a potential photovoltaic cell material, previous researches have proved that using 2D materials as components is a feasible way to obtain high performance. Here, we prudently present a comprehensive investigation on the BP and GeX (X = C/H/Se) with different twisted angles via first-principles calculation to lay a theoretical framework on the band alignment and carriers' separation. It reveals that the intrinsic electronic properties of BP and GeX are roughly preserved in the corresponding heterostructures. Upon strain applied, band alignment can be flexibly manipulated by varying external imposed strain. The heterostructures can maintain type-II character within a certain strain range, and thus the carriers are spatially separated to different portions. This work not only provides a deep insight into the construction of the heterostructure, but presents a new possibility to search for a flexible and feasible approach to promote its catalytic performance. The corresponding results would provide meaningful guidelines for designing 2D structure based novel materials.

scholarly journals Search for DIBs in Emission: MWC 922 - The Red Square Nebula

2013 ◽  
Vol 9 (S297) ◽  
pp. 226-228 ◽  
Author(s):  
N. Wehres ◽  
B. Ochsendorf ◽  
J. Bally ◽  
T Snow ◽  
V. Bierbaum ◽  
...  
Keyword(s):  
Spectral Range ◽  
Emission Lines ◽  
Central Object ◽  
Medium Resolution ◽  
Chemical Conditions ◽  
Physical And Chemical ◽  
Future Work ◽  
Insight Into

AbstractThis work focusses on MWC 922, the central object in the Red Square Nebula. We obtained low and medium resolution spectra of both, the central object and the surrounding nebula, using the DIS and TSpec spectrograph. The spectra show the whole spectral range between ~3 500 Å up to ~25 000 Å. The central object shows a plethora of emission lines, including many Fe II and forbidden Fe [II] lines. Here, we present the inventory of the emission lines of the central object, MWC 922. Future work will comprise the identification of the nebula emission lines by using newly obtained X-Shooter spectra. That way we want to gain further insight into the physical and chemical conditions in this environment. A comparison of the Red Square to the Red Rectangle Nebula is anticipated and will guide our search for DIBs in emission.

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