This table describes the Cepheid stars.
Columns description:
All Gaia data processed by the Data Processing and Analysis Consortium comes tagged with a solution identifier. This is a numeric field attached to each table row that can be used to unequivocally identify the version of all the subsystems that where used in the generation of the data as well as the input data used. It is mainly for internal DPAC use but is included in the published data releases to enable end users to examine the provenance of processed data products. To decode a given solution ID visit https://gaia.esac.esa.int/decoder/solnDecoder.jsp
A unique single numerical identifier of the source obtained from gaia_source (for a detailed description see gaia_source.source_id)
pf : Period corresponding to the fundamental pulsation mode (for multi mode pulsators) in the G band time series (double, Time[day])
pf: for single-mode pulsators classified as fundamental mode pulsators, this parameter is filled with the periodicity found in the time-series.
For double-mode RR Lyrae this parameter is filled with the period corresponding to the
longer periodicity. For double-mode DCEPs this parameter is filled with the period corresponding to the longer periodicity if the DCEP is classified as “F/1O” or “F/2O”. For triple-mode DCEPs this parameter is filled with
the period corresponding to the longer periodicity if the DCEP is classified as “F/1O/2O”
This value is obtained by modelling the $G$ band time series using the Levenberg-Marquardt non linear fitting algorithm
(see Clementini et al. 2016, A&A, 595, A133).
pf_error: this parameter is filled with the uncertainty of the pf parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the period is computed. The mean of all the periods
and its standard deviation are then derived, and the latter
value is used to fill the pf_error parameter.
The value refers to the analysis performed on the $G$ band time series.
p1_o : Period corresponding to the first overtone pulsation mode (for multi mode pulsators) in the G band time series (double, Time[day])
p1_o: for single-mode pulsators classified as first-overtone pulsators, this parameter is filled with the
periodicity found in the time-series.
For double-mode RR Lyrae this parameter is filled with the period corresponding to the
shortest periodicity. For double-mode DCEPs this parameter is filled with the period corresponding to the
shortest periodicity if the DCEP is classified as “F/1O”; otherwise it is filled with the longest one if the
classification is “1O/2O” or “1O/3O”. For triple-mode DCEPs this parameter is filled with the period
corresponding to the intermediate periodicity if the DCEP is classified as “F/1O/2O”;
it is filled with the longest periodicity if the classification is “1O/2O/3O”.
This value is obtained by modelling the $G$ time series using the Levenberg-Marquardt non linear fitting algorithm
(see Clementini et al. 2016, A&A, 595, A133).
p1_o_error: this parameter is filled with the uncertainty of the p1_o parameter.
Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the period is computed. The mean of all the periods
and its standard deviation are then derived, and the latter
value is used to fill the p1_o_error parameter.
p2_o : Period corresponding to the second overtone pulsation mode (for multi mode pulsators) in the G band time series (double, Time[day])
p2_o: For single-mode DCEPs classified as second-overtone pulsators, this parameter is filled with the
periodicity found in the time-series.
For double-mode DCEPs this parameter is filled with the period corresponding to the
shortest periodicity if the DCEP is classified as “1O/2O” of “F/2O”; otherwise it is filled with the longest periodicity if the classification is “2O/3O”.
For triple-mode DCEPs this parameter is filled with the period corresponding to the shortest periodicity if the
DCEP is classified as “F/1O/2O”;
it is filled with the intermediate periodicity if the classification is “1O/2O/3O”.
This value is obtained by modelling the $G$ time series using the Levenberg-Marquardt non linear fitting algorithm
(see Clementini et al. 2016, A&A, 595, A133).
p2_o_error: this parameter is filled with the uncertainty of the p2_o parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the period is computed. The mean of all the periods
and its standard deviation are then derived, and the latter
value is used to fill the p2_o_error parameter.
The value refers to the analysis performed on the $G$ band time-series.
p3_o : Period corresponding to the third overtone pulsation mode (for multi mode pulsators) in the G band time series (double, Time[day])
p3_o: for double-mode DCEPs this parameter is filled with the periodicity found in the time-series corresponding to the shortest periodicity if the DCEP is classified as “1O/3O” of “2O/3O”. For triple-mode DCEPs this parameter is filled with the period corresponding to the shortest periodicity if the DCEP is classified as “1O/2O/3O”. This value is obtained by modelling the $G$ time series using the Levenberg-Marquardt non linear fitting algorithm (see Clementini et al. 2016, A&A, 595, A133).
