An Approximation to Effective Temperature from the Curve of Growth.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS An Approximation to Effective Temperature from the Curve of Growth. Beardsley, W. R. Abstract The value of stellar opacity as determined from curve of growth analysis by Greenstein's method is used to calculate an absorption temperature. The same basic assumptions as made by Greenstein are involved, namely: (1)Abundance is quantitatively the same as a Persei. (2) Iron exists nearly all as Fe ii. In addition, a standard stellar abundance scale must also be assumed. For this I chose that of Aller as given by Suess and Urey, (1956, Revs. Modern Phys. 28, 56). This is used to calculate electron scattering from electron pressure and ionization temperature and to determine a value for hydrogen abundance. The negative hydrogen absorption is calculated from electron pressure and the H- absorption coefficient is as given by Chandrasekhar and Breen using ionization temperature to enter the table. Subtracting the electron scattering and the H- absorption from the stellar opacity gives the hydrogen absorption. Correcting this value for induced emission, ionization, and abundance, one can then use it in the fundamental relation between hydrogen absorption and temperature, solving for absorption temperature. The solution leads to a very sensitive determination of temperature. However, since H- absorption was originally derived using ionization temperature, one must now use this temperature to get a new value of H absorption and then re-solve for a new absorption temperature. Three such iterations are usually sufficient to achieve a change in temperature of less than 5~. A final absorption temperature is then adopted to be the nearest multiple of 250. The true probable error is difficult to estimate, however, an absorption temperature so determined should be of the same order of accuracy as the ionization temperature. Results for supergiants in the range FO to F8 give temperatures very close to the effective temperatures for this range as derived by Popper from the recently determined interferometric diameter of Sirius. Results for dwarfs give temperatures very much in excess, particularly those for the sun. This difficulty can be directly traced to the assumed hydrogen abundance. When improved values of the hydrogen abundance become available, this method should provide reasonable approximation to effective temperatures. Publication: The Astronomical Journal Pub Date: 1960 DOI: 10.1086/108069 Bibcode: 1960AJ.....65Q.341B full text sources ADS |