Engineering Papers⌕ Search

Engineering topics

Persson, S. E.

Publications and source records attributed to Persson, S. E..

43 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

The V - /2.2 micron/ colors of elliptical galaxies

Infrared photometric measurements of 19 normal and giant elliptical galaxies are reported which were made with apertures having diameters 0.1 to 1.3 times the visual galactic diameters. The derived V (2.2 micron) colors, ranging from 3.15 to 3.60 magnitudes, are compared with the results of Grasdalen (1975) for 28 spiral and elliptical galaxies. All but one of the present magnitudes are found to be systematically brighter than Grasdalen's by 0.07 to 0.46 magnitude, and no significant radial color gradient is observed.

Frogel, J. A.↗
NASA NTRS1974

Infrared emission from the southern H II region H2-3

The H II region H2-3 has been found to have a large infrared flux with a luminosity of 100,000 to 200,000 solar luminosity values between 1.65 and 25 microns. Most of this flux comes from a single component with a diameter of 110 sec (2 pc). At 2.2 microns there is an unresolved source which is identified as the exciting star of the nebula; it can provide the required ionization and the total luminosity observed at infrared wavelengths. The 3- to 25 micron radiation is shown to be consistent with dust heated by L-alpha radiation within the nebula, but much of the 40- to 350-micron radiation probably originates from outside the H II region.

Becklin, E. E.↗
NASA NTRS1974

Stellar content of the nuclei of elliptical galaxies determined from 2.3 micron CO band strengths

Observations of the luminosity sensitive CO absorption band at 2.3 micron are presented for the nuclei of 16 epsilon and SO galaxies. Preliminary data on the radial variation of the CO index in 6 galaxies are also given. The data show that the 2-u radiation from the nuclei is dominated by high luminosity stars of integrated spectral type later than K5. There is only a small variation in the CO absorption from galaxy to galaxy, and only a slight variation with measuring aperture size from 17.5 in. to 59 in. The data can be used to synthesize stellar populations for elliptical galaxy nuclei.

Frogel, J. A.↗
NASA NTRS1973

Infrared emission from the southern H 2 region H2-3

The H 2 region H2-3 has been found to have a large infrared flux with a luminosity of 100,000 to 200,000 solar luminosity between 1.65 and 25 microns. Most of this flux comes from a single component with the diameter of 110 in; (2 pc). At 2.2 microns there is an unresolved source which is identified as the exciting star of the nebula; it can provide the required ionization and the total luminosity observed at infrared wavelengths. The 3- to 25- microns radiation is shown to be consistent with dust heated by L alpha radiation within the nebula, but much of the 40- to 350- microns radiation probably originates from outside the H 2 region.

Becklin, E. E.↗