scholarly journals NGC 6302: high-ionization permitted lines. Applying X-SSN synthesis to VLT-UVES spectra

2011 ◽  
Vol 7 (S283) ◽  
pp. 470-471
Author(s):  
Daniel Péquignot ◽  
Christophe Morisset ◽  
Simon Casassus
Keyword(s):  
High Signal ◽  
Signal To Noise ◽  
High Ionization ◽  
Spectrum Synthesis ◽  
First Time

AbstractA preliminary VLT-UVES spectrum of NGC 6302 (Casassus et al. 2002, MN), which hosts one of the hottest PN nuclei known (Teff ~ 220000 K; Wright et al. 2011, MN), has been recently analysed by means of X-SSN, a spectrum synthesis code for nebulae (Morisset and Péquignot). Permitted recombination lines from highly-ionized species are detected/identified for the first time in a PN, and some of them probably for the first time in (astro)physics. The need for a homogeneous, high signal-to-noise UVES spectrum for NGC 6302 is advocated.

A Study of the Orbital and Intrinsic Variability of the Double-Lined Spectroscopic Binary β Centauri

2002 ◽  
Vol 185 ◽  
pp. 86-87
Author(s):  
M. Ausseloos ◽  
C. Aerts ◽  
K. Uytterhoeven
Keyword(s):  
High Resolution ◽  
Orbital Motion ◽  
High Signal ◽  
Mass Ratio ◽  
Eccentric Orbit ◽  
Intrinsic Variability ◽  
Signal To Noise ◽  
Orbital Parameters ◽  
Spectroscopic Binary ◽  
First Time

AbstractWe introduce our observational study of the orbital motion of β Cen. Using 463 high signal-to-noise, high-resolution spectra obtained over a timespan of 12 years it is shown that the radial velocity of β Cen varies with an orbital period of 357.0 days. We derive for the first time the orbital parameters of β Cen and find a very eccentric orbit (e = 0.81) and similar component masses with a mass ratio M1/M2 = 1.02. Both the primary and the secondary exhibit periodic line-profile variations.

Molybdenum carbide chemical sensors with ultrahigh signal-to-noise ratios and ambient stability

2018 ◽  
Vol 6 (46) ◽  
pp. 23408-23416 ◽  
Author(s):  
Soo-Yeon Cho ◽  
Ju Ye Kim ◽  
Ohmin Kwon ◽  
Jihan Kim ◽  
Hee-Tae Jung
Keyword(s):  
Chemical Sensors ◽  
Molybdenum Carbide ◽  
Gas Sensing ◽  
High Signal ◽  
Signal To Noise ◽  
Molybdenum Carbides ◽  
First Time ◽  
Sensing Performance

In this study, we investigate the gas sensing performance of molybdenum carbides for the first time and they show ultra-high signal-to-noise ratios and excellent ambient stability.

scholarly journals High Signal-to-Noise Ratio Mid-Infrared Quasar Spectral Templates

2013 ◽  
Vol 9 (S304) ◽  
pp. 315-318
Author(s):  
Allison R. Hill ◽  
S. C. Gallagher ◽  
R. P. Deo ◽  
E. Peeters ◽  
Gordon T. Richards
Keyword(s):  
Star Formation ◽  
Signal To Noise Ratio ◽  
Host Galaxy ◽  
High Signal ◽  
Host Galaxies ◽  
Signal To Noise ◽  
Mid Infrared ◽  
High Ionization ◽  
Noise Ratio ◽  
Luminous Objects

AbstractMid-infrared (MIR) quasar spectra exhibit a suite of emission features including high ionization coronal lines from the narrow line region (NLR) illuminated by the ionizing continuum, and hot dust features from grains, as well as polycyclic aromatic hydrocarbons (PAH) features from star formation in the host galaxy. Few features are detected in most spectra because of typically low signal-to-noise ratio (S/N) data. By generating spectral composites in three different luminosity bins from over 180 Spitzer Ifnfrared Spectrograph (IRS) observations, we boost the S/N and reveal important features in the complex spectra. We detect high-ionization, forbidden emission lines in all templates, PAH features in all but the most luminous objects, and broad silicate and graphite features in emission whose strength increases relative to the continuum with luminosity. We find that the intrinsic quasar spectrum for all luminosity templates is consistent, and the differences in the spectra can be explained by host galaxy contamination in the lower luminosity templates. We also posit that star formation may be active in most quasar host galaxies, but the spectral features of star formation are only detectable if the quasar is faint.

scholarly journals The well correlated diffuse interstellar bands at λλ 6196, 6614 Å and their possible companions

