H-alpha Intensity Research Articles

Observations of southern emission-line stars

A catalog of 1929 stars showing H-alpha emission on photographic plates is presented which covers the entire southern sky south of declination -25 deg to a red limiting magnitude of about 11.0. The catalog provides previous designations of known emission-line stars equatorial (1900) and galactic coordinates, visual and photographic magnitudes, H-alpha emission parameters, spectral types, and notes on unusual spectral features. The objects listed include 16 M stars, 25 S stars, 37 carbon stars, 20 symbiotic stars, 40 confirmed or suspected T Tauri stars, 16 novae, 14 planetary nebulae, 11 P Cygni stars, 9 Bep stars, 87 confirmed or suspected Wolf-Rayet stars, and 26 'peculiar' stars. Two new T associations are discovered, one in Lupus and one in Chamaeleon. Objects with variations in continuum or H-alpha intensity are noted, and the distribution by spectral type is analyzed. It is found that the sky distribution of these emission-line stars shows significant concentrations in the region of the small Sagittarius cloud and in the Carina region.

THE SPECTRAL ENERGY DISTRIBUTION OF NGC 1275.

ABSTRACT An analysis of absolute spectral energy distributions for NGC 1275 (Per A) covering the wavelength interval from 3300 A to 10,800 A is presented. The data are consistent with the heavy reddening discovered by Wampler (1971). The H-alpha intensity varied by less than 10% between the times of Wampler's earlier measurements and the two occasions of the present observations. The line-emitting region has a characteristic density of about 10 to the 4.5 power per cu cm, a mass of about 10 to the 5.5 power solar masses, and a volume filling factor of about 10 to the -6th power. The gas may be ionized by shock waves or by nonthermal or stellar radiation. It is suggested, in the vein of Minkowski's (1957) original proposal, that the high-velocity emission-line knots described by Minkowski are H II regions in a Perseus-cluster galaxy or intergalactic gas cloud seen in projection against NGC 1275.

Emission-line stars in the Chamaeleon T association.

view Abstract Citations (63) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Emission-line stars in the Chamaeleon T association. Henize, K. G. ; Mendoza v, E. E. Abstract Objective-prism spectrum surveys conducted in 1962 and in 1970 reveal 32 stars showing Ha emission in the region of the Chamaeleon T association. Twelve of these stars show variations in either continuum intensity or Ha intensity. The magnitudes range from V = 8.4 (spectrum B9.5 Ve) to approximately 16. Slit spectra have been obtained of 13 stars. Seven show classifiable absorptionline spectra, four show completely veiled continua, and two lack blue spectra. The veiling is strongly correlated with variability. The second brightest emission-line star, CD - , shows significant spectrum variations between 1962 and 1972. Subject headings: associations - emission-line stars - spectral classification - variable stars Publication: The Astrophysical Journal Pub Date: February 1973 DOI: 10.1086/151948 Bibcode: 1973ApJ...180..115H full text sources ADS | data products SIMBAD (35)