20.13.6 vari_cepheid
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 were 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 in the G band time series (double, Time[day])
For singlemode pulsators classified as fundamental mode pulsators, this parameter is filled with the periodicity found in the timeseries.
This value is obtained by modelling the $G$ band time series using the LevenbergMarquardt non–linear fitting algorithm (Clementini et al. 2016).
Information for vari_rrlyrae: For doublemode RR Lyrae this parameter is filled with the period corresponding to the longer periodicity.
Information for vari_cepheid: For doublemode 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 triplemode DCEPs this parameter is filled with the period corresponding to the longer periodicity if the DCEP is classified as ‘F/1O/2O’.
This parameter is filled with the uncertainty of the pf parameter, computed via a bootstrap technique.
p1_o : Period corresponding to the first overtone pulsation mode in the G band time series (double, Time[day])
For singlemode pulsators classified as firstovertone pulsators, this parameter is filled with the periodicity found in the timeseries.
This value is obtained by modelling the $G$ time series using the LevenbergMarquardt non linear fitting algorithm (see Clementini et al. 2016).
Information for vari_rrlyrae: For doublemode RR Lyrae this parameter is filled with the period corresponding to the shortest periodicity.
Information for vari_cepheid: For doublemode 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 triplemode 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 parameter is filled with the uncertainty of the p1_o parameter, computed via a bootstrap technique.
epoch_g : Epoch of the maximum of the light curve in the G band (double, Time[Barycentric JD in TCB $$ 2 455 197.5 (day)])
Epoch of maximum light for the Gaia $G$ band light curve. It corresponds to the barycentric Julian day (BJD) of the maximum value of the light curve model which is closest to the BJD of the first observations 3 times the period of the source (first periodicity depending on the pulsation mode).
The aforementioned BJD is offset by JD 2 455 197.5 (= J2010.0).
Value of the uncertainty of the epoch_g parameter. It corresponds to three times the error on the period of the source (first periodicity depending on the pulsation mode).
epoch_bp : Epoch of the maximum of the light curve in the BP band (double, Time[Barycentric JD in TCB $$ 2 455 197.5 (day)])
Epoch of maximum light for the Gaia integrated ${G}_{\mathrm{BP}}$ band light curve. It corresponds to the barycentric 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 aforementioned BJD is offset by JD 2 455 197.5 (= 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 $$ 2 455 197.5 (day)])
Epoch of maximum light for the Gaia integrated ${G}_{\mathrm{RP}}$ band light curve. It corresponds to the barycentric Julian day (BJD) of the maximum value of the light curve model which is closest to the BJD of the first observations 3 times the period of the source (first periodicity depending on the pulsation mode).
The aforementioned BJD is offset by JD 2 455 197.5 (= J2010.0).
Value of the uncertainty of the epoch_rp parameter. It corresponds to three times the error on the period of the source (first periodicity depending on the pulsation mode).
epoch_rv : Epoch of the minimum of the radial velocity curve (double, Time[Barycentric JD in TCB $$ 2 455 197.5 (day)])
Epoch of minimum radial velocity for the Gaia radial velocity curve.
Value of the uncertainty of the epoch_rv parameter. It corresponds to three times the error on the period of the source (first periodicity depending on the pulsation mode).
Value of the intensityaveraged magnitude in the $G$band. The intensityaveraged 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, computed via a bootstrap technique.
Value of the intensityaveraged magnitude in the ${G}_{\mathrm{BP}}$band. The intensityaveraged
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, computed via a bootstrap technique.
Value of the intensityaveraged magnitude in the ${G}_{\mathrm{RP}}$band. The intensityaveraged 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, computed via a bootstrap technique.
Average value of the Fourier modelled radial velocity curve, provided by the ${A}_{0}$ parameter of the Fourier fit.
Error of average_rv computed via bootstrap technique.
This parameter is filled with the peaktopeak amplitude value of the $G$ band light curve. The peaktopeak 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.
This parameter is filled with the uncertainty value of the peak_to_peak_g parameter, computed via a bootstrap technique.
This parameter is filled with the peaktopeak amplitude value of the ${G}_{\mathrm{BP}}$ light curve. The peaktopeak amplitude is calculated as the (maximum)  (minimum) of the modelled folded light curve in the ${G}_{\mathrm{BP}}$ band. The light curve of the target star is modelled with a truncated Fourier series.
