J/A+A/477/917 Beta Cephei stars in the ASAS-3 data. II. (Pigulski+, 2008)
Beta Cephei stars in the ASAS-3 data.
II. 103 new Beta Cephei stars and a discussion of low-frequency modes.
Pigulski A., Pojmanski G.
<Astron. Astrophys. 477, 917 (2008)>
=2008A&A...477..917P 2008A&A...477..917P
ADC_Keywords: Stars, early-type - Stars, OB - Stars, variable - Surveys
Keywords: stars: early-type - stars: oscillations - stars: binaries: eclipsing -
stars: variables: general - surveys
Abstract:
We analysed ASAS-3 photometry of bright early-type stars with the goal
of finding new Beta Cephei stars. We were particularly interested in
Beta Cephei stars that would be good for seismic analysis, i.e., stars
that (i) have a large number of excited modes, (ii) show rotationally
split modes, (iii) are components of eclipsing binary systems, (iv)
have low-frequency modes, that is, are hybrid Beta Cephei/SPB stars.
Our study was made with a homogeneous sample of over 4100 stars having
MK spectral type B5 or earlier. For these stars, the ASAS-3 photometry
was analysed by means of a Fourier periodogram. We have discovered 103
Beta Cephei stars, nearly doubling the number of previously known
stars of this type. Among these stars, four are components of
eclipsing binaries, seven have modes equidistant or nearly equidistant
in frequency. In addition, we found five Beta Cephei stars that show
low-frequency periodic variations, very likely due to pulsations. We
therefore regard them as candidate hybrid Beta Cephei/SPB pulsators.
All these stars are potentially very useful for seismic modeling.
Moreover, we found Beta Cephei-type pulsations in three late O-type
stars and fast period changes in one, HD 168050.
Description:
Time-series V-filter ASAS-3 photometry for 103 new Beta Cephei stars
is presented. Out of the original photometry, made in five apertures,
we chose that which had the smallest errors. In addition, measurements
made in different fields were accounted for zero point differences,
detrended and combined.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 140 103 Stars observed: names, and first mode parameters
(table1 and excerpts from table2 of paper)
lc2.dat 42 47137 Time-series photometry
table7.dat 114 24 The results of the verification of variability of
22 O and early B-type candidate short-period
variables observed by Hipparcos and found by
Koen (2001MNRAS.321...44K 2001MNRAS.321...44K) and
Koen & Eyer (2002, Cat. J/MNRAS/331/45)
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See also:
II/264 : ASAS Variable Stars in Southern hemisphere (Pojmanski+ 2002-05)
J/A+A/477/907 : Beta Cephei stars in the ASAS-3 data. I. (Pigulski+, 2007)
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 number of the star (Cat. III/135)
8- 15 A8 --- DM BD/CPD star number
17- 29 A13 --- ASAS-3 ASAS-3 number (Cat. II/264)
31 I1 --- Modes Number of variation modes found
33- 37 F5.2 mag Vmag Johnson V magnitude
39- 43 F5.2 mag B-V ? Color index (B-V)
45- 49 F5.2 mag U-B ? Color index (U-B)
51- 65 A15 --- SpType MK spectral type
68 I1 --- r_SpType ? Reference of spectral type (1)
72- 75 I4 --- Nobs Nmber of observations
77- 85 F9.6 d-1 f1 Frequency of first mode
87- 88 I2 10-6d-1 e_f1 ? Mean error on f1
91- 94 F4.1 mmag A1 ? Amplitude of first mode
96- 98 F3.1 mmag e_A1 ? Mean error on A1
101-140 A40 --- Rem Remarks
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Note (1): references to the MK spectral types as follows:
1 = Houk & Cowley (1975, Cat. III/31)
2 = Houk (1978, Cat. III/51)
3 = Houk (1982, Cat. III/80)
4 = Houk & Smith-Moore (1988, Cat. III/133)
5 = Houk & Swift (1999, Cat. III/214)
6 = Hill (1970MNRAS.150...23H 1970MNRAS.150...23H)
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Byte-by-byte Description of file: lc2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [HD]
4- 9 I6 --- HD Star HD number
13- 25 F13.5 d HJD Heliocentric Julian Day
28- 34 F7.4 mag Vmag Johnson V-filter magnitude
38- 42 F5.3 mag e_Vmag Error of Vmag
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 5 I5 -- HIP HIP number
7- 12 I6 --- HD(E) HD(E) number
14- 26 A13 --- ASAS-3 ASAS-3 number (Cat. II/264)
28- 32 F5.2 mag Vmag V magnitude
34- 41 F8.5 d-1 fH Hipparcos frequency
43- 46 F4.1 mmag AH Hipparcos amplitude
48- 54 F7.5 d-1 fA ?=- ASAS frequency
56- 59 F4.1 mmag AA ?=- ASAS amplitude
61- 64 F4.1 --- S/N ?=- Signal-to-noise ratio
66- 69 F4.1 mmag DT ? Detection threshold
71-114 A44 --- Rem Remarks
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Acknowledgements:
Andrzej Pigulski, pigulski(at)astro.uni.wroc.pl
(End) Andrzej Pigulski [UWr, Poland], Patricia Vannier [CDS] 04-Dec-2007