nova_balmer_decrement¶

Nebular extinction of a nova, symbiotic star or H II region from the observed H-alpha / H-beta Balmer decrement on a reduced, flux-calibrated (or at least relatively calibrated) spectrum: the two line fluxes are fitted, compared with the Case B intrinsic ratio, and turned into c(H-beta), E(B-V) and A_V with the CCM89 law. The same conventions for every observer of the campaign.

Conventions¶

Intrinsic H-alpha / H-beta = 2.86 (Case B, T_e = 10^4 K, n_e = 10^2 cm^-3), R_V = 3.1 with the CCM89 law, Gaussian line fluxes within 8 Angstrom of the rest wavelengths. The spectrum must be flux-calibrated in relative terms (the ratio matters, not the absolute scale); a strongly reddened nova with self-absorbed Balmer lines (Case B not applicable) is outside the recipe's validity, as the brick's documentation states.

References¶

• Osterbrock & Ferland 2006, Astrophysics of Gaseous Nebulae and AGN, 2nd ed., Table 4.4 and section 7.2 - Case B decrement and c(H-beta)
• Cardelli, Clayton & Mathis 1989, ApJ 345, 245 - the extinction law used to convert c(H-beta) into E(B-V)

Variables¶

This recipe declares no variables: it runs as is.

Steps¶

Run it¶

spectro pipeline nova_balmer_decrement --input spectrum.fits
spectro preset show nova_balmer_decrement      # variables and steps

from spectro_kernel import WorkContext
from spectro_kernel.pipeline import PipelineBuilder

pipeline = PipelineBuilder().from_preset("nova_balmer_decrement").build()
result = pipeline.execute(ctx)        # ctx holds the spectrum / frames
print(result.history[-1])             # pipeline:<name> vX.Y.Z + variables

{
  "tool": "run_preset",
  "arguments": {
    "session_id": "<session_id>",
    "preset_name": "nova_balmer_decrement"
  }
}