This parameter is filled with the uncertainty value of the peak_to_peak_bp parameter, computed via a bootstrap technique.
This parameter is filled with the peaktopeak amplitude value of the ${G}_{\mathrm{RP}}$ light curve. The peaktopeak amplitude is calculated as the (maximum)  (minimum) of the modelled folded light curve in the ${G}_{\mathrm{RP}}$ band. The light curve of the target star is modelled with a truncated Fourier series.
This parameter is filled with the uncertainty value of the peak_to_peak_rp parameter, computed via a bootstrap technique.
peak_to_peak_rv : Peaktopeak amplitude of the radial velocity curve (double, Velocity[km s${}^{1}$])
This parameter is filled with the peaktopeak amplitude value of the radial velocity curve. The peaktopeak amplitude is calculated as the (maximum)  (minimum) of the modelled folded $RV$ curve. The $RV$ curve of the target star is modelled with a truncated Fourier series.
peak_to_peak_rv_error : Uncertainty on the peak_to_peak_rv parameter (double, Velocity[km s${}^{1}$])
This parameter is filled with the uncertainty value of the peak_to_peak_rv parameter, computed via a bootstrap technique.
metallicity : Metallicity of the star from the Fourier parameters of the light curve (float, Abundances[dex])
This parameter is filled with the [Fe/H] metallicity derived for the source
from the Fourier parameters of the $G$band light curve.
This parameter is filled with the uncertainty of the metallicity derived from
the Fourier parameters of the $G$band light curve.
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 ($mag({t}_{j})=zp+\sum [{A}_{i}cos(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the $G$band light curve. Zeropoint ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$) of the harmonics, are determined using the LevenbergMarquardt non linear fitting algorithm.
This parameter is filled with the uncertainty value on the r21_g parameter, computed via a bootstrap technique.
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 ($mag({t}_{j})=zp+\sum [{A}_{i}cos(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the $G$band light curve. Zeropoint ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$) of the harmonics, are determined using the LevenbergMarquardt non linear fitting algorithm.
This parameter is filled with the uncertainty value of the r31_g parameter, computed via a bootstrap technique.
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 ($mag({t}_{j})=zp+\sum [{A}_{i}cos(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the $G$band light curve. Zeropoint ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$) of the harmonics, are determined using the LevenbergMarquardt non linear fitting algorithm.
phi21_g_error : Uncertainty on the phi21_g parameter: phi2  2*phi1 (for G band) (float, Angle[rad])
This parameter is filled with the uncertainty of the phi21_g parameter, computed via a bootstrap technique.
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 ($mag({t}_{j})=zp+\sum [{A}_{i}cos(i\times 2\pi {\nu}_{max}{t}_{j}+{\varphi}_{i})]$) used to model the $G$band light curve. Zeropoint ($zp$), period (1/${\nu}_{max}$), number of harmonics ($i$), amplitudes (${A}_{i}$), and phases (${\varphi}_{i}$) of the harmonics, are determined using the LevenbergMarquardt non linear fitting algorithm.
phi31_g_error : Uncertainty on the phi31_g parameter: phi3  3*phi1 (for G band) (float, Angle[rad])
This parameter is filled with the uncertainty of the phi31_g: ${\varphi}_{3}3{\varphi}_{1}$ parameter, computed via a bootstrap technique.
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.
This parameter is filled with the number of epochs that remain in the ${G}_{\mathrm{BP}}$band light curve after the SOS Cep & RRLyrae outlier removal process.
This parameter is filled with the number of epochs that remain in the ${G}_{\mathrm{RP}}$band light curve after the SOS Cep & RRLyrae outlier removal process.
This parameter is filled with the number of epochs that remain in the radial velocity curve after the SOS Cep & RRLyrae outlier removal process.
Zero point (mag) of the final model of the $G$band light curve for Cepheids and RR Lyrae stars.
Zero point (mag) of the final model of the ${G}_{BP}$ band light curve for Cepheids and RR Lyrae stars.
