Stellar Parameter Inference
and
Transit False Positive Probabilities
(isochrones)
(vespa)
Timothy Morton
(Princeton)
I have X-, Y-, and Z-band photometry of a star.
What kind of star is it?
~$ pip install isochrones
~$ ipython
In [1]: from isochrones.dartmouth import Dartmouth_Isochrone
In [2]: from isochrones import StarModel
In [3]: dar = Dartmouth_Isochrone()
In [4]: model = StarModel(dar, X=(12, 0.05), Y=(11, 0.05), Z=(10, 0.05))
In [5]: model.fit()
from python terminal/script:
X = 12, 0.05
Y = 11, 0.05
Z = 10, 0.05
mystar/star.ini
$ starfit mystar
From command line:
X = 12, 0.05
Y = 11, 0.05
Z = 10, 0.05
Teff = 5300, 80
feh = -0.1, 0.1
logg = 4.6, 0.15
mystar/star.ini
$ starfit mystar
Also:
X = 12, 0.05
Y = 11, 0.05
Z = 10, 0.05
delta_X = 1.2, 0.05
Teff = 5300, 80
feh = -0.1, 0.1
logg = 4.6, 0.15
mystar/star.ini
$ starfit mystar --binary
Or:
- In principle can use arbitrary stellar model grids
- 3-d linear interpolation in (M, log(age), [Fe/H])
- Any observable property can be called at any (in-bounds) values of (M, log(age), [Fe/H]); thus any property provided by stellar grids can be used as observed data for conditioning model
-
Uses MultiNest to fit by default; will use emcee if MultiNest not installed.
-
Uses local [Fe/H] prior based on SDSS
Demo
To do
- Update other built-in model grids (e.g., Padova)
- Try out cubic interpolation?
- Refactor data back-end to more easily accommodate denser grids?
I have a transit signal.
What is the probability it's an astrophysical false positive?
~$ pip install vespa
name = myplanet
ra = 296.003693
dec = 44.277561
rprs = 0.012585031528
period = 384.845905
photfile = myphotometry.csv
[constraints]
maxrad = 1.26
secthresh = 0.000120176767205
g = 13.8735234, 0.05
r = 13.3370844, 0.05
i = 13.1663488, 0.05
z = 13.1029807, 0.05
J = 12.263, 0.02
H = 11.919, 0.02
K = 11.852, 0.02
Kepler = 13.426
myplanet/star.ini
myplanet/fpp.ini
~$ calcfpp myplanet
isochrones-and-vespa
By Tim Morton
isochrones-and-vespa
A quick overview of my packages to streamline fitting of stellar parameters and transit false positive calculations.
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