Open AccessScandium and chromium in the strontium filament in the Homunculus of η Carinae
Author(s) -
Bautista M. A.,
Ballance C.,
Gull T. R.,
Hartman H.,
Lodders K.,
Martínez M.,
Meléndez M.
Publication year - 2009
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2008.14246.x
Subject(s) - physics , strontium , ejecta , astrophysics , abundance (ecology) , scandium , radiative transfer , atomic physics , chromium , astrochemistry , protein filament , excitation , abundance of the chemical elements , electron excitation , electron , interstellar medium , chemistry , stars , supernova , nuclear physics , biochemistry , organic chemistry , quantum mechanics , fishery , biology , galaxy
We continue a systematic study of chemical abundances of the strontium filament found in the ejecta of η Carinae. To this end we interpret the emission spectrum of Sc ii and Cr ii using multilevel non‐local thermodynamic equilibrium models. Since the atomic data for these ions were previously unavailable, we carry out ab initio calculations of radiative transition rates and electron impact excitation rate coefficients. The observed spectrum is consistent with an electron density of the order of 10 7 cm −3 and a temperature between 6000 and 7000 K, conditions previously determined from [Ni ii ], [Ti ii ] and [Sr ii ] diagnostics. The observed spectrum indicates an abundance of Sc relative to Ni more than 40 times the solar value, while the Cr/Ni abundance ratio is roughly solar. Various scenarios of depletion and dust destruction are suggested to explain such abnormal abundances.