Phosphorolytic synthesis of cellodextrins

Samain, E.; Lancelon‐Pin, Christine; Férigo, Frédéric; Moreau, Vincent; Chanzy, H.; Heyraud, A.; Driguez, Hugues

doi:10.1016/0008-6215(95)00022-l

Cited by 84 publications

(78 citation statements)

References 21 publications

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“…The wavelength calibration is based on identifying the position of chromospheric lines on the detector and the assumption of neglibible net Doppler flows for these lines. In quiet regions atomic lines and lines from singly ionized species are formed over a limited range in temperature and other physical conditions, and are known to show relatively small average absolute shifts (e.g., Samain 1991). Also, the observed small velocity variations along the slit in these lines indicate that these lines are very useful for establishing an absolute wavelength scale.…”

Section: Wavelength Calibrationmentioning

confidence: 99%

The SUMER spectral atlas of solar-disk features

Curdt

Brekke

Feldman

et al. 2001

A&A

289

292

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Abstract.A far-ultraviolet and extreme-ultraviolet (FUV, EUV) spectral atlas of the Sun between 670Å and 1609Å in the first order of diffraction has been derived from observations obtained with the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory). The atlas contains spectra of the average quiet Sun, a coronal hole and a sunspot on the disk. Different physical parameters prevalent in the bright network (BN) and in the cell interior (CI) -contributing in a distinct manner to the average quiet-Sun emission -have their imprint on the BN/CI ratio, which is also shown for almost the entire spectral range. With a few exceptions, all major lines are given with their identifications and wavelengths. Lines that appear in second order are superimposed on the first order spectra. These lines are clearly marked in the atlas. The spectra include emissions from atoms and ions in the temperature range 6 × 10 3 K to 2 × 10 6 K, i.e., continua and emission lines emitted from the lower chromosphere to the corona. This spectral atlas, with its broad wavelength coverage, provides a rich source of new diagnostic tools to study the physical parameters in the chromosphere, the transition region and the corona. In particular, the wavelength range below 1100Å as observed by SUMER represents a significant improvement over the spectra produced in the past. In view of the manifold appearance and temporal variation of the solar atmosphere, it is obvious that our atlas can only be a -hopefully typical -snapshot. Brief descriptions of the data reduction and calibration procedures are given. The spectral radiances are determined with a relative uncertainty of 0.15 to 0.30 (1σ) and the wavelength scale is accurate to typically 10 mÅ. The atlas is also available in a machine readable form.

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Section: Wavelength Calibrationmentioning

confidence: 99%

The SUMER spectral atlas of solar-disk features

Curdt

Brekke

Feldman

et al. 2001

A&A

289

292

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“…The Doppler shifts listed in Table 6 chromosphere at a temperature close to 6500 K (Chae et al 1998) and are expected to be at the rest velocity of the photosphere (Samain 1991). This velocity is very close to the radial velocity of −23.45 km s −1 obtained from contemporaneous AAT and CORALIE measurements (Pourbaix et al 2002).…”

Section: Turbulent Velocity and Velocity Shifts With Line Formation Tmentioning

confidence: 99%

HST/STIS high resolution echelle spectra ofαCentauri A (G2 V)

Pagano¹,

Linsky²,

Valenti³

et al. 2004

A&A

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Abstract. We describe and analyze HST/STIS observations of the G2 V star α Centauri A (α Cen A, HD 128620), a star similar to the Sun. The high resolution echelle spectra obtained with the E140H and E230H gratings cover the complete spectral range 1133−3150 Å with a resolution of 2.6 km s −1 , an absolute flux calibration accurate to ±5%, and an absolute wavelength accuracy of 0.6-1.3 km s −1 . We present here a study of the E140H spectrum covering the 1140-1670 Å spectral range, which includes 671 emission lines representing 37 different ions and the molecules CO and H 2 . For α Cen A and the quiet and active Sun, we intercompare the redshifts, nonthermal line widths, and parameters of two Gaussian representations of transition region lines (e.g., Si , C ), infer the electron density from the O  intersystem lines, and compare their differential emission measure distributions. One purpose of this study is to compare the α Cen A and solar UV spectra to determine how the atmosphere and heating processes in α Cen A differ from the Sun as a result of the small differences in gravity, age, and chemical composition of the two stars. A second purpose is to provide an excellent high resolution UV spectrum of a solar-like star that can serve as a proxy for the Sun observed as a point source when comparing other stars to the Sun.

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“…Chromospheric lines have been used as a reference (Doschek et al 1976;Athay & Dere 1989;Brekke 1993;Chae et al 1998;Teriaca et al 1999), for the measurement of transition region lines on the disk. The redshift of these chromospheric lines is considered to be negligible as in the case of the photosphere (Samain 1991). Limb motions are also considered negligible, because, statistically, the flow is perpendicular Send offprint requests to: C. Gontikakis, e-mail: cgontik@cc.uoa.gr to the solar surface and the horizontal motions are canceled (Doschek et al 1976;Hassler et al 1991Hassler et al , 1999Peter & Judge 1999).…”

Section: Introductionmentioning

confidence: 99%

Dopplershifts in the solar transition region

Gontikakis

Dara

Alissandrakis

et al. 2001

A&A

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Abstract.We study the dynamics of the quiet sun transition region, using observations obtained with the SOHO CDS/NIS and SUMER spectrographs. We examine the morphology of the network as a function of temperature and we compare the intensity features with those of the dopplergrams. The velocity distributions have a different behaviour for the bright features which outline the network and the dark ones, located in the internetwork. A redshift and a smaller standard deviation are observed for the bright feature distributions relative to the dark ones. It should be mentioned that the internetwork is also statistically redshifted, with the exception of the He i line. Velocity distributions from different lines are compared.

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Phosphorolytic synthesis of cellodextrins

Cited by 84 publications

References 21 publications

The SUMER spectral atlas of solar-disk features

The SUMER spectral atlas of solar-disk features

HST/STIS high resolution echelle spectra ofαCentauri A (G2 V)

Dopplershifts in the solar transition region

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