J/A+AS/129/289 Long-term spectrophotometry of Be stars (Moujtahid+ 1998)
Long-term visual spectrophotometric behaviour of Be stars
Moujtahid A., Zorec J.
<Astron. Astrophys. Suppl. Ser. 129, 289 (1998)>
=1998A&AS..129..289M 1998A&AS..129..289M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, Be ; Spectrophotometry
Keywords: Stars: Spectrophotometry, variability - Stars: Be
Abstract:
The long-term spectrophotometric variations of 49 Be stars are studied
using the U and V magnitudes of the UBV system, the total Balmer
discontinuity D and the visible gradient Φrb. BCD
(Barbier-Chalonge-Divan, see Chalonge & Divan, 1952AnAp...15..201C 1952AnAp...15..201C)
spectrophotometric and photometric data in five different photometric
systems, obtained in most cases since 1950 and reduced to the BCD
system, were used. The (U,D), (V,D), (Φrb,D) and (Φrb,V)
correlations obtained differ from star to star and they can be single
or double-valued. They differ clearly for Be phases or Be-shell
phases. Be stars with small V.sin(i) showing the "spectrophotometric
shell behaviour": D>D*, were found. This finding implies either
that strongly flattened models of circumstellar envelopes are in doubt
for these stars, or that not all Be stars are rapid rotators.
Comparison of observed variations with those predicted for model Be
stars with spherical circumstellar envelopes of variable densities and
dimensions implies that spectrophotometric patterns of Be phases are
due to circumstellar envelopes in low opacity regimes, while those of
spectrophotometric shell phases are due to circumstellar envelopes in
high opacity regimes. In a given star, the envelope regions
responsible for the observed variations of D and Φrb in
spectrophotometric shell phases seem to be smaller and denser than
those producing the observed variations of these parameters in
spectrophotometric Be phases. The high positive RV found in strong
shell phases might favor the formation of compact circumstellar layers
near the star.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 27 49 Star positions (from Simbad database)
table1.dat 198 49 The studied Be stars
refs.dat 125 198 References of table1.dat
fig/* . 24 *Figures
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Note on fig/*: Spectrophotometric behaviour of Be stars.
Symbols are:
bullet: BCD data
+: UBV data
star: UBVRI data
triangle: Geneva photometry
diamond: uvby data
square: 13 colour photometry data
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See also:
III/187 : Classification of stars in BCD (Barbier/Chalonge/Divan)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/135) number
8- 9 I2 h RAh Right ascension (J2000.0)
11- 12 I2 min RAm Right ascension (J2000.0)
14- 17 F4.1 s RAs Right ascension (J2000.0)
19 A1 --- DE- Declination sign
20- 21 I2 deg DEd Declination (J2000.0)
23- 24 I2 arcmin DEm Declination (J2000.0)
26- 27 I2 arcsec DEs Declination (J2000.0)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- HD HD (Cat. III/145) number
8- 11 I4 --- HR ? HR (Cat. V/50) number
13- 25 A13 --- Name Other name
27- 40 A14 --- SpType Spectral type
42 A1 --- n_SpType [a] Note on spectral type (1)
44- 53 A10 --- FigFile Figure name in subdirectory fig
55- 59 F5.3 mag Dstar Stellar Balmer discontinuity magnitude
60 A1 --- u_Dstar Uncertainty flag on Dstar
61 A1 --- n_Dstar [a] Note on Dstar (2)
63- 66 F4.2 mag <Vmag> Average V magnitude
68- 71 F4.2 mag e_<Vmag> rms uncertainty on <Vmag>
73- 78 F6.3 mag <Dmag> Average total Balmer discontinuity magnitude
80- 84 F5.3 mag e_<Dmag> rms uncertainty on <Dmag>
86- 89 F4.2 mag <Phirb> Average visible gradient
91- 94 F4.2 mag e_<Phirb> rms uncertainty on <Phirb>
96-100 I5 --- JDf First observation date (-2400000)
101 A1 --- n_JDf [-] Dash
102-106 I5 --- JDl Last observation date (-2400000)
108-110 I3 --- N Number of individual triads (Vmag, Dmag, Phirb)
112-198 A87 --- Ref References detailed in file refs.dat
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Note (1): An a indicates spectral classification form the BCD system.
Otherwise, it is taken from the
Hipparcos Input Catalogue (Turon et al. 1992, Cat. I/196),
Buscombe (1977, 1980, 1981, 1988, See Cat. III/189),
Hubert-Delplace & Hubert (1979, An Atlas of Be Stars,
Obs. de Paris-Meudon and Obs. de Haute-Provence),
Sletteback (1982ApJS...50...55S 1982ApJS...50...55S),
the Bright Star Catalogue (Cat. V/50), and Supplement (Cat. V/36)
Note (2): An a indicates BCD values of Dstar, otherwise Dstar is the mean value
for the adopted MK spectral classification.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Ref Reference number
5- 23 A19 --- BibCode Simbad bibcode
25-125 A101 --- Aut Author name, and comments
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Acknowledgements: Ali Moujtahid
(End) Patricia Bauer [CDS] 20-Apr-1998