scholarly journals An updated Type II supernova Hubble diagram

2018 ◽  
Vol 611 ◽  
pp. A25 ◽  
Author(s):  
E. E. E. Gall ◽  
R. Kotak ◽  
B. Leibundgut ◽  
S. Taubenberger ◽  
W. Hillebrandt ◽  
...  
Keyword(s):  
Spectral Lines ◽  
Balmer Line ◽  
Type Ii ◽  
Dependent Relation ◽  
Measuring Techniques ◽  
Distance Indicators ◽  
Larger Sample ◽  
Current Record ◽  
Initial Results ◽  
The Continuum

We present photometry and spectroscopy of nine Type II-P/L supernovae (SNe) with redshifts in the 0.045 ≲ z ≲ 0.335 range, with a view to re-examining their utility as distance indicators. Specifically, we apply the expanding photosphere method (EPM) and the standardized candle method (SCM) to each target, and find that both methods yield distances that are in reasonable agreement with each other. The current record-holder for the highest-redshift spectroscopically confirmed supernova (SN) II-P is PS1-13bni (z = 0.335−0.012+0.009), and illustrates the promise of Type II SNe as cosmological tools. We updated existing EPM and SCM Hubble diagrams by adding our sample to those previously published. Within the context of Type II SN distance measuring techniques, we investigated two related questions. First, we explored the possibility of utilising spectral lines other than the traditionally used Fe iiλ5169 to infer the photospheric velocity of SN ejecta. Using local well-observed objects, we derive an epoch-dependent relation between the strong Balmer line and Fe iiλ5169 velocities that is applicable 30 to 40 days post-explosion. Motivated in part by the continuum of key observables such as rise time and decline rates exhibited from II-P to II-L SNe, we assessed the possibility of using Hubble-flow Type II-L SNe as distance indicators. These yield similar distances as the Type II-P SNe. Although these initial results are encouraging, a significantly larger sample of SNe II-L would be required to draw definitive conclusions.

scholarly journals The Berkeley sample of Type II supernovae: BVRI light curves and spectroscopy of 55 SNe II

2019 ◽  
Vol 490 (2) ◽  
pp. 2799-2821 ◽  
Author(s):  
T de Jaeger ◽  
W Zheng ◽  
B E Stahl ◽  
A V Filippenko ◽  
T G Brink ◽  
...  
Keyword(s):  
Theoretical Models ◽  
Spectral Lines ◽  
Light Curves ◽  
Expansion Velocity ◽  
Type Ii ◽  
V Band ◽  
Evolution Analysis ◽  
Absolute Magnitudes ◽  
Distance Indicators ◽  
Good Agreement

ABSTRACT In this work, BVRI light curves of 55 Type II supernovae (SNe II) from the Lick Observatory Supernova Search programme obtained with the Katzman Automatic Imaging Telescope and the 1 m Nickel telescope from 2006 to 2018 are presented. Additionally, more than 150 spectra gathered with the 3 m Shane telescope are published. We conduct an analyse of the peak absolute magnitudes, decline rates, and time durations of different phases of the light and colour curves. Typically, our light curves are sampled with a median cadence of 5.5 d for a total of 5093 photometric points. In average, V-band plateau declines with a rate of 1.29 mag (100 d)−1, which is consistent with previously published samples. For each band, the plateau slope correlates with the plateau length and the absolute peak magnitude: SNe II with steeper decline have shorter plateau duration and are brighter. A time-evolution analysis of spectral lines in term of velocities and pseudo-equivalent widths is also presented in this paper. Our spectroscopic sample ranges between 1 and 200 d post-explosion and has a median ejecta expansion velocity at 50 d post-explosion of 6500 km s−1 (H α line) and a standard dispersion of 2000 km s−1. Nebular spectra are in good agreement with theoretical models using a progenitor star having a mass <16M⊙. All the data are available to the community and will help to understand SN II diversity better, and therefore to improve their utility as cosmological distance indicators.

