HR 1613: A Slowly Rotating A Dwarf Spectroscopic Binary with Solar Abundances

摘要

From two sets of radial velocities we have obtained the orbital elements of HR 1613. This single-lined binary has an orbital period of 8.11128 days and a nearly circular orbit. The primary has an A9 V spectral type and a v sin i value of 11 km s-1, while the unseen secondary is likely a K or M dwarf. Spectral classifications and spectrum synthesis analysis indicate that the abundances of the primary are normal. We reject the possibility that the primary of HR 1613 is seen nearly pole-on and instead argue that its rotational inclination is at least 20°, resulting in an equatorial rotational velocity of 30 km s-1 or less. Slowly rotating A stars almost always have spectrum peculiarities, being classified as either Ap or Am stars, but HR 1613, with its essentially solar abundances, appears to be an exception.