R99 (star)

Last updated
R99
Observation data
Epoch J2000       Equinox J2000
Constellation Dorado
Right ascension 05h 22m 59.809s [1]
Declination −68° 01′ 46.57″ [1]
Apparent magnitude  (V)11.46 [2]
Characteristics
Spectral type LBV
U−B color index −0.92 [2]
B−V color index +0.25 [2]
Variable type LBV [3]
Astrometry
Radial velocity (Rv)293±16.2 [4]  km/s
Proper motion (μ)RA: 3.4±2.5 [1]   mas/yr
Dec.: −0.4±2.3 [1]   mas/yr
Distance 50,000  pc
Absolute magnitude  (MV)−8.48 [5]
Details
Mass 103 [5]   M☉
Radius 74.8 [5]   R☉
Luminosity 3.2×106 [5]   L☉
Temperature 28,000 [5]   K
Other designations
HD  269445, BAT99-33, AAVSO  0523-68, 2MASS  J05225978-6801466
Database references
SIMBAD data

R99 (HD 269445) is a star in the Large Magellanic Cloud in the constellation Dorado. It is classified as a possible luminous blue variable and is one of the most luminous stars known.

R99 has a peculiar spectrum that has been described as OBf:pe, [6] "unclassifiable", peculiar WN10, "similar to the unusual LBV HD 5980", [7] "unique", and Ofpe/WN9. [8] The Ofpe/WN9 type remains even though other stars of this type have been reclassified to types between WN9 and WN11. [4] R99 has significant differences from those other stars which preclude it being given a simple WN spectral type: the ultraviolet spectrum is strongly blanketed over a different range of wavelengths; highly ionised iron lines are seen in absorption instead of emission; the Hi lines are unusually narrow and have no P Cygni profile; a lack of any significant absorption features near Hδ; a number of metal lines are unusually strong or weak compared to other stars of the type; there is a small unexplained infrared excess. [9]

The wind structure of R99 may be significantly different from most WR stars and LBVs. The normal temperature-stratified WR wind is accelerated to terminal velocity, causing lines of different ionisation levels of Helium to be created at different distances from the star. This does not seem to apply to R99. [9] Significant polarisation of the spectrum continuum is also seen, suggesting an asymmetric wind. This has not been observed in other WR stars. [10]

R99 shows brightness variations of about 0.3 magnitude over a period of decades, and smaller amplitudes with the strongest periods at two and ten days. The colour also varies, with the star being bluer at minimum light. [11] It has been classified as a luminous blue variable on account of the variability and spectrum, although it has never been observed in outburst. [3] Others still list it only as a candidate. [12] [13]

See also

Related Research Articles

<span class="mw-page-title-main">Wolf–Rayet star</span> Heterogeneous class of stars with unusual spectra

Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf–Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their spectral classification.

<span class="mw-page-title-main">S Doradus</span> Star in the Large Magellanic Cloud

S Doradus is one of the brightest stars in the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way, located roughly 160,000 light-years away. The star is a luminous blue variable, and one of the most luminous stars known, having a luminosity varying widely above and below 1,000,000 times the luminosity of the Sun, although it is too far away to be seen with the naked eye.

<span class="mw-page-title-main">R136b</span> Star in the constellation Dorado

R136b is a blue supergiant star in the R136 cluster in the Large Magellanic Cloud. It is one of the most massive and most luminous stars known. It is found in the dense R136 open cluster at the centre of NGC 2070 in the Tarantula Nebula.

<span class="mw-page-title-main">Hypergiant</span> Rare star with tremendous luminosity and high rates of mass loss by stellar winds

A hypergiant (luminosity class 0 or Ia+) is a very rare type of star that has an extremely high luminosity, mass, size and mass loss because of its extreme stellar winds. The term hypergiant is defined as luminosity class 0 (zero) in the MKK system. However, this is rarely seen in literature or in published spectral classifications, except for specific well-defined groups such as the yellow hypergiants, RSG (red supergiants), or blue B(e) supergiants with emission spectra. More commonly, hypergiants are classed as Ia-0 or Ia+, but red supergiants are rarely assigned these spectral classifications. Astronomers are interested in these stars because they relate to understanding stellar evolution, especially star formation, stability, and their expected demise as supernovae. Notable examples of hypergiants include the Pistol Star, a blue hypergiant located close to the Galactic Center and one of the most luminous stars known; Rho Cassiopeiae, a yellow hypergiant that is one of the brightest to the naked eye; and Mu Cephei (Herschel's "Garnet Star"), one of the largest and brightest stars known.