scholarly journals Internal structure and rotation of the Sun: First results from the MDI data

1997 ◽  
Vol 181 ◽  
pp. 203-210
Author(s):  
A.G. Kosovichev ◽  
J. Schou ◽  
P.H. Scherrer ◽  
R.S. Bogart ◽  
R.I. Bush ◽  
...  
Keyword(s):  
Thin Layer ◽  
Spectral Lines ◽  
Convective Boundary ◽  
Doppler Imager ◽  
Lower Amplitude ◽  
Oscillation Modes ◽  
First Results ◽  
Sharp Variation ◽  
The Mean ◽  
Initial Results

The Medium-l Program of the Michelson Doppler Imager (MDI) instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∼ 300. The initial results show that the noise in the Medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. In a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer.

scholarly journals FUV and optical spectrophotometry of X-ray selected Seyferts

1986 ◽  
Vol 119 ◽  
pp. 347-348
Author(s):  
J. T. Clarke ◽  
S. Bowyer ◽  
M. Grewing
Keyword(s):  
Seyfert Galaxies ◽  
Continuum Emission ◽  
Balmer Line ◽  
X Ray ◽  
Positive Correlation ◽  
Optical Spectrophotometry ◽  
Distinguishing Features ◽  
The Continuum

Nearly simultaneous FUV and optical spectrophotometry of X-ray selected Seyfert galaxies has revealed an average Ly α/H β ratio of 22, a positive correlation between the ratio Ly α/H β and the width of the lines, and additional Ly α emission in the wings of one source which is not matched by emission in the Balmer line wings. However, we find no distinguishing features in the continuum emission from these X-ray selected objects compared with other samples. If the correlation between Ly α/H β and the width of the lines is found to apply to larger samples of Seyferts, it may be that our objects appear Ly α bright because they are also broad-lined compared with other samples.

Type II supernovae - Nonstandard candles as extragalactic distance indicators

1979 ◽  
Vol 230 ◽  
pp. 11 ◽  
Author(s):  
S. R. Schurmann ◽  
W. D. Arnett ◽  
S. W. Falk
Keyword(s):  
Type Ii ◽  
Distance Indicators

scholarly journals Probing the star–formation modes in merging galaxies

2012 ◽  
Vol 8 (S292) ◽  
pp. 323-326
Author(s):  
P.-A. Duc ◽  
P.-E. Belles ◽  
E. Brinks ◽  
F. Bournaud
Keyword(s):  
Star Formation ◽  
Sharp Increase ◽  
Velocity Dispersion ◽  
State Of The Art ◽  
Spatial Scales ◽  
Merging Galaxies ◽  
Central Regions ◽  
Formation Efficiency ◽  
Larger Sample ◽  
Initial Results

AbstractMerging systems at low redshift provide the unique opportunity to study the processes related to star formation in a variety of environments that presumably resemble those seen at higher redshifts. Previous studies of distant starbursting galaxies suggest that stars are born in turbulent gas, with a higher efficiency than in MW-like spirals. We have investigated in detail the turbulent-driven regime of star-formation in nearby colliding galaxies combining high resolution VLA B array Hi maps and UV GALEX observations. With these data, we could check predictions of our state-of-the-art simulations of mergers, such as the global sharp increase of the fraction of dense gas, as traced by the SFR, with respect to the diffuse gas traced by Hi during the merging stage, following the increased velocity dispersion of the gas. We present here initial results obtained studying the SFR-Hi relation at 4.5 kpc resolution. We determined SFR/Hi mass ratios that are higher in the external regions of mergers than in the outskirts of isolated spirals, though both environments are Hi dominated. SFR/Hi increases towards the central regions following the decrease of the atomic gas fraction and possibly the increased star–formation efficiency. These results need to be checked with a larger sample of systems and on smaller spatial scales. This is the goal of the on-going Chaotic THINGS project that ultimately will allow us to determine why starbursting galaxies deviate from the Kennicutt-Schmidt relation between SFR density and gas surface density.

