Supergiant Eclipsing Binary BM CAS

Abstract

Observatory.-On the plates of the Harvard Patrol Collection, 6037 photographic estimates were obtained for this eclipsing system. We observed the behavior of the variable over an interval of more than 50 years and confirmed the irregularities in its maximum brightness shown by the photographic observations in the 1930's, particularly the "hump" (0 m 16) immediately after the primary minimum that seems to be a permanent feature of the system. The photographic light curve is tabulated in an abbreviated form : OpOOO 9 m 88 0p475 9 m 96 0p600 10 m 23 0p800 9 m 86 0.100 9.90 0.500 10.07 0.650 9.94 0.850 9.76 0.200 9.92 0.525 10.25 0.700 9.78 0.900 9.85 0.300 9.83 0.560 10.34 0.735 9.69 0.950 9.85 0.400 9.86 0.575 10.32 0.775 9.79 0.975 9.86The photoelectric observations, covering one complete cycle, were obtained in three colors on 56 nights during 1961-62. We used a photometer attached to the 24'' reflector at the George R. Agassiz Station of the Harvard College Observatory. The effective wavelengths of our system are similar to those of the UBV system. A 1P21 photomultiplier and a Brown recorder were used. The photoelectric light curve is similar to the photographic one, but shows detailed features : (2) The hump after the primary minimum is sharply defined and becomes more pronounced towards shorter wavelengths. Its amplitudes are about 0 m 126 in yellow and 0T279 in ultraviolet lights.(3) Other secondary fluctuations, especially strong before and after the primary minimum, appear on both the light and the color curves.(4) The color curves also indicate that the system has the largest color indices a few days after, possibly also before the mid-eclipse, but not during it.The photometric elements of BM Gas are : Min. = JD 2433859.0 +197 d 31E ; rni = 10 m 34, m 2 = 9 m 92, Mx = 9 m 69 (hump) ; the phase of the primary minimum is 0?56 (arbitrary).Since the system is a Beta Lyrae type and the secondary minimum is small and irregular, its dimensions are difficult to derive with certainty. They are, however, between those found by G. Thiessen (Z. Astrophys. 39, 65, 1956) and S. Gaposchkin {Harvard Ann. 113, No. 2, 1953).A Cislunar Orbit (IMP). Barbara E. Shute, Goddard Space Flight Center.-The orbital changes of a proposed cislunar satellite (IMP) have been investigated. Under the disturbing influence of the moon, the eccentricity changes from 0.95 to 0.85 in one year and the inclination (to the equator) moves from 33° to 48°-that is, a change of 15° with respect to the equator or 25° with respect to the plane of the ecliptic. In six years, the eccentricity decreases to a minimum of 0.209 and returns to 0.95 in 12 years, but perigee at this time is approximately 1 earth radius, indicating the demise of the satellite. The case quoted above assumes a ratio of semimajor axes of satellite to moon, a/a'=+ equivalent to a satellite period about 6 days. (Orbital changes are not due to sharp commensurability of the mean motions of the moon and satellite.) The other parameters are e 0 (eccentricity) =0.95, i 0 (inclination) =33...

BM Cas – a long-period eclipsing young supergiant binary system in common envelope stage

“…Also sporadic colour variations (like the one claimed in ref. [8]) were observed from time to time. How these transient phenomena can be interpreted in terms of the physical parameters of circumbinary gas in the frame of the proposed model?…”

Problems of the Algol Systems

“…In any case, we have a strong feeling that we see a bump just after the primary minimum, at a phase which is not very different from the corresponding phase of U Cep (14). A recent and striking example of a hump just after the primary minimum is given by BM Cas (15).…”