Lithium Abundances of Solar-Type Stars: A Critical Application of High Signal-to-Noise, High Resolution Spectroscopy

1988 ◽  
pp. 381-386 ◽  
Author(s):  
David R. Soderblom
Keyword(s):  
High Resolution ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Signal To Noise ◽  
Solar Type

scholarly journals Lithium Abundances of Solar-Type Stars: A Critical Application of High Signal-to-Noise, High Resolution Spectroscopy

1988 ◽  
Vol 132 ◽  
pp. 381-386
Author(s):  
David R. Soderblom
Keyword(s):  
High Resolution ◽  
The State ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Signal To Noise ◽  
High Quality ◽  
Essential Properties ◽  
Solar Type ◽  
Lithium Depletion

The study of lithium depletion in solar-type stars should help elucidate essential properties of convection in those objects. Recent high-quality observations have revealed extensive flaws in our understanding of this phenomenon. The state of our knowledge of Li depletion is reviewed, with a brief possible explanation of it all.

scholarly journals Airglow Derived Measurements of Q-Branch Transition Probabilities for Several Hydroxyl Meinel Bands

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 637 ◽  
Author(s):  
Christoph Franzen ◽  
Patrick Joseph Espy ◽  
Niklas Hofmann ◽  
Robert Edward Hibbins ◽  
Anlaug Amanda Djupvik
Keyword(s):  
High Resolution ◽  
Spontaneous Emission ◽  
Transition Probabilities ◽  
High Signal ◽  
Hitran Database ◽  
Signal To Noise ◽  
Optical Telescope ◽  
Spectroscopic Observations ◽  
Emission Transition ◽  
Airglow Emissions

Spectroscopic measurements of the hydroxyl (OH) airglow emissions are often used to infer neutral temperatures near the mesopause. Correct Einstein coefficients for the various transitions in the OH airglow are needed to calculate accurate temperatures. However, studies from some studys showed experimentally and theoretically that the most commonly used Einstein spontaneous emission transition probabilities for the Q-branch of the OH Meinel (6,2) transition are overestimated. Extending their work to several Δv = 2 and 3 transitions from v′ = 3 to 9, we have determined Einstein coefficients for the first four Q-branch rotational lines. These have been derived from high resolution, high signal to noise spectroscopic observations of the OH airglow in the night sky from the Nordic Optical Telescope. The Q-branch Einstein coefficients calculated from these spectra show that values currently tabulated in the HITRAN database overestimate many of the Q-branch transition probabilities. The implications for atmospheric temperatures derived from OH Q-branch measurements are discussed.

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.

scholarly journals Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

2020 ◽  
Vol 495 (1) ◽  
pp. 224-237 ◽  
Author(s):  
Siddharth Gandhi ◽  
Matteo Brogi ◽  
Sergei N Yurchenko ◽  
Jonathan Tennyson ◽  
Phillip A Coles ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Sections ◽  
Cross Correlation ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Pressure Broadening ◽  
Spectral Signatures ◽  
Hot Jupiters ◽  
Wide Range ◽  
Infrared Spectral

ABSTRACT High-resolution spectroscopy (HRS) has been used to detect a number of species in the atmospheres of hot Jupiters. Key to such detections is accurately and precisely modelled spectra for cross-correlation against the R ≳ 20 000 observations. There is a need for the latest generation of opacities which form the basis for high signal-to-noise detections using such spectra. In this study we present and make publicly available cross-sections for six molecular species, H2O, CO, HCN, CH4, NH3, and CO2 using the latest line lists most suitable for low- and high-resolution spectroscopy. We focus on the infrared (0.95–5 μm) and between 500 and 1500 K where these species have strong spectral signatures. We generate these cross-sections on a grid of pressures and temperatures typical for the photospheres of super-Earth, warm Neptunes, and hot Jupiters using the latest H2 and He pressure broadening. We highlight the most prominent infrared spectral features by modelling three representative exoplanets, GJ 1214 b, GJ 3470 b, and HD 189733 b, which encompass a wide range in temperature, mass, and radii. In addition, we verify the line lists for H2O, CO, and HCN with previous high-resolution observations of hot Jupiters. However, we are unable to detect CH4 with our new cross-sections from HRS observations of HD 102195 b. These high-accuracy opacities are critical for atmospheric detections with HRS and will be continually updated as new data become available.

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 The Composition of Warm Giants in M 71 and M 5

1988 ◽  
Vol 126 ◽  
pp. 497-498
Author(s):  
Catherine A. Pilachowski ◽  
Christopher Sneden
Keyword(s):  
High Resolution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
High Signal ◽  
Signal To Noise

In 1979 a disturbing controversy arose in the field of globular cluster research when Cohen (1980) and Pilachowski, Canterna, and Wallerstein (1980) announced the results of the first high dispersion studies of the composition of giants in the globular clusters M 71 and 47 Tucanae. In contrast to earlier studies, which found metallicities of typically −0.3 and −0.5 dex, these investigators obtained values of −1.3 and −1.1. Since then, many have attempted to redetermine the abundances of M 71 and 47 Tuc to explain the discrepant results. These efforts have all suffered from the absence of high signal-to-noise, high resolution spectra of stars with temperatures above 4300 K.

scholarly journals 53 Piscium, an SPB Star with Activity

2002 ◽  
Vol 185 ◽  
pp. 236-237
Author(s):  
J.-M. Le Contel ◽  
P. Mathias ◽  
E. Chapellier ◽  
J.-C. Valtier
Keyword(s):  
High Resolution ◽  
False Alarm ◽  
High Frequency ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Correlation Technique ◽  
Signal To Noise ◽  
Spectroscopic Observations ◽  
Auto Correlation ◽  
Frequency Variations

The star 53 Psc (HD 3379, B2.5IV) has been observed as variable by several authors (Sareyan et al., 1979) with frequencies around 10 c d–1 and has been classified as a β Cephei star. Conversely, other authors (e.g. Percy, 1971) found it to be constant.New high resolution, high signal-to-noise ratio, Spectroscopic observations have been performed at the Observatoire de Haute-Provence in 1996 over 11 nights. The spectral domain covers around 200 Å and is centered on Hδ. Radial velocities were deduced from an auto-correlation technique with a scatter around 0.4kms−1.No high frequency variations are observed. Three frequencies have been detected with a false alarm detection above the 1 % level. A fourth one may be present but its amplitude is below this 1 % level. Results are displayed in Table 1.

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