SP_ACE spectral analysis tool

SP_ACE computes stellar parameters (gravity, temperature) and element abundances from optical stellar spectra (sample spectrum). It employs 1D stellar atmosphere models in Local Thermodynamic Equilibrium (LTE).

The present service does not offer all the options available for SP_Ace as documented in the tutorial. All options are available if running SP_Ace locally (cf. download page).

This service exposes an updated version containing some bug fixes with respect to the one described in the paper.

ASCII file with two columns: wavelength (in Angstrom) and continuum normalized flux. The spectrum must be radial velocity corrected (wavelengths in rest frame). The spectral resolution power should be between 2000 and 20000. SP_Ace handles spectra in the stellar parameters intevals Teff=[3600,7400]K, logg=[0.2,5.0], [M/H]=[-2.4,0.4]dex.
Starting value for estimation of FWHM of the instrument line profile.
Give up to five wavelength intervals you want to analyze, starting from the lowest. Intervals not covered by the library will be ignored. The default setting is the range of wavelenghts currently processed by the software.
Force solver to assume this temperature. Leave empty to let SP_Ace estimate this parameter.
Force solver to assume this gravity. Leave empty to let SP_Ace estimate this parameter.
Force solver to assume this signal to noise ratio on every pixel. Suggestion: Leave empty to let SP_Ace to estimate this parameter pixel-by-pixel.
Make SP_Ace estimate errors (this increases runtime significantly).
If selected, the output will only contain two abundances: 'alphas' and 'metals', which are the estimation of the abundances of alpha-process elements and non-alpha-process elements as if they were one element. Hint: This option is mostly useful with low-resolution (R ~ 2000) spectra. See the tutorial for more details.
Process the spectrum with the normalization provided by the user? This option switches off the internal re-normalization done by SP_Ace. Suggestion: Do not set unless you are absolutely sure that your normalization is right.
This parameter determines the flexibility of the curve used to fit the continuum during the re-normalization of the spectrum. The higher the number the more rigid the curve is (see discussion in the tutorial and in Sec.7.4 of the paper). Suggestion: leave the default value unless you know very well what you are doing.
Switch on the loop that iteratively derives stellar parameters (Teff, log g, [M/H]) and chemical abundances. Suggestion: do not set (see Sec. 8.5.1 of the paper). If your spectrum has low resolution (R ~ 2000), see discussion in the tutorial.

The Data Center is currently running in emergency mode after our database server failed catastrophically (see our blog for infos and updates).

This means, in particular, that services built on top of large tables may currently be broken. Since our replacement server is much slower than our usual machine, restoring them will take quite some time.

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