J/AJ/107/1868 Cyclic period variability in SW Cyg (Berrington+, 1994)
The cyclic period variability in SW Cygni
BERRINGTON R.C., HALL D.S.
<Astron. J. 107, 1868 (1994)>
=1994AJ....107.1868B 1994AJ....107.1868B (SIMBAD/NED Reference)
ADC_Keywords: Binaries, eclipsing
Abstract:
Timings of primary eclipse up through 1992 are collected, plus a few
overlooked in earlier studies. Analysis shows that, after decreasing
until ∼1919 and increasing since then, the period has now started
decreasing again, with the inflection point of the O-C curve being
∼1972. The shortest period was 4.5727 days, the longest 4.5732 days,
with a full cycle length of 96 yr. Explanation by the time-delay
effect, due to orbital motion around a third body, would require an
unseen black hole companion of ≥10M☉. A magnetic cycle operating
in the K-type subgiant, an active dynamo star because of its convection
and rapid rotation, is the best explanation.
Addresses:
Berrington R.C. & Hall D.S.
Dyer Observatory, Vanderbilt University, Nashville, Tennesee 37235
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 47 226 Times of primary minimum for SW Cygni
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 5 I5 --- Cycle Cycle number
7- 13 F7.4 d O-C O-C curve value
15- 21 F7.4 d O-C' O-C' curve value
23- 35 F13.4 d JD Julian date
38- 43 F6.4 d Error []? Uncertainty or error in original source
44 A1 --- n_Error Weights assigned by Slovochotova (1954)
46- 47 I2 --- Ref Reference (1)
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Note (1): References:
1. Slovochotova 1954, P.Z., 10, 21 [pg,vp,ve]
2. Whitney 1959, AJ, 64, 258 [pg]
3. Szczepanowska 1956, AcA, 6, 144 [ve]
4. Lange 1959b, Astr. Circ. No. 201, 13 [ve]
5. Lange 1960, Astr. Circ. No. 209, 23 [ve]
6. Walter 1971, A&A, 13, 249 [pe]
7. Hall 1968, IBVS, No. 281 [pe]
8. Hall, Garrison 1972, PASP, 84, 552 [pe]
9. Frieboes-Conde, Herczeg 1973, A&AS, 12, 1 [pe]
10. Hall et al. 1979, AcA, 29, 653 [pe]
11. B.B.S.A.G. [ve]
12. Olson 1981, IBVS Mo. 1938 [pe]
13. Olson 1982, ApJ, 259, 702 [pe]
14. Flin 1983, M.V.S. 9, 89 [ve]
15. Kordylewski 1963, IBVS No. 35 [ve]
16. Scholz 1964, Harthaer Beobachtungs Zirkular No. 28 [pg]
17. B.A.A.V.S.S. [ve]
18. Struve 1946, ApJ, 104, 253 [sp]
19. Baldwin 1973, IBVS No. 795 [ve]
20. Parenago 1931, Russian AJ, 8, 229 [pg,vp]
pg = photographic
pe = photoelectric
sp = spectroscopic
ve = visual estimates
vp = visual photometer
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References:
Slovochotova N.P., 1954, P.Z., 10, 21
Origin: AAS CD-ROM series, Volume 3, 1995
(End) Lee Brotzman [ADS] 16-Aug-1994, Patricia Bauer [CDS] 15-Feb-1995