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Wavelength shifts in solar-type spectra

Dravins, Dainis LU ; Lindegren, Lennart LU ; Ludwig, Hans-Günter LU and Madsen, Søren LU (2005) 13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun In European Space Agency, (Special Publication) ESA SP 560. p.113-119
Abstract
Spectral-line displacements away from the wavelengths naively expected from the Doppler shift caused by stellar radial motion may originate as convective shifts (correlated velocity and brightness patterns in the photosphere), as gravitational redshifts, or perhaps be induced by wave motions. Absolute lineshifts, in the past studied only for the Sun, are now accessible also for other stars thanks to astrometric determination of stellar radial motion, and spectrometers with accurate wavelength calibration. Comparisons between spectroscopic apparent radial velocities and astrometrically determined radial motions reveal greater spectral blueshifts in F-type stars than in the Sun (as theoretically expected from their more vigorous convection),... (More)
Spectral-line displacements away from the wavelengths naively expected from the Doppler shift caused by stellar radial motion may originate as convective shifts (correlated velocity and brightness patterns in the photosphere), as gravitational redshifts, or perhaps be induced by wave motions. Absolute lineshifts, in the past studied only for the Sun, are now accessible also for other stars thanks to astrometric determination of stellar radial motion, and spectrometers with accurate wavelength calibration. Comparisons between spectroscopic apparent radial velocities and astrometrically determined radial motions reveal greater spectral blueshifts in F-type stars than in the Sun (as theoretically expected from their more vigorous convection), further increasing in A-type stars (possibly due to atmospheric shockwaves). Work is in progress to survey the spectra of the Sun and several solar-type stars for "unblended" photospheric lines of most atomic species with accurate laboratory wavelengths available. One aim is to understand the ultimate information content of stellar spectra, and in what detail it will be feasible to verify models of stellar atmospheric hydrodynamics. These may predict bisectors and shifts for widely different classes of lines, but there will not result any comparison with observations if such lines do not exist in real spectra, or are too blended for meaningful measurement. An important near-future development to enable a further analysis of stellar surface structure will be the study of wavelength variations across spatially resolved stellar disks, e.g., the center-to-limb wavelength changes along a stellar diameter, and their spatially resolved time variability. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
keywords
Radial velocities, Line profiles, Photiospheres, Wavelength
in
European Space Agency, (Special Publication) ESA SP
volume
560
pages
113 - 119
publisher
European Space Agency
conference name
13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun
external identifiers
  • wos:000231306900015
  • scopus:23844456583
ISSN
0379-6566
1609-042X
language
English
LU publication?
yes
id
9024efc6-8502-4874-95c2-12964a87ff62 (old id 615496)
alternative location
http://www.astro.lu.se/~dainis/Papers/astro-ph_0409212.pdf
date added to LUP
2007-11-25 09:49:31
date last changed
2017-10-01 03:57:42
@inproceedings{9024efc6-8502-4874-95c2-12964a87ff62,
  abstract     = {Spectral-line displacements away from the wavelengths naively expected from the Doppler shift caused by stellar radial motion may originate as convective shifts (correlated velocity and brightness patterns in the photosphere), as gravitational redshifts, or perhaps be induced by wave motions. Absolute lineshifts, in the past studied only for the Sun, are now accessible also for other stars thanks to astrometric determination of stellar radial motion, and spectrometers with accurate wavelength calibration. Comparisons between spectroscopic apparent radial velocities and astrometrically determined radial motions reveal greater spectral blueshifts in F-type stars than in the Sun (as theoretically expected from their more vigorous convection), further increasing in A-type stars (possibly due to atmospheric shockwaves). Work is in progress to survey the spectra of the Sun and several solar-type stars for "unblended" photospheric lines of most atomic species with accurate laboratory wavelengths available. One aim is to understand the ultimate information content of stellar spectra, and in what detail it will be feasible to verify models of stellar atmospheric hydrodynamics. These may predict bisectors and shifts for widely different classes of lines, but there will not result any comparison with observations if such lines do not exist in real spectra, or are too blended for meaningful measurement. An important near-future development to enable a further analysis of stellar surface structure will be the study of wavelength variations across spatially resolved stellar disks, e.g., the center-to-limb wavelength changes along a stellar diameter, and their spatially resolved time variability.},
  author       = {Dravins, Dainis and Lindegren, Lennart and Ludwig, Hans-Günter and Madsen, Søren},
  booktitle    = {European Space Agency, (Special Publication) ESA SP},
  issn         = {0379-6566},
  keyword      = {Radial velocities,Line profiles,Photiospheres,Wavelength},
  language     = {eng},
  pages        = {113--119},
  publisher    = {European Space Agency},
  title        = {Wavelength shifts in solar-type spectra},
  volume       = {560},
  year         = {2005},
}