LoTr 4 (Longmore-Tritton 4) is a planetary nebula with two separate shells. LoTr 4 was discovered with 11 other planetary nebula under the LoTr Catalog and was
| Nebula | |
|---|---|
| Planetary nebula | |
| Observation data: J2000 epoch | |
| Right ascension | 11h 52m 29.22s[1] |
| Declination | −42° 17′ 38.6″[1] |
| Distance | 19,569[2] ly |
| Apparent diameter | 30x26"[3] |
| Constellation | Centaurus |
| Designations | PN G 291.4+19.2, PK 291+19 1[1] |
LoTr 4 (Longmore-Tritton 4) is a planetary nebula with two separate shells. LoTr 4 was discovered with 11 other planetary nebula under the LoTr Catalog and was discovered in 1980 by astronomers A.J Longmore and S.B. Tritton using the UK Schmidt Telescope.[4]
LoTr 4 has a outer shell with a angular radius of 13.5" and an inner shell with a angular radius of 3", as estimated by the [O III] emission. A distance of 6 Kpc and a radius of 0.6 pc mean the inner and outer shells have linear radii of 0.22 and 0.39 pc.[2][5] The nebula has an average expansion velocity of 20 km/sec.[6] It may have a stellar mass of M = 0.65±0.11 and a stellar radius of 0.16-0.36.[7]
The star has a radius range of 7.5"-13.5".[5] It is also very hydrogen-deficient. Some studies indicate it is a "born-again post-AGB star.[8] The present position of LoTr 4 indicates a time of ~300 years since its second "born-again" departure from the AGB.[6] The central star has a effective temperature of ~120,000 K.[3]
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