Original three-dataset framework

Original three-dataset framework#

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The current multidimensional GP models support an arbitrary number of datasets and heterogeneous cadences. PyORBIT also keeps the older Rajpaul-style framework, where the model is built from exactly three synchronous datasets: radial velocities, one chromospheric activity indicator, and BIS.

This model is mainly retained for reproducibility of older analyses. For new analyses, the multidimensional models described in the quasi-periodic kernel page are usually more flexible.

Model definition and requirements#

model name: gp_framework_quasiperiodic

  • required common object: activity

  • expects three datasets with the same times and length

  • supported dataset roles: RV, one of H-alpha, S_index, or Ca_HK, and BIS

model name: gp_pyaneti_quasiperiodic

  • required common object: activity

  • multidimensional quasi-periodic model using the pyaneti backend

  • supports the same dataset coefficient notation as the newer multidimensional models

Keywords#

Model-wide keywords, with the default value in boldface.

hyperparameters_condition

  • accepted values: True | False

  • activates the quasi-periodic hyperparameter condition described in the quasi-periodic kernel.

rotation_decay_condition

  • accepted values: True | False

  • if activated, requires Pdec > 2 Prot.

use_stellar_rotation_period

  • accepted values: True | False

  • replaces Prot with rotation_period from star_parameters.

use_stellar_activity_decay

  • accepted values: True | False

  • replaces Pdec with activity_decay from star_parameters.

derivative

  • accepted values: mapping of dataset names to booleans

  • available for gp_pyaneti_quasiperiodic. If False, the derivative coefficient rot_amp is fixed to zero for that dataset.

Examples#

Original fixed framework:

 1inputs:
 2  RVdata:
 3    file: datasets/RV_PyORBIT.dat
 4    kind: RV
 5    models:
 6      - gp_framework
 7  Sdata:
 8    file: datasets/Sindex_PyORBIT.dat
 9    kind: S_index
10    models:
11      - gp_framework
12  BISdata:
13    file: datasets/BIS_PyORBIT.dat
14    kind: BIS
15    models:
16      - gp_framework
17common:
18  activity:
19    boundaries:
20      Prot: [10.0, 20.0]
21      Pdec: [20.0, 1000.0]
22      Oamp: [0.001, 1.0]
23      Vc: [-100.0, 100.0]
24      Vr: [-100.0, 100.0]
25      Lc: [-10.0, 10.0]
26      Bc: [-100.0, 100.0]
27      Br: [-100.0, 100.0]
28models:
29  gp_framework:
30    model: gp_framework_quasiperiodic
31    common: activity
32    hyperparameters_condition: True

pyaneti multidimensional backend:

 1models:
 2  gp_pyaneti:
 3    model: gp_pyaneti_quasiperiodic
 4    common: activity
 5    hyperparameters_condition: True
 6    RVdata:
 7      boundaries:
 8        rot_amp: [0.0, 20.0]
 9        con_amp: [-20.0, 20.0]
10      derivative: True
11    Sdata:
12      boundaries:
13        con_amp: [-1.0, 1.0]
14      derivative: False

Model parameters#

gp_framework_quasiperiodic#

Name

Parameter

Common?

Definition

Notes

Prot

Rotational period of the star

common

activity

Pdec

Decay timescale of active regions

common

activity

Oamp

Coherence scale

common

activity

Vc

Coefficient of G(t) in the RV model

common

activity

Vr

Coefficient of G'(t) in the RV model

common

activity

Lc

Coefficient of G(t) in the chromospheric-index model

common

activity

Bc

Coefficient of G(t) in the BIS model

common

activity

Br

Coefficient of G'(t) in the BIS model

common

activity

gp_pyaneti_quasiperiodic#

Name

Parameter

Common?

Definition

Notes

Prot

Rotational period of the star

common

activity

Pdec

Decay timescale of active regions

common

activity

Oamp

Coherence scale

common

activity

con_amp

Coefficient of the latent GP

dataset

activity

rot_amp

Coefficient of the first derivative of the latent GP

dataset

activity

Fixed to zero when derivative: False