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import astropy.units as u
from astropy.coordinates.sky_coordinate import SkyCoord
from astropy.units import Quantity
from astroquery.gaia import Gaia
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%matplotlib inline
import matplotlib.pyplot as plt
import numpy as np
# Suppress warnings. Comment this out if you wish to see the warning messages
import warnings
warnings.filterwarnings('ignore')
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from astroquery.gaia import Gaia
tables = Gaia.load_tables(only_names=True)
for table in (tables):
print (table.get_qualified_name())
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import math
au = 4.84813681 * 10 ** (-6) # [pc]
M = 1.9884 * 10 ** 30 * 10 ** 3 # [g]
radius = 150 # [pc]
parallax = math.atan2( au , radius) / math.pi * 180 * 10 ** 3 * 60 ** 2
query = "SELECT source_id,parallax FROM gaiadr2.gaia_source WHERE (parallax>=" + str(parallax) +")"
job = Gaia.launch_job_async(query, dump_to_file=True)
r = job.get_results()
rows = len(r)
n = []
X = []
Y = []
R = radius + 1
for j in range (10, R, 10):
number = 0
for i in range(1,rows):
if r['parallax'][i] >= math.atan2( au , j) / math.pi * 180 * 10 ** 3 * 60 ** 2:
number = number + 1
n = n + [number]
X = X + [j]
for k in range(0,len(X)):
y = n[k] * M / (4 / 3 * math.pi * (X[k] * 3.08567758 * 10 ** 18) **3)
Y = Y + [y]
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plt.title("The density of the amount of matter in the visible stars\n")
plt.plot(X,Y,'o')
plt.xlabel("distance [pc]")
plt.ylabel("density of matter [g / cm ^ 3]")
plt.xscale('log')
plt.yscale('log')
plt.show()
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import pandas as pd
table = pd.DataFrame({
" distance [pc] ":X,
"density of matter [g / cm ^ 3]":Y,
})
print(table)
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plt.title("The number of the visible stars\n")
plt.plot(X,n,'o')
plt.xlabel("distance [pc]")
plt.ylabel("number")
plt.xscale('log')
plt.yscale('log')
plt.show()
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N = []
for l in range(0,len(X)):
nn = n[l] / (4 / 3 * math.pi * X[l] ** 3)
N = N + [nn]
plt.title("The number density of the visible stars\n")
plt.plot(X,N,'o')
plt.xlabel("distance [pc]")
plt.ylabel("number density [/ pc^3]")
plt.xscale('log')
plt.yscale('log')
plt.show()
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