The parameter is NULL for RR Lyrae.
this parameter is filled with the uncertainty value of the p3_o parameter. Its value is derived from Monte Carlo simulations that generate several (100) time series with the same time path as the data points but with magnitudes generated randomly around the corresponding data values. For each of these time series the period is computed. The mean of all the periods and its standard deviation are then derived, and the latter value is used to fill the p3_o_error parameter. The value refers to the analysis performed on the $G$ band time-series.
The parameter is NULL for RR Lyrae.
epoch_g : Epoch of the maximum of the light curve in the G band (double, Time[Barycentric JD in TCB - 2455197.5 (day)])
Epoch of maximum light for the Gaia $G$ band light curve. It corresponds to the Baricentric Julian day (BJD) of the maximum value of the light curve model which is closest to the BJD of the first observations -3 times the period of the source (first periodicity depending on the pulsation mode).
The mentioned BJD is offset by JD 2455197.5 (= J2010.0).
Value of the uncertainty of the epoch_g parameter. It corresponds to three times the error on the period of the source (first periodicity depending on the pulsation mode).
epoch_bp : Epoch of the maximum of the light curve in the BP band (double, Time[Barycentric JD in TCB - 2455197.5 (day)])
Epoch of maximum light for the Gaia integrated ${G}_{BP}$ band light curve. It corresponds to the Baricentric Julian day (BJD) of the maximum value of the light curve model which is closest to the BJD of the first observations -3 times the period of the source (first periodicity depending on the pulsation mode).
The mentioned BJD is offset by JD 2455197.5 (= J2010.0).
Value of the uncertainty of the epoch_bp parameter. It corresponds to three times the error on the period of the source (first periodicity depending on the pulsation mode)
epoch_rp : Epoch of the maximum of the light curve in the RP band (double, Time[Barycentric JD in TCB - 2455197.5 (day)])
Epoch of maximum light for the Gaia integrated ${G}_{RP}$ band light curve. It corresponds to the Baricentric Julian day (BJD) of the maximum value of the light curve model which is closest to the BJD of the first observations -3 times the period of the source (first periodicity depending on the pulsation mode).
The mentioned BJD is offset by JD 2455197.5 (= J2010.0).
Value of the uncertainty of the epoch_rp parameter. It corresponds to three times the error on the period of the source (first periodicity depending on the pulsation mode)
Value of the intensity-averaged magnitude in the $G$-band. The intensity-averaged magnitude is obtained by computing
the average flux and then converting the average flux to magnitude.
This parameter is filled with the uncertainty
of the int_average_g parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the int_average_g is computed. The mean of all the magnitudes
found and its standard deviation are then computed, and the latter
value is kept to fill the int_average_g_error parameter.
Value of the intensity-averaged magnitude in the BP-band. The intensity-averaged
magnitude is obtained by computing the average flux and then converting the average flux to magnitude.
this parameter is filled with the uncertainty of
the int_average_bp parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the int_average_bp is computed. The mean of all the magnitudes
found and its standard deviation are then computed, and the latter
value is kept to fill the int_average_bpError parameter.
Value of the intensity-averaged magnitude in the RP-band. The intensity-averaged magnitude is obtained
by computing the average flux and then converting the average flux to magnitude.
this parameter is filled with the uncertainty of
the int_average_rp parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the int_average_rp is computed. The mean of all the magnitudes
found and its standard deviation are then computed, and the latter
value is kept to fill the int_average_rp_error parameter.
This parameter is filled with the peak-to-peak amplitude value of the $G$
band light curve. The peak-to-peak amplitude is calculated as the
(maximum) - (minimum) of the modelled folded light curve in the $G$
band. The light curve of the target star is modelled with a truncated
Fourier series ($mag({t}_{j})=zp+\sum [{A}_{i}sin(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$). Zero-point (zp), period (1/${\nu}_{max}$), number of
harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$) of the
harmonics, for the $G$-band light curve are determined using the
Levenberg-Marquardt non linear fitting algorithm.
