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Evidence for a 6 Year Periodicity in X Persei

Published online by Cambridge University Press:  14 August 2015

J. D. Dorren  and
E. F. Guinan
J. D. Dorren
Affiliation:
Biruni Observatory, Shiraz University, Shiraz, Iran
E. F. Guinan
Affiliation:
Villanova University, Villanova, Pennsylvania, 19085, USA

Extract

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Intermediate and narrow-band photoelectric observations obtained at Biruni and Villanova Observatories from 1977 to the present, when combined with previous data, strongly suggest that light increases of about 0.5 mag occur at 6 year intervals. Possible explanations are considered.

The X-ray pulsator X Persei (4U 0352+30) is an intriguing object at both X-ray and optical wavelengths. From the X-ray data a period of 13.9 minutes now appears well-established, but early suggestions of a 22.4 hour periodicity remain unconfirmed (White et al.,1976, Becker et al., 1979). The nature of the X-ray emission is unusual; the source is about 3 orders of magnitude weaker than other X-ray binary pulsars, and the spectrum contains a strong high-energy X-ray component (Mushotzky et al., 1977). Long known as an irregular variable, X Per has been classified as a Be star with an 09.5 (III-IV)e spectral type and showing broad hydrogen emission and absorption features (Brucato and Kristian 1972, Hutchings et al., 1975). A 581-day period is indicated by the radial velocity study of Hutchings et al., (1975). This has been variously interpreted as an orbital period (about a black hole) or an apsidal period, the models having in common accretion on to a neutron star as the source of the pulsed X-rays. In 1977 an increase in brightness of the star was observed by Kalv (1977) and Guinan et al., (1978), and by April 1979 we had accumulated sufficient evidence to suggest that X Per undergoes periodic (≃ 6-year) outbursts (Dorren et al., 1979a).

Type
VI. X-Ray Binaries
Information
Symposium - International Astronomical Union , Volume 88: Close Binary Stars: Observations and Interpretation , 1980 , pp. 361 - 365
Copyright
Copyright © Reidel 1980 

References

Becker, R.H., Boldt, E.A., Holt, S.S., Pravdo, S.H., Robinson-Saba, J., Serlemitsos, P.J., and Swank, J.H.: 1979, Astrophys. J. Letters 227, pp 21–24.Google Scholar
Brucato, R.J., and Kristian, J.: 1972, Astrophys. J. Letters 173, pp. 105–107.Google Scholar
Dorren, J.D., Guinan, E.F., and McCook, G.P.: 1979a, I.A.U. Circ. No. 3352.Google Scholar
Dorren, J.D., Guinan, E.F., McCook, G.P. and Siah, M.J.: 1979b, in preparation.Google Scholar
Guinan, E.F., Dorren, J.D., Siah, M.J. and Koch, R.H.: 1979, Astrophys. J. 229, pp. 296–303.Google Scholar
Guinan, E.F. and McCook, G.P.: 1974, Pub. Astron. Soc. Pac. 86, pp. 947–951.Google Scholar
Guinan, E.F., McCook, G.P. and Dorren, J.D.: 1978, I.A.U. Circ. No. 3182.Google Scholar
Harris, D.L.: 1956, Astrophys. J. 123, pp. 371–372.Google Scholar
Hiltner, W.A., 1956, Astrophys. J. Suppl. 2, pp. 389–462.Google Scholar
Hutchings, J.B., Cowley, A.P., Crampton, D., Redman, R.O.: 1974, Astrophys. J. Letters 191, pp. 101–104.CrossRefGoogle Scholar
Hutchings, J.B., Crampton, D., and Redman, R.O.: 1975, Monthly Notices Roy. Astron. Soc. 170, pp. 313–324.CrossRefGoogle Scholar
Kalv, P.: 1977, Inf. Bull. Var. Stars. No. 1359.Google Scholar
Margon, B., Bowyer, S., and Penegor, G.: 1976, Monthly Notices Roy. Astron. Soc. 176, pp. 217–223.CrossRefGoogle Scholar
Mook, D.E., Boley, F.I., Foltz, C.B., and Westpfahl, D.: 1974, Pub. Astron. Soc. Pac. 86, pp. 894–898.Google Scholar
Müller, G., and Kempf, P.: 1907, Astron. Nachr. 175, pp. 162–166.Google Scholar
Mushotzky, R.F., Roberts, D.H., Baity, W.A., and Peterson, L.E.: 1977, Astrophys. J. 211, pp. 129–133.Google Scholar
Underhill, A.: 1960, in Stellar Atmospheres, ed. Greenstein, J.L., Univ. of Chicago Press.Google Scholar
White, N.E., Mason, K.O., Sanford, P.W. and Murdin, P.: 1976, Monthly Notices Roy. Astron. Soc. 176, pp. 201–215.Google Scholar