Zeta<sup>1</sup> Scorpii Star in the constellation Scorpius.

Zeta1 Scorpii is a B-type hypergiant star in the constellation of Scorpius. It has an apparent visual magnitude which varies between 4.66 and 4.86. It is a member of the Scorpius OB1 association, and potentially of the open star cluster NGC 6231, also known as the "Northern jewel box" cluster. Around 36 times as massive as the Sun, it is also one of the most luminous stars known in the Galaxy, with an estimated bolometric luminosity of around 850,000 times that of the Sun and a radius 103 times that of the Sun.

<span class="mw-page-title-main">HD 5980</span> Triple star system in the constellation Tucana

HD 5980 is a multiple star system on the outskirts of NGC 346 in the Small Magellanic Cloud (SMC) and is one of the brightest stars in the SMC.

<span class="mw-page-title-main">Melnick 42</span> Massive blue supergiant star in the constellation Dorado

Melnick 42 is a massive blue supergiant star in the Tarantula Nebula in the Large Magellanic Cloud located in the constellation Dorado. Although it is only 21 times the size of the sun, its high temperature of 47,300 K makes it one of the most luminous stars of the Tarantula Nebula at 3,600,000 L☉. It is less than two parsecs from the centre of the R136 cluster, although that is well outside the central core.

HD 38282 is a massive spectroscopic binary star in the Tarantula Nebula, consisting of two hydrogen-rich Wolf-Rayet stars.

<span class="mw-page-title-main">WR 24</span> Wolf-Rayet star in the constellation Carina

WR 24 is a Wolf-Rayet star in the constellation Carina. It is one of the most luminous stars known. At the edge of naked eye visibility it is also one of the brightest Wolf Rayet stars in the sky.

<span class="mw-page-title-main">V1429 Aquilae</span> Star in the constellation Aquila

V1429 Aquilae is a candidate luminous blue variable multiple star system located in the constellation of Aquila. It is often referred to by its Mount Wilson Observatory catalog number as MWC 314. It is a hot luminous star with strong emission lines in its spectrum.

<span class="mw-page-title-main">Melnick 34</span> Binary star in the Large Magellanic cloud

Melnick 34, also called BAT99-116, is a binary Wolf–Rayet star near R136 in the 30 Doradus complex in the Large Magellanic Cloud. Both components are amongst the most massive and most luminous stars known, and the system is the most massive known binary system.

BAT99-98 is a Wolf–Rayet star located in the Large Magellanic Cloud, in NGC 2070 near the R136 cluster in the Tarantula Nebula. At 226 M☉ and 5,000,000 L☉ it is one of the most massive and luminous stars currently known.

<span class="mw-page-title-main">WR 31a</span> Wolf Rayet star in the constellation Carina

WR 31a, commonly referred to as Hen 3-519, is a Wolf–Rayet (WR) star in the southern constellation of Carina that is surrounded by an expanding Wolf–Rayet nebula. It is not a classical old stripped-envelope WR star, but a young massive star which still has some hydrogen left in its atmosphere.

<span class="mw-page-title-main">R145</span> Binary star in the constellation Dorado

R145 is a spectroscopic binary star in the Tarantula Nebula in the Large Magellanic Cloud located in the constellation Dorado. Both components are amongst the most luminous known.

<span class="mw-page-title-main">R85</span> Candidate luminous variable star in the constellation Dorado

R85 is a candidate luminous blue variable located in the LH-41 OB association in the Large Magellanic Cloud.

<span class="mw-page-title-main">R71 (star)</span> Star in the Large Magellanic Cloud

R71 is a star in the Large Magellanic Cloud (LMC) in the constellation Mensa. It is classified as a luminous blue variable and is one of the most luminous stars in the LMC. It lies three arc-minutes southwest of the naked-eye star β Mensae.

HD 37836 is a candidate luminous blue variable located in the Large Magellanic Cloud and one of the brightest stars in its galaxy.