This parameter is filled with the uncertainty
value of the peak_to_peak_g parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the peak_to_peak_g is computed. The mean of all the amplitudes
found and its standard deviation are then computed, and the latter
value is kept to fill the peak_to_peak_gError parameter.
this parameter is filled with the peak-to-peak
amplitude value of the $BP$
light curve. The peak-to-peak amplitude is calculated as the
(maximum) - (minimum) of the modelled folded light curve in the $BP$
band. The light curve of the target star is modelled with a truncated
Fourier series ($mag({t}_{j})=zp+\sum [{A}_{i}sin(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$). Zero-point (zp), period (1/${\nu}_{max}$), number of
harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$) of the
harmonics, for the $BP$-band light curve are determined using the
Levenberg-Marquardt non linear fitting algorithm.
this parameter is filled with the uncertainty
value of the peak_to_peak_bp parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the peak_to_peak_bp is computed. The mean of all the amplitudes
found and its standard deviation are then computed, and the latter
value is kept to fill the peak_to_peak_bpError parameter.
this parameter is filled with the peak-to-peak
amplitude value. The peak-to-peak amplitude is calculated as the
(maximum) - (minimum) of the modelled folded light curve in the $RP$
band. The light curve of the target star is modelled with a truncated
Fourier series ($mag({t}_{j})=zp+\sum [{A}_{i}sin(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$). Zero-point (zp), period (1/${\nu}_{max}$), number of
harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$) of the
harmonics, for the $RP$-band light curve are determined using the
Levenberg-Marquardt non linear fitting algorithm.
this parameter is filled with the uncertainty
value of the peak_to_peak_rp parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the peak_to_peak_rp is computed. The mean of all the amplitudes
found and its standard deviation are then computed, and the latter
value is kept to fill the peak_to_peak_rp_error parameter.
metallicity : Metallicity of the star from the Fourier parameters of the light curve (double, Abundances[dex])
metallicity: this parameter is filled with the [Fe/H] metallicity derived for the source
from the Fourier parameters of the G-band light curve.
metallicity_error: this parameter is filled with the uncertainty of the metallicity derived from
the Fourier parameters of the G-band light curve.
r21_g : Fourier decomposition parameter r21_g: A2/A1 (for G band) (double, Dimensionless[see description])
this parameter is filled with the Fourier decomposition parameter ${R}_{21}={A}_{2}/{A}_{1}$, where ${A}_{2}$
is the amplitude of the 2nd harmonic and ${A}_{1}$ is the amplitude of the fundamental harmonic of
the truncated Fourier series defined as ($mag({t}_{j})=zp+\sum [{A}_{i}sin(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the G-band light curve.
Zero-point ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$)
of the harmonics, are determined using the Levenberg-Marquardt non linear fitting algorithm.
r21_g_error : Uncertainty on the r21_g parameter: A2/A1 (for G band) (double, Dimensionless[see description])
this parameter is filled with the uncertainty value on the r21_g parameter.
Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the r21_g is computed. The mean of all the r21_g values
found and its standard deviation are then computed, and the latter
value is kept to fill the r21_gError parameter.
r31_g : Fourier decomposition parameter r31_g: A3/A1 (for G band) (double, Dimensionless[see description])
this parameter is filled with the Fourier decomposition parameter ${R}_{21}={A}_{3}/{A}_{1}$, where ${A}_{3}$
is the amplitude of the 3rd harmonic and ${A}_{1}$ is the amplitude of the fundamental harmonic of
the truncated Fourier series defined as ($mag({t}_{j})=zp+\sum [{A}_{i}sin(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the G-band light curve.
Zero-point ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$)
of the harmonics, are determined using the Levenberg-Marquardt non linear fitting algorithm.
r31_g_error : Uncertainty on the r31_g parameter: A3/A1 (for G band) (double, Dimensionless[see description])
this parameter is filled with the uncertainty value of
the r31_g parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the r31_g is computed. The mean of all the r31_g values
found and its standard deviation are then computed, and the latter
value is kept to fill the r31_g_error parameter.
this parameter is filled with the Fourier decomposition
parameter ${\varphi}_{21}$: ${\varphi}_{2}-2{\varphi}_{1}$ value, where ${\varphi}_{2}$
is the phase of the 2nd harmonic and ${\varphi}_{1}$ is the phase of the fundamental harmonic of
the truncated Fourier series defined as ($mag({t}_{j})=zp+\sum [{A}_{i}sin(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the G-band light curve.
Zero-point ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$)
of the harmonics, are determined using the Levenberg-Marquardt non linear fitting algorithm.
phi21_g_error : Uncertainty on the phi21_g parameter: phi2 - 2*phi1 (for G band) (double, Angle[rad])
this parameter is filled with the uncertainty of the phi21_g parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the phi21_g is computed. The mean of all the phi21_g values is
found and its standard deviation are then computed, and the latter
value is kept to fill the phi21_g_error parameter.
this parameter is filled with the Fourier decomposition
parameter ${\varphi}_{31}$: ${\varphi}_{3}-3{\varphi}_{1}$ value, where ${\varphi}_{3}$
is the phase of the 3rd harmonic and ${\varphi}_{1}$ is the phase of the fundamental harmonic of
the truncated Fourier series defined as ($mag({t}_{j})=zp+\sum [{A}_{i}sin(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the G-band light curve.
