Binary Stars among Cataclysmic Variables. III. Ten Old Novae.

ome of the spectroscopic and photometric properties of ten old novae of the spring, summer, and y autumn shy are considered. To the four binaries previously known (T CrB, DQ Her, T Aur, WZ ) are added GK Per (1901), V603 Aql (1918), and V1017 Sgr (1901, 1919). Orbits are given for the two of these three; the last is judged a binary from its composite spectrum. Two other novae, which e unusually narrow emission lines and show no certain velocity variations at the dispersions , are shown very probably to be pole-on objects. Since seven of the ten objects studied are certainly binaries, the hypothesis is advanced that member- in a certain type of close-binary system is a necessary condition for a star to become a nova. A binary el similar to that advanced earlier to explain the U Gem systems (Kraft 1962) is invoked for novae; te difficulties with its application to the case of VZ Sge are cited. A relationship, having a width of about + 1.5 mag., is shown to exist between the absolute magnitude he red component (at minimum h.ght) and the orbital period, in the sense that the brighter is the imal magnitude of the red star, the longer is the period. `ith decreasing period comes increasing tness of the red star relative to the blue. There is a tendency for the masses of novae to increase with easing period and higher luminosity. The masses so far found for novae range from 0.1 to 3 , and the luminosities from +10 ainter to 1. Any universal mechanism advanced to explain the outbursts of novae cannot depend mgly on mass or position in the HR diagram. [t is concluded that novae can belong to any population of stars, provided that population contains te close binaries of the appropriate hind. Most of them will therefore be found in stellar populations taining many binaries, such as the galactic disk, but their occasional presence in Type II systems is inctly possible. It is suggested that the frequency of novae per unit mass in a stellar system is a sure of angular momentum within that system.