deproject_sbp.py: split "AstroParams" to module "astro_params.py"

1 files changed, 33 insertions, 0 deletions

diff --git a/astro_params.py b/astro_params.py
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index 0000000..a272ba4
--- /dev/null
+++ b/astro_params.py
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+# -*- mode: python -*-
+#
+# Weitian LI
+# Created: 2016-06-24
+# Updated: 2016-06-24
+#
+
+"""
+This module contains the parameters/constants used in astronomy
+and astrophysics.
+"""
+
+import astropy.units as au
+
+
+class AstroParams:
+    """
+    The parameters/constants used in astronomy.
+
+    References:
+    [1] ref. [4], eq.(9) below
+    """
+    # Hubble constant at z=0
+    H0 = 71.0  # [ km/s/Mpc ]
+    # density of non-relativistic matter in units of the critical density
+    # at z=0
+    OmegaM0 = 0.27
+    # ratio of electron density (n_e) to proton density (n_p) [1]
+    ratio_ne_np = 1.211
+    # molecular weight per electron (0.3 solar abundance; grsa table) [1]
+    mu_e = 1.155
+    # atomic mass unit
+    m_atom = au.u.to(au.g)  # [ g ]