Apsidal Motion and Physical Parameters in the Eclipsing System V490 Sct

We report long-term UBVRIR c I c photometry of the highly eccentric 12.04 day detached eclipsing binary V490 Sct ( V = 13.1, B9.5+A0, e = 0.40), which we use to determine its relative and absolute parameters. The absolute masses, radii, and temperatures are M A = 2.33 ± 0.07 M ⊙ , R A = 1.90 ± 0.04 R ⊙ , and T A = 9960 ± 60 K for the primary and M B = 2.23±0.07 M ⊙ , R B = 1.86 ± 0.04 R ⊙ , and T B = 9700 ± 80 K for the secondary. The system displays a slow periastron advance that is dominated by General Relativity (GR). Our measurement, ω ̇ = 0.86 deg century −1 , is 32% less then the expected rate, ω ̇ = 1.24 deg century −1 , which has an 83% contribution from GR. A comparison with current stellar evolution models shows a good match to the measured properties at an age of about 130 Myr and Solar abundance. The photometric parallax of the system π = 0.73 ± 0.04 mas, matches the GAIA DR2 value, π = 0.76 ± 0.04 mas.