Open AccessThe electron pressure in the outer atmosphere of ε Eri (K2 V)
Author(s) -
Jordan C.,
Sim S.A.,
McMurry A.D.,
Aruvel M.
Publication year - 2001
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 - 10.1046/j.1365-8711.2001.04599.x
Subject(s) - physics , space telescope imaging spectrograph , chromosphere , flux (metallurgy) , line (geometry) , electron , spectrograph , spectral line , astrophysics , emission spectrum , electron density , atomic physics , atmosphere (unit) , hubble space telescope , astronomy , nuclear physics , meteorology , stars , materials science , geometry , mathematics , metallurgy
Observations of ε Eri (K2 V) have been made with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope . The spectra obtained show a number of emission lines which can be used to determine, or place limits on, the electron density and pressure. Values of the electron pressure are required in order to make quantitative models of the transition region and inner corona from absolute line fluxes, and to constrain semi‐empirical models of the chromosphere. Using line flux ratios in Si iii and O iv a mean electron pressure of P e =N e T e =4.8×10 15 cm −3 K is derived. This value is compatible with the lower and upper limits to P e found from flux ratios in C iii , O v and Fe xii . Some inconsistencies which may be because of small uncertainties in the atomic data used are discussed.