
Abstract We characterize blue straggler stars (BSSs) and yellow straggler stars (YSSs) of the open cluster (OC) Berkeley 39 using multiwavelength observations including the Swift/Ultraviolet and Optical Telescope (UVOT). Our analysis also makes use of ultraviolet (UV) data from Galaxy Evolution Explorer, optical data from Gaia DR3 and Panoramic Survey Telescope and Rapid Response System, and infrared data from Two Micron All Sky Survey, Spitzer/IRAC, and Wide-field Infrared Survey Explorer. Berkeley 39 is a ∼6 Gyr old Galactic OC located at a distance of ∼4200 pc. We identify 729 sources as cluster members utilizing a machine-learning algorithm, ML-MOC, on Gaia DR3 data. Of these, 17 sources are classified as BSS candidates and four as YSS candidates. We construct multiwavelength spectral energy distributions (SEDs) of 16 BSS and two YSS candidates, within the Swift/UVOT field, to analyze their properties. Out of these, eight BSS candidates and both the YSS candidates are successfully fitted with single-component SEDs. Five BSS candidates show marginal excess in the near-UV (NUV; fractional residual <0.3 in all but one UVOT filter), whereas three BSS candidates show moderate to significant excess in the NUV (fractional residual >0.3 in at least two UVOT filters). We present the properties of the BSS and YSS candidates, estimated based on the SED fits.
Open star clusters, Ultraviolet astronomy, Blue straggler stars, Yellow straggler stars, Astronomy, QB1-991, Stellar populations
Open star clusters, Ultraviolet astronomy, Blue straggler stars, Yellow straggler stars, Astronomy, QB1-991, Stellar populations
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 2 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Average | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
