II Lupi

II Lupi

A near-infrared (J band) light curve for II Lupi, adapted from Lykou et al. (2018)[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lupus
Right ascension 15h 23m 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]
Distanceapprox. 2,100 ly
(approx. 640 pc)
Absolute magnitude (MV)−5.15[7]
Details
Mass2.2[2] M☉
Radius400 to 500[1] R☉
Luminosity9,800[1] L☉
Surface gravity (log g)0.06[2] cgs
Temperature2,570 – 2,860[1] K
Age942[2] Myr
Other designations
II Lup, IRAS 15194-5115, 2MASS J15230507-5125587, WOS 48, Gaia DR2 5889797405925371392
Database references
SIMBADdata

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.[8] 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.[9]

On the basis of infrared photometry,[10] IRAS 15194-5115 was given the variable star designation II Lupi in 1995, although the variability type was still unknown.[11] 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.[12]

II Lupi has a strong stellar wind averaging 10−5 solar masses per year.[13]

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  2. ^ a b c d e f g h Cite error: The named reference dr3 was invoked but never defined (see the help page).
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  5. ^ a b Cite error: The named reference whitelock was invoked but never defined (see the help page).
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  12. ^ Cite error: The named reference feast was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Smith2015 was invoked but never defined (see the help page).