2020 ◽  
Vol 496 (2) ◽  
pp. 2231-2240
Author(s):  
A Bondar
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
High Resolution ◽  
Aromatic Hydrocarbons ◽  
Correlation Coefficients ◽  
High Signal ◽  
Signal To Noise ◽  
B Stars ◽  
Diffuse Interstellar Bands ◽  
Polycyclic Aromatic ◽  
First Time

ABSTRACT Considered here is the interrelation between five diffuse interstellar bands (DIBs), λλ 5545, 6113, 6196, 6445 and 6614 Å. Two DIBs (λλ 6196 and 6614 Å) are already known as being well correlated with each other; their relation with three other weaker bands is investigated for the first time. To accomplish this task, high-resolution spectra (λ/δλ ≈100 000) with high signal-to-noise ratios (S/N) of 54 hot O–B stars with reddening 0.12–1.45 mag were used. Analysis of measured equivalent widths has allowed us to establish linear dependences and evaluate linear correlation coefficients as high as 0.968–0.988 between the intensities of these five DIBs. Such a degree of correlation may indicate their common origin. Several spacings in wavenumbers found between these DIBs correspond to the energies of vibrational transitions in some polycyclic aromatic hydrocarbons resulting in IR emissions at λλ 16.4, 11.3, 7.7, 6.2 and 3.3 μm.

scholarly journals Beryllium abundances along the evolutionary sequence of the open cluster IC 4651

2009 ◽  
Vol 5 (S268) ◽  
pp. 357-358 ◽  
Author(s):  
Rodolfo Smiljanic ◽  
L. Pasquini ◽  
C. Charbonnel ◽  
N. Lagarde
Keyword(s):  
Main Sequence ◽  
Open Cluster ◽  
High Signal ◽  
Evolutionary Sequence ◽  
Main Sequence Stars ◽  
Signal To Noise ◽  
Mixing Processes ◽  
Hydrodynamical Models ◽  
Spectrum Synthesis ◽  
Hertzsprung Gap

AbstractThe simultaneous investigation of Li and Be in stars is a powerful tool in the study of the evolutionary mixing processes. Here, we present beryllium abundances in stars along the whole evolutionary sequence of the open cluster IC 4651. This cluster has a metallicity of [Fe/H] = +0.11 and an age of 1.2 or 1.7 Gyr. Abundances have been determined from high-resolution, high signal-to-noise UVES spectra using spectrum synthesis and model atmospheres. Lithium abundances for the same stars were determined in a previous work. Confirming previous results, we find that the Li dip is also a Be dip. For post-main-sequence stars, the Be dilution starts earlier within the Hertzsprung gap than expected from classical predictions, as does the Li dilution. Theoretical hydrodynamical models are able to reproduce well all the observed features.

Electroionization study of ethylene: structures in the ionization and appearance curves

1987 ◽  
Vol 65 (7) ◽  
pp. 803-807 ◽  
Author(s):  
Pierre Plessis ◽  
Paul Marmet
Keyword(s):  
Carbon Atom ◽  
High Signal ◽  
Signal To Noise ◽  
Monoenergetic Electron ◽  
Text Production ◽  
Text Fragment ◽  
First Time ◽  
Fragmentation Processes ◽  
Fragment Production ◽  
Very High

Ionization-efficiency curves with very high signal-to-noise ratios for ethylene and all fragments consisting of at least one carbon atom are presented and analyzed. The curves are produced by monoenergetic electron impact and extend up to 10 eV above threshold. Most of the structures observed thus far by this method for these regions are reported here for the first time. Competition between [Formula: see text] production and [Formula: see text] and [Formula: see text] fragment production is clearly seen in the respective curves. Features occurring at the same energy in several of the curves indicate that these are due to a common progenitor, particularly the [Formula: see text] complex. The appearance of different fragmentation processes accounts for the onset-type structure found in some of the fragment-ion curves.

scholarly journals Physical conditions in the NGC 6334 molecular cloud derived from non-LTE NH3(J,K)=(1,1) transitions

2002 ◽  
Vol 206 ◽  
pp. 240-243
Author(s):  
Anderson Caproni ◽  
Zulema Abraham ◽  
José W. S. Vilas-Boas
Keyword(s):  
Star Formation ◽  
Molecular Cloud ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Physical Parameters ◽  
Signal To Noise ◽  
Line Shapes ◽  
Physical Conditions ◽  
Ngc 6334 ◽  
First Time

The high signal-to-noise ratio of the NH3(J,K) = (1,1) spectra from NGC 6334 have allowed at a first time a detailed study of departures from LTE conditions in this molecular cloud. Differences in the line shapes have shown that the surveyed region is composed of at least three overlapped sources in different stages of star formation. Comparison between physical parameters of NGC 6334 derived from LTE and non-LTE conditions are presented and discussed here.

