Table 1.
Criteria for the classification of variable stars.
| Type | Pmin | Pmax | Ref. (c) | PLH | PLKs | Ref. (d) |
|---|---|---|---|---|---|---|
| days | days | mag | mag | |||
| NPSs | < 0.38 | > 1000 | 1 | ... | ... | ... |
| RRc(FO) | < 0.38 | ∼0.54 | 2 | ... | –1.56–2.72 ⋅ log P | 11 |
| RRab(FU) | ∼0.38 | ∼1 | 2 | –0.971–2.226 ⋅ log P | –0.998–2.250 ⋅ log P | 11 |
| ACFO | ∼0.38 | ∼1.2 | 3 | ... | –2.42–4.18 ⋅ log P | 12 |
| ACFU | ∼0.50 | ∼2.7 | 3 | ... | –1.74–3.54 ⋅ log P | 12 |
| CCFO | < 0.38 | ∼6.3 | 4,5 | –2.851–3.455 ⋅ log P | –2.890–3.455 ⋅ log P | 13 |
| CCFU | ∼0.80 | ∼210 | 4,5 | –2.366–3.227 ⋅ log P | –2.408–3.245 ⋅ log P | 13 |
| T2C | ∼1 | ∼100 | 6,7,8 | –3.358–2.202 ⋅ log P(a) | –3.418–2.232 ⋅ log P(a) | 14 |
| Miras | ∼80 | ∼2000 | 9,10 | ... | –6.865–3.555 ⋅ log P(b) | 15 |
Notes. The zero points of the relations based on LMC variables were derived assuming, as the distance of the LMC, dLMC = 49.59 ± 0.09 ± 0.54 kpc (Pietrzyński et al. 2019).
We did not derive distances of candidate T2Cs with Pbest > 20 days (RVTs) because there is no general consensus on whether RVTs can be used as distance tracers or not (Matsunaga et al. 2006; Ripepi et al. 2015; Bhardwaj et al. 2017b; Braga et al. 2018a).
C-rich Miras with periods longer than ∼320–350 days can be significantly affected by circumstellar reddening and do not obey the PL relation (Matsunaga et al. 2009; Ita & Matsunaga 2011). Since our color estimates are not accurate enough to separate C-rich and O-rich stars, we conclude that distance estimates for long-period Miras are not reliable.
References.
1: Soszyński et al. (2016), 2: Soszyński et al. (2014), 3: Soszyński et al. (2008b), 4: Soszyński et al. (2008a), 5: Soszyński et al. (2010), 6: Matsunaga et al. (2006), 7: Soszyński et al. (2017), 8: Soszyński et al. (2018), 9: Whitelock (2012), 10: Soszyński et al. (2013).
11: Marconi et al. (2015, conversion to VISTA photometric system negligible, because the coefficients have only two significant decimal digits), 12: Ripepi et al. (2014, conversion to VISTA photometric system negligible, because the coefficients have only two significant decimal digits), 13: Inno et al. (2016, converted to VISTA photometric system), 14: Bhardwaj et al. (2017b, converted to VISTA photometric system), 15: Matsunaga et al. (2009, converted to VISTA photometric system).
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