WR 16
WR 16 is a Wolf-Rayet star located in the constellation Carina. It is a massive, luminous, and evolved star in a late stage of evolution, surrounded by a complex nebula formed by its strong stellar winds and past mass ejections. WR 16 is classified as a runaway star due to its high velocity through the interstellar medium.
Physical characteristics
WR 16 is classified as a WN8h star, indicating a hydrogen-rich Wolf-Rayet star dominated by nitrogen emission lines. Its effective temperature of over is hotter than the Sun's typical value of, but cooler than many other WR stars.
WR 16 is a rotating ellipsoidal variable, meaning its brightness and shape change slightly due to rotation.
Runaway status
Motion measurements from the Gaia satellite show that WR 16 moves at about 61 km/s relative to its local interstellar medium, qualifying it as a runaway star. This rapid motion influences the shape of its surrounding nebula.
Nebular structure
WR 16 is surrounded by a bubble-like nebula formed by material ejected in previous evolutionary stages and shaped by its strong stellar winds. Observations reveal a round, bubble-shaped nebula visible in optical and infrared wavelengths. Multiple rings surround the star, likely from episodic mass ejections during its earlier Luminous Blue Variable phase. Ionized hydrogen and nitrogen-enriched gas are present, indicating processed stellar material.
Bow shock
Due to its high velocity, WR 16 creates a bow shock—a curved front where its stellar wind collides with the interstellar medium, compressing gas and dust. Radio and infrared imaging confirms the bow shock’s presence.