LSS 4067

LSS 4067, also known as CD−38°11748, is an O-type blue supergiant star located in the constellation Scorpius, very close to the galactic plane. It is part of the open cluster HM 1,[8] although its distance is not well known; it may be anywhere between 9,500 and 12,700 light years (2900 to 3900 parsecs) away from the Earth. Despite being a blue supergiant, it is extremely reddened by interstellar extinction, so its apparent magnitude is brighter for longer-wavelength passbands.[2] Without the extinction, it is estimated that LS 4067 would be 5.8 magnitudes brighter, a naked eye star with an apparent magnitude of 5.3.[9]

LSS 4067
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension  17h 19m 05.548s[1]
Declination −29° 43′ 41.1989″[1]
Apparent magnitude (V) 11.44[2]
Characteristics
Spectral type O4.5Ifpe[3]
U−B color index +0.37[2]
B−V color index +1.49[2]
V−R color index +1.28[2]
Astrometry
Radial velocity (Rv)−51.0[4] km/s
Proper motion (μ) RA: −2.5[5] mas/yr
Dec.: −6.6[5] mas/yr
Distance9,500–12,700 ly
(2,900–3,900[2] pc)
Absolute magnitude (MV)−6.335[6]
Details
Mass120[7] M☉
Luminosity802,000[6] L☉
Surface gravity (log g)3.61[6] cgs
Temperature40,000[6] K
Rotational velocity (v sin i)<107[4] km/s
Age1.10[7] Myr
Other designations
LS 4067, CD−38°11748, Hen 3-1374, HM 1 VB 4, TYC 7870-896-1, 2MASS J17190554-3848496
Database references
SIMBADdata

Although the Gaia Data Release 2 parallax for LS 4067 is negative, a likely distance can be calculated from it. The star is thought to be between 8,202 and 14,084 pc away, statistically most likely at 10,170 pc.[10] It was catalogued as a member of the faint cluster Havlen-Moffat No. 1, but is no longer thought to be a member. The cluster lies about 3,300 pc.[2]

LSS 4067 has an absolute bolometric magnitude of −11.4,[7] making it one of the most luminous stars known. Indeed, many of the hottest and most luminous stars known are O-type supergiants, or Wolf-Rayet stars. LSS 4067 has an unusual spectrum, with various emission lines including N III and He II emission lines, thus the "f" in its spectral type.[4] Because of this unusual spectrum, classifying the star or deducing its properties has proved relatively difficult: for example, the effective temperature is predicted to be too cool and the surface gravity too high.[4]

References
  1. Cutri, R. M. (2003). "2MASS All-Sky Catalog of Point Sources". VizieR On-line Data Catalog. Bibcode:2003yCat.2246....0C.
  2. Vázquez, R. A.; Baume, G. (2001). "The open cluster Havlen-Moffat No. 1 revisited". Astronomy and Astrophysics. 371 (3): 908–920. Bibcode:2001A&A...371..908V. doi:10.1051/0004-6361:20010410.
  3. Sota, A.; et al. (2014). "The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars". The Astrophysical Journal Supplement. 211 (1): 10. arXiv:1312.6222. Bibcode:2014ApJS..211...10S. doi:10.1088/0067-0049/211/1/10.
  4. Williams, S. J.; et al. (2011). "Radial Velocities of Galactic O-type Stars. I. Short-term Constant Velocity Stars". The Astronomical Journal. 142 (5): 146. Bibcode:2011AJ....142..146W. doi:10.1088/0004-6256/142/5/146.
  5. Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
  6. Nebot Gómez-Morán, A.; Oskinova, L. M. (2018). "The X-ray catalog of spectroscopically identified Galactic O stars. Investigating the dependence of X-ray luminosity on stellar and wind parameters". Astronomy and Astrophysics. 620: A89. arXiv:1808.07880. Bibcode:2018A&A...620A..89N. doi:10.1051/0004-6361/201833453.
  7. Massey, P.; Degioia-Eastwood, K.; Waterhouse, E. (2001). "The Progenitor Masses of Wolf-Rayet Stars and Luminous Blue Variables Determined from Cluster Turnoffs. II. Results from 12 Galactic Clusters and OB Associations". The Astronomical Journal. 121 (2): 1050–1070. arXiv:astro-ph/0010654. Bibcode:2001AJ....121.1050M. doi:10.1086/318769.
  8. "CD-38 11748". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 19 January 2016.
  9. Maíz Apellániz, J.; Barbá, R. H. (2018). "Optical-NIR dust extinction towards Galactic O stars". Astronomy and Astrophysics. 613: A9. arXiv:1712.09228. Bibcode:2018A&A...613A...9M. doi:10.1051/0004-6361/201732050.
  10. Bailer-Jones, C. A. L.; Rybizki, J.; Fouesneau, M.; Mantelet, G.; Andrae, R. (2018). "Estimating Distance from Parallaxes. IV. Distances to 1.33 Billion Stars in Gaia Data Release 2". The Astronomical Journal. 156 (2): 58. arXiv:1804.10121. Bibcode:2018AJ....156...58B. doi:10.3847/1538-3881/aacb21.
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