References

  1. 1 2 3 4 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862.
  2. 1 2 3 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
  3. 1 2 Van Genderen, A. M. (2001). "S Doradus variables in the Galaxy and the Magellanic Clouds". Astronomy and Astrophysics. 366 (2): 508–531. Bibcode:2001A&A...366..508V. doi: 10.1051/0004-6361:20000022 .
  4. 1 2 Schnurr, O.; Moffat, A. F. J.; St-Louis, N.; Morrell, N. I.; Guerrero, M. A. (2008). "A spectroscopic survey of WNL stars in the Large Magellanic Cloud: General properties and binary status". Monthly Notices of the Royal Astronomical Society. 389 (2): 806–828. arXiv: 0806.2801 . Bibcode:2008MNRAS.389..806S. doi: 10.1111/j.1365-2966.2008.13584.x . S2CID   6590534.
  5. 1 2 3 4 5 Hainich, R.; Rühling, U.; Todt, H.; Oskinova, L. M.; Liermann, A.; Gräfener, G.; Foellmi, C.; Schnurr, O.; Hamann, W. -R. (2014). "The Wolf-Rayet stars in the Large Magellanic Cloud". Astronomy & Astrophysics. 565: A27. arXiv: 1401.5474 . Bibcode:2014A&A...565A..27H. doi:10.1051/0004-6361/201322696. S2CID   55123954.
  6. ↑ Walborn, N. R. (1977). "Spectral classification of O and B0 supergiants in the Magellanic Clouds". Astrophysical Journal. 215: 53. Bibcode:1977ApJ...215...53W. doi: 10.1086/155334 .
  7. ↑ Crowther, P. A.; Smith, L. J. (1997). "Fundamental parameters of Wolf-Rayet stars. VI. Large Magellanic Cloud WNL stars". Astronomy and Astrophysics. 320: 500. Bibcode:1997A&A...320..500C.
  8. ↑ Bohannan, Bruce; Walborn, Nolan R. (1989). "The Ofpe/WN9 class in the Large Magellanic Cloud" (PDF). Publications of the Astronomical Society of the Pacific. 101: 520. Bibcode:1989PASP..101..520B. doi: 10.1086/132463 .
  9. 1 2 Pasquali, Anna; Langer, Norbert; Schmutz, Werner; Leitherer, Claus; Nota, Antonella; Hubeny, Ivan; Moffat, Anthony F. J. (1997). "O Stars in Transition. II. Fundamental Properties and Evolutionary Status of Ofpe/WN9 Stars from HST Ultraviolet Observations". The Astrophysical Journal. 478 (1): 340–357. Bibcode:1997ApJ...478..340P. doi: 10.1086/303767 .
  10. ↑ Vink, Jorick S. (2007). "Constraining GRB progenitor models by probing Wolf-Rayet wind geometries in the Large Magellanic Cloud". Astronomy and Astrophysics. 469 (2): 707–711. arXiv: 0704.2690 . Bibcode:2007A&A...469..707V. doi:10.1051/0004-6361:20077302. S2CID   19013584.
  11. ↑ Van Genderen, A. M.; Sterken, C.; De Groot, M.; Reijns, R. A. (1998). "Light variations of massive stars (alpha Cyg variables). XV. The LMC supergiants R99 (LBV), R103, R123 (LBV) and R128". Astronomy and Astrophysics. 332: 857. Bibcode:1998A&A...332..857V.
  12. ↑ Smith, Nathan; Tombleson, Ryan (2015). "Luminous blue variables are antisocial: Their isolation implies that they are kicked mass gainers in binary evolution". Monthly Notices of the Royal Astronomical Society. 447 (1): 598–617. arXiv: 1406.7431 . Bibcode:2015MNRAS.447..598S. doi: 10.1093/mnras/stu2430 . S2CID   119284620.
  13. ↑ Richardson, Noel D.; Mehner, Andrea (2018). "The 2018 Census of Luminous Blue Variables in the Local Group". Research Notes of the American Astronomical Society. 2 (3): 121. arXiv: 1807.04262 . Bibcode:2018RNAAS...2..121R. doi: 10.3847/2515-5172/aad1f3 . S2CID   119509358.
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