Model Atmosphere Spectra Research Articles

X-ray emission from the planetary nebula NGC 1360

The EXOSAT observatory has detected the nucleus of NGC 1360 in four photometric energy bands. The data rules out that the emission is from blackbody origin. Initial fits made with LTE model atmosphere spectra require the presence of highly ionized Oxygen and Neon in the stellar atmosphere.

CA II H and K lines in A type stellar spectra

view Abstract Citations (1) References (38) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS CA II H and K lines in A type stellar spectra Panek, R. J. ; Stutman, D. R. Abstract High-quality, high-resolution photoelectric and photographic spectra of Alpha CMa and Gamma Gem are used to obtain the profiles of the Ca II H and K lines. These profiles are analyzed using theoretical spectra of model atmospheres to determine the calcium abundance and to study the structure of the stellar atmosphere. Calcium is found to be underabundant in Sirius. Publication: The Astrophysical Journal Pub Date: July 1980 DOI: 10.1086/158147 Bibcode: 1980ApJ...239..598P Keywords: A Stars; Line Spectra; Metallic Stars; Stellar Atmospheres; Stellar Spectra; Balmer Series; Calcium; H Lines; K Lines; Astrophysics full text sources ADS |

The microwave spectrum of venus in the frequency range 18–36 Gc/sec

The microwave emission from Venus was measured at seven frequencies in the interval 18 to 36 Gc/sec in July 1964 shortly after inferior conjunction. The resulting spectrum shows a fairly smooth but rapid decrease in the planet's brightness toward the higher frequencies. The measurements are compared with the spectra of several model atmospheres which contain CO 2, N 2, water vapor, liquid water clouds, and high dust or ice clouds. None of the model spectra exactly fit all the present measurements. A best fit for the model in which absorption is due to CO 2 and N 2 requires a surface pressure of about 200 atm. A best fit for the model which contains, in addition, water vapor and liquid water clouds requires about 12 gm/cm 2 of the vapor and 0.06 gm/cm 2 of liquid water clouds at a temperature of 240°K. The nicest agreement is provided by a model which contains scattering particles. For dust particles of mean diameter 0.3 mm and dielectric constant 5, the required number of particles is 2.5 × 10 6/cm 2.