scholarly journals 12C/13C ratios in giants of open clusters

2006 ◽  
Vol 2 (S239) ◽  
pp. 298-300
Author(s):  
Rodolfo Smiljanic ◽  
R. Gauderon ◽  
P. North ◽  
B. Barbuy ◽  
C. Charbonnel ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Isotopic Ratio ◽  
Open Clusters ◽  
High Signal ◽  
Signal To Noise ◽  
Hydrogen Burning ◽  
Carbon Isotopic Ratio ◽  
Carbon Isotopic ◽  
Spectrum Synthesis ◽  
Convective Layer

AbstractThe carbon isotopic ratio,12C/13C, is a tracer of the mixing events during the evolution along the giant branch, due to the conversion of12C into13C (and14N) via the CN cycle. A decrease of this ratio from 90, the solar value, to 20–25, is expected due to the first dredge-up. However, ratios down to 3–4, the CN cycle equilibrium value, have been observed in giants of the field, of globular and of open clusters. Observations seem to indicate a non-standard mixing in the RGB, probably beginning in the luminosity bump, when the outward moving hydrogen burning shell crosses the molecular weight barrier left by the convective layer in its maximum extent. We are currently analyzing a sample of 24 giants in 8 open clusters for which we determined12C/13C from high resolution, high signal to noise spectra using spectrum synthesis. In this work we discuss the general characteristics of our results in comparison to previous analyses of giants in open clusters available in the literature.

scholarly journals The Belgian repository of fundamental atomic data and stellar spectra

2017 ◽  
Vol 95 (9) ◽  
pp. 833-839 ◽  
Author(s):  
A. Lobel ◽  
P. Royer ◽  
C. Martayan ◽  
M. Laverick ◽  
T. Merle ◽  
...  
Keyword(s):  
Atomic Line ◽  
Atomic Data ◽  
High Signal ◽  
Atmospheric Parameter ◽  
Synthetic Spectrum ◽  
Signal To Noise ◽  
Stellar Spectra ◽  
Novel Approach ◽  
Spectrum Synthesis ◽  
Quality Assessments

BRASS is an international networking project of the Federal Government of Belgium for the development of a new public database providing accurate fundamental atomic data of vital importance for stellar spectroscopic research. The BRASS database will offer atomic line data that is thoroughly tested by comparing theoretical and observed stellar spectra. We are in the course of performing extensive quality assessments of selected atomic input data with advanced radiative transfer spectrum synthesis calculations that we compare in detail to high-resolution Mercator-HERMES and ESO-VLT-UVES spectra of very high signal-to-noise ratios for about 30 hot and cool bright stars of B, A, F, G, and K spectral types. The new database will provide the tested and validated values of absorption lines we retrieve from various existing atomic repositories, such as NIST and VAMDC. The validated atomic datasets, combined with the observed and theoretical spectra, will be interactively offered online at brass.sdf.org. The combination of these datasets is a novel approach for its development, which will provide a universal reference for advanced stellar spectroscopic research. We present the atmospheric parameter results of a subset of five benchmark stars observed with signal-to-noise ratios of 800–1200. The observed and theoretical spectra of the Sun and 51 Peg between 4000 and 6800 Å are offered online in the BRASS Data Interface. It also incorporates a new list of ∼900 metal lines for which we compute blending below 5% of the equivalent width useful for detailed line profile modeling and synthetic spectrum fit quality assessments of atomic line data.

scholarly journals Oxygen in Unevolved Starss

2002 ◽  
Vol 12 ◽  
pp. 416-419
Author(s):  
Ann Merchant Boesgaard
Keyword(s):  
Spectral Resolution ◽  
Linear Relation ◽  
Spectral Region ◽  
High Spectral Resolution ◽  
High Signal ◽  
Signal To Noise ◽  
Spectrum Synthesis ◽  
Ultraviolet Spectral Region

AbstractWe have made observations of 24unevolvedstars of the OH lines in the ultraviolet spectral region at high spectral resolution and high signal-to-noise, typically 60 − 110 with Keck + HIRES. The O abundances have been computed by spectrum synthesis. For these cool, unevolved stars there is a linear relation between [O/H] and [Fe/H] over three orders of magnitude with very little scatter and a slope of +0.66 ±0.02. The relation between [O/Fe] and [Fe/H] is robustly linear with [O/Fe] = −0.35 (±0.03) [Fe/H]. There is no sign of a break at metallicities between −1.0 and −2.0.

Sign in / Sign up

Export Citation Format

Share Document