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J/A+A/308/481      Metallic line doubling phenomenon in RR Lyrae (Chadid+, 1996)
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Observation of the metallic line doubling phenomenon in the variable star
RR Lyrae.
      Chadid M., Gillet D.
     <Astron. Astrophys. 308, 481 (1996)>
     =1996A&A...308..481C      (SIMBAD/NED BibCode)
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ADC_Keywords: Line Profiles ; Stars, variable
Keywords: hydrodynamics - shock waves - stars: pulsation -
          stars: individual: RR Lyrae

Description:
    For the first time, the observation of the line doubling phenomenon
    over two metallic absorption lines of a RR Lyrae star (RR Lyr) is
    reported. A resolving power of 42,000 and a time resolution close to
    1% of the pulsating period were necessary. Although a smaller exposure
    time would be required to completely resolve this phenomenon over the
    whole spectrum, we interpret it as the consequence of a "two-step"
    Schwarzschild's mechanism. Thus a strong shock wave propagating
    throughout the photosphere around phase 0.93 would be at the origin of
    the observed line doubling. Because the shock undergoes a sudden
    acceleration phase, a "jump" appears in the line profile evolution.
    The shock is first receding and then almost stationary. Our
    qualitative interpretation needs a theoretical confirmation with the
    help of a nonlinear nonadiabatic pulsational model with an extended
    atmosphere taking into account the presence of shock waves.
    Nevertheless it appears from our observations that the dynamics of the
    atmosphere of RR Lyr is important just above the photosphere and that
    strong shock exists at this level because the doubling is already
    present in FeI lines.

Ojects:
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    RA   (2000)   DE        Name
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    19 25 28.3 +42 47 14    RR Lyr = HD 182989
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File Summary:
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  FileName      Lrecl  Records   Explanations
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ReadMe             80        .   This file
table1             52       92  *Journal of the spectrovelocimetric 
				 observations of RR Lyr
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Note on table1: 
    this table corresponds to table1 and table2 of the printed version
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Byte-by-byte Description of file: table1
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   Bytes Format Units   Label     Explanations
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   2-  8  F7.3  ---     Phi       Phase (1)
  10- 22  F13.4 d       JD        Julian Date
  24- 26  I3    s       Time      Exposure time
  28- 29  I2    ---     S/N       Signal to noise ratio
  31- 38  F8.3  km/s    HRV       Heliocentric radial velocity
  40- 45  F6.3  km/s    Sigma     FWHM/2.35 of the line
  47- 52  F6.4  ---     Amp       Line deep
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Note (1): According to the ephemeris:
          HJD (maximum brightness) = 2444003.8537 + 0.566839*E.
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(End)                                             Simona Mei [CDS]   18-Sep-1995