Effect of fluctuations in Doppler width on the center of strong absorption lines

Details Effect of fluctuations in Doppler width on the center of strong absorption lines Effect of fluctuations in Doppler width on the center of strong absorption lines

Dec 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011ap.....54..581s&link_type=abstract

Astrophysics, Volume 54, Issue 4, pp.581-592

Astronomy and Astrophysics

Astrophysics

Turbulence: Fluctuations: Absorption Lines

Scientific paper

Stochastic temperatures and turbulence are characterized by average velocities u th and < u turb > ≡ u 0 and fluctuations {u'_{th}} and u' (< u' > = 0). Thus, the Doppler width of a line also has a fluctuating component Δ {λ '_D} . Observed spectra correspond to the radiative flux averaged over time and over a star's surface, . Usually, only the average velocities u th and u 0 are taken into account in photospheric models and these yield the Doppler width Δ λ_D^{(0)} of a line in the customary way. The fluctuations Δ {λ '_D} mean that near a line center the average absorption coefficient < αλ > is larger than the usual αλ, which depends only on the average velocities u th and u 0. This enhances the absorption line near the center and is not explained by the photospheric models. This new statistical effect depends on the wavelength of the line. A comparison of observed lines with model profiles yields an estimate for the average level of fluctuations in the Doppler width, η = {{{left< {left| {Δ {{λ '}_D}} right|} rightrangle }} left/ {{Δ λ_D^{(0)}}} right.} , which characterizes the average stochasticity of a photosphere and is important for understanding the physics of photospheres. The depths of lines in synthetic spectra of stars are often greater than the observed values. The observed disagreement between the theoretical and actually observed depths of lines can be corrected by introducing an additional parameter, the fluctuation level η. Then it is possible to obtain estimates of η for a number of stars.

Affiliated with

Also associated with

No associations

Rating

Effect of fluctuations in Doppler width on the center of strong absorption lines does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Effect of fluctuations in Doppler width on the center of strong absorption lines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Effect of fluctuations in Doppler width on the center of strong absorption lines will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1892065