Absolute Properties of the Eclipsing Binary Star V501 Herculis

V501 Her is a well detached G3 eclipsing binary star with a period of 8.597687 days for which we have determined very accurate light and radial-velocity curves by using robotic telescopes. Results of these data indicate that the component stars have masses of 1.269 +/- 0.004 and 1.211 +/- 0.003 solar masses, radii of 2.001 +/- 0.003 and 1.511 +/- 0.003 solar radii, and temperatures of 5683 +/- 100K and 5720 +/- 100K, respectively. Comparison with the Yonsei-Yale series of evolutionary models results in good agreement at an age of about 5.1 Gyr for a somewhat metal rich composition. Those models indicate that the more massive, larger, slightly cooler star is just beyond core hydrogen exhaustion while the less massive, smaller, slightly hotter star has not quite reached core hydrogen exhaustion. The orbit is not yet circularized, and the components are rotating at or near their pseudosynchronous velocities. The distance to the system is 420 +/- 30 pc

Absolute Properties of the Eclipsing Binary Star HY Virginis

HY Vir is found to be a double-lined F0m+F5 binary star with relatively shallow (0.3 mag) partial eclipses. Previous studies of the system are improved with 7509 differential photometric observations from the URSA WebScope and 8862 from the NFO WebScope, and 68 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope, and the 1 m coudé-feed spectrometer at Kitt Peak National Observatory. Very accurate (better than 0.5%) masses and radii are determined from analysis of the new light curves and radial velocity curves. Theoretical models match the absolute properties of the stars at an age of about 1.35 Gy

Absolute dimensions of the early F-type eclipsing binary V506 Ophiuchi

We report extensive differential V-band photometry and high-resolution spectroscopic observations of the early F-type, 1.06-day detached eclipsing binary V506 Oph. The observations along with times of minimum light from the literature are used to derive a very precise ephemeris and the physical properties for the components, with the absolute masses and radii being determined to 0.7% or better. The masses are 1.4153 +/- 0.0100 M(Sun) and 1.4023 +/- 0.0094 M(sun) for the primary and secondary, the radii are 1.725 +/- 0.010 R(Sun) and 1.692 +/- 0.012 R(Sun), and the effective temperatures 6840 +/- 150 K and 6780 +/- 110 K, respectively. The orbit is circular and the stars are rotating synchronously. The accuracy of the radii and temperatures is supported by the resulting distance estimate of 564 +/- 30 pc, in excellent agreement with the value implied by the trigonometric parallax listed in the Gaia/DR2 catalog. Current stellar evolution models from the MIST series for a composition of [Fe/H] = -0.04 match the properties of both stars in V506 Oph very well at an age of 1.83 Gyr, and indicate they are halfway through their core hydrogen-burning phase.Comment: Accepted for publication in The Astrophysical Journal, 8 pages in emulateapj format including figures and tables. Tables 3, 5, and 6 available only electronically from the Journa

Absolute dimensions of the unevolved F-type eclipsing binary BT Vulpeculae

We report extensive differential V-band photometry and high-resolution spectroscopy for the 1.14 day, detached, double-lined eclipsing binary BT Vul (F0+F7). Our radial-velocity monitoring and light curve analysis lead to absolute masses and radii of M1 = 1.5439 +/- 0.0098 MSun and R1 = 1.536 +/- 0.018 RSun for the primary, and M2 = 1.2196 +/- 0.0080 MSun and R2 = 1.151 +/- 0.029 RSun for the secondary. The effective temperatures are 7270 +/- 150 K and 6260 +/- 180 K, respectively. Both stars are rapid rotators, and the orbit is circular. A comparison with stellar evolution models from the MIST series shows excellent agreement with these determinations, for a composition of [Fe/H] = +0.08 and an age of 350 Myr. The two components of BT Vul are very near the zero-age main sequence.Comment: 9 pages in emulateapj format, including tables and figures. Accepted for publication in The Astrophysical Journa

Absolute Properties of the Eclipsing Binary Star V335 Serpentis

V335 Ser is now known to be an eccentric double-lined A1+A3 binary star with fairly deep (0.5 mag) partial eclipses. Previous studies of the system are improved with 7456 differential photometric observations from the URSA WebScope and 5666 from the NFO WebScope, and 67 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope. From dates of minima, the apsidal period is about 880 years. Accurate (better than 2%) masses and radii are determined from analysis of the two new light curves and the radial velocity curve. Theoretical models match the absolute properties of the stars at an age of about 380 Myr, though the age agreement for the two components is poor. Tidal theory correctly confirms that the orbit should still be eccentric, but we find that standard tidal theory is unable to match the observed asynchronous rotation rates of the components\u27 surface layers

The quadruple-lined, doubly-eclipsing system V482 Persei

We report spectroscopic and differential photometric observations of the A-type system V482 Per that reveal it to be a rare hierarchical quadruple system containing two eclipsing binaries. One has the previously known orbital period of 2.4 days and a circular orbit, and the other a period of 6 days, a slightly eccentric orbit (e = 0.11), and shallow eclipses only 2.3% deep. The two binaries revolve around their common center of mass in a highly elongated orbit (e = 0.85) with a period of 16.67 yr. Radial velocities are measured for all components from our quadruple-lined spectra, and are combined with the light curves and with measurements of times of minimum light for the 2.4 day binary to solve for the elements of the inner and outer orbits simultaneously. The line-of-sight inclination angles of the three orbits are similar, suggesting they may be close to coplanar. The available observations appear to indicate that the 6 day binary experiences significant retrograde apsidal motion in the amount of about 60 degrees per century. We derive absolute masses for the four stars good to better than 1.5%, along with radii with formal errors of 1.1% and 3.5% for the 2.4 day binary and about 9% for the 6 day binary. A comparison of these and other physical properties with current stellar evolution models gives excellent agreement for a metallicity of [Fe/H] = -0.15 and an age of 360 Myr.Comment: 15 pages in emulateapj format, including figures and tables. Accepted for publication in The Astrophysical Journa