view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Orion absorption spectra of two novae. McLaughlin, Dean B. Abstract Orion spectra have not been reported previously for the two novae discussed here. Nova V 528 A quilae (ip45). This nova reached magnitude 6.9 at maximum on August 26 and declined 3 mag. 1n 35 days. Secondary oscillations though small were probably real. Observations beginning August 31 showed a normal and smooth spectral devel6pment. Velocities of principal and diffuse enhanced systems are given in Table I. TABLE I. NOVA AQUILAE 1945: ABSORPTION VELOCITIES (KM/SEC) Date. UT Principal Diffuse enhanced II 112 III 1112 Aug. 31 -1135 .... -2040 Sept. 5 -1180 -1370 -2085 -2280 12 -1210 -1460 -2215 -2520 20 -1270 -1555 .... -2635: Oct. 2 -1250 -1630 Weak Orion lines first appeared Sept. 4. By Sept. 12 several lines were present, but on Sept. 21 the Orion system suddenly developed maximum strength which lasted, with variations, until Sept. 30, then rapidly weakened. Numerous lines of Hei, 011, and NIl were present, but NIlI was not surely recorded and no "nitrogen flaring" was observed. Velocity was about - 2500 km/sec with slight changes until Sept. 17, but individual lines were discordant. Oscillations then set in, as shown in Table II. Such oscillations characterize Orion spectra of novae that have large secondary light variations, but it is remarkable to find them associated with a fairly smooth decline. Nevertheless, the changes, Sept. 24-27, anticipated by a few days a small but definite brightening. Similar correlations have been noted in other- novae. CP Lacertae 1936, with a smooth decline, also had an Orion spectrum that oscillated strongly. TABLE II. NOVA AQUILAE 1945: ORION VELOCITIES (KM/SEc) Date, UT Velocity Date, UT Velocity Sept. 17 -2485 Sept. 25 -2505 -2675 26 -2295 19 -2600 27 -2160 20 -2570 30 -2285 21 -2460 Oct. 2 -2280 24 -2745 Nova V 450 Cygrn (1942). This star of Nova Herculis type was discovered nearly 3 months after maximum, and spectrographic observation began only 8 days before the steep decline. Principal and diffuse enhanced components had velocities ranging from -500 to -1500 km/sec. Orion lines were present Sept. 15-22, with velocities given in Table III. Especially note- TABLE III. NOVA CYGNI 1942: ORION VELOCITIES (KM/SEC) Date, UT Velocity Date, UT Velocity Sept. 15 -1335 Sept. 19 -1425 16 -1260 20 -1285 17 -1105 21 -1455 i8 -1410 22 -1400, -1575 worthy was the clear doubling on Sept. 22. On the two following days no Orion lines were measurable, and other absorptions were weakening as decline set in. The velocity oscillation, Sept. 15-18, anticipated by one or two days an increase and decrease of more than one magnitude. The author is grateful for the use of Mount Wilson, Lick, and McDonald spectrograms, and for a grant from Faculty Research Funds of the Graduate School, University of Michigan. Observatory, University of Michigan, Ann Arbor, Mich. Publication: The Astronomical Journal Pub Date: 1953 DOI: 10.1086/106925 Bibcode: 1953AJ.....58R.220M full text sources ADS | data products SIMBAD (2)