Zero point (mag) of the final model of the ${G}_{RP}$ band light curve for Cepheids and RR Lyrae stars.
num_harmonics_for_p1_g : Number of harmonics used to model the first periodicity of the Gband light curve (byte)
This parameter is filled with the number of harmonics used to model the $G$band light curve folded with the P1 period. The $G$band light curve of the target star is modelled with a truncated Fourier series.
num_harmonics_for_p1_bp : Number of harmonics used to model the first periodicity of the BPband light curve (byte)
This parameter is filled with the number of harmonics used to model the ${G}_{\mathrm{BP}}$band light curve folded with the P1 period. The ${G}_{\mathrm{BP}}$band light curve of the target star is modelled with a truncated Fourier series.
num_harmonics_for_p1_rp : Number of harmonics used to model the first periodicity of the RPband light curve (byte)
This parameter is filled with the number of harmonics used to model the ${G}_{\mathrm{RP}}$band light curve folded with the P1 period. The ${G}_{\mathrm{RP}}$band light curve of the target star is modelled with a truncated Fourier series.
num_harmonics_for_p1_rv : Number of harmonics used to model the first periodicity of the radial velocity curve (byte)
This parameter is filled with the number of harmonics used to model the radial velocity curve folded with the P1 period. The radial velocity curve of the target star is modelled with a truncated Fourier series.
reference_time_g : Reference time of the Fourier modelled Gband light curve (double, Time[Barycentric JD in TCB $$ 2 455 197.5 (day)])
Reference time for the Fourier modelled $G$band light curve.
reference_time_bp : Reference time of the Fourier modelled BPband light curve (double, Time[Barycentric JD in TCB $$ 2 455 197.5 (day)])
Reference time for the Fourier modelled ${G}_{\mathrm{BP}}$band light curve.
reference_time_rp : Reference time of the Fourier modelled RPband light curve (double, Time[Barycentric JD in TCB $$ 2 455 197.5 (day)])
Reference time for the Fourier modelled ${G}_{\mathrm{RP}}$band light curve.
reference_time_rv : Reference time of the Fourier modelled radial velocity curve (double, Time[Barycentric JD in TCB $$ 2 455 197.5 (day)])
Reference time for the Fourier modelled radial velocity curve.
First frequency of the nonlinear Fourier modelling. It applies to all three $G$, ${G}_{\mathrm{BP}}$, and ${G}_{\mathrm{RP}}$ bands and the radial velocity curve.
fund_freq1_error : Error of the first frequency of the nonlinear Fourier modelling (float, Frequency[day${}^{1}$])
Error of the first frequency of the nonlinear Fourier modelling.
fund_freq2 : Second frequency of the nonlinear Fourier modelling in the G band (double, Frequency[day${}^{1}$])
Second frequency of the nonlinear Fourier modelling for the $G$ band only.
fund_freq2_error : Error of the second frequency of the nonlinear Fourier modelling in the G band (float, Frequency[day${}^{1}$])
Error of the second frequency of the nonlinear Fourier modelling. It applies to the $G$ band only.
fund_freq1_harmonic_ampl_g : Amplitudes of the Fourier model for the first frequency in the G band (float[16] array, Magnitude[mag])
Amplitudes of the Fourier model fitted to the observed $G$band light curve.
fund_freq1_harmonic_ampl_g_error : Errors of the amplitudes of the Fourier model for the first frequency in the G band (float[16] array, Magnitude[mag])
Errors of the amplitudes of the Fourier model fitted to the observed $G$band light curve.
fund_freq1_harmonic_phase_g : Phases of the Fourier model for the first frequency in the G band (float[16] array, Angle[rad])
Phases of the Fourier model fitted to the observed $G$band light curve.
fund_freq1_harmonic_phase_g_error : Errors of the phases of the Fourier model for the first frequency in the G band (float[16] array, Angle[rad])
Errors of the phases of the Fourier model fitted to the observed $G$band light curve.
fund_freq1_harmonic_ampl_bp : Amplitudes of the Fourier model for the first frequency in the BP band (float[16] array, Magnitude[mag])
Amplitudes of the Fourier model fitted to the observed ${G}_{\mathrm{BP}}$band light curve.
fund_freq1_harmonic_ampl_bp_error : Errors of the amplitudes of the Fourier model for the first frequency in the BP band (float[16] array, Magnitude[mag])
Errors of the amplitudes of the Fourier model fitted to the observed ${G}_{\mathrm{BP}}$band light curve.