Zero-point ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$)
of the harmonics, are determined using the Levenberg-Marquardt non linear fitting algorithm.
phi31_g_error : Uncertainty on the phi31_g parameter: phi3 - 3*phi1 (for G band) (double, Angle[rad])
this parameter is filled with the uncertainty
of the phi31_g: ${\varphi}_{3}-3{\varphi}_{1}$ parameter. Its value is derived from Monte Carlo
simulations that generate several (100) time series with the same
time path as the data points but with magnitudes generated randomly
around the corresponding data values. For each of these time series
the phi31_g is computed. The mean of all the phi31_g values is
found and its standard deviation are then computed, and the latter
value is kept to fill the phi31_g_error parameter.
num_clean_epochs_g : Number of G FoV epochs used in the fitting algorithm (int, Dimensionless[see description])
this parameter is filled with the number of epochs that remain in the G
band light curve after the SOS Cep & RRLyrae outlier removal process.
num_clean_epochs_bp : Number of BP epochs used in the fitting algorithm (int, Dimensionless[see description])
this parameter is filled with the number of epochs that remain in the BP
band light curve after the SOS Cep&RRLyrae outlier removal process.
num_clean_epochs_rp : Number of RP epochs used in the fitting algorithm (int, Dimensionless[see description])
this parameter is filled with the number of epochs that remain in the RP
band light curve after the SOS Cep&RRLyrae outlier removal process.
This parameter is filled with values coming from the estimate of the
interstellar extinction toward the investigated pulsators. For
RR Lyrae stars the period-colour-amplitude relation was used, whereas the parameter is not available for Cepheids in DR2.
Error on the interstellar absorption in the G-band (g_absorption_error):
This parameter is filled with the r.m.s. errors of the relations used to estimate the interstellar
absorption.
type_best_classification : Best type classification estimate out of: ”DCEP”, ”T2CEP”, ”ACEP” (string, Dimensionless[see description])
Classification of a Cepheid into ”DCEP”, ”T2CEP” or ”ACEP” using the period-luminosity relations, which are different for the three different types of Cepheids.
type2_best_sub_classification : Best subclassification estimate for type_best_classification=”T2CEP” out of: ”BL_HER”, ”W_VIR”, ”RV_TAU” (string, Dimensionless[see description])
Sub-classification of a T2CEP Cepheids into BL Herculis (”BL_HER”), W Virginis (”W_VIR”) or RV Tauris (”RV_TAU”) sub-types depending on the source periodicity.
mode_best_classification : Best mode classification estimate out of: ”FUNDAMENTAL”, ”FIRST_OVERTONE”, ”SECOND_OVERTONE”, ”MULTI”,”UNDEFINED”, ”NOT_APPLICABLE” (string, Dimensionless[see description])
Best mode classification estimate:
”FUNDAMENTAL”: fundamental mode for type_best_classification="DCEP" or "ACEP"
”FIRST_OVERTONE”: first overtone for type_best_classification="DCEP" or "ACEP"
”SECOND_OVERTONE”: second overtone for type_best_classification="DCEP"
”MULTI”: multi-mode pulsators for type_best_classification="DCEP"
”UNDEFINED”: if mode could not be clearly determined for type_best_classification="DCEP" or "ACEP"
”NOT_APPLICABLE”: when type_best_classification="T2CEP"
The Cepheid pulsation mode is assigned using the period-luminosity and period-Wesenheit relations,
which are different for the various pulsation modes as well as analysing the Fourier parameters vs period
plots. The type “MULTI” is assigned to stars pulsating in two or more modes simultaneously.
multi_mode_best_classification : Best multi mode DCEP classification out of: ”F/1O”, ”F/2O”, ”1O/2O”, ”1O/3O”,”2O/3O”,”F/1O/2O”,”1O/2O/3O” (string, Dimensionless[see description])
Sub-classification of multi mode DCEP variables according to their position in the “Petersen diagram” (see e.g. Fig. 1 in Soszyński et al. 2015, AcA, 65, 329).
F,1O,2O and 3O mean fundamental, first, second and third overtone, respectively.