Star

class libra.Star(spots=None, u1=0.4987, u2=0.1772, r=1, radius_threshold=0.1, rotation_period=<Quantity 25. d>)[source] [edit on github]

Bases: object

Object defining a star.

The star is assumed to have stellar inclination 90 deg (equator-on).

Parameters:

u1 : float (optional)

Quadratic limb-darkening parameter, linear term

u2 : float (optional)

Quadratic limb-darkening parameter, quadratic term

r : float (optional)

Stellar radius (default is unity)

radius_threshold : float (optional)

If all spots are smaller than this radius, use the analytic solution to compute the stellar centroid, otherwise use the numerical solution.

spots : list (optional)

List of spots on this star.

rotation_period : Quantity

Stellar rotation period [default = 25 d].

contrast : float (optional)

Spot contrast relative to photosphere. Default is c=0.7

Methods Summary

derotate()
flux(times[, t0]) Compute flux at times as the star rotates.
fractional_flux(times[, t0]) Compute stellar flux as a fraction of the unspotted stellar flux at times as the star rotates.
limb_darkening(r) Compute the intensity at radius r for quadratic limb-darkening law with parameters Star.u1, Star.u2.
limb_darkening_normed(r) Compute the normalized intensity at radius r for quadratic limb-darkening law with parameters Star.u1, Star.u2.
plot([n, ax]) Plot a 2D projected schematic of the star and its spots.
rotate(angle) Rotate the star, by moving the spots.
spotted_area(times[, t0]) Compute flux at times as the star rotates.
with_k296_spot_distribution()
with_trappist1_spot_distribution()

Methods Documentation

derotate()[source] [edit on github]
flux(times, t0=0)[source] [edit on github]

Compute flux at times as the star rotates.

Parameters:

times: `~numpy.ndarray`

Times

t0 : float

Reference epoch.
Returns:

flux : ndarray

Fluxes at times
fractional_flux(times, t0=0)[source] [edit on github]

Compute stellar flux as a fraction of the unspotted stellar flux at times as the star rotates.

Parameters:

times: `~numpy.ndarray`

Times

t0 : float

Reference epoch.
Returns:

flux : ndarray

Fluxes at times
limb_darkening(r)[source] [edit on github]

Compute the intensity at radius r for quadratic limb-darkening law with parameters Star.u1, Star.u2.

Parameters:

r : float or ndarray

Stellar surface position in radial coords on (0, 1)
Returns:

intensity : float

Intensity in un-normalized units
limb_darkening_normed(r)[source] [edit on github]

Compute the normalized intensity at radius r for quadratic limb-darkening law with parameters Star.u1, Star.u2.

Parameters:

r : float or ndarray

Stellar surface position in radial coords on (0, 1)
Returns:

intensity : float

Intensity relative to the intensity at the center of the disk.
plot(n=3000, ax=None)[source] [edit on github]

Plot a 2D projected schematic of the star and its spots.

Parameters:

ax : Axes

Axis object to draw the plot on

n : int

Number of pixels per side in the image.
Returns:

ax : Axes

Matplotlib axis object, with the new plot on it.
rotate(angle)[source] [edit on github]

Rotate the star, by moving the spots.

Parameters:angle : Quantity
spotted_area(times, t0=0)[source] [edit on github]

Compute flux at times as the star rotates.

Parameters:

times: `~numpy.ndarray`

Times

t0 : float

Reference epoch.
Returns:

area : ndarray

Area covered by spots at times [Hem]
classmethod with_k296_spot_distribution()[source] [edit on github]
classmethod with_trappist1_spot_distribution()[source] [edit on github]