2022, Gatto, M., Ripepi, V., Bellazzini, M., Tosi, M., Tortora, C., Cignoni, M., Dall’Ora, M., Cioni, M.-R.L., Cusano, F., Longo, G., Marconi, M., Musella, I., Schipani, P., Spavone, M.

Context. The star cluster (SC) age distribution of the Large Magellanic Cloud (LMC) exhibits a gap from ∼4 to 10 Gyr ago, with an almost total absence of SCs. Within this age gap, only two confirmed SCs have been identified hitherto. Nonetheless, the star field counterpart does not show the same characteristics, making the LMC a peculiar galaxy where the star formation history and cluster formation history appear to differ significantly. Aims. We re-analysed the colour-magnitude diagram (CMD) of the KMHK 1762 SC by using the deep optical photometry provided by the ‘Yes, Magellanic Clouds Again’ survey, so as to robustly assess its age. Methods. First, we partially removed foreground and/or field stars by means of parallaxes and proper motions obtained from the Gaia Early Data Release 3. Then, we applied the Automated Stellar Cluster Analysis package to the cleaned photometric catalogue to identify the isochrone that best matches the CMD of KMHK 1762. Results. The estimated age of KMHK 1762 is log(t) = 9.74 ± 0.15 dex (∼5.5 Gyr), which is more than 2 Gyr older than the previous estimation which was obtained with shallower photometry. This value makes KMHK 1762 the third confirmed age-gap SC of the LMC. Conclusions. The physical existence of a quiescent period of the LMC SC formation is questioned. We suggest it can be the result of an observational bias, originating from the combination of shallow photometry and limited investigation of the LMC periphery.

2023, Braga, V.F., Crestani, J., Fabrizio, M., Bono, G., Sneden, C., Preston, G.W., Storm, J., Kamann, S., Latour, M., Lala, H., Lemasle, B., Prudil, Z., Altavilla, G., Chaboyer, B., Dall’Ora, M., Ferraro, I., Gilligan, C.K., Fiorentino, G., Iannicola, G., Inno, L., Kwak, S., Marengo, M., Marinoni, S., Marrese, P.M., Martínez-Vázquez, C.E., Monelli, M., Mullen, J.P., Matsunaga, N., Neeley, J., Stetson, P.B., Valenti, E., Zoccali, M.

[no abstract available]

2021, Braga, V.F., Crestani, J., Fabrizio, M., Bono, G., Sneden, C., Preston, G. W., Storm, J., Kamann, S., Latour, M., Lala, H., Lemasle, B., Prudil, Z., Altavilla, G., Chaboyer, B., Dall’Ora, M., Ferraro, I., Gilligan, C. K., Fiorentino, G., Iannicola, G., Inno, L., Kwak, S., Marengo, M., Marinoni, S., Marrese, P. M., Martínez-Vázquez, C.E., Monelli, M., Mullen, J.P., Matsunaga, N., Neeley, J., Stetson, P. B., Valenti, E., Zoccali, M.

We collected the largest spectroscopic catalog of RR Lyrae (RRLs) including ≈20,000 high-, medium-, and low-resolution spectra for ≈10,000 RRLs. We provide the analytical forms of radial velocity curve (RVC) templates. These were built using 36 RRLs (31 fundamental - split into three period bins - and five first-overtone pulsators) with well-sampled RVCs based on three groups of metallic lines (Fe, Mg, Na) and four Balmer lines (H α , H β , H γ , H δ ). We tackled the long-standing problem of the reference epoch to anchor light-curve and RVC templates. For the V-band, we found that the residuals of the templates anchored to the phase of the mean magnitude along the rising branch are ∼35% to ∼45% smaller than those anchored to the phase of maximum light. For the RVC, we used two independent reference epochs for metallic and Balmer lines and we verified that the residuals of the RVC templates anchored to the phase of mean RV are from 30% (metallic lines) up to 45% (Balmer lines) smaller than those anchored to the phase of minimum RV. We validated our RVC templates by using both the single-point and the three phase point approaches. We found that barycentric velocities based on our RVC templates are two to three times more accurate than those available in the literature. We applied the current RVC templates to Balmer lines RVs of RRLs in the globular NGC 3201 collected with MUSE at VLT. We found the cluster barycentric RV of V γ = 496.89 ± 8.37(error) ± 3.43 (standard deviation) km s-1, which agrees well with literature estimates.