Multiple-Frequency Measurements of a Flare Continuum Event

1982 ◽  
Vol 4 (4) ◽  
pp. 389-392 ◽  
Author(s):  
R.D. Robinson
Keyword(s):  
Solar Flares ◽  
Electromagnetic Waves ◽  
Plasma Frequency ◽  
Close Association ◽  
Type Ii ◽  
Multiple Frequency ◽  
Langmuir Waves ◽  
Long Duration ◽  
Type Ii Radio Bursts ◽  
The Continuum

A type of metre-wavelength continuum is observed in close association with solar flares and Type II radio bursts. This continuum is stationary in position, often intense, of a long duration (occasionally lasting well over an hour) and highly polarized (Robinson and Smerd 1975; Robinson 1978). It is thought to be produced by the conversion of Langmuir waves to electromagnetic waves near the local plasma frequency. Because of its close association with Type II bursts, the class has been designated as Type II related flare continuum, or FCII. In this paper I examine a particularly clear example of such an event, with emphasis on the relation between the Type II and the start of the continuum.

scholarly journals Characterization and formation of on-disk spicules in the Ca II K and Mg II k spectral lines

2019 ◽  
Vol 631 ◽  
pp. L5 ◽  
Author(s):  
Souvik Bose ◽  
Vasco M. J. Henriques ◽  
Jayant Joshi ◽  
Luc Rouppe van der Voort
Keyword(s):  
Doppler Shift ◽  
Spectral Lines ◽  
Solar Telescope ◽  
Type Ii ◽  
Line Formation ◽  
Line Core ◽  
Chromospheric Line ◽  
First Time ◽  
Time Type

We characterize, for the first time, type-II spicules in Ca II K 3934 Å using the CHROMIS instrument at the Swedish 1 m Solar Telescope. We find that their line formation is dominated by opacity shifts with the K3 minimum best representing the velocity of the spicules. The K2 features are either suppressed by the Doppler-shifted K3 or enhanced via increased contribution from the lower layers, leading to strongly enhanced but unshifted K2 peaks, with widening towards the line core as consistent with upper-layer opacity removal via Doppler-shift. We identify spicule spectra in concurrent IRIS Mg II k 2796Å observations with very similar properties. Using our interpretation of spicule chromospheric line formation, we produce synthetic profiles that match observations.

Solar Magnetic Fields and Velocities

1970 ◽  
Vol 1 (8) ◽  
pp. 363-364 ◽  
Author(s):  
R. G. Giovanelli
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Temperature Increase ◽  
Spectral Lines ◽  
Solar Magnetic Fields ◽  
Similar Increase ◽  
Physical Conditions ◽  
High Ionization ◽  
Reduced Intensity ◽  
The Continuum

It has long been known that Fraunhofer lines show variations in intensity from place to place over the Sun’s surface, these being particularly noticeable in spectroheliograms obtained in the strong chromospheric lines. An early account of the weaker Unes was given by d’Azam-buja. McMath, Mohler, Pierce and Goldberg attributed intensity increases in (or decreases in depth of) metallic spectral lines to local temperature increases. Sheeley used high-resolution spectra to study these line weakenings further, finding them where, and only where, strong non-spot magnetic fields occurred. He also reported that in many cases the continuum in such regions was of reduced intensity, suggesting that fields often occur in the dark lanes and pores in the granulation. Spectroheliograms obtained in the cores of the weakened lines (e.g., Fel 6302.5Å) by Chapman and Sheeley showed that the bright network which these weakenings form appears as a sequence of sharp, bright points in the cores of the fainter lines and the wings of stronger lines but is more diffuse in the cores of stronger lines. They found the bright network in Zeeman-insensitive Unes (e.g., 5123.7A) also, indicating that it is due, at least in part, to variations in physical conditions. Lines of low ionization and excitation are weakened more than those of high ionization and excitation, and they attributed this to a temperature increase by 100-200 °K in the region of formation of the line cores ; a similar increase of 250 °K was found by Harvey and Livingston.

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