The Spectrum of Th‐Ar Hollow Cathode Lamps in the 691–5804 nm region: Establishing Wavelength Standards for the Calibration of Infrared Spectrographs

Kerber, F.; Nave, Gillian; Sansonetti, Craig J.

doi:10.1086/590111

Cited by 80 publications

(80 citation statements)

References 30 publications

(33 reference statements)

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“…In addition to that, for the high-resolution NIR spectrograph CRIRES, mounted on the UT1/VLT at the ESO Paranal Observatory in Chile, a ThAr lamp is used for wavelength calibration. This lamp produces more than 1800 lines in the wavelength range of λ = 0.9 to 2.5 μm (Kerber et al 2008), which is only slightly smaller than in the optical. Controversially for the gas cell, the usage of a lamp does not allow us to monitor changes in the response of the instrument.…”

Section: Instrumental Limitationsmentioning

confidence: 93%

Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

Rodler

Burgo

Witte

et al. 2011

A&A

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Context. Radial velocity monitoring of very cool dwarfs such as late M-and hot L-dwarfs has become a promising tool in the search for rocky planets as well as follow-up planetary candidates around dwarfs detected by transit surveys. These stars are faint at optical wavelengths, as their spectral flux distribution peaks at near-infrared (NIR) wavelengths. For this reason, it is desirable to measure the radial velocities in this wavelength regime. However, in the NIR very few medium-and high-resolution spectrographs are available at large telescopes. In the near future, high-resolution spectrographs for the NIR will be built, which will allow us to search for rocky planets around cool M-dwarfs and L-dwarfs from radial velocities monitoring. Aims. We investigate the precision that can be attained in radial velocity measurements of very cool dwarfs in the NIR. The goal is to determine in which atmospheric window of the Earth's atmosphere the highest radial velocity precision can be achieved to help in designing the next generation of NIR high-resolution spectrographs. Methods. We use stellar atmosphere synthetic models for an M-and an L-dwarf with temperatures of 2200 K and 1800 K, respectively, and a theoretical spectrum of the Earth's transmission in the spectral range from 0.9 to 2.5 μm. We simulate a series of Doppler-shifted spectra observed with different resolving powers and signal-to-noise ratios, and for different rotational broadenings of the dwarf. For different combinations of the input parameters, we recover the radial velocity by means of cross-correlation with a high signal-to-noise ratio template and determine the associate uncertainties. Results. The highest precision in radial velocity measurements for the cool M-dwarf is found in the Y band around 1.0 μm, while for the L-dwarf it is determined in the J band around 1.25 μm. We note that synthetic models may lack some faint absorption features or underestimate their abundances. In addition, some instrumental/calibration aspects that are not taken into account in our estimations would increase the uncertainties.

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Section: Instrumental Limitationsmentioning

confidence: 93%

Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

Rodler

Burgo

Witte

et al. 2011

A&A

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“…The CRIRES pipeline is based on the general and coherent approach by ESO using common routines, also employed in other instruments . The wavelength solution is based on a physical model approach for CRIRES (Kerber et al 2008a) using telluric emission lines and the new infrared line catalog for ThAr hollow arc lamps (Kerber et al 2008b). For the extraction of one-dimensional spectra, the data taken for different positions of the star along the slit (resulting from nodding and dithering) are corrected in the usual way for glitches and bad pixels and then rebinned in wavelength space before co-addition.…”

Section: Observationsmentioning

confidence: 99%

Chemical abundances of 11 bulge stars from high-resolution, near-IR spectra

Ryde

Gustafsson

Edvardsson

et al. 2010

A&A

114

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Context. It is debated whether the Milky Way bulge has characteristics more similar to those of a classical bulge than those of a pseudobulge. Detailed abundance studies of bulge stars are important when investigating the origin, history, and classification of the bulge. These studies provide constraints on the star-formation history, initial mass function, and differences between stellar populations. Not many similar studies have been completed because of the large distance and high variable visual extinction along the line-of-sight towards the bulge. Therefore, near-IR investigations can provide superior results. Aims. To investigate the origin of the bulge and study its chemical abundances determined from near-IR spectra for bulge giants that have already been investigated with optical spectra. The optical spectra also provide the stellar parameters that are very important to the present study. In particular, the important CNO elements are determined more accurately in the near-IR. Oxygen and other α elements are important for investigating the star-formation history. The C and N abundances are important for determining the evolutionary stage of the giants and the origin of C in the bulge. Methods. High-resolution, near-infrared spectra in the H band were recorded using the CRIRES spectrometer mounted on the Very Large Telescope. The CNO abundances are determined from the numerous molecular lines in the wavelength range observed. Abundances of the α elements Si, S, and Ti are also determined from the near-IR spectra. Results. The abundance ratios [O/Fe], [Si/Fe], and [S/Fe] are enhanced to metallicities of at least [Fe/H] = −0.3, after which they decline. This suggests that the Milky Way bulge experienced a rapid and early burst of star formation similar to that of a classical bulge. However, a similarity between the bulge trend and the trend of the local thick disk seems to be present. This similarity suggests that the bulge could have had a pseudobulge origin. The C and N abundances suggest that our giants are first-ascent red-giants or clump stars, and that the measured oxygen abundances are those with which the stars were born. Our [C/Fe] trend does not show any increase with [Fe/H], which is expected if W-R stars contributed substantially to the C abundances. No "cosmic scatter" can be traced around our observed abundance trends: the measured scatter is expected, given the observational uncertainties.

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“…The actual values of the energy levels can be found in Table 7. GBCZ74, Giacchetti et al (1974); ZC74, Z76, Zalubas (1976);PE83, Palmer & Engleman (1983);EHW03, Engleman et al (2003); LP07, Lovis & Pepe (2007); KNS08, Kerber et al (2008); RNS13, this publication. An "A" in the last column indicates a measured line that matches more than one classification.…”

Section: Optimized Energy Levels and Ritz Wavelengthsmentioning

confidence: 89%

“…Since we see this same deviation when we compare the PE83 wavenumber measurements to the laser-spectroscopy measurements of DeGraffenreid et al (2012), but not when we compare our own measurements to these standards, this suggests the trend exists in the PE83 line list. Kerber et al (2008) The near-infrared Th/Ar line list of Kerber et al (2008) was based on observations with the 2 m FTS at NIST, the same spectrometer we used to make our measurements. It should be noted that we are using a different beam splitter, mirrors, and detector, and we would not expect any systematics to be common between the observations.…”

Section: Comparison Withmentioning

confidence: 99%

THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

Redman

Nave

Sansonetti

2014

ApJS

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We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350 nm and 1175 nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th i, Th ii, and Th iii). Using the optimized level values, we calculate accurate Ritz wavelengths for 19,874 thorium lines between 250 nm and 5500 nm (40,000 cm −1 to 1800 cm −1 ). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer & Engleman and typographical errors and incorrect classifications in Kerber et al. We also found a large scatter with respect to the thorium line list of Lovis & Pepe. We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.

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The Spectrum of Th‐Ar Hollow Cathode Lamps in the 691–5804 nm region: Establishing Wavelength Standards for the Calibration of Infrared Spectrographs

Cited by 80 publications

References 30 publications

Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

Detecting planets around very cool dwarfs at near infrared wavelengths with the radial velocity technique

Chemical abundances of 11 bulge stars from high-resolution, near-IR spectra

THE SPECTRUM OF THORIUM FROM 250 nm TO 5500 nm: RITZ WAVELENGTHS AND OPTIMIZED ENERGY LEVELS

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