Table 2.
List of univariate variability features, morphology feature, and color features used in this work.
| Feature | Description | Reference | |
|---|---|---|---|
| classic var. features | ASF | rms magnitude difference of the SF, computed over a 1 yr timescale | Schmidt et al. (2010) |
| γSF | Logarithmic gradient of the mean change in magnitude | Schmidt et al. (2010) | |
| GP_DRW_τ | Relaxation time τ (i.e., time necessary for the time series to become uncorrelated), from a DRW model for the light curve | Graham et al. (2017) | |
| GP_DRW_σ | Variability of the time series at short timescales (t ≪ τ), | Graham et al. (2017) | |
| from a DRW model for the light curve | |||
| ExcessVar | Measure of the intrinsic variability amplitude | Allevato et al. (2013) | |
| Pvar | Probability that the source is intrinsically variable | McLaughlin et al. (1996) | |
| IARϕ | Level of autocorrelation using a discrete-time representation of a DRW model | Eyheramendy et al. (2018) | |
| FATS features | Amplitude | Half of the difference between the median of the maximum 5% and of the minimum 5% magnitudes | Richards et al. (2011) |
| AndersonDarling | Test of whether a sample of data comes from a population with a specific distribution | Nun et al. (2015) | |
| Autocor_length | Lag value where the auto-correlation function becomes smaller than ηe | Kim et al. (2011) | |
| Beyond1Std | Percentage of points with photometric mag that lie beyond 1σ from the mean | Richards et al. (2011) | |
| ηe | Ratio of the mean of the squares of successive mag differences to the variance of the light curve | Kim et al. (2014) | |
| Gskew | Median-based measure of the skew | – | |
| LinearTrend | Slope of a linear fit to the light curve | Richards et al. (2011) | |
| MaxSlope | Maximum absolute magnitude slope between two consecutive observations | Richards et al. (2011) | |
| Meanvariance | Ratio of the standard deviation to the mean magnitude | Nun et al. (2015) | |
| MedianAbsDev | Median discrepancy of the data from the median data | Richards et al. (2011) | |
| MedianBRP | Fraction of photometric points within amplitude/10 of the median mag | Richards et al. (2011) | |
| MHAOV_Period | Periodo obtained via the Multi-Harmonic Analysis of Variability periodogram | Huijse et al. (2018) | |
| PairSlopeTrend | Fraction of increasing first differences minus fraction of decreasing first differences over the last 30 time-sorted mag measures | Richards et al. (2011) | |
| PercentAmplitude | Largest percentage difference between either max or min mag and median mag | Richards et al. (2011) | |
| Q31 | Difference between the 3rd and the 1st quartile of the light curve | Kim et al. (2014) | |
| Period_fit | False-alarm probability of the largest periodogram value obtained with LS | Kim et al. (2011) | |
| ΨCS | Range of a cumulative sum applied to the phase-folded light curve | Kim et al. (2011) | |
| Ψη | ηe index calculated from the folded light curve | Kim et al. (2014) | |
| Rcs | Range of a cumulative sum | Kim et al. (2011) | |
| Skew | Skewness measure | Richards et al. (2011) | |
| Std | Standard deviation of the light curve | Nun et al. (2015) | |
| StetsonK | Robust kurtosis measure | Kim et al. (2011) | |
| morph. | class_star | HST stellarity index | Koekemoer et al. (2007), |
| Scoville et al. (2007a) | |||
| colors | u-B | CFHT u magnitude – Subaru B magnitude | Laigle et al. (2016) |
| B-r | Subaru SuprimeCam B mag – Subaru SuprimeCam r+ mag | Laigle et al. (2016) | |
| r-i | Subaru SuprimeCam r+ mag – Subaru SuprimeCam i+ mag | Laigle et al. (2016) | |
| i-z | Subaru SuprimeCam i+ mag – Subaru SuprimeCam z + + mag | Laigle et al. (2016) | |
| z-y | Subaru SuprimeCam z + + mag – Subaru Hyper-SuprimeCam y mag | Laigle et al. (2016) | |
| ch21 | Spitzer 4.5 μm (channel2) mag – 3.6 μm (channel1) mag | Laigle et al. (2016) | |
Notes. The first two sections of the table report variability features; class_star is the only morphology feature used; the bottom section of the table lists the color features used, where ch21 is the only MIR color used, while the others are optical/near-infrared (NIR) colors. This table corresponds to Table 1 in De Cicco et al. (2021).
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