J/A+A/308/481 Metallic line doubling phenomenon in RR Lyrae (Chadid+, 1996)
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 1996A&A...308..481C (SIMBAD/NED BibCode)
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