HD 84810
 Location of l Carinae (circled) |
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| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Carina |
| Right ascension | 09h 45m 14.81122s |
| Declination | –62° 30′ 28.4519″ |
| Apparent magnitude (V) | 3.39(3.35 - 4.06) |
| Characteristics | |
| Spectral type | F6Ib-K0Ib |
| U−B color index | +0.76 |
| B−V color index | +1.03 |
| Variable type | Classical Cepheid |
| Astrometry | |
| Radial velocity (Rv) | +3.3 km/s |
| Proper motion (μ) |
RA: –12.88 mas/yr Dec.: +8.19 mas/yr |
| Parallax (π) | 2.09 ± 0.29mas |
| Distance | 525pc |
| Absolute magnitude (MV) | –5.22 |
| Details | |
| Mass | 8.4 to 13 M☉ |
| Radius | 169±8 R☉ |
| Surface gravity (log g) | 1.5 cgs |
| Temperature | 5,091 K |
| Metallicity [Fe/H] | 0.30 dex |
| Age | 17-19 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 84810, also known as l Carinae (l Car), is a star in the southern constellation of Carina. It has a mean apparent magnitude of +3.4, making it readily visible to the naked eye and one of the brighter members of Carina. Based upon parallax measurements, it is approximately 1,600 light-years (490 parsecs) from Earth.
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 8–13 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. The radial velocity of the star likewise varies by 39 km/s during each pulsation cycle. 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.
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