This version includes the following added features: (i) Inclusion of all elements up to Z=30. The atomic data for the energy level structure of ions with 3 or more electrons for many of these are scaled hydrogenic and so the associated line emission must be treated with caution. (ii) Inclusion of two new input parameters: the radius exponent (radexp) and the number of continuum energy bind (ncn2). These are described in the chapter on input to xstar. (iii) Inclusion of the radiation scattered in resonance lines as a column in the output fits file xout_spect1.fits. This is provided in the same units of specific luminosity as the other columns. (iv) Use of a new algorithm for the multilevel calculation which is considerably faster and requires less storage. Hence smaller values of critf (even 0) can be accomodated for many problems. (v) The input parameter critf now refers to the fractional ion abundance (i.e. relative to the parent element) rather than the absolute (i.e. relative to H) ion abundance. (vi) Minor changes have been made to some of the output formats in the ascii file xout_step.lis. (vii) The atomic data for dielectronic recombination has been changed to incorporate the results from Badnell and coworkers (http://amdpp.phys.strath.ac.uk/tamoc/DATA/RR/) in place of the rates from [] and []. This has quantitative effects on many of the results from xstar. Notable is the effect on the ionization balance of iron for ionization parameters in the range 0 2, where the m-shell ions dominate, and where the new rates are greater than the previous ones by large factors.

- Version v2.2.1 (April 2010)
- Version v2.2.1bc (September 2010)
- Version v2.2.1bg (May 2011)
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- Version v2.2.1bk (January 2012)
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- v2.2.1bn18 (Jan. 2014)
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- v2.2.1bn20 (Mar. 2014)
- v2.2.1bn21 (May. 2014)