(8567) 1996 HW1

was discovered on 23 April 1996 by astronomer Tom Gehrels, who was working as a part of the Spacewatch survey at Steward Observatory, Arizona, United States. The asteroid was assigned the provisional designation by the Minor Planet Center (MPC), and its discovery was published in a Minor Planet Circular on 2 May 1996. Once its orbit was sufficiently determined, it was numbered (8567) by the MPC on 11 April 1998. , it remains unnamed. == Orbit ==

orbits the Sun at an average distance—its semi-major axis—of 2.05 astronomical units (AU), with an orbital period of 2.93 years. It is classified as a near-Earth asteroid; because its orbit lies entirely outside Earth's orbit, it is also classified as an Amor asteroid. Along its orbit, its distance from the Sun varies between 1.13 AU at perihelion to 2.96 AU at aphelion due to its orbital eccentricity of 0.45. Its orbit is inclined by 8.45° with respect to the ecliptic plane. == Physical characteristics ==

is a contact binary object with dimensions of and an equivalent mean diameter of . Its two lobes have an estimated mass ratio of 2:1, and are separated by a prominent neck. Spectroscopic observations of show that it is classified as an Sq-type asteroid, with spectral properties between S-type asteroids and Q-type asteroids. It has a geometric albedo of 0.156, though its visible light albedo is higher at approximately 0.33. Its spectrum is significantly reddened, indicating that its surface has undergone appreciable space weathering. Spin and evolution has a sidereal rotation period of 8.76 hours, spinning in a retrograde direction with pole ecliptic coordinates of (281°, –31°). Its spin properties were derived from its lightcurve, or variations in its observed brightness, which was additionally supported by radar observations. Assuming a bulk density of 2.0 g/cm3, the asteroid is spinning slower than its minimum energy state of 7.4 hours, placing its neck under compressive and shear stress. A lower assumed density of 1.43 g/cm3 makes its observed rotation period its minimum energy state, but such a density requires an improbable porosity of 58%. 's spin is likely being slowed by the YORP effect, where irregularly shaped asteroids experience a torque by emitting thermal radiation. 's faster rotation period in the past suggests that its two lobes originally may have been separated as a binary system. The YORP effect slowly removes angular momentum from binary asteroids, though how quickly this leads to the two components merging depends on the mass ratio. Given the mass ratio of 's two lobes, they could have merged in a span of 1 million years (Myr), within the typical 10 Myr dynamical lifetimes of NEAs. == Notes ==