scholarly journals High-Resolution 3 μm Spectroscopy of Extreme Carbon Stars

1987 ◽  
Vol 120 ◽  
pp. 387-390
Author(s):  
J.-P. Maillard ◽  
S.C. Foster ◽  
T. Amano ◽  
P.A. Feldman
Keyword(s):  
Fourier Transform ◽  
Silicon Nitride ◽  
High Resolution ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Fourier Transform Spectrometer ◽  
Carbon Stars ◽  
Signal To Noise ◽  
Fundamental Band ◽  
Upper Limits

We have used the Cassegrain-focus Fourier Transform Spectrometer of the Canada-France-Hawaii Telescope to record high-resolution (0.03 cm−1), high signal-to-noise ratio spectra of the extreme carbon stars IRC+10°216 and CIT6 in the 2850–3100 cm−1 region. Upper limits were obtained for the column densities of silicon nitride (2-0 band of the A-X system), ethylene (ν11 fundamental band at ν0 = 2988.7 cm−1), and ethane (ν7 fundamental band at ν0 = 2985.4 cm−1).

scholarly journals A New Multichannel Fourier Transform Spectrometer

1999 ◽  
Vol 170 ◽  
pp. 36-40
Author(s):  
Tyler E. Nordgren ◽  
Arsen R. Hajian
Keyword(s):  
Fourier Transform ◽  
Extrasolar Planets ◽  
Signal To Noise Ratio ◽  
Fourier Transform Spectrometer ◽  
Test Bed ◽  
Signal To Noise ◽  
Stellar Spectra ◽  
Band Emission ◽  
Noise Ratio ◽  
Ratio Scales

AbstractStellar spectra have been obtained using a multichannel Fourier Transform Spectrometer (FTS) which incorporates components of the Navy Prototype Optical Interferometer. It is well known that a FTS can provide superior wavelength stability as compared to traditional spectrometers. Unfortunately the FTS traditionally suffers from exceptionally poor sensitivity, which until now has limited its uses to sources with high fluxes and/or those with narrow band emission (e.g. the Sun, nebulae, and laboratory samples). We present stellar observations using a new FTS design which overcomes this sensitivity limitation by using a conventional multichannel spectrometer in conjunction with the FTS system. The signal-to-noise ratio of spectra from our test-bed observations are consistent with the theoretical prediction and show that for N channels the sensitivity scales like N, while the signal-to-noise ratio scales like . With this type of an instrument on a 3-m telescope and 9 000 channels we expect to be able to detect and measure such exciting astrophysical phenomenon as gravitational redshifts from single, main sequence stars and extrasolar planets of terrestrial mass.

scholarly journals A high signal-to-noise HST spectrum towards J1009+0713: precise absorption measurements in the CGM of two galaxies

2019 ◽  
Vol 489 (1) ◽  
pp. 78-98 ◽  
Author(s):  
Cassandra Lochhaas ◽  
Smita Mathur ◽  
Stephan Frank ◽  
Debopam Som ◽  
Yair Krongold ◽  
...  
Keyword(s):  
Galactic Halo ◽  
Hubble Space Telescope ◽  
Signal To Noise Ratio ◽  
Noise Spectrum ◽  
High Signal ◽  
Signal To Noise ◽  
Additional Absorption ◽  
Upper Limits ◽  
Collisional Ionization ◽  
Density Ratios

ABSTRACT High signal-to-noise spectra towards background quasars are crucial for uncovering weak absorption in the circumgalactic medium (CGM) of intervening galaxies, such as the diagnostic lines of N v that provide insight to the ionization process of warm gas but typically have low equivalent widths. We present a new spectrum from the Hubble Space Telescope with a signal-to-noise ratio of ∼20–35 towards the quasar SDSS J1009+0713 and analyse absorption systems in the CGM of two L⋆ galaxies close to the line of sight. We identify additional absorption in the CGM of these galaxies that was not reported by the previous lower signal-to-noise spectrum, as well as Milky Way absorbers and quasar outflows from J1009+0713. We measure log (NN v/NO vi) ∼ −1.1 for two CGM absorbers, inconsistent with gas in collisional ionization equilibrium and consistent with a radiatively cooling bulk flow of ∼50–150 km s−1, which could be produced by galactic winds. These column density ratios are also consistent with those found for other L⋆ galaxies and for some gas in the Milky Way’s halo. We place upper limits of log (NN v/NO vi) < −1.8 to −1.2 for other O vi absorbers in the same haloes, which suggests that O vi is produced by different processes in different parts of the CGM, even within the same galactic halo. Together with the kinematically different structure of high- and low-ionization lines, these results indicate there are many components to a single galaxy’s gaseous halo. We find the redshift number density of Ly α forest absorbers and broad Ly α absorbers are consistent with expectations at this redshift.

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.

A search for interstellar H + 3

1981 ◽  
Vol 303 (1480) ◽  
pp. 543-549 ◽  
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Interstellar Space ◽  
Fourier Transform Spectrometer ◽  
National Observatory ◽  
Laboratory Observation ◽  
Fundamental Band ◽  
Molecular Ion ◽  
Recent Laboratory

Based on the results of recent laboratory observation of the infrared v2 fundamental band of the H3 molecular ion, the possibility of observing this important ion in interstellar space is discussed. An observation of this spectrum has been attempted with the aid of the high-resolution Fourier transform spectrometer on the 4 m Mayall telescope of the Kitt Peak National Observatory.

scholarly journals The 12C/13C Ratio in Unevolved Cool Stars

1988 ◽  
Vol 132 ◽  
pp. 589-592
Author(s):  
Y. Chmielewski ◽  
D. L. Lambert
Keyword(s):  
High Resolution ◽  
Preliminary Analysis ◽  
Isotope Ratio ◽  
Signal To Noise Ratio ◽  
Carbon Isotope Ratio ◽  
High Signal ◽  
Reasonable Accuracy ◽  
Signal To Noise ◽  
Dwarf Stars ◽  
Cool Stars

We show that the carbon isotope ratio 12C/13C in the atmosphere of dwarf stars can be determined with reasonable accuracy from high resolution, high signal-to-noise ratio observations of the CH G-band in their spectra. Lines suitable for this purpose are selected from consideration of the solar case, for which 12C/13C = 89 is derived. A preliminary analysis of these features in the spectra of μ Her, δ Eri and τ Cet yields 12C/13C values of 84, 80 and 150 respectively.

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