Helium abundance of ejecta from V1500 Cygni (Nova Cygni 1975)

Journal Article · Sun Jan 15 04:00:00 EST 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155818· OSTI ID:6467772

Ferland, G J

The He emission spectrum of V1500 Cygni (Nova Cygni 1975) was studied in the nebular phase of the outburst. The steep Balmer decrement is interpreted as evidence for optical depth in the Balmer series. The observed strength of H..beta.. was corrected for self-absorption by matching observed and predicted Balmer decrements. He I recombination lines yield the He/sup +/ abundance. The good agreement between the abundances obtained from triplet (lambda 5876) and singlet (lambda 6678) lines shows that these lines are unaffected by optical-depth and collisional excitation effects. The He/sup + +/ abundance was derived from the He II line lambda 5412. The principal result is that the He abundance is identical to that found in planetary nebulae, He/H = 0.11 +- 0.01. The He/sup +//H ratio decreases and the He/sup + +//H ratio increases in the interval, but the total abundance He/H is constant to within the errors. This agreement constitutes a check on the analysis. The color temperature of the ionizing radiation field is derived by matching the observed ratio He/sup + +//He/sup +/ with that of the models of Hummer and Mihalas. The color temperature increased from below 5 x 10/sup 4/ K on day 10 to about 1.7 x 10/sup 5/ K by day 300. High temperatures during the late decline are supported by the presence of strong lines of (Ne V) and (Fe VII). 6 figures, 1 table.

• Research Organization: Univ. of Texas, Austin
• OSTI ID: 6467772
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 219:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALMER LINES
CHEMICAL COMPOSITION
CHEMISTRY
COSMOCHEMISTRY
CRYOGENIC FLUIDS
ELEMENTS
EMISSION SPECTRA
ERUPTIVE VARIABLE STARS
FLUIDS
HELIUM
NONMETALS
NOVAE
RARE GASES
SPECTRA
SPECTROPHOTOMETRY
STARS
VARIABLE STARS