fund_freq1_harmonic_phase_bp : Phases of the Fourier model for the first frequency in the BP band (float[16] array, Angle[rad])
Phases of the Fourier model fitted to the observed ${G}_{\mathrm{BP}}$band light curve.
fund_freq1_harmonic_phase_bp_error : Errors of the phases of the Fourier model for the first frequency in the BP band (float[16] array, Angle[rad])
Errors of the phases of the Fourier model fitted to the observed ${G}_{\mathrm{BP}}$band light curve.
fund_freq1_harmonic_ampl_rp : Amplitudes of the Fourier model for the first frequency in the RP band (float[16] array, Magnitude[mag])
Amplitudes of the Fourier model fitted to the observed ${G}_{\mathrm{RP}}$band light curve.
fund_freq1_harmonic_ampl_rp_error : Errors of the amplitudes of the Fourier model for the first frequency in the RP band (float[16] array, Magnitude[mag])
Errors of the amplitudes of the Fourier model fitted to the observed ${G}_{\mathrm{RP}}$band light curve.
fund_freq1_harmonic_phase_rp : Phases of the Fourier model for the first frequency in the RP band (float[16] array, Angle[rad])
Phases of the Fourier model fitted to the observed ${G}_{\mathrm{RP}}$band light curve.
fund_freq1_harmonic_phase_rp_error : Errors of the phases of the Fourier model for the first frequency in the RP band (float[16] array, Angle[rad])
Errors of the phases of the Fourier model fitted to the observed ${G}_{\mathrm{RP}}$band light curve.
fund_freq1_harmonic_ampl_rv : Amplitudes of the Fourier model for the first frequency of the radial velocity curve (float[16] array, Velocity[km s${}^{1}$])
Amplitudes of the Fourier model fitted to the observed radial velocity curve.
fund_freq1_harmonic_ampl_rv_error : Errors of the amplitudes of the Fourier model for the first frequency of the radial velocity curve (float[16] array, Velocity[km s${}^{1}$])
Errors of the amplitudes of the Fourier model fitted to the observed radial velocity curve.
fund_freq1_harmonic_phase_rv : Phases of the Fourier model for the first frequency of the radial velocity curve (float[16] array, Angle[rad])
Phases of the Fourier model fitted to the observed radial velocity curve.
fund_freq1_harmonic_phase_rv_error : Errors of the phases of the Fourier model for the first frequency of the radial velocity curve (float[16] array, Angle[rad])
Errors of the phases of the Fourier model fitted to the observed radial velocity curve.
p2_o : Period corresponding to the second overtone pulsation mode (for multi mode pulsators) in the G band time series (double, Time[day])
For doublemode 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 triplemode 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 LevenbergMarquardt non linear fitting algorithm (see Clementini et al. 2016).
This parameter is filled with the uncertainty of the p2_o parameter, computed via a bootstrap technique.
type_best_classification : Best type classification estimate out of: ‘DCEP’, ‘T2CEP’, ‘ACEP’ (string)
Classification of a Cepheid into ‘DCEP’, ‘T2CEP’ or ‘ACEP’ using the periodluminosity 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)
Subclassification of a T2CEP Cepheids into BL Herculis (‘BL_HER’), W Virginis (‘W_VIR’) or RV Tauris (‘RV_TAU’) subtypes depending on the source periodicity.
mode_best_classification : Best mode classification estimate out of: ‘FUNDAMENTAL’, ‘FIRST_OVERTONE’, ‘SECOND_OVERTONE’, ‘MULTI’,‘UNDEFINED’, ‘NOT_APPLICABLE’ (string)
Best mode classification estimate:

•
‘FUNDAMENTAL’: fundamental mode for type_best_classification=‘DCEP’ or ‘ACEP’

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‘FIRST_OVERTONE’: first overtone for type_best_classification=‘DCEP’ or ‘ACEP’

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‘SECOND_OVERTONE’: second overtone for type_best_classification=‘DCEP’

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‘MULTI’: multimode 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 periodluminosity and periodWesenheit 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)
Subclassification of multi mode DCEP variables according to their position in the ‘Petersen diagram’ — see for example Fig. 1 in Soszyński et al. (2015).
F,1O,2O and 3O correspond with fundamental, first, second and third overtone, respectively.