| |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lupus |
| Right ascension | 15h23m 05.073s[2] |
| Declination | −51° 25′ 58.76″[2] |
| Characteristics | |
| Spectral type | C[3] |
| Apparent magnitude (I) | 10.18[4] |
| Apparent magnitude (J) | 5.92[5] |
| Apparent magnitude (K) | 1.79[5] |
| Variable type | Mira[6] |
| Astrometry | |
| Proper motion (μ) | RA: −12.992[2] mas/yr Dec.: −13.119[2] mas/yr |
| Parallax (π) | 1.5633 ± 0.2138 mas[2] |
| Distance | approx. 2,100 ly (approx. 640 pc) |
| Absolute magnitude (MV) | −5.15[7] |
| Details | |
| Mass | 2.2[2] M☉ |
| Radius | 547[3] R☉ |
| Luminosity | 8,900[8] L☉ |
| Surface gravity (log g) | 0.06[2] cgs |
| Temperature | 2,800[8] K |
| Age | 942[2] Myr |
| Other designations | |
II Lup, IRAS 15194-5115, 2MASS J15230507-5125587, WOS 48, Gaia DR2 5889797405925371392 | |
| Database references | |
| SIMBAD | data |
II Lupi (IRAS 15194-5115) is a Mira variable and carbon star located in the constellation Lupus. It is the brightest carbon star in the southern hemisphere at 12 μm.
In 1987, the infrared source IRAS 15194-5115 was identified as an extreme carbon star. It was seen to be strongly variable at optical and infrared wavelengths. It is very faint visually, 15th or 16th magnitude in a red filter and below 21st magnitude in a blue filter, but at mid-infrared wavelengths (N band) it is the third-brightest carbon star in the sky.[9] A star at the location had earlier been catalogued as WOS 48, a possible S-type star, on the basis of strong LaO bands in its spectrum.[10]
On the basis of infrared photometry,[11] IRAS 15194-5115 was given the variable star designation II Lupi in 1995, although the variability type was still unknown.[12] More detailed infrared photometry confirmed that II Lupi was a Mira variable and showed regular variations with a period of 575 days over 18 years. The mean magnitude also dimmed and brightened during that time and has been characterised as a 6,900-day secondary period although less than a full cycle was observed. The secondary period could be interpreted as an isolated or irregular obscuration event in a dust shell surrounding the star.[13]
II Lupi has a strong stellar wind averaging 10−5 solar masses per year.[14]
