HD 84810

From the characteristics of its spectrum, l Carinae has a stellar classification of G5 Iab/Ib. This indicates the star has reached a stage in its evolution where it has expanded to become a supergiant with 169 times the radius of the Sun. As this is a massive star with 8.7 times the mass of the Sun, it rapidly burns through its supply of nuclear fuel and has become a supergiant in roughly 17-19 million years, after spending 15–17 million years as a main sequence star.

l Carinae is classified as a Cepheid variable star and its brightness varies over an amplitude range of 0.725 in magnitude with a long period of 35.560 days. This unusually long period makes it essential for calibrating the period-luminosity relation for Cepheid variables; additionally, it is one of the nearest Cepheid variables, making it relatively easy to observe. The radial velocity of the star likewise varies by 39 km/s during each pulsation cycle. Its radius varies by about 40 R_☉ as it pulsates, reaching maximum size as its brightness is decreasing towards minimum.

It has a compact circumstellar envelope that can be discerned using interferometry. The envelope has been resolved at an infrared wavelength of 10μm, showing a radius of 10–100 AU at a mean temperature of 100 K. The material for this envelope was supplied by mass ejected from the central star.

The period of l Carinae is calculated to be slowly increasing and it is thought to be crossing the instability strip for the third time, cooling as it evolves towards a red supergiant after a blue loop.