Lick Observatory Bulletins Volume a -A - 131-175
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 edition. Excerpt: ...that have been suggested as to the cause of their variability and test these explanations, as far as possible, by means of the observed facts. The principal characteristics of stars of this type are: 1. Their light varies without pause. 2. The amount of their light variation is usually about one magnitude. 3. Their periods are short--a few days only. 4. They are of a spectral type approximately solar; no Orion, Sirian or Antarian stars having been found among them. 5. They seem to be found in greater numbers in certain parts of the sky, notably in the Milky Way,17 but exhibit no tendency to form close clusters. 6. All those stars whose radial velocities have been studied have been found to be binaries, whose period of orbital revolution coincides with that of their light change. 7. The orbits, so far as determined, are all small, a sin i being 2,000,000 km. or less. 8. Their maximum light synchronizes very closely with their maximum velocity of approach, and minimum light with maximum velocity of recession.18 9. No case has been found in which the spectrum of more than one component has been bright enough to be recorded in the spectrograms. The first mentioned characteristic sharply separates these stars from stars of the Algol type, whose light curves always contain horizontal straight lines; and the eighth shows that their variation cannot be due to occultation by the dark companion, since in that case minimum must occur at inferior conjunction. The third property makes it imperative that a theory, to be successful, should connect the light variation with the orbital revolution. In his discussion of the orbit of Geminorum,1" Dr. Campbell suggested tidal disturbances20 in an atmosphere surrounding the brighter component, due...
- 189 x 246 x 5mm | 177g
- 13 Sep 2013
- United States
- black & white illustrations