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-circle dot, R-A = 1.90 +/- 0.04 R-circle dot, and T-A = 9960 +/- 60 K for the primary and M-B = 2.23 +/- 0.07 M-circle dot, R-B = 1.86 +/- 0.04 R-circle dot, 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, (omega) over dot = 0.86 deg century(-1), is 32% less then the expected rate, (omega) over dot = 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 pi = 0.73 +/- 0.04 mas, matches the GAIA DR2 value, pi = 0.76 +/- 0.04 mas.