57 lines
2.7 KiB
Python
57 lines
2.7 KiB
Python
from ..target.ATarget import ATarget
|
|
from ..SpectralQty import SpectralQty
|
|
import astropy.units as u
|
|
from astropy.modeling.models import BlackBody
|
|
from esbo_etc.lib.helpers import error
|
|
|
|
|
|
class BlackBodyTarget(ATarget):
|
|
"""
|
|
This class models the spectral flux density of a star of given magnitude using as black body radiator
|
|
"""
|
|
# Bands from Handbook of Space Astronomy and Astrophysics
|
|
# band_sfd = {"U": 1790*u.Jansky, "B": 4063*u.Jansky, "V": 3636*u.Jansky, "R": 3064*u.Jansky,
|
|
# "I": 2416*u.Jansky, "J": 1590*u.Jansky, "H": 1020*u.Jansky, "K": 640*u.Jansky}
|
|
_band = dict(U=dict(wl=366 * u.nm, sfd=4.175e-11 * u.W / (u.m ** 2 * u.nm)),
|
|
B=dict(wl=438 * u.nm, sfd=6.32e-11 * u.W / (u.m ** 2 * u.nm)),
|
|
V=dict(wl=545 * u.nm, sfd=3.631e-11 * u.W / (u.m ** 2 * u.nm)),
|
|
R=dict(wl=641 * u.nm, sfd=2.177e-11 * u.W / (u.m ** 2 * u.nm)),
|
|
I=dict(wl=798 * u.nm, sfd=1.126e-11 * u.W / (u.m ** 2 * u.nm)),
|
|
J=dict(wl=1220 * u.nm, sfd=3.15e-12 * u.W / (u.m ** 2 * u.nm)),
|
|
H=dict(wl=1630 * u.nm, sfd=1.14e-12 * u.W / (u.m ** 2 * u.nm)),
|
|
K=dict(wl=2190 * u.nm, sfd=3.96e-13 * u.W / (u.m ** 2 * u.nm)))
|
|
|
|
@u.quantity_input(wl_bins='length', temp=[u.Kelvin, u.Celsius], mag=u.mag)
|
|
def __init__(self, wl_bins: u.Quantity, temp: u.Quantity = 5778 * u.K,
|
|
mag: u.Quantity = 0 * u.mag, band: str = "V"):
|
|
"""
|
|
Initialize a new black body point source
|
|
|
|
Parameters
|
|
----------
|
|
wl_bins : length-Quantity
|
|
Wavelengths used for binning
|
|
temp : Quantity in Kelvin / Celsius
|
|
Temperature of the black body
|
|
mag : Quantity in mag
|
|
Desired apparent magnitude of the point source
|
|
band : str
|
|
Band used for fitting the planck curve to a star of 0th magnitude. Can be one of [U, B, V, R, I, J, H, K].
|
|
|
|
Returns
|
|
-------
|
|
"""
|
|
if band not in self._band.keys():
|
|
error("Band has to be one of '[" + ", ".join(list(self._band.keys())) + "]'")
|
|
# Create blackbody model with given temperature
|
|
bb = BlackBody(temperature=temp, scale=1 * u.W / (u.m ** 2 * u.nm * u.sr))
|
|
|
|
# Calculate the correction factor for a star of 0th magnitude using the spectral flux density
|
|
# for the central wavelength of the given band
|
|
factor = self._band[band]["sfd"] / (bb(self._band[band]["wl"]) * u.sr) * u.sr
|
|
# Calculate spectral flux density for the given wavelengths and scale it for a star of the given magnitude
|
|
sfd = bb(wl_bins) * factor * 10 ** (- 2 / 5 * mag / u.mag)
|
|
|
|
# Initialize super class
|
|
super().__init__(SpectralQty(wl_bins, sfd))
|