Preliminary results of spectrographic observations of 7 epsilon Aurigae.

Abstract

view Abstract Citations (15) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Preliminary results of spectrographic observations of 7 epsilon Aurigae. Struve, O. ; Elvey, C. T. Abstract During the eclipse of 7 Aurigae in 1928-1930 many absorption lines were unsym- metrical; in the beginning of the eclipse they were sharp on the red side; in the middle of the eclipse they were approximately symmetrical; and in the latter part of the eclipse they were sharp on the violet side. Most of the strong lines showed this effect. However, the strong line Mg~ ~8r and most of the faint lines remained symmetrical throughout the eclipse. The absorption lines were appreciably strengthened during eclipse. The line Hfl was found to be practically black near the center. In the exact center, however, there appeared a narrow emission line. The contour of the H~3 line photographed during the eclipse agrees closely with Unsold's theoretical curve, giving for NHf, 2.5 X ~ The absence of wings suggests that Stark effect is not present, and that the pressure in the reversing layer is very low. The radial velocity shows oscillations having a period of about iio days. These are independent of the eclipse. The period is variable from one oscillation to the next, and the amplitude does not remain constant. The shape of the curve is also variable. These oscillations are probably related to the ftuctuatioiis in light discovered by Stebbins, Fri. Güssow, and McLaughlin. H$ and many other strong lines gave discc~rdant velocities in 1928-1930. In the first part of the eclipse they gave more positive velocities than the fainter lines, while in the latter part the velocities were much too small, disagreeing completely with Ludendorif's velocity-curve. This effect was well shown by XX zi~i~z~, 4468, 4583, etc., and is probably related to the unsymmetrical broadening of these lines. The sym- metrical lines, e.g., X 4481, give radial velocities in good agreement with Ludendorif's curve. The variation in velocity with a period of 27.1 years is confirmed. It proceeds in agreement with the predicted curve. Outside the eclipse there occurred no appreciable changes in the character of the ab- sorption lines. Most of them were weaker than during the time of the eclipse. No trace of the spectrum of the second component of the long-period binary system could be found at the time of maximum relative velocity (1922-1923) Publication: The Astrophysical Journal Pub Date: March 1930 DOI: 10.1086/143237 Bibcode: 1930ApJ....71..136S full text sources ADS |