II Lupi

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.

II Lupi
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Lupus
Right ascension 15h 23m 05.075s[1]
Declination −51° 25′ 58.73″[1]
Characteristics
Spectral type C[2]
Apparent magnitude (I) 10.18[3]
Apparent magnitude (J) 5.92[4]
Apparent magnitude (K) 1.79[4]
Variable type Mira[5]
Astrometry
Proper motion (μ) RA: −13.837[6] mas/yr
Dec.: 5.415[6] mas/yr
Parallax (π)0.5217 ± 0.2778[6] mas
Distance500[7] pc
Absolute magnitude (MV)−5.15[8]
Details
Radius547[2] R☉
Luminosity8,800[7] L☉
Temperature2,400[7] K
Other designations
II Lup, IRAS 15194-5115, 2MASS J15230507-5125587, WOS 48, Gaia DR2 5889797405925371392
Database references
SIMBAD48 data

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]

References
  1. Cutri, R. M; Skrutskie, M. F; Van Dyk, S; Beichman, C. A; Carpenter, J. M; Chester, T; Cambresy, L; Evans, T; Fowler, J; Gizis, J; Howard, E; Huchra, J; Jarrett, T; Kopan, E. L; Kirkpatrick, J. D; Light, R. M; Marsh, K. A; McCallon, H; Schneider, S; Stiening, R; Sykes, M; Weinberg, M; Wheaton, W. A; Wheelock, S; Zacarias, N (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". VizieR On-line Data Catalog. 2246. Bibcode:2003yCat.2246....0C.
  2. De Beck, E.; Decin, L.; De Koter, A.; Justtanont, K.; Verhoelst, T.; Kemper, F.; Menten, K. M. (2010). "Probing the mass-loss history of AGB and red supergiant stars from CO rotational line profiles. II. CO line survey of evolved stars: Derivation of mass-loss rate formulae". Astronomy and Astrophysics. 523: A18. arXiv:1008.1083. Bibcode:2010A&A...523A..18D. doi:10.1051/0004-6361/200913771. S2CID 16131273.
  3. DENIS Consortium (2003). "VizieR Online Data Catalog: The DENIS database (DENIS Consortium, 2003)". VizieR On-line Data Catalog. Bibcode:2003yCat....102002T.
  4. Whitelock, Patricia A; Feast, Michael W; Marang, Freddy; Groenewegen, M. A. T (2006). "Near-infrared photometry of carbon stars". Monthly Notices of the Royal Astronomical Society. 369 (2): 751–782. arXiv:astro-ph/0603504. Bibcode:2006MNRAS.369..751W. doi:10.1111/j.1365-2966.2006.10322.x. S2CID 14453496.
  5. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  6. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  7. Schöier, F. L; Ramstedt, S; Olofsson, H; Lindqvist, M; Bieging, J. H; Marvel, K. B (2013). "The abundance of HCN in circumstellar envelopes of AGB stars of different chemical type". Astronomy & Astrophysics. 550: A78. arXiv:1301.2129. Bibcode:2013A&A...550A..78S. doi:10.1051/0004-6361/201220400. S2CID 96447896.
  8. Guandalini, R; Cristallo, S (2013). "Luminosities of carbon-rich asymptotic giant branch stars in the Milky Way". Astronomy & Astrophysics. 555: A120. arXiv:1305.4203. Bibcode:2013A&A...555A.120G. doi:10.1051/0004-6361/201321225. S2CID 54918450.
  9. Meadows, P. J; Good, A. R; Wolstencroft, R. D (1987). "The identification of IRAS 15194-5115 with a bright extreme carbon star". Monthly Notices of the Royal Astronomical Society. 225: 43p–49p. Bibcode:1987MNRAS.225P..43M. doi:10.1093/mnras/225.1.43P.
  10. Westerlund, B. E; Olander, N (1978). "S stars in the southern Milky Way". Astronomy and Astrophysics Supplement Series. 32: 401. Bibcode:1978A&AS...32..401W.
  11. Le Bertre, T (1992). "Carbon-star lightcurves in the 1-20 micron range". Astronomy and Astrophysics Supplement Series. 94: 377. Bibcode:1992A&AS...94..377L.
  12. Kazarovets, E. V; Samus, N. N (1995). "The 72nd Name-List of Variable Stars". Information Bulletin on Variable Stars. 4140: 1. Bibcode:1995IBVS.4140....1K.
  13. Feast, Michael W; Whitelock, Patricia A; Marang, Freddy (2003). "The case for asymmetric dust around a C-rich asymptotic giant branch star". Monthly Notices of the Royal Astronomical Society. 346 (3): 878. arXiv:astro-ph/0308417. Bibcode:2003MNRAS.346..878F. doi:10.1111/j.1365-2966.2003.07136.x. S2CID 18362625.
  14. Smith, C. L.; Zijlstra, A. A.; Fuller, G. A. (2015), "A molecular line survey of a sample of AGB stars and planetary nebulae", Monthly Notices of the Royal Astronomical Society, 454 (1): 177–200, arXiv:1508.05014, Bibcode:2015MNRAS.454..177S, doi:10.1093/mnras/stv1934, S2CID 119294505
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