HR 3562
HR 3562 is a visual binary consisting of a bluish-white hued variable star and a Sun-like secondary star in the southern constellation of Vela. It has the variable-star designation IY Velorum. With an apparent magnitude of 6.26, the brighter primary is near the limit for naked eye visibility. The fainter companion has an apparent magnitude of 12.639 and can be observed with a telescope with an aperture of 76 mm or wider. It is located approximately distant according to Gaia EDR3 parallax measurements, and is receding away from the Solar System at a heliocentric radial velocity of 22.0 km/s.
HR 3562A
This is a hot, luminous B-type subgiant with a mass of 5.644 and a radius of 5.648. It radiates 832 times the luminosity of the Sun from its photosphere at an effective temperature of, almost three times hotter than the Sun. It is thought to be very young at around 36-38 million years old.File:IYVelLightCurve.png|thumb|left|A light curve for IY Velorum, plotted from Transiting Exoplanet [Survey Satellite|TESS] data. The mean 2.22 day period is marked in red.
In 1982, Burki et al. reported that the star showed pulsations with multiple periods, namely 1.97 days, 1.73 days, and 1.66 days, all with amplitudes of several mmag that produce a combined peak-to-peak amplitude of about 0.04 mag. As such, they categorized the star as a multiperiodic B-type star">Stellar classification">B-type star. In 1986, however, Balona & Laing were only able to confirm one major period of 2.22 days. Due to the small projected rotational velocity, they classified it as a rotating ellipsoidal variable instead, which would have been indicative of a close binary with an orbital period of 4.44 days. Further observations were conducted by Balona, who, in 1994, changed his position and concluded that the star was indeed a SPB, having discovered that the 2.22 day period he previously found was actually the mean of three distinct periods at 1.9566 days, 2.1072 days, and 2.4563 days. It shows similarities to HR 2680, another SPB.