LSS 4067
O-type blue supergiant star
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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]
| 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 |
| Distance | 9,500–12,700 ly (2,900–3,900[2] pc) |
| Absolute magnitude (MV) | −6.335[6] |
| Details | |
| Mass | 120[7] M☉ |
| Radius | 18.65[citation needed] R☉ |
| Luminosity | 802,000[6] L☉ |
| Surface gravity (log g) | 3.61[6] cgs |
| Temperature | 40,000[6] K |
| Rotational velocity (v sin i) | <107[4] km/s |
| Age | 1.10[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 | |
| SIMBAD | data |
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]